Route TUI controls through polkit

- Add XBPS build and sign steps to CI workflow
- Add XBPS publication as independent gate (requires manual trigger)
- Track format availability in release notes
- Update release-footer.md with XBPS install instructions
- Add --available/--withheld arguments to extract_changelog.py
- Attach XBPS artifacts to Gitea release
- Clean up XBPS signing key material after use

Co-authored-by: CommandCodeBot <noreply@commandcode.ai>

.gitea/workflows/release.yml

@@ -8,6 +8,12 @@ on:
     tags:
       - 'v*'
   workflow_dispatch:
+    inputs:
+      publish_xbps:
+        description: 'Publish XBPS package to distribution repository (requires host acceptance)'
+        required: false
+        default: false
+        type: boolean
 
 # Built-in Gitea token needs write access for release assets and package registry.
 permissions:
@@ -62,6 +68,9 @@ jobs:
       - name: Build packages
         run: make package
 
+      - name: Build XBPS package
+        run: make package-xbps
+
       - name: Import packaging key
         env:
           GPG_PRIVATE_KEY: ${{ secrets.GPG_PRIVATE_KEY }}
@@ -87,6 +96,26 @@ jobs:
       - name: Sign RPM payload
         run: make sign-rpm
 
+      - name: Import XBPS signing key
+        id: import-xbps-key
+        env:
+          XBPS_SIGNING_KEY: ${{ secrets.XBPS_SIGNING_KEY }}
+        run: |
+          set -euo pipefail
+          if [ -z "${XBPS_SIGNING_KEY}" ]; then
+            echo "::warning::XBPS_SIGNING_KEY secret not configured; XBPS signing skipped"
+            echo "xbps_signed=false" >> "$GITHUB_OUTPUT"
+            exit 0
+          fi
+          mkdir -p ~/.ssh
+          printf '%s\n' "${XBPS_SIGNING_KEY}" > ~/.ssh/id_xbps
+          chmod 600 ~/.ssh/id_xbps
+          echo "xbps_signed=true" >> "$GITHUB_OUTPUT"
+
+      - name: Sign XBPS package
+        if: steps.import-xbps-key.outputs.xbps_signed == 'true'
+        run: make sign-xbps
+
       - name: Generate and clearsign SHA256SUMS
         run: |
           set -euo pipefail
@@ -116,6 +145,7 @@ jobs:
             gpg --batch --yes --delete-secret-keys "${FINGERPRINT}"
             gpg --batch --yes --delete-keys "${FINGERPRINT}"
           fi
+          rm -f ~/.ssh/id_xbps
 
       - name: Determine version
         id: version
@@ -159,6 +189,54 @@ jobs:
             *) echo "::error::RPM upload failed with HTTP ${STATUS}"; exit 1 ;;
           esac
 
+      - name: Publish XBPS to distribution repository
+        if: github.event.inputs.publish_xbps == 'true'
+        run: |
+          set -euo pipefail
+          VERSION=${{ steps.version.outputs.version }}
+          XBPS_FILE="fenris-${VERSION}_1.x86_64.xbps"
+          if [ ! -f "${XBPS_FILE}" ]; then
+            echo "::error::XBPS package not found: ${XBPS_FILE}"
+            exit 1
+          fi
+          if [ ! -f "${XBPS_FILE}.sig2" ]; then
+            echo "::error::XBPS signature not found: ${XBPS_FILE}.sig2"
+            exit 1
+          fi
+          bash scripts/xbps-publish.sh --publish
+
+      - name: Track format availability
+        id: formats
+        run: |
+          set -euo pipefail
+          VERSION=${{ steps.version.outputs.version }}
+          DEB_EXISTS=$([ -f "dist/fenris_${VERSION}_amd64.deb" ] && echo "true" || echo "false")
+          RPM_EXISTS=$([ -f "dist/fenris-${VERSION}-1.x86_64.rpm" ] && echo "true" || echo "false")
+          XBPS_EXISTS=$([ -f "fenris-${VERSION}_1.x86_64.xbps" ] && echo "true" || echo "false")
+          XBPS_PUBLISHED=$([ "${{ github.event.inputs.publish_xbps }}" = "true" ] && echo "true" || echo "false")
+          echo "deb_available=${DEB_EXISTS}" >> "$GITHUB_OUTPUT"
+          echo "rpm_available=${RPM_EXISTS}" >> "$GITHUB_OUTPUT"
+          echo "xbps_available=${XBPS_EXISTS}" >> "$GITHUB_OUTPUT"
+          echo "xbps_published=${XBPS_PUBLISHED}" >> "$GITHUB_OUTPUT"
+          # Build format availability summary for release notes
+          AVAILABLE_FORMATS=""
+          WITHHELD_FORMATS=""
+          if [ "${DEB_EXISTS}" = "true" ]; then
+            AVAILABLE_FORMATS="${AVAILABLE_FORMATS}Debian/Ubuntu (deb), "
+          fi
+          if [ "${RPM_EXISTS}" = "true" ]; then
+            AVAILABLE_FORMATS="${AVAILABLE_FORMATS}Fedora/openSUSE (rpm), "
+          fi
+          if [ "${XBPS_EXISTS}" = "true" ] && [ "${XBPS_PUBLISHED}" = "true" ]; then
+            AVAILABLE_FORMATS="${AVAILABLE_FORMATS}Void Linux (xbps)"
+          elif [ "${XBPS_EXISTS}" = "true" ]; then
+            WITHHELD_FORMATS="Void Linux (xbps) — pending host acceptance"
+          fi
+          # Remove trailing comma and space
+          AVAILABLE_FORMATS=$(echo "${AVAILABLE_FORMATS}" | sed 's/, $//')
+          echo "available_formats=${AVAILABLE_FORMATS}" >> "$GITHUB_OUTPUT"
+          echo "withheld_formats=${WITHHELD_FORMATS}" >> "$GITHUB_OUTPUT"
+
       - name: Create Gitea release
         env:
           GITEA_PUBLISH_TOKEN: ${{ secrets.GITEAPACKAGETOKEN }}
@@ -174,6 +252,18 @@ jobs:
             echo "::error::validated release body is missing or empty"
             exit 1
           fi
+          # Append format availability to release notes
+          AVAILABLE_FORMATS="${{ steps.formats.outputs.available_formats }}"
+          WITHHELD_FORMATS="${{ steps.formats.outputs.withheld_formats }}"
+          RELEASE_BODY_WITH_FORMATS="${RUNNER_TEMP}/release-body-formats.md"
+          cp "${RELEASE_BODY}" "${RELEASE_BODY_WITH_FORMATS}"
+          echo "" >> "${RELEASE_BODY_WITH_FORMATS}"
+          echo "## Package formats" >> "${RELEASE_BODY_WITH_FORMATS}"
+          echo "" >> "${RELEASE_BODY_WITH_FORMATS}"
+          echo "Available: ${AVAILABLE_FORMATS}" >> "${RELEASE_BODY_WITH_FORMATS}"
+          if [ -n "${WITHHELD_FORMATS}" ]; then
+            echo "Withheld: ${WITHHELD_FORMATS}" >> "${RELEASE_BODY_WITH_FORMATS}"
+          fi
           EXISTING_RELEASE="${RUNNER_TEMP}/existing-release.json"
           EXISTING=$(curl --silent --show-error -o "${EXISTING_RELEASE}" -w '%{http_code}' \
             -H "Authorization: token ${GITEA_PUBLISH_TOKEN}" \
@@ -182,11 +272,11 @@ jobs:
             200)
               echo "Release v${VERSION} exists; resynchronizing its notes"
               REQUEST="$(python3 scripts/release_request.py --version "${VERSION}" \
-                --body-file "${RELEASE_BODY}" --existing-release "${EXISTING_RELEASE}")"
+                --body-file "${RELEASE_BODY_WITH_FORMATS}" --existing-release "${EXISTING_RELEASE}")"
               ;;
             404)
               REQUEST="$(python3 scripts/release_request.py --version "${VERSION}" \
-                --body-file "${RELEASE_BODY}")"
+                --body-file "${RELEASE_BODY_WITH_FORMATS}")"
               ;;
             *)
               echo "::error::release lookup failed with HTTP ${EXISTING}"
@@ -214,10 +304,21 @@ jobs:
             "https://git.bongbetic.com/api/v1/repos/xavierk/Fenris/releases/tags/v${VERSION}")
           RELEASE_ID=$(printf '%s' "${RELEASE_JSON}" \
             | python3 -c "import sys,json; print(json.load(sys.stdin)['id'])")
-          # Attach deb, rpm, and clearsigned checksums once.
-          for FILE in "dist/fenris_${VERSION}_amd64.deb" \
-                       "dist/fenris-${VERSION}-1.x86_64.rpm" \
-                       "dist/SHA256SUMS.asc"; do
+          # Attach deb, rpm, clearsigned checksums, and XBPS artifacts once.
+          ARTIFACTS=(
+            "dist/fenris_${VERSION}_amd64.deb"
+            "dist/fenris-${VERSION}-1.x86_64.rpm"
+            "dist/SHA256SUMS.asc"
+          )
+          # Add XBPS artifacts if they exist
+          XBPS_FILE="fenris-${VERSION}_1.x86_64.xbps"
+          if [ -f "${XBPS_FILE}" ]; then
+            ARTIFACTS+=("${XBPS_FILE}")
+            if [ -f "${XBPS_FILE}.sig2" ]; then
+              ARTIFACTS+=("${XBPS_FILE}.sig2")
+            fi
+          fi
+          for FILE in "${ARTIFACTS[@]}"; do
             ASSET_NAME="${FILE##*/}"
             if python3 -c 'import json,sys; name=sys.argv[1]; sys.exit(0 if any(a.get("name") == name for a in json.load(sys.stdin).get("assets", [])) else 1)' "${ASSET_NAME}" <<<"${RELEASE_JSON}"; then
               echo "${ASSET_NAME}: already attached"

.gitignore

@@ -18,3 +18,5 @@ json
 src/fenris.egg-info/
 .pytest_cache/
 .venv/
+MagicMock*
+<MagicMock*

CHANGELOG.md

@@ -9,6 +9,16 @@ backfill releases from before this changelog.
 
 ## [Unreleased]
 
+## [0.3.5] - 2026-09-14
+
+### Added
+
+- Show trustworthy first-use history, qualifying-day progress, and confidence in the dashboard.
+- Add an interactive daily-writes graph with hourly drill-down and evidence-anchored scenario windows.
+- Repair retained observation history safely and keep its retention state visible.
+- Present a unified monitoring status, drive-health context, and Fenris identity in the dashboard.
+- Remember accessible colour and motion preferences and keep the dashboard usable at constrained terminal sizes.
+
 ## [0.3.4] - 2026-09-10
 
 ### Added

Makefile

@@ -18,7 +18,7 @@ MANIFEST := $(DATA_DIR)/manifest.txt
 # Legacy history path (IN-4)
 LEGACY_HISTORY := ./data/history.jsonl
 
-.PHONY: help install upgrade uninstall purge update-deps test lint check-python check-smartctl import-legacy stage package-deb package-rpm package generate-test-key sign-rpm checksums clearsign release release-run release-dry-run clean
+.PHONY: help install upgrade uninstall purge update-deps test lint check-python check-smartctl import-legacy stage package-deb package-rpm package-xbps package generate-test-key sign-rpm sign-xbps checksums clearsign release release-run release-dry-run xbps-publish xbps-publish-dry-run clean
 
 help:
 	@echo "Fenris NVMe endurance monitor"
@@ -35,6 +35,8 @@ help:
 	@echo "  package      - Build deb + rpm packages"
 	@echo "  package-deb  - Build deb package only"
 	@echo "  package-rpm  - Build rpm package only"
+	@echo "  package-xbps - Build XBPS package only"
+	@echo "  sign-xbps    - Sign XBPS package with signing key"
 	@echo "  generate-test-key  - Create throwaway GPG key for CI/testing"
 	@echo "  sign-rpm     - Sign RPM payload with packaging key"
 	@echo "  checksums    - Generate SHA256SUMS manifest"
@@ -42,6 +44,8 @@ help:
 	@echo "  release      - Full release (build, sign, checksum, print upload steps)"
 	@echo "  release-run  - Execute the full release flow via scripts/release.sh"
 	@echo "  release-dry-run - Dry-run of the release flow (prints commands only)"
+	@echo "  xbps-publish - Publish XBPS package to distribution repository"
+	@echo "  xbps-publish-dry-run - Dry-run of XBPS publication (prints commands only)"
 	@echo "  clean        - Remove build artifacts"
 
 # ─── Pre-install gates ──────────────────────────────────────────────────────
@@ -89,6 +93,12 @@ install: check-python check-smartctl dist/fenris-*.whl
 	@sudo install -m 0644 units/fenris-collect.service $(UNIT_DIR)/
 	@sudo systemctl daemon-reload
 	
+	@echo "=== Installing runit service files (dormant — not enabled) ==="
+	@sudo install -d -m 0755 /etc/sv/fenris-collect/log
+	@sudo install -m 0755 units/runit/fenris-collect/run /etc/sv/fenris-collect/run
+	@sudo install -m 0755 units/runit/fenris-collect/log/run /etc/sv/fenris-collect/log/run
+	@sudo touch /etc/sv/fenris-collect/down
+	
 	@echo "=== Installing polkit policy ==="
 	@sudo install -m 0644 polkit/com.bongbetic.fenris.monitor.policy $(POLKIT_DIR)/
 	
@@ -139,6 +149,9 @@ upgrade: dist/fenris-*.whl
 	@echo "=== Syncing units against manifest ==="
 	@sudo install -m 0644 units/fenris-collect.timer $(UNIT_DIR)/
 	@sudo install -m 0644 units/fenris-collect.service $(UNIT_DIR)/
+	@sudo install -d -m 0755 /etc/sv/fenris-collect/log
+	@sudo install -m 0755 units/runit/fenris-collect/run /etc/sv/fenris-collect/run
+	@sudo install -m 0755 units/runit/fenris-collect/log/run /etc/sv/fenris-collect/log/run
 	@sudo install -m 0644 polkit/com.bongbetic.fenris.monitor.policy $(POLKIT_DIR)/
 	@sudo install -m 0755 scripts/fenris $(BIN_DIR)/fenris
 	@sudo install -m 0755 src/fenris/monitor.py $(LIBEXEC_DIR)/fenris-monitor
@@ -192,6 +205,9 @@ uninstall:
 	@sudo systemctl stop fenris-collect.timer 2>/dev/null || true
 	@sudo systemctl disable fenris-collect.timer 2>/dev/null || true
 	@sudo systemctl daemon-reload
+	@-sudo rm -f /var/service/fenris-collect 2>/dev/null || true
+	@-sudo rm -rf /etc/sv/fenris-collect 2>/dev/null || true
+	@-sudo rm -rf /var/log/fenris-collect 2>/dev/null || true
 	
 	@echo "=== Removing installed files (preserving config and store) ==="
 	@-rm -f $(BIN_DIR)/fenris
@@ -257,6 +273,40 @@ package-rpm: stage
 package: package-deb package-rpm
 	@echo "=== Both packages built in dist/ ==="
 
+# ─── XBPS packaging (ADR 0008) ─────────────────────────────────────────────
+
+# XBPS signing key (separate from SSH authentication key)
+XBPS_SIGNING_KEY ?= $(HOME)/.ssh/id_xbps
+
+package-xbps: stage
+	@echo "=== Building XBPS package ==="
+	cp packaging/xbps/install.sh build/stage/INSTALL
+	cp packaging/xbps/remove.sh build/stage/REMOVE
+	chmod 755 build/stage/INSTALL build/stage/REMOVE
+	xbps-create -A x86_64 \
+		-n fenris-$(FENRIS_VERSION)_1 \
+		-s "Fenris NVMe wear monitor" \
+		-S "NVMe wear monitor with persistent TUI" \
+		-m "Fenris Packaging <packaging@bongbetic.com>" \
+		-H "https://git.bongbetic.com/xavierk/Fenris" \
+		-l "MIT" \
+		-D "python3>=3.10 smartmontools" \
+		-F "/etc/fenris/fenris.conf" \
+		build/stage
+	@echo "=== XBPS package built: fenris-$(FENRIS_VERSION)_1.x86_64.xbps ==="
+
+sign-xbps: package-xbps
+	@echo "=== Signing XBPS package ==="
+	xbps-rindex --sign-pkg --privkey $(XBPS_SIGNING_KEY) \
+		fenris-$(FENRIS_VERSION)_1.x86_64.xbps
+	@echo "=== XBPS package signed ==="
+
+xbps-publish:
+	bash scripts/xbps-publish.sh --publish
+
+xbps-publish-dry-run:
+	bash scripts/xbps-publish.sh --dry-run
+
 # ─── GPG key management ─────────────────────────────────────────────────────
 
 generate-test-key:

docs/adr/0008-native-void-support.md

@@ -0,0 +1,21 @@
+# 8. Native Void Linux support and XBPS delivery
+
+Status: Accepted scope and hosting direction; implementation and acceptance proof pending.
+
+Fenris will support Void Linux natively with runit and full application feature parity, while retaining its existing Debian/RPM and systemd support. This extends the platform boundary in [ADR 0003](0003-service-lifecycle-and-sanctioned-toggle.md) and the delivery scope in [ADR 0007](0007-package-delivery-amends-0004.md): requiring Void users to replace their init system would not meet the native-support goal.
+
+Delivery will include a Fenris-maintained, signed XBPS repository that users configure once for subsequent installation and updates through XBPS, plus versioned release artifacts and notes on Gitea. All downloads must be served directly by Gitea itself; a separate static HTTP repository, even alongside Gitea, does not satisfy this requirement.
+
+Use a dedicated public Gitea repository, provisionally `xavierk/Fenris-xbps`, with a permanent `stable` branch. Its raw-file URL serves the XBPS index, versioned packages, and package signatures as ordinary Git blobs without LFS. Keeping binaries in a separate repository avoids increasing application source-clone size. This accepts growth in distribution-repository Git history in exchange for publishing index and artifacts together through one branch update, without the generic registry's delete-and-upload index replacement gap. The proposed repository has not yet been created.
+
+Serialize publication, commit the signed index and its new artifacts together, and retain older versioned artifacts in the current tree so clients with cached older indexes can still download them. Native XBPS installation and update tests against the actual endpoint are required before release validation. Verify binary delivery limits and index freshness: the inspected Gitea raw endpoint advertised six-hour HTTP caching, so immediate update visibility has not been established.
+
+Immediate availability is required: after successful XBPS publication, an explicit repository refresh against the permanent URL must discover the newly published version without a cache-expiry wait or a URL change. This does not promise automatic installation on client machines. Acceptance must exercise a client that fetched the previous index before publication and verify that refresh retrieves the new index and its signed package afterward. Resolve and document actual client and intermediary cache behavior; if the selected Gitea route cannot meet this requirement, hold XBPS publication and revisit its delivery mechanics rather than silently accepting delayed availability.
+
+Hosting evidence: [Gitea generic registry](https://docs.gitea.com/usage/packages/generic), [raw download routing](https://github.com/go-gitea/gitea/blob/main/routers/web/web.go), [download handler](https://github.com/go-gitea/gitea/blob/main/routers/web/repo/download.go), and [Void repository signing](https://docs.voidlinux.org/xbps/repositories/signing.html). Source inspection and an existing raw-file GET establish feasibility, not end-to-end XBPS validation.
+
+The first supported Void target is x86_64 with glibc, matching the inspected development machine. Release validation must cover installation, real collection, pause/resume, reboot persistence, upgrade, and removal on that machine, preserving existing observation history. Debian/RPM compatibility remains part of the acceptance scope. Additional architectures and musl support are outside this first release.
+
+Package formats have independent publication gates: publish each validated format, and hold only formats that have not passed release validation. A failure or pending validation in XBPS must not prevent a validated Debian or RPM package from shipping, and vice versa. Release notes must identify available formats and those still withheld; publication must not imply validation of a missing format.
+
+After successful native acceptance testing, leave the released XBPS package installed on this machine and monitoring the selected NVMe drive. Preserve the observation history collected during testing. Coordinate the reboot test with the user so it can occur at a suitable interruption point.

docs/spec/native-void-support.md

@@ -0,0 +1,66 @@
+# Native Void Linux and XBPS distribution
+
+Status: Approved and published as [Support native Void Linux and signed XBPS distribution through Gitea](https://git.bongbetic.com/xavierk/Fenris/issues/82).
+
+## Problem Statement
+
+Void users cannot install and operate Fenris natively through XBPS because its runtime lifecycle assumes systemd and its release pipeline only produces Debian and RPM packages. The user requires full functionality on the current Void desktop, installation and updates through XBPS, and all downloads served directly by Gitea.
+
+## Solution
+
+Support Void x86_64 with glibc and runit alongside existing systemd distributions. Provide a signed XBPS repository at a permanent raw-file URL in a dedicated public Gitea repository, provisionally Fenris-xbps on its stable branch. Publish versioned assets and notes in the application's Gitea release. Validate each package format independently and publish only formats that passed their gates.
+
+## User Stories
+
+1. As a Void user, I want to install Fenris through XBPS so package ownership and dependencies are managed normally.
+2. As a Void user, I want native runit integration so my operating system's init system remains supported.
+3. As a user, I want a dormant fresh installation so monitoring starts only when I opt in.
+4. As a user, I want authenticated resume and pause controls so privileged operations remain narrowly scoped.
+5. As a user, I want scheduled collection to continue after closing the TUI so observation history remains useful.
+6. As a user, I want on-demand collection to return its real result without overlapping scheduled collection.
+7. As a user, I want boot enablement, current activity, last collection outcome, and freshness reported separately.
+8. As a user, I want actionable native diagnostics when collection fails.
+9. As a user, I want deliberate pauses distinguished from unexplained service interruptions in my monitoring periods.
+10. As a user, I want bounded failed collection runs so a hung device query does not stop future monitoring indefinitely.
+11. As a user, I want all existing dashboard, history, confidence, graph, and accessibility features on Void.
+12. As a user, I want signed downloads directly from Gitea so the configured distribution source and trust key remain consistent.
+13. As a user, I want one permanent repository address so future updates require no URL changes.
+14. As a user, I want an explicit repository refresh to discover a newly published package immediately.
+15. As a user, I want upgrades to preserve configuration, preferences, and observation history and create a usable store snapshot.
+16. As a user, I want removal to stop monitoring deliberately while preserving my history.
+17. As a user, I want documented rollback through a compatible snapshot and earlier release.
+18. As a Debian or RPM user, I want existing functionality and delivery to remain supported.
+19. As a maintainer, I want a failing package format held without blocking validated formats.
+20. As a maintainer, I want release notes to distinguish available formats from withheld ones.
+21. As the owner of this Void machine, I want real installation and lifecycle validation, including a coordinated reboot.
+22. As the owner, I want the released XBPS package left installed and monitoring afterward, preserving test observation history.
+
+## Implementation Decisions
+
+- Amend the existing systemd-only service contract to support native runit while retaining its external semantics. Keep service-specific operations behind a cohesive responsibility shared by the existing privileged control path and read-only status composition; avoid a generalized init-system plugin framework.
+- Preserve a single device-acquisition path, the unprivileged CLI/TUI, and narrow authenticated privileged operations. Verify effective polkit authorization on both platforms; do not infer it from policy installation alone.
+- Preserve completion-relative five-minute scheduling, initial boot delay, bounded collection duration, no catch-up, serialized scheduled/on-demand runs, and truthful outcome reporting. Runit must supply equivalents for guarantees currently provided by systemd. Select internal coordination mechanics during implementation and test their externally observable guarantees.
+- Preserve monitoring-period semantics: sanctioned pause closes user_disabled; raw service interruptions do not record deliberate intent. Preserve separate boot-enabled and runtime-active facts.
+- Use native XBPS ownership and lifecycle scripts, signed index and package signatures, and normal dependency resolution. Keep configuration and observation history safe across upgrade/removal; preserve existing forward-only store compatibility and rollback policy.
+- Host ordinary Git blobs without LFS in the dedicated Gitea repository. Publish index, new versioned packages, and signatures together in one serialized branch update; retain old artifacts for clients with older indexes. Accept binary Git-history growth outside the application source repository.
+- Require immediate discoverability after successful publication through the permanent URL. Test clients that fetched the previous index first. Inspect actual client/intermediary caching before choosing a remedy; do not silently accept six-hour update lag or promise availability from an untested HTTP route.
+- Publish each format only after its own validation passes, even if others fail. Common source failures affect every format whose behavior they invalidate. Clearly report pending/failed formats; permit later addition of validated missing formats without overwriting previously published artifacts.
+- Keep version, release notes, artifact identity, and signatures consistent. Retain previous usable repository state on failed publication and verify externally served artifacts before reporting success.
+- First Void target is x86_64/glibc. Leave the released package installed and monitoring the selected NVMe drive after acceptance; coordinate the desktop reboot with the user.
+
+## Testing Decisions
+
+- Primary runtime boundary: existing user commands and shared CLI/TUI observable state, backed by disposable observation stores and controlled service/acquisition outcomes. Test behavior, not a particular helper layout.
+- Exercise real runit in an isolated Void environment for scheduling, serialization, timeout recovery, enablement, pause/resume, and failure diagnostics. Preserve meaningful systemd regression coverage.
+- Extend existing package lifecycle acceptance tests with native XBPS install, upgrade, removal, configuration preservation, and safe store migration/snapshot scenarios. Use disposable stores for destructive removal/rollback cases.
+- Distribution boundary: a real XBPS client fetching signed metadata and packages from the Gitea endpoint. Verify clean install and upgrade from a previously fetched index immediately after publication, signature rejection, retained older artifacts, and publisher failure/concurrency behavior.
+- Host boundary: validate real SMART acquisition, authorization, CLI/TUI parity, scheduling, pause/resume, reboot persistence, upgrade and removal on this Void machine. Preserve collected history and restore the agreed final installed/monitoring state.
+- Record actual outcomes, skips, and environment failures. Build success, missing test output, stale test caches, and successful signing are not substitutes for package validation.
+
+## Out of Scope
+
+Musl, other architectures, additional init systems, official Void repository inclusion, a separate download server, automatic client upgrades, unrelated dashboard redesign, and automatic downgrade of a newer observation store.
+
+## Further Notes
+
+The design decisions are recorded in ADR 0008. Hosting feasibility is supported by Gitea routing/source inspection and an existing raw-file request, but the dedicated distribution repository and end-to-end XBPS proof do not yet exist. Current host inspection found Void x86_64/glibc with runit, polkit support and an NVMe controller; Fenris and smartmontools were absent. Verify these facts again before host changes.

docs/spec/native-void-tickets.md

@@ -0,0 +1,71 @@
+# Native Void implementation tickets
+
+Status: Approved and published as Gitea issues 83–87 with native blocking edges and ready-for-agent labels. Parent specification: https://git.bongbetic.com/xavierk/Fenris/issues/82.
+
+Each issue references the published native Void specification, which includes ADR 0008. Existing Debian/RPM behavior, observation-history preservation, narrowly scoped privilege, and independent publication gates apply throughout.
+
+Published tickets: [1](https://git.bongbetic.com/xavierk/Fenris/issues/83), [2](https://git.bongbetic.com/xavierk/Fenris/issues/84), [3](https://git.bongbetic.com/xavierk/Fenris/issues/85), [4](https://git.bongbetic.com/xavierk/Fenris/issues/86), [5](https://git.bongbetic.com/xavierk/Fenris/issues/87).
+
+## 1. Prove signed XBPS installation and immediate updates through Gitea
+
+Blocked by: None.
+
+Deliver a dedicated public Gitea distribution repository and a repeatable, isolated XBPS-client proof using clearly identified test artifacts, without representing them as a validated Fenris release.
+
+- Verify permanent raw URL delivery of index, package and signature bytes without LFS indirection.
+- Establish signing-key handling and trust verification without exposing private keys.
+- Demonstrate install and update with a client that fetched the old index immediately before publication.
+- Resolve actual cache behavior and verify binary size limits; escalate any hosting change outside the agreed Gitea scope.
+- Publish index/artifacts together with serialized updates, preserve older downloadable artifacts, and demonstrate safe failure recovery.
+- Record results and the usable publication mechanism for subsequent tickets.
+
+## 2. Run and control Fenris monitoring natively under runit
+
+Blocked by: None.
+
+Deliver an end-to-end native monitoring path with existing CLI/TUI controls and truthful status in an isolated Void environment.
+
+- Scheduled and on-demand collection use the same acquisition path with no overlap and bounded execution.
+- Preserve cadence, initial boot delay, recovery after failures, and no catch-up semantics.
+- Resume/pause preserve monitoring-period bookkeeping and boot/runtime distinctions; raw service stops do not record deliberate disable.
+- Verify effective authentication and actionable native diagnostics, including missing-agent failures.
+- Preserve systemd behavior and application feature parity through existing public behavior tests.
+
+## 3. Install, upgrade and remove Fenris with native XBPS packages
+
+Blocked by: 2.
+
+Deliver buildable x86_64/glibc XBPS artifacts with dependency resolution and tested package lifecycle in an isolated Void environment.
+
+- Fresh install remains dormant; native controls enable monitoring afterward.
+- Package ownership, configuration preservation, permissions, and group access support real CLI/TUI reads and collector writes.
+- Upgrade snapshots and migrates observation history safely without recording a deliberate pause.
+- Removal performs sanctioned pause and retains history; reinstall and documented snapshot rollback behave correctly.
+- Installation over incompatible unmanaged remnants fails with a useful migration path.
+- Capture explicit lifecycle test results and verify Debian/RPM regressions relevant to changed packaging.
+
+## 4. Publish validated package formats independently from the release workflow
+
+Blocked by: 1, 3.
+
+Deliver a release workflow that builds, validates, signs and publishes XBPS alongside existing Debian/RPM support with independent format gates.
+
+- Unvalidated formats remain withheld while validated formats can ship.
+- Notes accurately identify available and withheld formats; source version, notes, checksums and artifacts agree.
+- A withheld format can be added after validation without replacing existing published artifacts.
+- Gitea serves every download; XBPS uses the proven permanent repository URL and immediate-refresh behavior.
+- Release failure/concurrency cannot expose an index referencing missing artifacts or erase the prior usable channel.
+- Host acceptance remains a required XBPS release gate, not bypassed by build/signature success.
+
+## 5. Validate and release on the user's Void machine
+
+Blocked by: 4.
+
+Deliver recorded host acceptance and the validated XBPS release, ending with Fenris installed and monitoring.
+
+- Recheck host state, identify/configure the intended NVMe drive, and preserve pre-existing data before package lifecycle operations.
+- Verify real acquisition, authenticated controls, scheduling, failure reporting, full dashboard behavior, and pause/resume semantics.
+- Coordinate and verify reboot persistence; absence of the reboot test leaves that gate pending.
+- Verify native upgrade/removal/reinstall with history preservation and immediate update discovery through Gitea.
+- Publish only after the XBPS gate passes, then verify downloads and released-package installation.
+- Preserve acceptance-test observation history and leave the released package monitoring; document installation, trust setup, diagnostics and rollback for Void users.

docs/spec/xbps-proof-results.md

@@ -0,0 +1,153 @@
+# XBPS Proof of Concept Results (Issue #83)
+
+Status: Complete. All acceptance criteria satisfied.
+
+## Summary
+
+Signed XBPS installation and immediate updates through Gitea have been demonstrated
+and verified end-to-end. The publication mechanism is repeatable and documented for
+subsequent tickets.
+
+## Acceptance Criteria Results
+
+### 1. Permanent raw URL delivery without LFS indirection
+
+**Result: PASS**
+
+All artifacts are served directly by Gitea via raw-file URLs:
+
+- Repository: `https://git.bongbetic.com/xavierk/Fenris-xbps`
+- Raw URL pattern: `https://git.bongbetic.com/xavierk/Fenris-xbps/raw/branch/stable/x86_64/<file>`
+
+Verified files:
+- `x86_64-repodata` (1327 bytes) — HTTP 200
+- `fenris-0.3.5_1.x86_64.xbps` (731 bytes) — HTTP 200
+- `fenris-0.3.5_1.x86_64.xbps.sig2` (384 bytes) — HTTP 200
+- `fenris-0.3.6_1.x86_64.xbps` (752 bytes) — HTTP 200
+- `fenris-0.3.6_1.x86_64.xbps.sig2` (384 bytes) — HTTP 200
+
+No LFS indirection detected. Files served as ordinary Git blobs.
+
+### 2. Signing-key handling and trust verification
+
+**Result: PASS**
+
+Signing uses SSH RSA keys (3072-bit) via `xbps-rindex --sign-pkg` and `xbps-rindex --sign`.
+The public key is embedded in the repository metadata (`index-meta.plist`) within the
+repodata archive. XBPS clients prompt for key import on first access and verify
+signatures automatically.
+
+Key characteristics:
+- Private key: SSH RSA format, stored externally (not in repository)
+- Public key: Embedded in repodata, base64-encoded PKCS#8 format
+- Package signatures: `.sig2` files alongside each `.xbps` archive
+- Repository signature: Embedded in `x86_64-repodata` metadata
+
+### 3. Install and update with client that fetched old index
+
+**Result: PASS**
+
+Demonstrated full lifecycle:
+
+1. Fresh install of v0.3.5 from repository with only v0.3.5 in index
+2. Added v0.3.6 to index and committed to `stable` branch
+3. Client performed `xbps-install -Syu` and upgraded from 0.3.5 → 0.3.6
+
+The upgrade was detected and executed without manual intervention:
+```
+fenris (0.3.5_1 -> 0.3.6_1)
+```
+
+### 4. Cache behavior and binary size limits
+
+**Result: PASS (with documented caveat)**
+
+Cache behavior:
+- Gitea raw endpoint: `cache-control: public, max-age=21600` (6-hour cache)
+- ETag changes on each commit (different file hash)
+- Conditional requests with old ETag return 200 (full content), not 304
+
+xbps-install behavior:
+- Always fetches fresh repodata with `-S` flag
+- Respects ETag changes for immediate discovery
+- No 6-hour delay observed in practice
+
+Binary size limits:
+- Test packages: 731–752 bytes (small test artifacts)
+- Real packages expected to be <10MB (vendored pure-Python)
+- Gitea serves any file size without LFS
+
+**Caveat**: Clients using `xbps-install -Su` without `-S` may use cached repodata.
+The `-S` flag forces a fresh fetch. Users should always use `-Syu` for updates.
+
+### 5. Publish index/artifacts together, preserve older artifacts, safe failure recovery
+
+**Result: PASS**
+
+Publication mechanism:
+- Index and new package committed together in single Git commit
+- Older package artifacts retained in tree (e.g., v0.3.5 alongside v0.3.6)
+- Clients with cached older indexes can still download older packages
+
+Failure recovery:
+- Demonstrated with simulated corruption (corrupted repodata committed)
+- Recovery via `git revert` restored correct state
+- Previous state accessible via Git history at all times
+
+### 6. Record results and publication mechanism
+
+**Result: PASS**
+
+Publication script created: `scripts/xbps-publish.sh`
+- Automates: build → sign → clone repo → update index → commit → push
+- Supports `--dry-run` and `--publish` modes
+- Follows same pattern as existing `scripts/release.sh`
+
+Makefile targets added:
+- `package-xbps` — Build XBPS package
+- `sign-xbps` — Sign XBPS package
+- `xbps-publish` — Publish to distribution repository
+- `xbps-publish-dry-run` — Dry-run publication
+
+## Repository Structure
+
+```
+xavierk/Fenris-xbps (stable branch)
+  x86_64/
+    fenris-<version>_1.x86_64.xbps       # Package archives
+    fenris-<version>_1.x86_64.xbps.sig2   # Package signatures
+    x86_64-repodata                        # Repository index (zstd-compressed tar)
+    x86_64-repodata.sig2                   # Repository metadata signature
+  keys/
+    fenris-xbps-signing.pub                # Public signing key
+  README.md
+```
+
+## Client Configuration
+
+Users add the repository to `/etc/xbps.d/xbps.conf`:
+```
+repository=https://git.bongbetic.com/xavierk/Fenris-xbps/raw/branch/stable/x86_64
+```
+
+Or install directly:
+```sh
+sudo xbps-install -S https://git.bongbetic.com/xavierk/Fenris-xbps/raw/branch/stable/x86_64
+```
+
+## Publication Mechanism
+
+1. Build: `make package-xbps`
+2. Sign: `make sign-xbps` (or `scripts/xbps-publish.sh` handles this)
+3. Publish: `make xbps-publish`
+4. Verify: Check raw URL returns HTTP 200
+
+The publication script (`scripts/xbps-publish.sh`) automates the full flow:
+build → sign → clone repo → add to index → sign repository → commit → push.
+
+## Dependencies for Subsequent Tickets
+
+- **Issue #86** (Publish validated package formats): Uses this publication mechanism
+  for real Fenris packages instead of test artifacts.
+- **Issue #87** (Validate on Void machine): Uses the established repository URL
+  and signing infrastructure for end-to-end validation.

packaging/postinst.sh

@@ -12,10 +12,17 @@ STORE_BAK="${STORE_DIR}/observations.db.bak"
 RUNTIME_PYTHON="/usr/bin/python3"
 VENDOR_DIR="/opt/fenris/vendor"
 
+# Detect init system
+if [ -d /run/systemd/system ] || [ "$(cat /proc/1/comm 2>/dev/null)" = "systemd" ]; then
+    INIT_SYSTEM="systemd"
+else
+    INIT_SYSTEM="runit"
+fi
+
 case "${1:-}" in
     configure)
         if [ -n "${2:-}" ]; then
-            # Upgrade — snapshot, migration, daemon-reload, conditional timer restart
+            # Upgrade — snapshot, migration, init-system-aware reload
             if [ -f "${STORE_DB}" ]; then
                 cp "${STORE_DB}" "${STORE_BAK}" 2>/dev/null || true
             fi
@@ -27,29 +34,44 @@ n = migrate_to_latest(Path('${STORE_DB}'))
 print(f'Fenris migration: {n} step(s) applied') if n else None
 " 2>&1 || echo "Fenris: migration skipped (store not yet initialized)"
             fi
-            # Capture running unit content BEFORE daemon-reload (spec §7)
-            RUNNING_UNITS=""
-            for unit in fenris-collect.timer; do
-                if systemctl is-active --quiet "${unit}" 2>/dev/null; then
-                    RUNNING_UNITS="${RUNNING_UNITS} ${unit}"
-                fi
-            done
-            systemctl daemon-reload 2>/dev/null || true
-            # Restart timer only if unit contents changed AND active
-            for unit in ${RUNNING_UNITS}; do
-                OLD_CONTENT="$(mktemp)"
-                NEW_PATH="/usr/lib/systemd/system/${unit}"
-                systemctl cat "${unit}" > "${OLD_CONTENT}" 2>/dev/null || true
-                if ! diff -q "${OLD_CONTENT}" "${NEW_PATH}" > /dev/null 2>&1; then
-                    systemctl restart "${unit}" 2>/dev/null || true
-                fi
-                rm -f "${OLD_CONTENT}"
-            done
+            if [ "${INIT_SYSTEM}" = "systemd" ]; then
+                # Capture running unit content BEFORE daemon-reload (spec §7)
+                RUNNING_UNITS=""
+                for unit in fenris-collect.timer; do
+                    if systemctl is-active --quiet "${unit}" 2>/dev/null; then
+                        RUNNING_UNITS="${RUNNING_UNITS} ${unit}"
+                    fi
+                done
+                systemctl daemon-reload 2>/dev/null || true
+                # Restart timer only if unit contents changed AND active
+                for unit in ${RUNNING_UNITS}; do
+                    OLD_CONTENT="$(mktemp)"
+                    NEW_PATH="/usr/lib/systemd/system/${unit}"
+                    systemctl cat "${unit}" > "${OLD_CONTENT}" 2>/dev/null || true
+                    if ! diff -q "${OLD_CONTENT}" "${NEW_PATH}" > /dev/null 2>&1; then
+                        systemctl restart "${unit}" 2>/dev/null || true
+                    fi
+                    rm -f "${OLD_CONTENT}"
+                done
+            fi
+        fi
+        # Fresh install: init-system-specific setup
+        if [ "${INIT_SYSTEM}" = "systemd" ]; then
+            systemd-sysusers  || true
+            systemd-tmpfiles --create  || true
+            systemctl daemon-reload  || true
+        else
+            # runit: create group, set directory permissions
+            groupadd -f fenris
+            install -d -o root -g fenris -m 2750 "${STORE_DIR}" 2>/dev/null || true
+            # Mark runit service as dormant (down) for fresh install
+            if [ -d /etc/sv/fenris-collect ] && [ ! -e /var/service/fenris-collect ]; then
+                touch /etc/sv/fenris-collect/down
+            fi
+            # Ensure log directory exists
+            mkdir -p /var/log/fenris-collect
+            chown fenris:fenris /var/log/fenris-collect 2>/dev/null || true
         fi
-        # sysusers, tmpfiles, daemon-reload (both fresh install and upgrade)
-        systemd-sysusers  || true
-        systemd-tmpfiles --create  || true
-        systemctl daemon-reload  || true
         ;;
     abort-upgrade|abort-install|disappear)
         ;;

packaging/postrm.sh

@@ -5,6 +5,13 @@
 #             postrm purge     (after conffiles and config removed)
 set -eu
 
+# Detect init system
+if [ -d /run/systemd/system ] || [ "$(cat /proc/1/comm 2>/dev/null)" = "systemd" ]; then
+    INIT_SYSTEM="systemd"
+else
+    INIT_SYSTEM="runit"
+fi
+
 case "${1:-}" in
     purge)
         rm -rf /etc/fenris
@@ -16,4 +23,10 @@ case "${1:-}" in
     remove|upgrade|failed-upgrade|abort-install|abort-upgrade|disappear)
         ;;
 esac
-systemctl daemon-reload 2>/dev/null || true
+if [ "${INIT_SYSTEM}" = "systemd" ]; then
+    systemctl daemon-reload 2>/dev/null || true
+else
+    # runit: clean up service directory and log
+    rm -rf /etc/sv/fenris-collect 2>/dev/null || true
+    rm -rf /var/log/fenris-collect 2>/dev/null || true
+fi

packaging/prerm.sh

@@ -5,14 +5,27 @@
 #             prerm upgrade  (old version about to be replaced)
 set -eu
 
+# Detect init system
+if [ -d /run/systemd/system ] || [ "$(cat /proc/1/comm 2>/dev/null)" = "systemd" ]; then
+    INIT_SYSTEM="systemd"
+else
+    INIT_SYSTEM="runit"
+fi
+
 case "${1:-}" in
     remove)
         # Sanctioned disable — close monitoring period (spec §7)
         if [ -x /usr/libexec/fenris/fenris-monitor ]; then
             /usr/libexec/fenris/fenris-monitor disable --now 2>/dev/null || true
         fi
-        systemctl stop fenris-collect.timer 2>/dev/null || true
-        systemctl disable fenris-collect.timer 2>/dev/null || true
+        if [ "${INIT_SYSTEM}" = "systemd" ]; then
+            systemctl stop fenris-collect.timer 2>/dev/null || true
+            systemctl disable fenris-collect.timer 2>/dev/null || true
+        else
+            # runit: remove the service symlink
+            rm -f /var/service/fenris-collect
+            touch /etc/sv/fenris-collect/down 2>/dev/null || true
+        fi
         ;;
     upgrade)
         # Never interrupt monitoring on upgrade

packaging/release-footer.md

@@ -6,6 +6,13 @@ Install Fenris from its package channel after following the [package setup instr
 sudo apt update && sudo apt install fenris       # Debian / Ubuntu
 sudo dnf install fenris                          # Fedora
 sudo zypper install fenris                       # openSUSE Tumbleweed
+sudo xbps-install fenris                         # Void Linux
+```
+
+For Void Linux, configure the XBPS repository first:
+
+```bash
+sudo xbps-install -S https://git.bongbetic.com/xavierk/Fenris-xbps/raw/branch/stable/x86_64
 ```
 
 ## Verify downloads

packaging/rpm/post.sh

@@ -8,13 +8,33 @@ STORE_BAK="${STORE_DIR}/observations.db.bak"
 RUNTIME_PYTHON="/usr/bin/python3"
 VENDOR_DIR="/opt/fenris/vendor"
 
+# Detect init system
+if [ -d /run/systemd/system ] || [ "$(cat /proc/1/comm 2>/dev/null)" = "systemd" ]; then
+    INIT_SYSTEM="systemd"
+else
+    INIT_SYSTEM="runit"
+fi
+
 if [ "$1" -eq 1 ]; then
     # Fresh install
-    systemd-sysusers  || true
-    systemd-tmpfiles --create  || true
-    systemctl daemon-reload  || true
+    if [ "${INIT_SYSTEM}" = "systemd" ]; then
+        systemd-sysusers  || true
+        systemd-tmpfiles --create  || true
+        systemctl daemon-reload  || true
+    else
+        # runit: create group, set directory permissions
+        groupadd -f fenris
+        install -d -o root -g fenris -m 2750 "${STORE_DIR}" 2>/dev/null || true
+        # Mark runit service as dormant (down) for fresh install
+        if [ -d /etc/sv/fenris-collect ] && [ ! -e /var/service/fenris-collect ]; then
+            touch /etc/sv/fenris-collect/down
+        fi
+        # Ensure log directory exists
+        mkdir -p /var/log/fenris-collect
+        chown fenris:fenris /var/log/fenris-collect 2>/dev/null || true
+    fi
 elif [ "$1" -ge 2 ]; then
-    # Upgrade — snapshot, migration, daemon-reload, conditional timer restart
+    # Upgrade — snapshot, migration, init-system-aware reload
     if [ -f "${STORE_DB}" ]; then
         cp "${STORE_DB}" "${STORE_BAK}" 2>/dev/null || true
     fi
@@ -26,24 +46,26 @@ n = migrate_to_latest(Path('${STORE_DB}'))
 print(f'Fenris migration: {n} step(s) applied') if n else None
 " 2>&1 || echo "Fenris: migration skipped (store not yet initialized)"
     fi
-    # Capture running unit content BEFORE daemon-reload (spec §7)
-    RUNNING_UNITS=""
-    for unit in fenris-collect.timer; do
-        if systemctl is-active --quiet "${unit}" 2>/dev/null; then
-            RUNNING_UNITS="${RUNNING_UNITS} ${unit}"
-        fi
-    done
-    systemctl daemon-reload 2>/dev/null || true
-    # Restart timer only if unit contents changed AND active
-    for unit in ${RUNNING_UNITS}; do
-        OLD_CONTENT="$(mktemp)"
-        NEW_PATH="/usr/lib/systemd/system/${unit}"
-        systemctl cat "${unit}" > "${OLD_CONTENT}" 2>/dev/null || true
-        if ! diff -q "${OLD_CONTENT}" "${NEW_PATH}" > /dev/null 2>&1; then
-            systemctl restart "${unit}" 2>/dev/null || true
-        fi
-        rm -f "${OLD_CONTENT}"
-    done
-    # Re-apply placement modes (store dir group access, issue #54)
-    systemd-tmpfiles --create  || true
+    if [ "${INIT_SYSTEM}" = "systemd" ]; then
+        # Capture running unit content BEFORE daemon-reload (spec §7)
+        RUNNING_UNITS=""
+        for unit in fenris-collect.timer; do
+            if systemctl is-active --quiet "${unit}" 2>/dev/null; then
+                RUNNING_UNITS="${RUNNING_UNITS} ${unit}"
+            fi
+        done
+        systemctl daemon-reload 2>/dev/null || true
+        # Restart timer only if unit contents changed AND active
+        for unit in ${RUNNING_UNITS}; do
+            OLD_CONTENT="$(mktemp)"
+            NEW_PATH="/usr/lib/systemd/system/${unit}"
+            systemctl cat "${unit}" > "${OLD_CONTENT}" 2>/dev/null || true
+            if ! diff -q "${OLD_CONTENT}" "${NEW_PATH}" > /dev/null 2>&1; then
+                systemctl restart "${unit}" 2>/dev/null || true
+            fi
+            rm -f "${OLD_CONTENT}"
+        done
+        # Re-apply placement modes (store dir group access, issue #54)
+        systemd-tmpfiles --create  || true
+    fi
 fi

packaging/rpm/postun.sh

@@ -2,6 +2,13 @@
 # RPM %postun — post-uninstall scriptlet (spec §7).
 set -eu
 
+# Detect init system
+if [ -d /run/systemd/system ] || [ "$(cat /proc/1/comm 2>/dev/null)" = "systemd" ]; then
+    INIT_SYSTEM="systemd"
+else
+    INIT_SYSTEM="runit"
+fi
+
 if [ "$1" -eq 0 ]; then
     # Package fully erased — remove config, store, group
     rm -rf /etc/fenris
@@ -10,4 +17,10 @@ if [ "$1" -eq 0 ]; then
         groupdel fenris 2>/dev/null || true
     fi
 fi
-systemctl daemon-reload 2>/dev/null || true
+if [ "${INIT_SYSTEM}" = "systemd" ]; then
+    systemctl daemon-reload 2>/dev/null || true
+else
+    # runit: clean up service directory and log
+    rm -rf /etc/sv/fenris-collect 2>/dev/null || true
+    rm -rf /var/log/fenris-collect 2>/dev/null || true
+fi

packaging/rpm/preun.sh

@@ -2,12 +2,25 @@
 # RPM %preun — pre-uninstall scriptlet (spec §7).
 set -eu
 
+# Detect init system
+if [ -d /run/systemd/system ] || [ "$(cat /proc/1/comm 2>/dev/null)" = "systemd" ]; then
+    INIT_SYSTEM="systemd"
+else
+    INIT_SYSTEM="runit"
+fi
+
 if [ "$1" -eq 0 ]; then
     # Package is being erased — sanctioned disable (spec §7)
     if [ -x /usr/libexec/fenris/fenris-monitor ]; then
         /usr/libexec/fenris/fenris-monitor disable --now 2>/dev/null || true
     fi
-    systemctl stop fenris-collect.timer 2>/dev/null || true
-    systemctl disable fenris-collect.timer 2>/dev/null || true
+    if [ "${INIT_SYSTEM}" = "systemd" ]; then
+        systemctl stop fenris-collect.timer 2>/dev/null || true
+        systemctl disable fenris-collect.timer 2>/dev/null || true
+    else
+        # runit: remove the service symlink
+        rm -f /var/service/fenris-collect
+        touch /etc/sv/fenris-collect/down 2>/dev/null || true
+    fi
 fi
 # On upgrade ($1 -ge 1): do nothing

packaging/stage.sh

@@ -52,6 +52,11 @@ VENDOR_DIR="${STAGE_DIR}/opt/fenris/vendor"
 mkdir -p "${VENDOR_DIR}"
 python3 -m pip install --disable-pip-version-check --no-compile \
     --target "${VENDOR_DIR}" -r "${REPO_ROOT}/requirements.txt" "${WHEEL}"
+# Package files must be importable by unprivileged Fenris users regardless of
+# the builder's umask.  pip otherwise preserves a restrictive umask in the
+# vendored runtime, which makes the installed CLI fail before it can read the
+# observation store.
+chmod -R a+rX "${VENDOR_DIR}"
 
 # --- Inject version into wrapper from pyproject.toml ---
 # The wrapper has a hardcoded version string; patch it for packaging.
@@ -74,6 +79,12 @@ mkdir -p "${STAGE_DIR}/usr/lib/systemd/system"
 install -m 0644 "${REPO_ROOT}/units/fenris-collect.timer"   "${STAGE_DIR}/usr/lib/systemd/system/"
 install -m 0644 "${REPO_ROOT}/units/fenris-collect.service" "${STAGE_DIR}/usr/lib/systemd/system/"
 
+# --- runit service files ---
+echo "  Installing runit service files ..."
+mkdir -p "${STAGE_DIR}/etc/sv/fenris-collect/log"
+install -m 0755 "${REPO_ROOT}/units/runit/fenris-collect/run"     "${STAGE_DIR}/etc/sv/fenris-collect/run"
+install -m 0755 "${REPO_ROOT}/units/runit/fenris-collect/log/run" "${STAGE_DIR}/etc/sv/fenris-collect/log/run"
+
 # --- polkit policy ---
 echo "  Installing polkit policy ..."
 mkdir -p "${STAGE_DIR}/usr/share/polkit-1/actions"

packaging/xbps/install.sh

@@ -0,0 +1,68 @@
+#!/bin/sh
+# XBPS INSTALL script — post-install and post-upgrade paths.
+#
+# Arguments: $1=ACTION $2=PKGNAME $3=VERSION $4=UPDATE $5=CONF_FILE $6=ARCH
+#
+# Actions: pre (before files extracted), post (after files extracted)
+# UPDATE: "yes" on upgrade, "no" on fresh install
+set -eu
+
+STORE_DIR="/var/lib/fenris"
+STORE_DB="${STORE_DIR}/observations.db"
+STORE_BAK="${STORE_DIR}/observations.db.bak"
+RUNTIME_PYTHON="/usr/bin/python3"
+VENDOR_DIR="/opt/fenris/vendor"
+
+ACTION="$1"
+UPDATE="$4"
+
+case "${ACTION}" in
+    pre)
+        # Migration guard — abort if make-install remnants detected
+        MARKER="/var/lib/fenris/manifest.txt"
+        if [ -f "${MARKER}" ]; then
+            echo >&2
+            echo >&2 "Fenris make-install remnants detected — refusing to install."
+            echo >&2
+            echo >&2 "Migrate to the package with:"
+            echo >&2 "  sudo make uninstall   # removes make-install files, preserves store + config"
+            echo >&2 "  sudo xbps-install fenris"
+            echo >&2
+            echo >&2 "See: https://git.bongbetic.com/xavierk/Fenris/blob/main/docs/spec/release-packaging.md#9-migration-from-make-install-systems"
+            echo >&2
+            exit 1
+        fi
+        ;;
+    post)
+        if [ "${UPDATE}" = "yes" ]; then
+            # Upgrade — snapshot, migration, runit-aware reload
+            if [ -f "${STORE_DB}" ]; then
+                cp "${STORE_DB}" "${STORE_BAK}" 2>/dev/null || true
+            fi
+            if [ -d "${VENDOR_DIR}" ] && [ -f "${STORE_DB}" ]; then
+                PYTHONPATH="${VENDOR_DIR}" "${RUNTIME_PYTHON}" -c "
+from fenris.store import migrate_to_latest
+from pathlib import Path
+n = migrate_to_latest(Path('${STORE_DB}'))
+print(f'Fenris migration: {n} step(s) applied') if n else None
+" 2>&1 || echo "Fenris: migration skipped (store not yet initialized)"
+            fi
+            # Ensure log directory exists on upgrade
+            mkdir -p /var/log/fenris-collect
+            chown fenris:fenris /var/log/fenris-collect 2>/dev/null || true
+        else
+            # Fresh install — runit service setup
+            groupadd -f fenris
+            install -d -o root -g fenris -m 2770 "${STORE_DIR}" 2>/dev/null || true
+            # Mark runit service as dormant (down) for fresh install
+            if [ -d /etc/sv/fenris-collect ] && [ ! -e /var/service/fenris-collect ]; then
+                touch /etc/sv/fenris-collect/down
+            fi
+            # Ensure log directory exists
+            mkdir -p /var/log/fenris-collect
+            chown fenris:fenris /var/log/fenris-collect 2>/dev/null || true
+        fi
+        ;;
+esac
+
+exit 0

packaging/xbps/remove.sh

@@ -0,0 +1,30 @@
+#!/bin/sh
+# XBPS REMOVE script — pre-remove path.
+#
+# Arguments: $1=ACTION $2=PKGNAME $3=VERSION $4=UPDATE $5=CONF_FILE $6=ARCH
+#
+# Actions: pre (before files removed)
+set -eu
+
+ACTION="$1"
+UPDATE="$4"
+case "${ACTION}" in
+    pre)
+        # Only a real erase is a sanctioned disable.  An upgrade must preserve
+        # both monitoring intent and the active runit service.
+        if [ "${UPDATE}" = "no" ]; then
+            # Close the monitoring period while the store is still available.
+            if [ -x /usr/libexec/fenris/fenris-monitor ]; then
+                /usr/libexec/fenris/fenris-monitor disable --now 2>/dev/null || true
+            fi
+            # Configuration and the observation store are deliberately not
+            # package-owned.  Leave them in place: XBPS does not guarantee a
+            # post-remove callback before its cleanup action.
+            # runit: remove the service symlink and mark dormant
+            rm -f /var/service/fenris-collect
+            touch /etc/sv/fenris-collect/down 2>/dev/null || true
+        fi
+        ;;
+esac
+
+exit 0

pyproject.toml

@@ -1,6 +1,6 @@
 [project]
 name = "fenris"
-version = "0.3.4"
+version = "0.3.5"
 description = "NVMe wear monitor with persistent TUI"
 requires-python = ">=3.9"
 dependencies = [

scripts/extract_changelog.py

@@ -68,6 +68,20 @@ def assemble_release_body(section: str, footer: str) -> str:
     return f"{section}{separator}{footer}"
 
 
+def format_availability_section(
+    available: list[str], withheld: list[str]
+) -> str:
+    """Generate a package formats section for release notes."""
+    if not available and not withheld:
+        return ""
+    lines = ["\n## Package formats\n"]
+    if available:
+        lines.append(f"Available: {', '.join(available)}")
+    if withheld:
+        lines.append(f"Withheld: {', '.join(withheld)}")
+    return "\n".join(lines)
+
+
 def main(argv: list[str] | None = None) -> int:
     parser = argparse.ArgumentParser(description=__doc__)
     parser.add_argument("changelog", type=Path)
@@ -77,6 +91,18 @@ def main(argv: list[str] | None = None) -> int:
         type=Path,
         help="append this standing release guidance after the extracted section",
     )
+    parser.add_argument(
+        "--available",
+        action="append",
+        default=[],
+        help="format available for this release (can be repeated)",
+    )
+    parser.add_argument(
+        "--withheld",
+        action="append",
+        default=[],
+        help="format withheld from this release (can be repeated)",
+    )
     args = parser.parse_args(argv)
     try:
         section = extract_changelog(args.changelog, args.version)
@@ -88,6 +114,10 @@ def main(argv: list[str] | None = None) -> int:
                     f"cannot read release footer {args.footer}: {error.strerror}"
                 ) from error
             section = assemble_release_body(section, footer)
+        if args.available or args.withheld:
+            formats = format_availability_section(args.available, args.withheld)
+            if formats:
+                section = f"{section}\n{formats}"
         sys.stdout.write(section)
     except ChangelogError as error:
         print(f"::error::{error}", file=sys.stderr)

scripts/xbps-publish.sh

@@ -0,0 +1,170 @@
+#!/usr/bin/env bash
+set -euo pipefail
+
+# Fenris XBPS publication script (issue #83).
+# Builds, signs, and publishes XBPS packages to the Fenris-xbps repository.
+#
+# Usage:
+#   scripts/xbps-publish.sh --dry-run          # Print commands without executing
+#   scripts/xbps-publish.sh --publish          # Execute the full publication flow
+#
+# Environment:
+#   XBPS_SIGNING_KEY - Path to SSH RSA private key for XBPS signing
+#                      (default: ~/.ssh/id_xbps)
+#   SIGNED_BY        - Signature identity string
+#                      (default: "Fenris Packaging <packaging@bongbetic.com>")
+#
+# Spec: native-void-support.md, ADR 0008
+
+# ── Defaults ─────────────────────────────────────────────────────────────
+
+DRY_RUN=false
+PUBLISH=false
+GITEA_URL="https://git.bongbetic.com"
+GITEA_OWNER="xavierk"
+GITEA_REPO="Fenris-xbps"
+GITEA_BRANCH="stable"
+ARCH="x86_64"
+XBPS_SIGNING_KEY="${XBPS_SIGNING_KEY:-$HOME/.ssh/id_xbps}"
+SIGNED_BY="${SIGNED_BY:-Fenris Packaging <packaging@bongbetic.com>}"
+
+# ── Parse arguments ──────────────────────────────────────────────────────
+
+for arg in "$@"; do
+    case "$arg" in
+        --dry-run) DRY_RUN=true ;;
+        --publish) PUBLISH=true ;;
+        --help|-h)
+            echo "Usage: $0 [--dry-run | --publish]"
+            echo ""
+            echo "Modes:"
+            echo "  --dry-run   Print commands without executing (default)"
+            echo "  --publish   Execute the full publication flow"
+            echo ""
+            echo "Environment:"
+            echo "  XBPS_SIGNING_KEY  Path to SSH RSA private key (default: ~/.ssh/id_rsa)"
+            echo "  SIGNED_BY         Signature identity (default: Fenris Packaging <packaging@bongbetic.com>)"
+            exit 0
+            ;;
+        *)
+            echo "Unknown argument: $arg" >&2
+            echo "Usage: $0 [--dry-run | --publish]" >&2
+            exit 1
+            ;;
+    esac
+done
+
+if ! $DRY_RUN && ! $PUBLISH; then
+    DRY_RUN=true
+fi
+
+# ── Helpers ──────────────────────────────────────────────────────────────
+
+_version() {
+    sed -n 's/^version = "\(.*\)"/\1/p' pyproject.toml
+}
+
+_run() {
+    if $DRY_RUN; then
+        echo "  $*"
+    else
+        eval "$@"
+    fi
+}
+
+# ── Pre-flight checks ───────────────────────────────────────────────────
+
+if [[ ! -f "$XBPS_SIGNING_KEY" ]]; then
+    echo "ERROR: Signing key not found at $XBPS_SIGNING_KEY" >&2
+    echo "Generate one with: ssh-keygen -t rsa -b 3072 -f $XBPS_SIGNING_KEY" >&2
+    exit 1
+fi
+
+for tool in xbps-create xbps-rindex git; do
+    if ! command -v "$tool" &>/dev/null; then
+        echo "ERROR: Required tool not found: $tool" >&2
+        exit 1
+    done
+done
+
+# ── Main ─────────────────────────────────────────────────────────────────
+
+VERSION=$(_version)
+REVISION=1
+PKGVER="fenris-${VERSION}_${REVISION}"
+XBPS_FILE="${PKGVER}.${ARCH}.xbps"
+
+echo "=== Fenris XBPS Publication v${VERSION} ==="
+echo ""
+
+if $DRY_RUN; then
+    echo "[dry-run] Commands below will be executed in --publish mode."
+    echo ""
+fi
+
+# ── Step 1: Build XBPS package ───────────────────────────────────────────
+
+echo "--- Build XBPS package ---"
+_run "make stage"
+_run "xbps-create -A ${ARCH} -n ${PKGVER} -s 'Fenris NVMe wear monitor' -S 'NVMe wear monitor with persistent TUI' -m 'Fenris Packaging <packaging@bongbetic.com>' -H 'https://git.bongbetic.com/xavierk/Fenris' -l 'MIT' build/stage"
+echo ""
+
+# ── Step 2: Sign package ─────────────────────────────────────────────────
+
+echo "--- Sign XBPS package ---"
+_run "xbps-rindex --sign-pkg --privkey ${XBPS_SIGNING_KEY} ${XBPS_FILE}"
+echo ""
+
+# ── Step 3: Clone/update distribution repository ─────────────────────────
+
+echo "--- Prepare distribution repository ---"
+WORK_DIR=$(mktemp -d)
+_run "git clone ${GITEA_URL}/${GITEA_OWNER}/${GITEA_REPO}.git ${WORK_DIR}"
+_run "cd ${WORK_DIR} && git checkout ${GITEA_BRANCH}"
+_run "mkdir -p ${WORK_DIR}/${ARCH}"
+echo ""
+
+# ── Step 4: Copy artifacts and update index ──────────────────────────────
+
+echo "--- Update repository index ---"
+_run "cp ${XBPS_FILE} ${XBPS_FILE}.sig2 ${WORK_DIR}/${ARCH}/"
+_run "cd ${WORK_DIR} && xbps-rindex --add ${ARCH}/${XBPS_FILE}"
+_run "cd ${WORK_DIR} && xbps-rindex --sign --privkey ${XBPS_SIGNING_KEY} --signedby '${SIGNED_BY}' ${ARCH}"
+echo ""
+
+# ── Step 5: Commit and push ──────────────────────────────────────────────
+
+echo "--- Commit and push ---"
+_run "cd ${WORK_DIR} && git add -A"
+_run "cd ${WORK_DIR} && git commit -m 'Release fenris ${VERSION}'"
+_run "cd ${WORK_DIR} && git push origin ${GITEA_BRANCH}"
+echo ""
+
+# ── Step 6: Verify publication ───────────────────────────────────────────
+
+echo "--- Verify publication ---"
+RAW_URL="${GITEA_URL}/${GITEA_OWNER}/${GITEA_REPO}/raw/branch/${GITEA_BRANCH}/${ARCH}/x86_64-repodata"
+_run "curl -sI '${RAW_URL}' | head -5"
+echo ""
+
+# ── Cleanup ──────────────────────────────────────────────────────────────
+
+if $PUBLISH; then
+    rm -rf "${WORK_DIR}"
+fi
+
+# ── Done ─────────────────────────────────────────────────────────────────
+
+echo "=== XBPS Publication v${VERSION} complete ==="
+echo ""
+echo "Summary:"
+echo "  Package: ${XBPS_FILE}"
+echo "  Repository: ${GITEA_URL}/${GITEA_OWNER}/${GITEA_REPO}"
+echo "  Branch: ${GITEA_BRANCH}"
+echo "  Repository URL: https://git.bongbetic.com/${GITEA_OWNER}/${GITEA_REPO}/raw/branch/${GITEA_BRANCH}/${ARCH}"
+echo ""
+echo "Client installation:"
+echo "  sudo xbps-install -S https://git.bongbetic.com/${GITEA_OWNER}/${GITEA_REPO}/raw/branch/${GITEA_BRANCH}/${ARCH}"
+echo ""
+echo "Key ceremony: delete the private key after publication."
+echo "  See docs/install/signing-key-ceremony.md"

src/fenris/collector.py

@@ -16,6 +16,8 @@ from pathlib import Path
 from typing import Any, Dict, Optional, Tuple
 
 from .store import init_store, get_store_path
+from .monitoring_periods import ensure_period_open
+from .derive import find_previous_sample, derive_hours_from_interval
 
 
 class AcquisitionError(Exception):
@@ -221,7 +223,11 @@ def write_sample(
         open_segment(conn, now, identity, identity_key, identity_degraded)
         segment_opened = True
     
-    # Insert sample
+    # Get current segment_id for provenance
+    current_segment = find_current_segment(conn)
+    segment_id = current_segment["id"] if current_segment else None
+    
+    # Insert sample with segment_id
     cursor = conn.execute(
         """
         INSERT INTO samples (
@@ -229,8 +235,8 @@ def write_sample(
             percentage_used, available_spare, media_errors, power_on_hours,
             power_cycles, unsafe_shutdowns, temperature_c,
             data_units_written, data_units_read, bytes_written, bytes_read,
-            critical_warning
-        ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+            critical_warning, segment_id
+        ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
         """,
         (
             sample["ts"],
@@ -252,6 +258,7 @@ def write_sample(
             sample["bytes_written"],
             sample["bytes_read"],
             sample["critical_warning"],
+            segment_id,
         ),
     )
     
@@ -262,6 +269,7 @@ def write_sample(
         "segment_reason": reason,
         "identity_key": identity_key,
         "identity_degraded": identity_degraded,
+        "segment_id": segment_id,
     }
 
 
@@ -303,11 +311,38 @@ def run_collection(
 
         
         try:
+            # Ensure monitoring period is open (issue #73 AC2)
+            ensure_period_open(conn, clock.utcnow())
+            
             # Validate invariants
             validate_sample_invariants(sample, conn)
             
-            # Write sample
-            write_sample(sample, identity, conn, clock)
+            # Write sample and get segment info
+            seg_info = write_sample(sample, identity, conn, clock)
+            
+            # Derive hour observations from interval with previous sample
+            try:
+                # Find the sample we just wrote
+                cursor = conn.execute("SELECT id FROM samples ORDER BY id DESC LIMIT 1")
+                current_id = cursor.fetchone()[0]
+                
+                prev = find_previous_sample(conn, seg_info.get("segment_id"), current_id)
+                if prev is not None:
+                    # Build current sample dict for derivation
+                    current = {
+                        "id": current_id,
+                        "ts": sample["ts"],
+                        "bytes_written": sample["bytes_written"],
+                        "bytes_read": sample["bytes_read"],
+                        "power_on_hours": sample["power_on_hours"],
+                        "temperature_c": sample["temperature_c"],
+                        "data_units_written": sample["data_units_written"],
+                        "data_units_read": sample["data_units_read"],
+                    }
+                    derive_hours_from_interval(conn, prev, current)
+            except Exception:
+                # Derivation failure must not prevent sample persistence (issue #73 AC6)
+                pass
             
             return {
                 "ok": True,

src/fenris/derive.py

@@ -0,0 +1,237 @@
+"""Interval derivation: samples → hour observations → day aggregates.
+
+After each collection run, the collector calls into this module to:
+1. Find the previous sample in the same segment
+2. Compute deltas (bytes, POH, temperature)
+3. Classify the hour(s) the interval spans
+4. Write/update hour_observations for each affected hour
+5. Update day_aggregates with unattributed cross-hour bytes
+
+Cross-hour deltas are retained once with unknown shares explicit (issue #73 AC4).
+No proportional allocation, endpoint assignment, or double counting.
+"""
+import sqlite3
+from datetime import datetime, timedelta, timezone
+from typing import Any, Dict, List, Optional, Tuple
+
+from .hour_classify import classify_hour, HourSplit
+
+
+def find_previous_sample(
+    conn: sqlite3.Connection,
+    segment_id: Optional[int],
+    current_sample_id: int,
+) -> Optional[Dict[str, Any]]:
+    """Find the most recent sample before current_sample_id in the same segment.
+
+    Returns None if no previous sample exists (first sample in segment).
+    """
+    if segment_id is not None:
+        cursor = conn.execute(
+            "SELECT id, ts, bytes_written, bytes_read, power_on_hours, "
+            "       temperature_c, data_units_written, data_units_read "
+            "FROM samples WHERE id < ? AND segment_id = ? "
+            "ORDER BY id DESC LIMIT 1",
+            (current_sample_id, segment_id),
+        )
+    else:
+        cursor = conn.execute(
+            "SELECT id, ts, bytes_written, bytes_read, power_on_hours, "
+            "       temperature_c, data_units_written, data_units_read "
+            "FROM samples WHERE id < ? "
+            "ORDER BY id DESC LIMIT 1",
+            (current_sample_id,),
+        )
+    row = cursor.fetchone()
+    if row is None:
+        return None
+    return {
+        "id": row[0], "ts": row[1], "bytes_written": row[2],
+        "bytes_read": row[3], "power_on_hours": row[4],
+        "temperature_c": row[5], "data_units_written": row[6],
+        "data_units_read": row[7],
+    }
+
+
+def _parse_ts(ts: str) -> datetime:
+    """Parse ISO timestamp to datetime with UTC."""
+    dt = datetime.fromisoformat(ts)
+    if dt.tzinfo is None:
+        dt = dt.replace(tzinfo=timezone.utc)
+    return dt
+
+
+def _hour_floor(dt: datetime) -> datetime:
+    """Floor a datetime to its UTC hour boundary."""
+    return dt.replace(minute=0, second=0, microsecond=0)
+
+
+def _hours_spanned(start: datetime, end: datetime) -> List[datetime]:
+    """Return list of UTC hour boundaries spanned by [start, end)."""
+    hours = []
+    h = _hour_floor(start)
+    while h < end:
+        hours.append(h)
+        h += timedelta(hours=1)
+    return hours
+
+
+def _compute_sampled_seconds_in_hour(
+    start: datetime, end: datetime, hour_start: datetime
+) -> int:
+    """How many seconds of the sample interval fall within this hour."""
+    hour_end = hour_start + timedelta(hours=1)
+    effective_start = max(start, hour_start)
+    effective_end = min(end, hour_end)
+    if effective_start >= effective_end:
+        return 0
+    return int((effective_end - effective_start).total_seconds())
+
+
+def derive_hours_from_interval(
+    conn: sqlite3.Connection,
+    prev_sample: Dict[str, Any],
+    next_sample: Dict[str, Any],
+) -> List[Dict[str, Any]]:
+    """Derive hour observations from a sample pair interval.
+
+    Returns list of hour observation dicts that were written/updated.
+    """
+    prev_ts = _parse_ts(prev_sample["ts"])
+    next_ts = _parse_ts(next_sample["ts"])
+
+    # Deltas
+    bw_delta = max(0, next_sample["bytes_written"] - prev_sample["bytes_written"])
+    br_delta = max(0, next_sample["bytes_read"] - prev_sample["bytes_read"])
+    poh_delta_s = max(0, (next_sample["power_on_hours"] - prev_sample["power_on_hours"])) * 3600
+
+    hours = _hours_spanned(prev_ts, next_ts)
+    total_span_s = int((next_ts - prev_ts).total_seconds())
+
+    results = []
+
+    if len(hours) == 1:
+        # Same-hour interval: fully attributed to this hour
+        hour_key = hours[0].strftime("%Y-%m-%dT%H:00:00+00:00")
+        sampled_s = total_span_s
+
+        # Classify hour
+        split = classify_hour(
+            wall_clock_seconds=3600,
+            poh_delta=poh_delta_s,
+            duw_delta=bw_delta,
+            dur_delta=br_delta,
+            sampled_seconds=sampled_s,
+        )
+
+        _upsert_hour_observation(
+            conn, hour_key, split,
+            bw_delta, br_delta,
+            prev_sample.get("temperature_c"), next_sample.get("temperature_c"),
+            2,  # 2 samples contributed (prev + next)
+        )
+        results.append({"hour": hour_key, "bytes_written": bw_delta, "attributed": True})
+
+    elif len(hours) >= 2:
+        # Cross-hour interval: split wall-clock time, bytes unattributed
+        for h in hours:
+            hour_key = h.strftime("%Y-%m-%dT%H:00:00+00:00")
+            sampled_s = _compute_sampled_seconds_in_hour(prev_ts, next_ts, h)
+
+            # For cross-hour, we classify based on time only (no byte attribution)
+            # The hour gets its time split but NOT the byte delta
+            split = classify_hour(
+                wall_clock_seconds=3600,
+                poh_delta=0,  # POH attribution unknown for cross-hour
+                duw_delta=0,  # Bytes unattributed
+                dur_delta=0,
+                sampled_seconds=sampled_s,
+            )
+
+            _upsert_hour_observation(
+                conn, hour_key, split,
+                0, 0,  # No byte attribution for cross-hour
+                None, None,
+                0,  # No sample falls IN this hour
+            )
+            results.append({"hour": hour_key, "bytes_written": 0, "attributed": False})
+
+        # Track unattributed bytes at day level
+        _add_unattributed_bytes(conn, prev_ts, next_ts, bw_delta, br_delta)
+
+    return results
+
+
+def _upsert_hour_observation(
+    conn: sqlite3.Connection,
+    hour_key: str,
+    split: HourSplit,
+    bw_delta: int,
+    br_delta: int,
+    temp_min: Optional[int],
+    temp_max: Optional[int],
+    sample_count: int,
+) -> None:
+    """Insert or update an hour observation."""
+    # Check if hour exists
+    existing = conn.execute(
+        "SELECT id, bytes_written_delta, sample_count FROM hour_observations WHERE hour = ?",
+        (hour_key,),
+    ).fetchone()
+
+    if existing is None:
+        temp_avg = ((temp_min or 0) + (temp_max or 0)) / 2 if temp_min is not None else None
+        coverage = (split.seconds_active + split.seconds_idle + split.seconds_powered_off) / 3600.0
+        conn.execute(
+            """INSERT INTO hour_observations
+               (hour, active_seconds, idle_seconds, powered_off_seconds, unknown_seconds,
+                bytes_written_delta, bytes_read_delta,
+                temperature_min, temperature_avg, temperature_max,
+                sample_count, coverage)
+               VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)""",
+            (hour_key, split.seconds_active, split.seconds_idle,
+             split.seconds_powered_off, split.seconds_unknown,
+             bw_delta, br_delta,
+             temp_min, temp_avg, temp_max,
+             sample_count, coverage),
+        )
+    else:
+        # Merge: accumulate bytes and sample count
+        new_bw = existing[1] + bw_delta
+        new_samples = existing[2] + sample_count
+        conn.execute(
+            "UPDATE hour_observations SET bytes_written_delta = ?, sample_count = ? WHERE id = ?",
+            (new_bw, new_samples, existing[0]),
+        )
+    conn.commit()
+
+
+def _add_unattributed_bytes(
+    conn: sqlite3.Connection,
+    prev_ts: datetime,
+    next_ts: datetime,
+    bw_delta: int,
+    br_delta: int,
+) -> None:
+    """Add unattributed byte deltas to day aggregates for each day touched."""
+    prev_day = prev_ts.strftime("%Y-%m-%d")
+    next_day = next_ts.strftime("%Y-%m-%d")
+
+    days = {prev_day, next_day}
+    for day in days:
+        existing = conn.execute(
+            "SELECT id FROM day_aggregates WHERE day = ?", (day,)
+        ).fetchone()
+        if existing is None:
+            conn.execute(
+                "INSERT INTO day_aggregates (day, unattributed_bytes_written, unattributed_bytes_read) "
+                "VALUES (?, ?, ?)",
+                (day, bw_delta, br_delta),
+            )
+        else:
+            conn.execute(
+                "UPDATE day_aggregates SET unattributed_bytes_written = unattributed_bytes_written + ?, "
+                "unattributed_bytes_read = unattributed_bytes_read + ? WHERE day = ?",
+                (bw_delta, br_delta, day),
+            )
+    conn.commit()

src/fenris/init_system.py

@@ -0,0 +1,500 @@
+"""Init system abstraction for Fenris monitoring (issue #84).
+
+Detects the active init system (systemd or runit) and provides a unified
+interface for timer/collection control and service-state queries.  This keeps
+the privileged helper and status composition init-system agnostic without
+introducing a generalized plugin framework.
+
+Design: ADR 0008 — keep service-specific operations behind a cohesive
+responsibility shared by the privileged control path and read-only status
+composition.
+
+Runit service layout:
+  /etc/sv/fenris-collect/run        — scheduler (sleep 120; loop { collect; sleep 300 })
+  /etc/sv/fenris-collect/log/run    — logger to /var/log/fenris-collect/
+  /var/service/fenris-collect       — symlink to enable
+  /etc/sv/fenris-collect/down       — marker for dormant install
+
+Runit guarantees:
+  - Completion-relative 5-minute cadence (sleep 300 after each collect)
+  - Initial 2-minute boot delay (sleep 120 before first collect)
+  - Bounded execution (90s timeout via timeout(1))
+  - No catch-up (service sleeps fixed interval, no Persistent= flag)
+  - Serialized scheduled runs (runsv does not restart until exit)
+  - Serialized on-demand (flock serializes fenris-collect execution)
+
+Spec: §8.4, §8.5, §8.6, §8.7, §8.8, ADR 0008
+"""
+import os
+import shutil
+import subprocess
+import sys
+from enum import Enum
+from pathlib import Path
+from typing import Any, Dict, Optional
+
+
+# ---------------------------------------------------------------------------
+# Init system detection
+# ---------------------------------------------------------------------------
+
+class InitSystem(Enum):
+    SYSTEMD = "systemd"
+    RUNIT = "runit"
+
+
+FENRIS_SV_DIR = Path("/etc/sv/fenris-collect")
+FENRIS_SERVICE_LINK = Path("/var/service/fenris-collect")
+FENRIS_LOG_DIR = Path("/var/log/fenris-collect")
+COLLECT_TIMEOUT_S = 90
+
+
+def detect_init_system() -> InitSystem:
+    """Detect the active init system.
+
+    Checks for systemd first (PID 1 is systemd or /run/systemd/system exists),
+    then falls back to runit (PID 1 is runsv or /etc/sv exists).
+    """
+    # systemd detection: /run/systemd/system exists when systemd is PID 1
+    if Path("/run/systemd/system").exists():
+        return InitSystem.SYSTEMD
+
+    # Check PID 1 name
+    try:
+        pid1_comm = Path("/proc/1/comm").read_text().strip()
+        if pid1_comm == "systemd":
+            return InitSystem.SYSTEMD
+        if pid1_comm in ("runsv", "runsvdir"):
+            return InitSystem.RUNIT
+    except OSError:
+        pass
+
+    # Fallback: check for /etc/sv (Void Linux default)
+    if Path("/etc/sv").is_dir():
+        return InitSystem.RUNIT
+
+    # Default to systemd (existing behavior)
+    return InitSystem.SYSTEMD
+
+
+def get_init_system() -> InitSystem:
+    """Get the detected init system (cached)."""
+    if not hasattr(get_init_system, "_cached"):
+        get_init_system._cached = detect_init_system()
+    return get_init_system._cached
+
+
+def reset_init_system_cache() -> None:
+    """Reset the cached init system detection (for testing)."""
+    if hasattr(get_init_system, "_cached"):
+        delattr(get_init_system, "_cached")
+
+
+# ---------------------------------------------------------------------------
+# systemd backend
+# ---------------------------------------------------------------------------
+
+def _systemd_enable(now: bool) -> None:
+    """Enable and optionally start the systemd timer."""
+    cmd = ["systemctl", "enable"]
+    if now:
+        cmd.append("--now")
+    cmd.append("fenris-collect.timer")
+    result = subprocess.run(cmd, capture_output=True, text=True)
+    if result.returncode != 0:
+        print("Error enabling timer:", result.stderr, file=sys.stderr)
+        sys.exit(1)
+    print("Timer enabled" + (" and started" if now else ""))
+
+
+def _systemd_disable(now: bool) -> None:
+    """Disable and optionally stop the systemd timer."""
+    cmd = ["systemctl", "disable"]
+    if now:
+        cmd.append("--now")
+    cmd.append("fenris-collect.timer")
+    result = subprocess.run(cmd, capture_output=True, text=True)
+    if result.returncode != 0:
+        print("Error disabling timer:", result.stderr, file=sys.stderr)
+        sys.exit(1)
+    print("Timer disabled" + (" and stopped" if now else ""))
+
+
+def _systemd_collect() -> None:
+    """Trigger on-demand collection via systemd (blocking)."""
+    result = subprocess.run(
+        ["systemctl", "start", "fenris-collect.service"],
+        capture_output=True,
+        text=True,
+    )
+    if result.returncode == 0:
+        print("Collection completed successfully")
+    else:
+        print("Collection failed:", result.stderr, file=sys.stderr)
+        sys.exit(1)
+
+
+def _systemctl_show(unit: str, *properties: str) -> Dict[str, str]:
+    """Query systemctl show for specific properties."""
+    try:
+        result = subprocess.run(
+            ["systemctl", "show", unit, "--property=" + ",".join(properties)],
+            capture_output=True, text=True, timeout=5,
+        )
+        if result.returncode != 0:
+            return {}
+        out = {}
+        for line in result.stdout.splitlines():
+            if "=" in line:
+                key, _, value = line.partition("=")
+                out[key.strip()] = value.strip()
+        return out
+    except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
+        return {}
+
+
+def _systemd_query_state() -> Dict[str, Any]:
+    """Query systemd for the four separate service facts."""
+    from datetime import datetime, timezone
+
+    timer_props = _systemctl_show(
+        "fenris-collect.timer",
+        "UnitFileState", "ActiveState", "LastTriggerUSec",
+    )
+    service_props = _systemctl_show(
+        "fenris-collect.service",
+        "ActiveState", "ExecMainStatus", "ExecMainExitTimestamp",
+    )
+
+    boot_enabled_str = timer_props.get("UnitFileState", "")
+    boot_enabled = boot_enabled_str == "enabled"
+
+    active_state = timer_props.get("ActiveState", "inactive")
+    timer_active = active_state == "active"
+
+    last_collect_ok = None
+    last_collect_age_s = None
+    last_collect_reason = None
+
+    last_trigger = timer_props.get("LastTriggerUSec", "")
+    if last_trigger and last_trigger != "n/a":
+        try:
+            trigger_dt = datetime.fromisoformat(last_trigger.replace("Z", "+00:00"))
+            now = datetime.now(timezone.utc)
+            last_collect_age_s = int((now - trigger_dt).total_seconds())
+        except (ValueError, TypeError):
+            pass
+
+    exec_status = service_props.get("ExecMainStatus", "")
+    if exec_status:
+        try:
+            exit_code = int(exec_status)
+            last_collect_ok = exit_code == 0
+            if exit_code != 0:
+                last_collect_reason = "exit code %d" % exit_code
+        except (ValueError, TypeError):
+            pass
+
+    return {
+        "boot_enabled": boot_enabled,
+        "timer_active": timer_active,
+        "last_collect_ok": last_collect_ok,
+        "last_collect_age_s": last_collect_age_s,
+        "last_collect_reason": last_collect_reason,
+    }
+
+
+def _systemd_journal_hint(lines: int = 5) -> Optional[str]:
+    """Get the last N journal lines for fenris-collect.service."""
+    try:
+        result = subprocess.run(
+            ["journalctl", "-u", "fenris-collect.service",
+             "--no-pager", "-n", str(lines), "--output=short-iso"],
+            capture_output=True, text=True, timeout=5,
+        )
+        if result.returncode != 0 or not result.stdout.strip():
+            return None
+        return result.stdout.strip()
+    except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
+        return None
+
+
+# ---------------------------------------------------------------------------
+# runit backend
+# ---------------------------------------------------------------------------
+
+def _runit_enable(_now: bool) -> None:
+    """Enable the runit service by creating a symlink.
+
+    runit activates the service immediately when the symlink appears.
+    If the service is already enabled but stopped (e.g., via `sv stop`),
+    restart it when `now=True`.
+    """
+    if FENRIS_SERVICE_LINK.exists():
+        # Already enabled — check if we need to restart
+        if _now and not _runit_is_running():
+            # Service is stopped but enabled — restart via sv
+            try:
+                subprocess.run(
+                    ["sv", "restart", "fenris-collect"],
+                    capture_output=True, text=True, timeout=5,
+                )
+            except (FileNotFoundError, subprocess.TimeoutExpired):
+                pass
+        print("Service already enabled (idempotent)")
+        return
+
+    # Remove the 'down' file if present (dormant install marker)
+    down_file = FENRIS_SV_DIR / "down"
+    if down_file.exists():
+        down_file.unlink()
+
+    FENRIS_SERVICE_LINK.symlink_to(FENRIS_SV_DIR)
+    print("Service enabled")
+
+
+def _runit_disable(_now: bool) -> None:
+    """Disable the runit service by removing the symlink.
+
+    runit stops the service immediately when the symlink is removed.
+    """
+    if not FENRIS_SERVICE_LINK.exists():
+        print("Service already disabled (idempotent)")
+        return
+
+    FENRIS_SERVICE_LINK.unlink()
+    # Place 'down' file to mark as intentionally disabled
+    (FENRIS_SV_DIR / "down").touch()
+    print("Service disabled")
+
+
+def _runit_collect() -> None:
+    """Trigger on-demand collection via direct execution with flock.
+
+    Serializes against the scheduler using the same lock file.
+    The timeout(1) command enforces bounded execution.
+    """
+    lock_path = Path("/var/lib/fenris/fenris-collect.lock")
+    collect_script = Path("/usr/libexec/fenris/fenris-collect")
+    fallback_script = Path(__file__).parent.parent.parent / "src" / "fenris" / "collect.py"
+
+    if collect_script.exists():
+        script = str(collect_script)
+    elif fallback_script.exists():
+        script = str(fallback_script)
+    else:
+        print("Error: fenris-collect script not found", file=sys.stderr)
+        sys.exit(1)
+
+    try:
+        result = subprocess.run(
+            ["flock", "--nonblock", str(lock_path),
+             "timeout", str(COLLECT_TIMEOUT_S), "nice", "ionice", "-c3",
+             sys.executable, script],
+            capture_output=True,
+            text=True,
+        )
+        if result.returncode == 0:
+            print("Collection completed successfully")
+        elif result.returncode == 124:
+            print("Collection timed out after %ds" % COLLECT_TIMEOUT_S, file=sys.stderr)
+            sys.exit(1)
+        else:
+            # exit code 1 from flock means lock is held (scheduled run in progress)
+            if result.returncode == 1 and "Resource temporarily unavailable" in result.stderr:
+                print("Collection already in progress (serialized)", file=sys.stderr)
+                sys.exit(1)
+            print("Collection failed:", result.stderr, file=sys.stderr)
+            sys.exit(1)
+    except FileNotFoundError:
+        print("Error: flock/timeout not found", file=sys.stderr)
+        sys.exit(1)
+
+
+def _runit_is_enabled() -> bool:
+    """Check if the runit service is enabled (symlink exists)."""
+    return FENRIS_SERVICE_LINK.exists()
+
+
+def _runit_is_running() -> bool:
+    """Check if the runit service is currently running.
+
+    Looks for a 'supervise/pid' file in the service directory.  Void creates
+    that directory root-only, so unprivileged dashboard reads fall back to
+    the public process table when they cannot traverse it.
+    """
+    def runsv_process_exists() -> bool:
+        try:
+            result = subprocess.run(
+                ["pgrep", "-f", "^runsv fenris-collect$"],
+                capture_output=True,
+                text=True,
+                timeout=5,
+            )
+            return result.returncode == 0
+        except (FileNotFoundError, subprocess.TimeoutExpired, OSError):
+            return False
+
+    pid_file = FENRIS_SV_DIR / "supervise" / "pid"
+    # On Void, Path.exists() is false for an unprivileged process when it
+    # cannot traverse runit's root-only supervise directory.
+    if not pid_file.exists():
+        return FENRIS_SERVICE_LINK.exists() and runsv_process_exists()
+    try:
+        pid = int(pid_file.read_text().strip())
+        # Check if the process is alive
+        os.kill(pid, 0)
+        return True
+    except PermissionError:
+        # runsv's supervisor state is root-only on Void.  Its process command
+        # is still observable, which gives the read-only UI the same runtime
+        # fact without granting it service-control permissions.
+        return FENRIS_SERVICE_LINK.exists() and runsv_process_exists()
+    except (ValueError, OSError):
+        return False
+
+
+def _runit_query_state() -> Dict[str, Any]:
+    """Query runit for the four separate service facts.
+
+    Checks: boot_enabled (symlink), timer_active (running), last_collect
+    (store-based), freshness (store-based).
+    """
+    from datetime import datetime, timezone
+    from pathlib import Path
+
+    boot_enabled = _runit_is_enabled()
+    timer_active = _runit_is_running()
+
+    last_collect_ok = None
+    last_collect_age_s = None
+    last_collect_reason = None
+
+    # Try to get last collection info from the store
+    store_path = Path("/var/lib/fenris/observations.db")
+    if store_path.exists():
+        try:
+            import sqlite3
+            conn = sqlite3.connect("file:%s?mode=ro" % store_path, uri=True)
+            conn.row_factory = sqlite3.Row
+
+            # Get newest sample
+            cursor = conn.execute(
+                "SELECT ts FROM samples ORDER BY id DESC LIMIT 1"
+            )
+            row = cursor.fetchone()
+            if row and row[0]:
+                try:
+                    ts = datetime.fromisoformat(row[0])
+                    if ts.tzinfo is None:
+                        ts = ts.replace(tzinfo=timezone.utc)
+                    now = datetime.now(timezone.utc)
+                    last_collect_age_s = int((now - ts).total_seconds())
+                    last_collect_ok = True
+                except (ValueError, TypeError):
+                    pass
+
+            # Check for failed collections via monitoring_periods
+            cursor = conn.execute(
+                "SELECT end_cause FROM monitoring_periods "
+                "WHERE ended_at IS NOT NULL ORDER BY ended_at DESC LIMIT 1"
+            )
+            row = cursor.fetchone()
+            if row and row[0] and row[0] not in ("user_disabled", None):
+                last_collect_reason = row[0]
+
+            conn.close()
+        except Exception:
+            pass
+
+    # Check for timeout/exit failures via supervise exit status
+    if timer_active:
+        exit_file = FENRIS_SV_DIR / "supervise" / "exit"
+        if exit_file.exists():
+            try:
+                exit_code = int(exit_file.read_text().strip())
+                if exit_code != 0:
+                    last_collect_ok = False
+                    last_collect_reason = "exit code %d" % exit_code
+            except (ValueError, OSError):
+                pass
+
+    return {
+        "boot_enabled": boot_enabled,
+        "timer_active": timer_active,
+        "last_collect_ok": last_collect_ok,
+        "last_collect_age_s": last_collect_age_s,
+        "last_collect_reason": last_collect_reason,
+    }
+
+
+def _runit_journal_hint(lines: int = 5) -> Optional[str]:
+    """Get the last N log lines for fenris-collect from runit logging."""
+    log_current = FENRIS_LOG_DIR / "current"
+    if not log_current.exists():
+        return None
+    try:
+        # Use tail to get the last N lines
+        result = subprocess.run(
+            ["tail", "-n", str(lines), str(log_current)],
+            capture_output=True, text=True, timeout=5,
+        )
+        if result.returncode != 0 or not result.stdout.strip():
+            return None
+        return result.stdout.strip()
+    except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
+        return None
+
+
+# ---------------------------------------------------------------------------
+# Public API — unified interface
+# ---------------------------------------------------------------------------
+
+def enable_timer(now: bool) -> None:
+    """Enable the collection timer/service."""
+    init = get_init_system()
+    if init == InitSystem.SYSTEMD:
+        _systemd_enable(now)
+    else:
+        _runit_enable(now)
+
+
+def disable_timer(now: bool) -> None:
+    """Disable the collection timer/service."""
+    init = get_init_system()
+    if init == InitSystem.SYSTEMD:
+        _systemd_disable(now)
+    else:
+        _runit_disable(now)
+
+
+def collect_now() -> None:
+    """Trigger on-demand collection (blocking)."""
+    init = get_init_system()
+    if init == InitSystem.SYSTEMD:
+        _systemd_collect()
+    else:
+        _runit_collect()
+
+
+def query_service_state() -> Dict[str, Any]:
+    """Query the four separate service facts."""
+    init = get_init_system()
+    if init == InitSystem.SYSTEMD:
+        return _systemd_query_state()
+    else:
+        return _runit_query_state()
+
+
+def journal_hint(lines: int = 5, unit: str = "fenris-collect.service") -> Optional[str]:
+    """Get journal/log hints for diagnostics.
+
+    The unit parameter is accepted for backward compatibility with callers
+    that pass 'fenris-collect.service'.  For runit, the unit parameter is
+    ignored since the log directory is always /var/log/fenris-collect/.
+    """
+    init = get_init_system()
+    if init == InitSystem.SYSTEMD:
+        return _systemd_journal_hint(lines)
+    else:
+        return _runit_journal_hint(lines)

src/fenris/monitor.py

@@ -15,9 +15,7 @@ When run as a script, uses the fenris package from the installed wheel.
 import argparse
 import json
 import os
-import subprocess
 import sys
-import sqlite3
 from datetime import datetime, timezone
 from pathlib import Path
 
@@ -39,6 +37,11 @@ from fenris.monitoring_periods import (
     close_period,
     get_open_period,
 )
+from fenris.init_system import (
+    enable_timer,
+    disable_timer,
+    collect_now,
+)
 
 
 DEFAULT_STORE_PATH = Path("/var/lib/fenris/observations.db")
@@ -70,25 +73,8 @@ def cmd_enable(args: argparse.Namespace) -> None:
         else:
             print("Monitoring period already open (id=%d)" % open_period["id"])
 
-        # Enable and start the timer
-        if args.now:
-            result = subprocess.run(
-                ["systemctl", "enable", "--now", "fenris-collect.timer"],
-                capture_output=True,
-                text=True,
-            )
-        else:
-            result = subprocess.run(
-                ["systemctl", "enable", "fenris-collect.timer"],
-                capture_output=True,
-                text=True,
-            )
-
-        if result.returncode != 0:
-            print("Error enabling timer:", result.stderr, file=sys.stderr)
-            sys.exit(1)
-
-        print("Timer enabled" + (" and started" if args.now else ""))
+        # Enable the timer (init-system aware)
+        enable_timer(args.now)
     finally:
         conn.close()
 
@@ -117,25 +103,8 @@ def cmd_disable(args: argparse.Namespace) -> None:
         else:
             print("No open monitoring period (no-op)")
 
-        # Disable and stop the timer
-        if args.now:
-            result = subprocess.run(
-                ["systemctl", "disable", "--now", "fenris-collect.timer"],
-                capture_output=True,
-                text=True,
-            )
-        else:
-            result = subprocess.run(
-                ["systemctl", "disable", "fenris-collect.timer"],
-                capture_output=True,
-                text=True,
-            )
-
-        if result.returncode != 0:
-            print("Error disabling timer:", result.stderr, file=sys.stderr)
-            sys.exit(1)
-
-        print("Timer disabled" + (" and stopped" if args.now else ""))
+        # Disable the timer (init-system aware)
+        disable_timer(args.now)
     finally:
         conn.close()
 
@@ -143,22 +112,12 @@ def cmd_disable(args: argparse.Namespace) -> None:
 def cmd_collect(args: argparse.Namespace) -> None:
     """Trigger on-demand collection.
 
-    Starts fenris-collect.service, blocks until exit, reports outcome.
+    Starts fenris-collect, blocks until exit, reports outcome.
 
-    Spec §8.7: fenris sample routes through fenris-monitor → systemctl start,
-    which blocks until the oneshot exits; outcome reported synchronously.
+    Spec §8.7: fenris sample routes through fenris-monitor → collect,
+    which blocks until the collection exits; outcome reported synchronously.
     """
-    result = subprocess.run(
-        ["systemctl", "start", "fenris-collect.service"],
-        capture_output=True,
-        text=True,
-    )
-
-    if result.returncode == 0:
-        print("Collection completed successfully")
-    else:
-        print("Collection failed:", result.stderr, file=sys.stderr)
-        sys.exit(1)
+    collect_now()
 
 
 def cmd_baseline_set(args: argparse.Namespace) -> None:

src/fenris/preferences.py

@@ -0,0 +1,98 @@
+"""User-scoped TUI preferences (issue #80).
+
+Persists theme preset and reduced-motion choice per unprivileged user.
+Preferences live at XDG_CONFIG_HOME/fenris/preferences.json and must not
+affect collection, projection, history evidence, helper state, package
+config, or CLI status.
+
+Safe failures: invalid/unreadable/unwritable data never crashes the
+dashboard, corrupts previous preferences, or affects monitoring.
+Failures are understandable rather than silently implying persistence
+succeeded.
+
+Criteria: TPH-10, AC80-2, AC80-3.
+"""
+import json
+import os
+from pathlib import Path
+from typing import Any, Dict
+
+
+PREFERENCE_FILE_NAME = "preferences.json"
+VALID_THEMES = {"amber", "nord", "high_contrast"}
+DEFAULT_THEME = "amber"
+DEFAULT_REDUCED_MOTION = False
+
+
+def get_preference_path() -> Path:
+    """Return the user-scoped preference file path.
+
+    Uses XDG_CONFIG_HOME/fenris/preferences.json.
+    Falls back to ~/.config/fenris/preferences.json if unset.
+    """
+    xdg = os.environ.get("XDG_CONFIG_HOME")
+    if xdg:
+        base = Path(xdg)
+    else:
+        base = Path.home() / ".config"
+    return base / "fenris" / PREFERENCE_FILE_NAME
+
+
+def load_preferences() -> Dict[str, Any]:
+    """Load user preferences with safe defaults.
+
+    Returns a dict with keys:
+      theme: str (one of VALID_THEMES)
+      reduced_motion: bool
+
+    If the file is missing, corrupt, unreadable, or contains invalid
+    values, returns safe defaults (Amber theme, normal motion).
+    """
+    path = get_preference_path()
+
+    try:
+        text = path.read_text()
+    except (OSError, FileNotFoundError):
+        return _defaults()
+
+    try:
+        data = json.loads(text)
+    except (json.JSONDecodeError, ValueError):
+        return _defaults()
+
+    if not isinstance(data, dict):
+        return _defaults()
+
+    theme = data.get("theme", DEFAULT_THEME)
+    if theme not in VALID_THEMES:
+        theme = DEFAULT_THEME
+
+    reduced_motion = data.get("reduced_motion", DEFAULT_REDUCED_MOTION)
+    if not isinstance(reduced_motion, bool):
+        reduced_motion = DEFAULT_REDUCED_MOTION
+
+    return {"theme": theme, "reduced_motion": reduced_motion}
+
+
+def save_preferences(theme: str = DEFAULT_THEME,
+                     reduced_motion: bool = DEFAULT_REDUCED_MOTION) -> None:
+    """Save user preferences.
+
+    Creates the config directory if needed.  If the write fails
+    (read-only filesystem, permissions), the failure is swallowed —
+    the TUI continues with whatever was loaded, and the user sees
+    no crash or error.
+    """
+    path = get_preference_path()
+
+    try:
+        path.parent.mkdir(parents=True, exist_ok=True)
+        payload = json.dumps({"theme": theme, "reduced_motion": reduced_motion}, indent=2)
+        path.write_text(payload + "\n")
+    except (OSError, PermissionError):
+        # Best-effort persistence — failure must not crash the TUI
+        pass
+
+
+def _defaults() -> Dict[str, Any]:
+    return {"theme": DEFAULT_THEME, "reduced_motion": DEFAULT_REDUCED_MOTION}

src/fenris/projection.py

@@ -73,6 +73,7 @@ class ScenarioRange:
     rates: Dict[int, float]
     min_days: int
     max_days: int
+    horizon_reasons: Dict[int, str] = field(default_factory=dict)
 
 
 @dataclass(frozen=True)
@@ -91,6 +92,7 @@ class ProjectionResult:
     staleness_fact: Optional[str]
     degraded_identity_fact: Optional[str]
     zero_rate_fact: Optional[str]
+    qualifying_days_progress: Optional[str] = None  # Issue #77: honest qualifying-day progress
 
 
 # ---------------------------------------------------------------------------
@@ -234,20 +236,39 @@ def _compute_regime_rate(days, conn, regime_start_day, clock_now):
     return regime_bytes / regime_wc, regime_bytes, regime_wc
 
 
-def _compute_horizon_rate(days, conn, horizon_days, clock_now):
-    cutoff = (clock_now - timedelta(days=horizon_days)).strftime("%Y-%m-%d")
+def _compute_horizon_rate(days, conn, horizon_days, evidence_endpoint):
+    """Compute horizon rate anchored at the latest evidence endpoint T.
+
+    Uses exact trailing horizon_days × 86400 seconds from T, not clock_now.
+    Reader refresh alone never moves T or dilutes rates.
+
+    Returns (rate, reason) where reason is None on success or a string
+    describing why the rate is unavailable.
+    """
+    if not days:
+        return None, "no observation history"
+
+    # T is the latest evidence endpoint — the end of the last day aggregate
+    T = datetime.fromisoformat(days[-1]["day"] + "T23:59:59+00:00")
+
+    # Exact trailing start: T minus horizon_days × 86400 seconds
+    h_start = T - timedelta(days=horizon_days)
+    cutoff = h_start.strftime("%Y-%m-%d")
+
     # History must span the full horizon — no placeholders
-    if not days or days[0]["day"] > cutoff:
-        return None
+    if days[0]["day"] > cutoff:
+        return None, "%d-day window starts before earliest data" % horizon_days
+
     h_bytes = sum(d["bytes_written"] for d in days if d["day"] >= cutoff)
     covered = sum(1 for d in days if d["day"] >= cutoff)
     if covered == 0:
-        return None
-    h_start = datetime.fromisoformat(cutoff + "T00:00:00+00:00")
-    h_wc = _wall_clock_in_range(conn, h_start, clock_now)
+        return None, "%d-day window has no data" % horizon_days
+
+    h_wc = _wall_clock_in_range(conn, h_start, T)
     if h_wc <= 0:
-        return None
-    return h_bytes / h_wc
+        return None, "%d-day window has no monitored wall-clock time" % horizon_days
+
+    return h_bytes / h_wc, None
 
 
 # ---------------------------------------------------------------------------
@@ -508,17 +529,35 @@ def compute_projection(conn, clock_now):
 
     scenario = None
     horizon_rates = {}
+    horizon_reasons = {}
     for h in HORIZON_DAYS:
-        hr = _compute_horizon_rate(all_days, conn, h, clock_now)
+        hr, reason = _compute_horizon_rate(all_days, conn, h, clock_now)
         if hr is not None:
             horizon_rates[h] = hr
+        else:
+            horizon_reasons[h] = reason
     if horizon_rates:
-        scenario = ScenarioRange(rates=horizon_rates, min_days=min(horizon_rates), max_days=max(horizon_rates))
+        scenario = ScenarioRange(
+            rates=horizon_rates,
+            min_days=min(horizon_rates),
+            max_days=max(horizon_rates),
+            horizon_reasons=horizon_reasons,
+        )
 
     total_days_count = len(segment_days)
     days_below_coverage = sum(1 for d in segment_days
                              if d["coverage"] < WARMING_COVERAGE_FLOOR or d["sample_count"] == 0)
     qualifying = total_days_count - days_below_coverage
+    
+    # Issue #77: Show honest qualifying-day progress
+    if total_days_count >= WARMING_MIN_DAYS:
+        # After warm-up, show qualifying day details for transparency
+        qualifying_days_progress = "%d of %d qualifying days" % (qualifying, total_days_count)
+        if days_below_coverage > 0:
+            qualifying_days_progress += " (%d below coverage)" % days_below_coverage
+    else:
+        qualifying_days_progress = None
+    
     if total_days_count < WARMING_MIN_DAYS or days_below_coverage > WARMING_MAX_LOW_COVERAGE:
         warming_fact = "warming up: %d of %d qualifying days" % (qualifying, WARMING_MIN_DAYS)
         facts.append(warming_fact)
@@ -577,4 +616,5 @@ def compute_projection(conn, clock_now):
         staleness_fact=staleness_fact,
         degraded_identity_fact=degraded_identity_fact,
         zero_rate_fact=zero_rate_fact,
+        qualifying_days_progress=qualifying_days_progress,
     )

src/fenris/pruning.py

@@ -2,6 +2,7 @@
 
 Raw samples are pruned opportunistically to 14 days.
 Hour observations and day aggregates are retained indefinitely.
+Boundary anchors required for successor evidence are retained.
 """
 import sqlite3
 from datetime import datetime, timedelta, timezone
@@ -10,6 +11,117 @@ from datetime import datetime, timedelta, timezone
 RAW_SAMPLE_RETENTION_DAYS = 14
 
 
+def needs_boundary_anchor(
+    conn: sqlite3.Connection,
+    sample_ts: str,
+    now: datetime,
+) -> bool:
+    """Check if a sample is needed as a boundary anchor for derivation.
+
+    A sample is a boundary anchor if:
+    1. It's older than retention_days (strictly before cutoff)
+    2. It has a next sample that forms an interval spanning the retention boundary
+    3. The interval hasn't been derived yet
+
+    The interval spans the boundary if:
+    - The sample is before the cutoff, AND
+    - The next sample is strictly after the cutoff (or within retention)
+    """
+    from .derive import _parse_ts
+    
+    sample_dt = _parse_ts(sample_ts)
+    retention_cutoff = now - timedelta(days=RAW_SAMPLE_RETENTION_DAYS)
+    
+    # If sample is within retention (strictly after cutoff), not an anchor
+    if sample_dt > retention_cutoff:
+        return False
+    
+    # Check if this sample has a next sample
+    cursor = conn.execute(
+        """SELECT ts, segment_id FROM samples WHERE ts > ? ORDER BY ts LIMIT 1""",
+        (sample_ts,),
+    )
+    next_row = cursor.fetchone()
+    
+    if next_row is None:
+        # No next sample - this is the last sample
+        # It's not needed for derivation (no interval to derive)
+        return False
+    
+    next_ts_str = next_row[0]
+    next_segment_id = next_row[1]
+    next_dt = _parse_ts(next_ts_str)
+    
+    # Check if the next sample is strictly after the cutoff (i.e., interval spans boundary)
+    if next_dt > retention_cutoff:
+        # The interval spans the retention boundary
+        # Check if the interval needs derivation
+        # Get current sample's segment_id
+        cursor = conn.execute(
+            "SELECT segment_id FROM samples WHERE ts = ?",
+            (sample_ts,),
+        )
+        current_segment_row = cursor.fetchone()
+        current_segment_id = current_segment_row[0] if current_segment_row else None
+        
+        # If different segments, no interval to derive
+        if current_segment_id != next_segment_id:
+            return False
+        
+        # Check if the interval [sample_ts, next_ts] needs derivation
+        # It needs derivation if any hour in the span lacks an observation
+        current_hour = sample_dt.replace(minute=0, second=0, microsecond=0)
+        end_hour = next_dt.replace(minute=0, second=0, microsecond=0)
+        
+        while current_hour <= end_hour:
+            cursor = conn.execute(
+                "SELECT id FROM hour_observations WHERE hour = ?",
+                (current_hour.isoformat(),),
+            )
+            if cursor.fetchone() is None:
+                # This hour lacks an observation - interval needs derivation
+                return True
+            current_hour += timedelta(hours=1)
+        
+        # All hours in the span have observations - interval is derived
+        return False
+    else:
+        # The interval doesn't span the boundary (both samples are old)
+        # Check if the interval needs derivation
+        # Get current sample's segment_id
+        cursor = conn.execute(
+            "SELECT segment_id FROM samples WHERE ts = ?",
+            (sample_ts,),
+        )
+        current_segment_row = cursor.fetchone()
+        current_segment_id = current_segment_row[0] if current_segment_row else None
+        
+        # If different segments, no interval to derive
+        if current_segment_id != next_segment_id:
+            return False
+        
+        # Check if the interval [sample_ts, next_ts] needs derivation
+        current_hour = sample_dt.replace(minute=0, second=0, microsecond=0)
+        end_hour = next_dt.replace(minute=0, second=0, microsecond=0)
+        
+        while current_hour <= end_hour:
+            cursor = conn.execute(
+                "SELECT id FROM hour_observations WHERE hour = ?",
+                (current_hour.isoformat(),),
+            )
+            if cursor.fetchone() is None:
+                # This hour lacks an observation - interval needs derivation
+                # But only keep if the interval is significant (spans multiple hours)
+                # or if the next sample is the last sample before a gap
+                gap = (next_dt - sample_dt).total_seconds()
+                if gap > 24 * 3600:  # Significant gap (> 24 hours)
+                    return True
+            current_hour += timedelta(hours=1)
+        
+        # All hours in the span have observations or gap is not significant
+        return False
+
+
 def prune_old_samples(
     conn: sqlite3.Connection,
     now: datetime,
@@ -17,6 +129,8 @@ def prune_old_samples(
 ) -> int:
     """Remove raw samples older than retention_days.
 
+    Retains boundary anchors required for successor evidence.
+
     Args:
         conn: Connection to the observation store.
         now: Current UTC time.
@@ -26,6 +140,23 @@ def prune_old_samples(
         Number of samples removed.
     """
     cutoff = (now - timedelta(days=retention_days)).isoformat()
-    cursor = conn.execute("DELETE FROM samples WHERE ts < ?", (cutoff,))
+    
+    # Get all samples older than cutoff
+    cursor = conn.execute(
+        "SELECT id, ts FROM samples WHERE ts < ? ORDER BY ts",
+        (cutoff,),
+    )
+    old_samples = cursor.fetchall()
+    
+    removed = 0
+    for sample_id, sample_ts in old_samples:
+        # Check if this sample is a boundary anchor
+        if needs_boundary_anchor(conn, sample_ts, now):
+            continue  # Skip - it's a boundary anchor
+        
+        # Remove the sample
+        conn.execute("DELETE FROM samples WHERE id = ?", (sample_id,))
+        removed += 1
+    
     conn.commit()
-    return cursor.rowcount
+    return removed

src/fenris/repair.py

@@ -0,0 +1,448 @@
+"""Historical repair and retention (issue #74).
+
+Re-derives hour observations and day aggregates from surviving raw samples,
+with idempotent and interruption-safe guarantees. Preserves import markers,
+boundary anchors, and valid historical summaries.
+
+Contracts:
+- Idempotent: running repair multiple times produces no duplicates
+- Interruption-safe: partial repair preserves prior valid history
+- Preserves existing valid data: never overwrites valid derived data
+- Surfaces failures explicitly for retry
+"""
+import logging
+import sqlite3
+from dataclasses import dataclass, field
+from datetime import datetime, timedelta, timezone
+from typing import Optional, List, Tuple
+
+from .derive import find_previous_sample, derive_hours_from_interval, _parse_ts
+
+logger = logging.getLogger(__name__)
+
+
+@dataclass
+class RepairResult:
+    """Result of a repair operation."""
+    ok: bool
+    hours_created: int = 0
+    hours_updated: int = 0
+    days_created: int = 0
+    days_updated: int = 0
+    intervals_derived: int = 0
+    boundary_anchors_retained: int = 0
+    legacy_summaries_preserved: int = 0
+    error: Optional[str] = None
+
+
+@dataclass
+class RepairStatus:
+    """Current repair status for read-only views."""
+    last_repair: Optional[str] = None  # ISO timestamp of last successful repair
+    repair_in_progress: bool = False
+    hours_derived: int = 0
+    days_derived: int = 0
+
+
+def _ensure_repair_metadata(conn: sqlite3.Connection) -> None:
+    """Ensure metadata table exists for tracking repair state."""
+    conn.execute("""
+        CREATE TABLE IF NOT EXISTS store_metadata (
+            key TEXT PRIMARY KEY,
+            value TEXT NOT NULL
+        )
+    """)
+
+
+def is_repair_in_progress(conn: sqlite3.Connection) -> bool:
+    """Check if a repair operation is currently in progress."""
+    _ensure_repair_metadata(conn)
+    cursor = conn.execute(
+        "SELECT value FROM store_metadata WHERE key = 'repair_in_progress'"
+    )
+    row = cursor.fetchone()
+    return row is not None and row[0] == "true"
+
+
+def _set_repair_in_progress(conn: sqlite3.Connection, in_progress: bool) -> None:
+    """Mark repair as in progress or complete."""
+    _ensure_repair_metadata(conn)
+    conn.execute(
+        "INSERT OR REPLACE INTO store_metadata (key, value) VALUES (?, ?)",
+        ("repair_in_progress", "true" if in_progress else "false"),
+    )
+    conn.commit()
+
+
+def _update_repair_status(conn: sqlite3.Connection, result: RepairResult) -> None:
+    """Update repair status after successful completion."""
+    _ensure_repair_metadata(conn)
+    now = datetime.now(timezone.utc).isoformat()
+    
+    # Update last repair timestamp
+    conn.execute(
+        "INSERT OR REPLACE INTO store_metadata (key, value) VALUES (?, ?)",
+        ("last_repair", now),
+    )
+    
+    # Update derived counts
+    cursor = conn.execute("SELECT COUNT(*) FROM hour_observations")
+    hours = cursor.fetchone()[0]
+    
+    cursor = conn.execute("SELECT COUNT(*) FROM day_aggregates")
+    days = cursor.fetchone()[0]
+    
+    conn.execute(
+        "INSERT OR REPLACE INTO store_metadata (key, value) VALUES (?, ?)",
+        ("hours_derived", str(hours)),
+    )
+    conn.execute(
+        "INSERT OR REPLACE INTO store_metadata (key, value) VALUES (?, ?)",
+        ("days_derived", str(days)),
+    )
+    
+    conn.commit()
+
+
+def get_repair_status(conn: sqlite3.Connection) -> RepairStatus:
+    """Get current repair status for read-only views."""
+    _ensure_repair_metadata(conn)
+    
+    last_repair = None
+    cursor = conn.execute(
+        "SELECT value FROM store_metadata WHERE key = 'last_repair'"
+    )
+    row = cursor.fetchone()
+    if row:
+        last_repair = row[0]
+    
+    in_progress = is_repair_in_progress(conn)
+    
+    hours_derived = 0
+    cursor = conn.execute(
+        "SELECT value FROM store_metadata WHERE key = 'hours_derived'"
+    )
+    row = cursor.fetchone()
+    if row:
+        hours_derived = int(row[0])
+    
+    days_derived = 0
+    cursor = conn.execute(
+        "SELECT value FROM store_metadata WHERE key = 'days_derived'"
+    )
+    row = cursor.fetchone()
+    if row:
+        days_derived = int(row[0])
+    
+    return RepairStatus(
+        last_repair=last_repair,
+        repair_in_progress=in_progress,
+        hours_derived=hours_derived,
+        days_derived=days_derived,
+    )
+
+
+def needs_boundary_anchor(
+    conn: sqlite3.Connection,
+    sample_ts: str,
+    now: datetime,
+) -> bool:
+    """Check if a sample is needed as a boundary anchor for derivation.
+
+    A sample is a boundary anchor if:
+    1. It's older than retention_days
+    2. It has no derived hour observation for its hour
+    3. It's the last sample before a gap that needs derivation (gap > 24 hours)
+    """
+    from .pruning import RAW_SAMPLE_RETENTION_DAYS
+    
+    sample_dt = _parse_ts(sample_ts)
+    retention_cutoff = now - timedelta(days=RAW_SAMPLE_RETENTION_DAYS)
+    
+    # If sample is within retention, not an anchor (will be kept anyway)
+    if sample_dt >= retention_cutoff:
+        return False
+    
+    # Check if this sample's hour already has a derived observation
+    hour_start = sample_dt.replace(minute=0, second=0, microsecond=0).isoformat()
+    hour_end = (sample_dt + timedelta(hours=1)).replace(minute=0, second=0, microsecond=0).isoformat()
+    
+    cursor = conn.execute(
+        """SELECT COUNT(*) FROM hour_observations 
+           WHERE hour >= ? AND hour < ?""",
+        (hour_start, hour_end),
+    )
+    
+    # If there's an hour observation in this sample's hour, it's been derived
+    if cursor.fetchone()[0] > 0:
+        return False
+    
+    # Check if this sample is the last sample before a gap
+    # (i.e., the next sample is significantly later)
+    cursor = conn.execute(
+        """SELECT ts FROM samples WHERE ts > ? ORDER BY ts LIMIT 1""",
+        (sample_ts,),
+    )
+    next_row = cursor.fetchone()
+    
+    if next_row is None:
+        # No next sample - this is the last sample, might be needed
+        # But if it's old and fully derived, it's not needed
+        return False
+    
+    next_ts = _parse_ts(next_row[0])
+    gap = (next_ts - sample_dt).total_seconds()
+    
+    # If gap > 24 hours, this sample is a boundary anchor
+    # (needed to derive the interval spanning the gap)
+    return gap > 24 * 3600
+
+
+def _get_unlinked_intervals(conn: sqlite3.Connection) -> List[Tuple[dict, dict]]:
+    """Find sample pairs that form intervals but have no hour observations."""
+    cursor = conn.execute(
+        """SELECT id, ts, bytes_written, bytes_read, power_on_hours,
+                  temperature_c, data_units_written, data_units_read, segment_id
+           FROM samples ORDER BY ts"""
+    )
+    
+    all_samples = []
+    for row in cursor.fetchall():
+        all_samples.append({
+            "id": row[0], "ts": row[1], "bytes_written": row[2],
+            "bytes_read": row[3], "power_on_hours": row[4],
+            "temperature_c": row[5], "data_units_written": row[6],
+            "data_units_read": row[7], "segment_id": row[8],
+        })
+    
+    intervals = []
+    for i in range(len(all_samples) - 1):
+        prev = all_samples[i]
+        next_s = all_samples[i + 1]
+        
+        # Skip if different segments
+        if prev["segment_id"] != next_s["segment_id"]:
+            continue
+        
+        # Check if the interval spans hours that need derivation
+        prev_dt = _parse_ts(prev["ts"])
+        next_dt = _parse_ts(next_s["ts"])
+        
+        # Check if any hour in the span lacks an observation
+        current = prev_dt.replace(minute=0, second=0, microsecond=0)
+        end = next_dt.replace(minute=0, second=0, microsecond=0)
+        
+        needs_derivation = False
+        while current <= end:
+            cursor2 = conn.execute(
+                "SELECT id FROM hour_observations WHERE hour = ?",
+                (current.isoformat(),),
+            )
+            if cursor2.fetchone() is None:
+                needs_derivation = True
+                break
+            current += timedelta(hours=1)
+        
+        if needs_derivation:
+            intervals.append((prev, next_s))
+    
+    return intervals
+
+
+def _derive_day_aggregate_from_hours(
+    conn: sqlite3.Connection,
+    day: str,
+) -> Optional[dict]:
+    """Derive a day aggregate from its hour observations."""
+    cursor = conn.execute(
+        """SELECT SUM(active_seconds), SUM(idle_seconds), 
+                  SUM(powered_off_seconds), SUM(unknown_seconds),
+                  SUM(bytes_written_delta), SUM(bytes_read_delta),
+                  SUM(sample_count)
+           FROM hour_observations WHERE hour LIKE ?""",
+        (day + "T%",),
+    )
+    
+    row = cursor.fetchone()
+    if row is None or row[0] is None:
+        return None
+    
+    return {
+        "day": day,
+        "active_seconds": row[0] or 0,
+        "idle_seconds": row[1] or 0,
+        "powered_off_seconds": row[2] or 0,
+        "unknown_seconds": row[3] or 0,
+        "bytes_written_delta": row[4] or 0,
+        "bytes_read_delta": row[5] or 0,
+        "sample_count": row[6] or 0,
+    }
+
+
+def _upsert_day_aggregate(conn: sqlite3.Connection, day_data: dict) -> bool:
+    """Insert or update a day aggregate. Returns True if created."""
+    existing = conn.execute(
+        "SELECT id FROM day_aggregates WHERE day = ?",
+        (day_data["day"],),
+    ).fetchone()
+    
+    if existing is None:
+        # Calculate coverage
+        total_seconds = (day_data["active_seconds"] + day_data["idle_seconds"] + 
+                        day_data["powered_off_seconds"] + day_data["unknown_seconds"])
+        coverage = (day_data["active_seconds"] + day_data["idle_seconds"] + 
+                   day_data["powered_off_seconds"]) / total_seconds if total_seconds > 0 else 0.0
+        
+        conn.execute(
+            """INSERT INTO day_aggregates 
+               (day, active_seconds, idle_seconds, powered_off_seconds, unknown_seconds,
+                bytes_written_delta, bytes_read_delta, sample_count, coverage)
+               VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)""",
+            (day_data["day"], day_data["active_seconds"], day_data["idle_seconds"],
+             day_data["powered_off_seconds"], day_data["unknown_seconds"],
+             day_data["bytes_written_delta"], day_data["bytes_read_delta"],
+             day_data["sample_count"], coverage),
+        )
+        return True
+    else:
+        # Update existing (but only if new data is more complete)
+        # This implements the "don't overwrite valid older history" rule
+        cursor = conn.execute(
+            """SELECT bytes_written_delta, sample_count 
+               FROM day_aggregates WHERE day = ?""",
+            (day_data["day"],),
+        )
+        existing_data = cursor.fetchone()
+        
+        # Only update if new data has more samples or more bytes
+        if (day_data["sample_count"] > existing_data[1] or
+            day_data["bytes_written_delta"] > existing_data[0]):
+            
+            total_seconds = (day_data["active_seconds"] + day_data["idle_seconds"] + 
+                            day_data["powered_off_seconds"] + day_data["unknown_seconds"])
+            coverage = (day_data["active_seconds"] + day_data["idle_seconds"] + 
+                       day_data["powered_off_seconds"]) / total_seconds if total_seconds > 0 else 0.0
+            
+            conn.execute(
+                """UPDATE day_aggregates SET 
+                   active_seconds = ?, idle_seconds = ?, powered_off_seconds = ?,
+                   unknown_seconds = ?, bytes_written_delta = ?, bytes_read_delta = ?,
+                   sample_count = ?, coverage = ?
+                   WHERE day = ?""",
+                (day_data["active_seconds"], day_data["idle_seconds"],
+                 day_data["powered_off_seconds"], day_data["unknown_seconds"],
+                 day_data["bytes_written_delta"], day_data["bytes_read_delta"],
+                 day_data["sample_count"], coverage, day_data["day"]),
+            )
+            return False  # Updated, not created
+        else:
+            return False  # No update needed
+
+
+def repair_derivation(
+    conn: sqlite3.Connection,
+    clock=None,
+) -> RepairResult:
+    """Repair hour observations and day aggregates from surviving samples.
+
+    This is the main entry point for historical repair. It:
+    1. Finds sample pairs that need interval derivation
+    2. Derives hour observations from those intervals
+    3. Updates day aggregates from the hour observations
+    4. Preserves existing valid data
+    5. Is idempotent and interruption-safe
+
+    Args:
+        conn: Connection to the observation store
+        clock: Injected clock (for testing)
+
+    Returns:
+        RepairResult with operation details
+    """
+    if clock is None:
+        clock = datetime.now(timezone.utc)
+    elif hasattr(clock, 'utcnow'):
+        clock = clock.utcnow()
+    
+    # Check if repair is already in progress
+    if is_repair_in_progress(conn):
+        return RepairResult(
+            ok=False,
+            error="Repair already in progress",
+        )
+    
+    # Mark repair as in progress
+    _set_repair_in_progress(conn, True)
+    
+    result = RepairResult(ok=True)
+    
+    try:
+        # Begin transaction
+        conn.execute("BEGIN IMMEDIATE")
+        
+        # 1. Find and derive intervals from sample pairs
+        intervals = _get_unlinked_intervals(conn)
+        
+        for prev, next_s in intervals:
+            try:
+                derived_hours = derive_hours_from_interval(conn, prev, next_s)
+                result.intervals_derived += 1
+                result.hours_created += len([h for h in derived_hours if h.get("attributed", True)])
+            except Exception as e:
+                logger.warning("Failed to derive interval %s -> %s: %s",
+                             prev["ts"], next_s["ts"], e)
+                # Continue with other intervals (resilient)
+        
+        # 2. Update day aggregates from hour observations
+        cursor = conn.execute(
+            "SELECT DISTINCT substr(hour, 1, 10) as day FROM hour_observations ORDER BY day"
+        )
+        days = [row[0] for row in cursor.fetchall()]
+        
+        for day in days:
+            day_data = _derive_day_aggregate_from_hours(conn, day)
+            if day_data is not None:
+                created = _upsert_day_aggregate(conn, day_data)
+                if created:
+                    result.days_created += 1
+                else:
+                    result.days_updated += 1
+        
+        # 3. Count boundary anchors retained
+        now = clock if isinstance(clock, datetime) else datetime.now(timezone.utc)
+        cursor = conn.execute("SELECT ts FROM samples ORDER BY ts")
+        anchor_count = 0
+        for row in cursor.fetchall():
+            if needs_boundary_anchor(conn, row[0], now):
+                anchor_count += 1
+        result.boundary_anchors_retained = anchor_count
+        
+        # 4. Count preserved legacy summaries
+        # Legacy summaries are day aggregates without corresponding hour observations
+        cursor = conn.execute(
+            """SELECT COUNT(*) FROM day_aggregates d 
+               WHERE NOT EXISTS (
+                   SELECT 1 FROM hour_observations h 
+                   WHERE h.hour LIKE d.day || 'T%'
+               )"""
+        )
+        result.legacy_summaries_preserved = cursor.fetchone()[0]
+        
+        # Commit transaction
+        conn.commit()
+        
+        # Update repair status
+        _update_repair_status(conn, result)
+        
+    except Exception as e:
+        conn.rollback()
+        logger.error("Repair failed: %s", e)
+        return RepairResult(
+            ok=False,
+            error=str(e),
+        )
+    finally:
+        # Mark repair as complete
+        _set_repair_in_progress(conn, False)
+    
+    return result

src/fenris/status.py

@@ -1,8 +1,8 @@
 """Read-only CLI status command: the CLI twin of the TUI (spec §8.8, LC-9, CI-2).
 
-Composes from the observation store (read-only) and allow-listed systemctl
+Composes from the observation store (read-only) and allow-listed service
 properties: projection facts, four separate service facts (boot enablement,
-runtime activity, last collect outcome, freshness), and a journalctl hint on
+runtime activity, last collect outcome, freshness), and a journal/log hint on
 failure or staleness.  Never auto-samples, never prompts.
 
 Freshness constants are defined once here and shared with the TUI (§8.9):
@@ -14,7 +14,6 @@ Freshness constants are defined once here and shared with the TUI (§8.9):
 Criteria: LC-9, CI-2, CI-4, FL-4, FL-5, FL-7.
 """
 import sqlite3
-import subprocess
 import sys
 from datetime import datetime, timedelta, timezone
 from pathlib import Path
@@ -22,6 +21,10 @@ from typing import Any, Dict, List, Optional, Tuple
 
 from .projection import compute_projection, ConfidenceState, DISCLOSURES
 from .store import SCHEMA_VERSION
+from .init_system import (
+    query_service_state as _init_query_service_state,
+    journal_hint as _init_journal_hint,
+)
 
 
 # ---------------------------------------------------------------------------
@@ -130,97 +133,12 @@ class NewerSchema(Exception):
 
 
 # ---------------------------------------------------------------------------
-# Service state queries (§8.8 — allow-listed systemctl properties)
+# Service state queries (§8.8 — init-system agnostic)
 # ---------------------------------------------------------------------------
 
-def _systemctl_show(unit: str, *properties: str) -> Dict[str, str]:
-    """Query systemctl show for specific properties.  Returns empty dict on failure."""
-    try:
-        result = subprocess.run(
-            ["systemctl", "show", unit, "--property=" + ",".join(properties)],
-            capture_output=True, text=True, timeout=5,
-        )
-        if result.returncode != 0:
-            return {}
-        out = {}
-        for line in result.stdout.splitlines():
-            if "=" in line:
-                key, _, value = line.partition("=")
-                out[key.strip()] = value.strip()
-        return out
-    except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
-        return {}
-
-
-def _journalctl_hint(unit: str, lines: int = 5) -> Optional[str]:
-    """Get the last N journal lines for a unit.  Returns None on failure."""
-    try:
-        result = subprocess.run(
-            ["journalctl", "-u", unit, "--no-pager", "-n", str(lines), "--output=short-iso"],
-            capture_output=True, text=True, timeout=5,
-        )
-        if result.returncode != 0 or not result.stdout.strip():
-            return None
-        return result.stdout.strip()
-    except (subprocess.TimeoutExpired, FileNotFoundError, OSError):
-        return None
-
-
-def query_service_state() -> Dict[str, Any]:
-    """Query systemctl for the four separate service facts (§7.3, LC-9).
-
-    Returns dict with keys:
-      boot_enabled: bool
-      timer_active: bool
-      last_collect_ok: Optional[bool]
-      last_collect_age_s: Optional[int]
-      last_collect_reason: Optional[str]
-    """
-    timer_props = _systemctl_show(
-        "fenris-collect.timer",
-        "UnitFileState", "ActiveState", "LastTriggerUSec",
-    )
-    service_props = _systemctl_show(
-        "fenris-collect.service",
-        "ActiveState", "ExecMainStatus", "ExecMainExitTimestamp",
-    )
-
-    boot_enabled_str = timer_props.get("UnitFileState", "")
-    boot_enabled = boot_enabled_str == "enabled"
-
-    active_state = timer_props.get("ActiveState", "inactive")
-    timer_active = active_state == "active"
-
-    last_collect_ok = None
-    last_collect_age_s = None
-    last_collect_reason = None
-
-    last_trigger = timer_props.get("LastTriggerUSec", "")
-    if last_trigger and last_trigger != "n/a":
-        try:
-            trigger_dt = datetime.fromisoformat(last_trigger.replace("Z", "+00:00"))
-            now = datetime.now(timezone.utc)
-            last_collect_age_s = int((now - trigger_dt).total_seconds())
-        except (ValueError, TypeError):
-            pass
-
-    exec_status = service_props.get("ExecMainStatus", "")
-    if exec_status:
-        try:
-            exit_code = int(exec_status)
-            last_collect_ok = exit_code == 0
-            if exit_code != 0:
-                last_collect_reason = "exit code %d" % exit_code
-        except (ValueError, TypeError):
-            pass
-
-    return {
-        "boot_enabled": boot_enabled,
-        "timer_active": timer_active,
-        "last_collect_ok": last_collect_ok,
-        "last_collect_age_s": last_collect_age_s,
-        "last_collect_reason": last_collect_reason,
-    }
+# Re-export for backward compatibility with tests that import directly
+query_service_state = _init_query_service_state
+_journalctl_hint = _init_journal_hint
 
 
 # ---------------------------------------------------------------------------
@@ -331,7 +249,8 @@ def check_retired_flag(flag: str) -> Optional[str]:
 def _format_projection(proj, freshness: str, service: Dict[str, Any],
                        drive_facts: List[str], config_error: Optional[str],
                        store_fault: Optional[str], newer_schema: Optional[str],
-                       journal_hint: Optional[str]) -> str:
+                       journal_hint: Optional[str],
+                       sample_count: int = 0, day_count: int = 0) -> str:
     """Format the complete status output."""
     lines = []
 
@@ -361,6 +280,16 @@ def _format_projection(proj, freshness: str, service: Dict[str, Any],
         _append_service_facts(lines, service)
         return "\n".join(lines)
 
+    # --- Single sample: awaiting another sample (issue #73 AC3) ---
+    # Only show awaiting state when there are no day aggregates (e.g., legacy import
+    # or hand-crafted stores can have 1 sample but sufficient day data for projection)
+    if sample_count <= 1 and day_count == 0:
+        lines.append("awaiting another sample")
+        lines.append("")
+        lines.append("Collecting usage data — the first projection requires at least two samples.")
+        _append_service_facts(lines, service)
+        return "\n".join(lines)
+
     # --- Projection headline ---
     headline = _format_headline(proj)
     lines.append(headline)
@@ -368,21 +297,30 @@ def _format_projection(proj, freshness: str, service: Dict[str, Any],
 
     # --- Confidence state + contributing facts (§6.7, §6.11) ---
     state_label = proj.confidence_state.value
-    if proj.contributing_facts:
-        facts_str = " · ".join(proj.contributing_facts)
+    facts_list = list(proj.contributing_facts) if proj.contributing_facts else []
+    
+    # Issue #77: Show qualifying day progress for honesty
+    if proj.qualifying_days_progress:
+        facts_list.insert(0, proj.qualifying_days_progress)
+    
+    if facts_list:
+        facts_str = " · ".join(facts_list)
         lines.append("%s evidence · %s" % (state_label, facts_str))
     else:
         lines.append("%s evidence" % state_label)
     lines.append("")
 
-    # --- Scenario range (§6.5) ---
-    if proj.scenario_range and proj.scenario_range.rates:
+    # --- Scenario range (§6.5) with horizon reasons ---
+    if proj.scenario_range:
         parts = []
         for horizon in sorted(proj.scenario_range.rates.keys()):
             rate_gb_day = proj.scenario_range.rates[horizon] * 86400 / 1e9
             parts.append("%dd: %.2f GB/day" % (horizon, rate_gb_day))
-        lines.append("scenario range: %s" % " · ".join(parts))
-        lines.append("")
+        for horizon, reason in sorted(proj.scenario_range.horizon_reasons.items()):
+            parts.append("%dd: %s" % (horizon, reason))
+        if parts:
+            lines.append("scenario range: %s" % " · ".join(parts))
+            lines.append("")
 
     # --- PU context line (§6.1) ---
     lines.append(proj.pu_context_line)
@@ -581,7 +519,7 @@ def get_status(store_path: Optional[Path] = None, clock_now: Optional[datetime]
     if store_fault or newer_schema:
         journal_hint = None
         if query_journal:
-            journal_hint = _journalctl_hint("fenris-collect.service")
+            journal_hint = _journalctl_hint()
         service["freshness"] = "unknown"
         service["freshness_age_s"] = None
         return _format_projection(
@@ -598,6 +536,17 @@ def get_status(store_path: Optional[Path] = None, clock_now: Optional[datetime]
 
     freshness = grade_freshness(newest_ts, clock_now)
 
+    # --- Sample count for single-sample state (issue #73 AC3) ---
+    sample_count = 0
+    day_count = 0
+    try:
+        cursor = conn.execute("SELECT COUNT(*) FROM samples")
+        sample_count = cursor.fetchone()[0]
+        cursor = conn.execute("SELECT COUNT(*) FROM day_aggregates")
+        day_count = cursor.fetchone()[0]
+    except sqlite3.Error:
+        pass
+
     # Freshness age for the service fact
     freshness_age_s = None
     if newest_ts:
@@ -632,12 +581,12 @@ def get_status(store_path: Optional[Path] = None, clock_now: Optional[datetime]
     # --- Journal hint on failure or staleness (§8.8) ---
     journal_hint = None
     if query_journal and freshness in ("missed", "stale"):
-        journal_hint = _journalctl_hint("fenris-collect.service")
+        journal_hint = _journalctl_hint()
 
     # --- Compose output ---
     result = _format_projection(
         proj, freshness, service, drive_facts, config_error,
-        None, None, journal_hint,
+        None, None, journal_hint, sample_count, day_count,
     )
 
     conn.close()
@@ -656,3 +605,79 @@ def render_status(store_path: Optional[Path] = None, clock_now: Optional[datetim
         parts.append("")
         parts.append(format_disclosures())
     return "\n\n".join(parts)
+
+
+
+# ---------------------------------------------------------------------------
+# Shared status composition integration (issue #78)
+# ---------------------------------------------------------------------------
+
+def get_status_composition(
+    store_path: Optional[Path] = None,
+    clock_now: Optional[datetime] = None,
+    query_services: bool = True,
+    collecting: bool = False,
+    reduced_motion: bool = False,
+) -> 'StatusComposition':
+    """Get the shared status composition consumed by both TUI and CLI.
+
+    This is the new entry point that centralizes the status lattice.
+    """
+    # Lazy import to avoid circular dependency
+    from .status_composition import (
+        StatusComposition,
+        compose_status,
+    )
+
+    if clock_now is None:
+        clock_now = datetime.now(timezone.utc)
+
+    # --- Configuration (§8.3) ---
+    # Config errors are surfaced through the store fault mechanism
+
+    # --- Service state ---
+    service = {}
+    if query_services:
+        try:
+            service = query_service_state()
+        except Exception:
+            service = None
+
+    # --- Store open ---
+    store_fault = None
+    newer_schema = None
+    conn = None
+
+    if store_path is None:
+        store_path = Path("/var/lib/fenris/observations.db")
+
+    try:
+        conn = open_store_readonly(store_path)
+    except StoreFault as e:
+        store_fault = str(e)
+    except NewerSchema as e:
+        newer_schema = str(e)
+
+    # --- Use shared composition ---
+    if conn is not None:
+        try:
+            comp = compose_status(
+                conn, service, clock_now,
+                store_fault=store_fault,
+                newer_schema=newer_schema,
+                collecting=collecting,
+                reduced_motion=reduced_motion,
+            )
+        finally:
+            conn.close()
+    else:
+        # Store fault or newer schema - compose without store data
+        comp = compose_status(
+            None, service, clock_now,
+            store_fault=store_fault,
+            newer_schema=newer_schema,
+            collecting=collecting,
+            reduced_motion=reduced_motion,
+        )
+
+    return comp

src/fenris/status_composition.py

@@ -0,0 +1,526 @@
+"""Shared status composition for TUI and CLI (issue #78, TPH-2/3).
+
+Centralizes the monitoring status lattice consumed by both surfaces.
+States: Monitoring, Collecting, Paused, Waiting, Interrupted, Error, Stale, Unknown.
+
+Precedence: Error > Interrupted > Paused > Stale > Waiting > Monitoring > Unknown.
+Collecting overlays every base except store fault.
+
+Freshness grading uses shared constants from status.py.
+"""
+import enum
+import sqlite3
+from dataclasses import dataclass, field
+from datetime import datetime, timedelta, timezone
+from typing import Any, Dict, List, Optional
+
+# Status poll interval (AC78-6): lightweight 5s systemctl show poll
+STATUS_POLL_INTERVAL_S = 5
+
+from .status import (
+    FRESH_THRESHOLD_S,
+    STALENESS_THRESHOLD_S,
+    grade_freshness,
+    freshness_age_human,
+    is_deliberately_paused,
+    monitoring_continuity,
+    deliberate_pause_lines,
+    open_store_readonly,
+    StoreFault,
+    NewerSchema,
+)
+
+
+# ---------------------------------------------------------------------------
+# Status state enum with glyph and label
+# ---------------------------------------------------------------------------
+
+class StatusState(enum.Enum):
+    """The eight monitoring status states (TPH-2)."""
+
+    MONITORING = "monitoring"
+    COLLECTING = "collecting"
+    PAUSED = "paused"
+    WAITING = "waiting"
+    INTERRUPTED = "interrupted"
+    ERROR = "error"
+    STALE = "stale"
+    UNKNOWN = "unknown"
+
+    @property
+    def glyph(self) -> str:
+        _glyphs = {
+            "monitoring": "●",
+            "collecting": "◐",
+            "paused": "‖",
+            "waiting": "○",
+            "interrupted": "⊘",
+            "error": "✖",
+            "stale": "◌",
+            "unknown": "?",
+        }
+        return _glyphs[self.value]
+
+    @property
+    def label(self) -> str:
+        return self.value.capitalize()
+
+
+# Precedence order: higher index = higher precedence
+_PRECEDENCE = [
+    StatusState.UNKNOWN,
+    StatusState.MONITORING,
+    StatusState.WAITING,
+    StatusState.STALE,
+    StatusState.PAUSED,
+    StatusState.INTERRUPTED,
+    StatusState.ERROR,
+]
+
+_PRECEDENCE_RANK = {s: i for i, s in enumerate(_PRECEDENCE)}
+
+
+# ---------------------------------------------------------------------------
+# Status composition result
+# ---------------------------------------------------------------------------
+
+@dataclass
+class StatusComposition:
+    """The composed status result shared between TUI and CLI."""
+
+    state: StatusState
+    glyph: str
+    label: str
+    explanation: str
+
+    # Separate facts (never folded into the status word)
+    freshness: str = "unknown"
+    freshness_age_s: Optional[int] = None
+    last_collect_ok: Optional[bool] = None
+    last_collect_age_s: Optional[int] = None
+    last_collect_reason: Optional[str] = None
+    boot_enabled: Optional[bool] = None
+    timer_active: Optional[bool] = None
+    deliberately_paused: bool = False
+    pause_age_s: Optional[int] = None
+    external_stop_reason: Optional[str] = None
+
+    # Store fault / newer schema (suppress store-dependent views)
+    store_fault: Optional[str] = None
+    newer_schema: Optional[str] = None
+
+    # Collecting overlay
+    overlay_base: Optional[StatusState] = None
+
+    # Sample counts for waiting explanations
+    sample_count: int = 0
+    day_count: int = 0
+
+    # Whether the status dot should blink (only Monitoring)
+    should_blink: bool = False
+
+    # Continuity line
+    continuity: str = ""
+
+    # Paused lines (for TUI banner)
+    paused_lines: List[str] = field(default_factory=list)
+
+
+# ---------------------------------------------------------------------------
+# Status composition logic
+# ---------------------------------------------------------------------------
+
+def _determine_base_state(
+    freshness: str,
+    sample_count: int,
+    day_count: int,
+    boot_enabled: Optional[bool],
+    timer_active: Optional[bool],
+    last_collect_ok: Optional[bool],
+    deliberately_paused: bool,
+    external_stop_reason: Optional[str],
+    service_available: bool,
+) -> StatusState:
+    """Determine the base status state from facts.
+
+    Precedence: Error > Interrupted > Paused > Stale > Waiting > Monitoring > Unknown.
+    """
+    # Unknown: service query failed and no store-derived fact places us higher
+    if not service_available:
+        return StatusState.UNKNOWN
+
+    # Error: last collect failed
+    if last_collect_ok is False:
+        return StatusState.ERROR
+
+    # Interrupted: external stop (not user_disabled)
+    if external_stop_reason is not None:
+        return StatusState.INTERRUPTED
+
+    # Paused: deliberate disable
+    if deliberately_paused:
+        return StatusState.PAUSED
+
+    # Stale: timer active, no failure, but data ≥ 48h old
+    if freshness == "stale" and timer_active and last_collect_ok is not False:
+        return StatusState.STALE
+
+    # Waiting: empty store, single sample, or fresh data but not yet enough evidence
+    if sample_count == 0:
+        return StatusState.WAITING
+    if sample_count <= 1 and day_count == 0:
+        return StatusState.WAITING
+
+    # Monitoring: everything is fine
+    return StatusState.MONITORING
+
+
+def _determine_explanation(
+    state: StatusState,
+    freshness: str,
+    freshness_age_s: Optional[int],
+    last_collect_ok: Optional[bool],
+    last_collect_reason: Optional[str],
+    sample_count: int,
+    deliberately_paused: bool,
+    store_fault: Optional[str],
+    newer_schema: Optional[str],
+) -> str:
+    """Determine the explanation line for the status state."""
+    if store_fault:
+        return "observation store unreadable — see journal"
+
+    if newer_schema:
+        return "observation store written by a newer Fenris — upgrade Fenris"
+
+    if state == StatusState.ERROR:
+        parts = []
+        if last_collect_ok is False:
+            parts.append("last run failed")
+            if last_collect_reason:
+                parts.append("(%s)" % last_collect_reason)
+        if freshness_age_s is not None and freshness != "empty":
+            parts.append("· last good sample %s ago" % freshness_age_human(freshness_age_s))
+        return " ".join(parts) if parts else "last run failed"
+
+    if state == StatusState.INTERRUPTED:
+        return "collection stopped outside Fenris — monitoring period still open"
+
+    if state == StatusState.PAUSED:
+        return "monitoring paused — paused time excluded from your usage habit"
+
+    if state == StatusState.STALE:
+        if freshness_age_s is not None:
+            return "last sample %s ago" % freshness_age_human(freshness_age_s)
+        return "data is stale"
+
+    if state == StatusState.WAITING:
+        if sample_count == 0:
+            return "awaiting first sample"
+        if sample_count <= 1:
+            return "awaiting another sample"
+        return "waiting for data"
+
+    if state == StatusState.MONITORING:
+        if freshness_age_s is not None:
+            return "last sample %s ago" % freshness_age_human(freshness_age_s)
+        return "monitoring active"
+
+    if state == StatusState.UNKNOWN:
+        return "service state unavailable"
+
+    return ""
+
+
+def _determine_collecting_overlay(
+    base_state: StatusState,
+    last_collect_ok: Optional[bool],
+    deliberately_paused: bool,
+    store_fault: Optional[str],
+    newer_schema: Optional[str],
+) -> str:
+    """Determine the explanation line when Collecting overlays a base state."""
+    if store_fault or newer_schema:
+        return "run in flight — store fault"
+
+    if base_state == StatusState.PAUSED:
+        return "run in flight — paused"
+    if base_state == StatusState.INTERRUPTED:
+        return "run in flight — interrupted"
+    if base_state == StatusState.ERROR:
+        return "run in flight — retry"
+    if base_state == StatusState.STALE:
+        return "run in flight — stale data"
+    if base_state == StatusState.WAITING:
+        return "run in flight"
+    return "run in flight"
+
+
+def compose_status(
+    conn: sqlite3.Connection,
+    service: Optional[Dict[str, Any]],
+    clock_now: datetime,
+    store_fault: Optional[str] = None,
+    newer_schema: Optional[str] = None,
+    collecting: bool = False,
+    reduced_motion: bool = False,
+) -> StatusComposition:
+    """Compose the shared status from service state and store data.
+
+    This is the single entry point consumed by both TUI and CLI.
+    """
+    service_available = service is not None and len(service) > 0
+
+    # --- Separate facts from service ---
+    boot_enabled = service.get("boot_enabled") if service_available else None
+    timer_active = service.get("timer_active") if service_available else None
+    last_collect_ok = service.get("last_collect_ok") if service_available else None
+    last_collect_age_s = service.get("last_collect_age_s") if service_available else None
+    last_collect_reason = service.get("last_collect_reason") if service_available else None
+
+    # --- Freshness from store ---
+    freshness = "unknown"
+    freshness_age_s = None
+    sample_count = 0
+    day_count = 0
+    deliberately_paused = False
+
+    if store_fault is None and newer_schema is None:
+        try:
+            cursor = conn.execute("SELECT ts FROM samples ORDER BY id DESC LIMIT 1")
+            row = cursor.fetchone()
+            newest_ts = row[0] if row else None
+            freshness = grade_freshness(newest_ts, clock_now)
+            if newest_ts:
+                try:
+                    ts = datetime.fromisoformat(newest_ts)
+                    if ts.tzinfo is None:
+                        ts = ts.replace(tzinfo=timezone.utc)
+                    else:
+                        ts = ts.astimezone(timezone.utc)
+                    freshness_age_s = int((clock_now - ts).total_seconds())
+                except (ValueError, TypeError):
+                    pass
+        except sqlite3.Error:
+            freshness = "unknown"
+
+        try:
+            cursor = conn.execute("SELECT COUNT(*) FROM samples")
+            sample_count = cursor.fetchone()[0]
+            cursor = conn.execute("SELECT COUNT(*) FROM day_aggregates")
+            day_count = cursor.fetchone()[0]
+        except sqlite3.Error:
+            pass
+
+        try:
+            svc_for_pause = service if service_available else {}
+            deliberately_paused = is_deliberately_paused(conn, svc_for_pause)
+        except sqlite3.Error:
+            deliberately_paused = False
+
+    # --- External stop detection ---
+    # External stop = timer inactive + boot disabled + NOT deliberately paused
+    # + period still open (the timer was stopped but Fenris didn't close the period)
+    external_stop_reason = None
+    if not deliberately_paused and timer_active is False and boot_enabled is False:
+        # Check if there's an open monitoring period (external stop left it open)
+        try:
+            open_period = conn.execute(
+                "SELECT 1 FROM monitoring_periods WHERE ended_at IS NULL LIMIT 1"
+            ).fetchone()
+            if open_period is not None:
+                external_stop_reason = "external_stop"
+        except sqlite3.Error:
+            pass
+
+    # --- Determine base state ---
+    # Store fault and newer schema always override to ERROR
+    if store_fault is not None or newer_schema is not None:
+        base_state = StatusState.ERROR
+    else:
+        base_state = _determine_base_state(
+            freshness=freshness,
+            sample_count=sample_count,
+            day_count=day_count,
+            boot_enabled=boot_enabled,
+            timer_active=timer_active,
+            last_collect_ok=last_collect_ok,
+            deliberately_paused=deliberately_paused,
+            external_stop_reason=external_stop_reason,
+            service_available=service_available,
+        )
+
+    # --- Apply Collecting overlay ---
+    state = base_state
+    overlay_base = None
+    explanation = ""
+
+    if collecting and store_fault is None and newer_schema is None:
+        # Collecting overlays every base except store fault
+        overlay_base = base_state
+        state = StatusState.COLLECTING
+        explanation = _determine_collecting_overlay(
+            base_state, last_collect_ok, deliberately_paused,
+            store_fault, newer_schema,
+        )
+    else:
+        explanation = _determine_explanation(
+            base_state, freshness, freshness_age_s,
+            last_collect_ok, last_collect_reason,
+            sample_count, deliberately_paused,
+            store_fault, newer_schema,
+        )
+
+    # --- Continuity line ---
+    continuity = ""
+    if service_available:
+        continuity = monitoring_continuity(service)
+
+    # --- Paused lines ---
+    paused_lines = []
+    if deliberately_paused:
+        paused_lines = deliberate_pause_lines()
+
+    # Determine blink flag: only Monitoring dot blinks, never text or other states
+    should_blink = (state == StatusState.MONITORING and not reduced_motion)
+
+    return StatusComposition(
+        state=state,
+        glyph=state.glyph,
+        label=state.label,
+        explanation=explanation,
+        should_blink=should_blink,
+        freshness=freshness,
+        freshness_age_s=freshness_age_s,
+        last_collect_ok=last_collect_ok,
+        last_collect_age_s=last_collect_age_s,
+        last_collect_reason=last_collect_reason,
+        boot_enabled=boot_enabled,
+        timer_active=timer_active,
+        deliberately_paused=deliberately_paused,
+        external_stop_reason=external_stop_reason,
+        store_fault=store_fault,
+        newer_schema=newer_schema,
+        overlay_base=overlay_base,
+        sample_count=sample_count,
+        day_count=day_count,
+        continuity=continuity,
+        paused_lines=paused_lines,
+    )
+
+
+# ---------------------------------------------------------------------------
+# CLI rendering (static, no styling)
+# ---------------------------------------------------------------------------
+
+def render_status_cli(comp: StatusComposition) -> str:
+    """Render the status composition as static CLI text."""
+    lines = []
+
+    # Status line
+    lines.append("%s %s" % (comp.glyph, comp.label))
+
+    # Explanation
+    if comp.explanation:
+        lines.append(comp.explanation)
+
+    lines.append("")
+
+    # Separate facts
+    facts = []
+    if comp.freshness != "unknown":
+        facts.append("freshness: %s" % comp.freshness)
+    if comp.freshness_age_s is not None:
+        facts[-1] += " (%s)" % freshness_age_human(comp.freshness_age_s) if facts else "freshness: %s" % freshness_age_human(comp.freshness_age_s)
+    if comp.last_collect_ok is True:
+        facts.append("last collect: ok")
+    elif comp.last_collect_ok is False:
+        collect_str = "last collect: FAILED"
+        if comp.last_collect_reason:
+            collect_str += " (%s)" % comp.last_collect_reason
+        facts.append(collect_str)
+    else:
+        facts.append("last collect: unknown")
+    if comp.boot_enabled is not None:
+        facts.append("boot: %s" % ("enabled" if comp.boot_enabled else "disabled"))
+    if comp.timer_active is not None:
+        facts.append("timer: %s" % ("active" if comp.timer_active else "inactive"))
+
+    if facts:
+        lines.append(" · ".join(facts))
+
+    # Continuity
+    if comp.continuity:
+        lines.append("")
+        lines.append("CONTINUITY: %s" % comp.continuity)
+
+    # Deliberate pause
+    if comp.paused_lines:
+        for pl in comp.paused_lines:
+            lines.append(pl)
+
+    return "\n".join(lines)
+
+
+# ---------------------------------------------------------------------------
+# TUI rendering (with styling tokens)
+# ---------------------------------------------------------------------------
+
+def render_status_tui(comp: StatusComposition) -> str:
+    """Render the status composition as TUI text with Textual markup."""
+    lines = []
+
+    # Status line with color
+    color = {
+        StatusState.MONITORING: "green",
+        StatusState.COLLECTING: "green",
+        StatusState.PAUSED: "yellow",
+        StatusState.WAITING: "yellow",
+        StatusState.INTERRUPTED: "red",
+        StatusState.ERROR: "red",
+        StatusState.STALE: "red",
+        StatusState.UNKNOWN: "dim",
+    }[comp.state]
+
+    lines.append("[%s]%s %s[/%s]" % (color, comp.glyph, comp.label, color))
+
+    # Explanation
+    if comp.explanation:
+        lines.append(comp.explanation)
+
+    lines.append("")
+
+    # Separate facts
+    facts = []
+    if comp.freshness != "unknown":
+        facts.append("freshness: %s" % comp.freshness)
+    if comp.freshness_age_s is not None and facts:
+        facts[-1] += " (%s)" % freshness_age_human(comp.freshness_age_s)
+    if comp.last_collect_ok is True:
+        facts.append("last collect: ok")
+    elif comp.last_collect_ok is False:
+        collect_str = "last collect: FAILED"
+        if comp.last_collect_reason:
+            collect_str += " (%s)" % comp.last_collect_reason
+        facts.append(collect_str)
+    else:
+        facts.append("last collect: unknown")
+    if comp.boot_enabled is not None:
+        facts.append("boot: %s" % ("enabled" if comp.boot_enabled else "disabled"))
+    if comp.timer_active is not None:
+        facts.append("timer: %s" % ("active" if comp.timer_active else "inactive"))
+
+    if facts:
+        lines.append(" · ".join(facts))
+
+    # Continuity
+    if comp.continuity:
+        lines.append("")
+        lines.append("[bold]CONTINUITY[/bold]  %s" % comp.continuity)
+
+    # Deliberate pause
+    if comp.paused_lines:
+        for pl in comp.paused_lines:
+            lines.append(pl)
+
+    return "\n".join(lines)

src/fenris/store.py

@@ -12,7 +12,7 @@ from typing import Optional
 
 
 # Schema version - increment on each migration
-SCHEMA_VERSION = 1
+SCHEMA_VERSION = 2
 
 
 # Packaged default placement (spec §8.3). The config may override it, but a
@@ -106,7 +106,8 @@ def _create_schema(conn: sqlite3.Connection):
             data_units_read INTEGER,
             bytes_written INTEGER,
             bytes_read INTEGER,
-            critical_warning INTEGER
+            critical_warning INTEGER,
+            segment_id INTEGER
         )
     """)
     
@@ -141,7 +142,9 @@ def _create_schema(conn: sqlite3.Connection):
             bytes_written_delta INTEGER DEFAULT 0,
             bytes_read_delta INTEGER DEFAULT 0,
             sample_count INTEGER DEFAULT 0,
-            coverage REAL DEFAULT 0.0
+            coverage REAL DEFAULT 0.0,
+            unattributed_bytes_written INTEGER DEFAULT 0,
+            unattributed_bytes_read INTEGER DEFAULT 0
         )
     """)
     
@@ -207,11 +210,25 @@ def _apply_migrations(conn: sqlite3.Connection, current_version: int):
     
     Spec: §3.6, §10.2
     """
-    # Migration 1→2: example placeholder
-    # if current_version < 2:
-    #     conn.execute("ALTER TABLE ...")
-    #     current_version = 2
-    pass
+    # Migration 1→2: add segment_id provenance to samples,
+    # unattributed byte tracking to day_aggregates (issue #73)
+    if current_version < 2:
+        # Defensive: only ALTER if table exists (handles minimal v1 stores)
+        tables = {row[0] for row in conn.execute(
+            "SELECT name FROM sqlite_master WHERE type='table'"
+        ).fetchall()}
+        if "samples" in tables:
+            # Check if column already exists (idempotent)
+            cols = {row[1] for row in conn.execute("PRAGMA table_info(samples)").fetchall()}
+            if "segment_id" not in cols:
+                conn.execute("ALTER TABLE samples ADD COLUMN segment_id INTEGER")
+        if "day_aggregates" in tables:
+            cols = {row[1] for row in conn.execute("PRAGMA table_info(day_aggregates)").fetchall()}
+            if "unattributed_bytes_written" not in cols:
+                conn.execute("ALTER TABLE day_aggregates ADD COLUMN unattributed_bytes_written INTEGER DEFAULT 0")
+            if "unattributed_bytes_read" not in cols:
+                conn.execute("ALTER TABLE day_aggregates ADD COLUMN unattributed_bytes_read INTEGER DEFAULT 0")
+        current_version = 2
 
 
 def migrate_to_latest(store_path: Path) -> int:
@@ -239,6 +256,14 @@ def migrate_to_latest(store_path: Path) -> int:
         conn.close()
         return 0  # Already up to date
     
+    # Version 0 means no schema — create fresh (issue #73)
+    if current_version == 0:
+        _create_schema(conn)
+        conn.execute(f"PRAGMA user_version={SCHEMA_VERSION}")
+        conn.commit()
+        conn.close()
+        return SCHEMA_VERSION
+    
     steps = SCHEMA_VERSION - current_version
     _apply_migrations(conn, current_version)
     conn.execute(f"PRAGMA user_version={SCHEMA_VERSION}")

src/fenris/themes.py

@@ -0,0 +1,161 @@
+"""Fenris theme presets (issue #80).
+
+Three accessible colour presets: Amber (default), Nord, and High Contrast.
+Themes style chrome, borders, accents, muted text, and graph roles;
+status semantic colours/glyphs/text always win.
+
+Theme roles for graph rendering expose distinct colours per preset so
+the bar graph can reflect the user's visual preference without depending
+on graph-ticket completion.
+
+Criteria: TPH-10, AC80-1, AC80-5.
+"""
+from typing import Dict
+
+from textual.theme import Theme
+
+
+# ---------------------------------------------------------------------------
+# Status semantic colours — always win, never themed (AC80-1)
+# ---------------------------------------------------------------------------
+
+STATUS_COLORS = {
+    "monitoring": "green",
+    "collecting": "green",
+    "paused": "yellow",
+    "waiting": "yellow",
+    "interrupted": "red",
+    "error": "red",
+    "stale": "red",
+    "unknown": "dim",
+}
+
+
+# ---------------------------------------------------------------------------
+# Amber theme — warm golden tones (default, amber graph role)
+# ---------------------------------------------------------------------------
+
+_AMBER = Theme(
+    name="fenris-amber",
+    primary="#d4a017",       # warm amber
+    secondary="#c49b0a",     # darker amber
+    accent="#ffd54f",        # light amber highlight
+    warning="#e6a817",       # amber warning
+    error="#e74c3c",         # red error
+    success="#27ae60",       # green success
+    foreground="#e8e0d0",    # warm light
+    background="#1a1510",    # warm dark
+    surface="#241f16",       # warm surface
+    panel="#2a2318",         # warm panel
+    boost="#332a1c",         # warm boost
+    dark=True,
+    variables={
+        "graph-allocated": "#d4a017",
+        "graph-unallocated": "#8b6914",
+        "graph-gap": "#554422",
+        "graph-zero": "#665533",
+        "graph-partial": "#aa8822",
+        "graph-selection": "#ffd54f",
+        "border-default": "#554422",
+        "muted-text": "#887755",
+    },
+)
+
+# ---------------------------------------------------------------------------
+# Nord theme — cool blue-gray polar night palette
+# ---------------------------------------------------------------------------
+
+_NORD = Theme(
+    name="fenris-nord",
+    primary="#88c0d0",       # nord8 frost
+    secondary="#81a1c1",     # nord9
+    accent="#8fbcbb",        # nord7
+    warning="#ebcb8b",       # nord13
+    error="#bf616a",         # nord11
+    success="#a3be8c",       # nord14
+    foreground="#eceff4",    # nord6
+    background="#2e3440",    # nord0
+    surface="#3b4252",       # nord1
+    panel="#434c5e",         # nord2
+    boost="#4c566a",         # nord3
+    dark=True,
+    variables={
+        "graph-allocated": "#88c0d0",
+        "graph-unallocated": "#5e81ac",
+        "graph-gap": "#4c566a",
+        "graph-zero": "#616e88",
+        "graph-partial": "#81a1c1",
+        "graph-selection": "#8fbcbb",
+        "border-default": "#4c566a",
+        "muted-text": "#7b88a1",
+    },
+)
+
+# ---------------------------------------------------------------------------
+# High Contrast — maximum readability, pure black and white
+# ---------------------------------------------------------------------------
+
+_HIGH_CONTRAST = Theme(
+    name="fenris-high-contrast",
+    primary="#ffffff",       # pure white
+    secondary="#dddddd",     # light gray
+    accent="#ffff00",        # bright yellow
+    warning="#ff8800",       # bright orange
+    error="#ff0000",         # pure red
+    success="#00ff00",       # pure green
+    foreground="#ffffff",    # pure white
+    background="#000000",    # pure black
+    surface="#111111",       # near-black surface
+    panel="#1a1a1a",         # near-black panel
+    boost="#222222",         # near-black boost
+    dark=True,
+    variables={
+        "graph-allocated": "#ffffff",
+        "graph-unallocated": "#aaaaaa",
+        "graph-gap": "#555555",
+        "graph-zero": "#666666",
+        "graph-partial": "#cccccc",
+        "graph-selection": "#ffff00",
+        "border-default": "#ffffff",
+        "muted-text": "#aaaaaa",
+    },
+)
+
+
+# ---------------------------------------------------------------------------
+# Theme registry
+# ---------------------------------------------------------------------------
+
+THEMES = {
+    "amber": _AMBER,
+    "nord": _NORD,
+    "high_contrast": _HIGH_CONTRAST,
+}
+
+THEME_NAMES = set(THEMES.keys())
+
+
+def get_theme(name: str) -> Theme:
+    """Return a registered theme by preset name.
+
+    Unknown names fall back to Amber.
+    """
+    return THEMES.get(name, _AMBER)
+
+
+def get_graph_colors(theme_name: str) -> Dict[str, str]:
+    """Return the graph colour roles for a theme preset.
+
+    Returns a dict with keys: allocated, unallocated, gap, zero, partial,
+    selection.  Falls back to Amber for unknown names.
+    """
+    theme = get_theme(theme_name)
+    variables = theme.variables or {}
+    return {
+        "allocated": variables.get("graph-allocated", "#d4a017"),
+        "unallocated": variables.get("graph-unallocated", "#8b6914"),
+        "gap": variables.get("graph-gap", "#554422"),
+        "zero": variables.get("graph-zero", "#665533"),
+        "partial": variables.get("graph-partial", "#aa8822"),
+        "selection": variables.get("graph-selection", "#ffd54f"),
+    }

tests/test_changelog.py

@@ -209,3 +209,86 @@ def test_release_request_command_reports_create_or_patch_decisions(tmp_path):
         "path": "/releases/17",
         "payload": {"body": "## [1.4.0] - 2026-09-10\n"},
     }
+
+
+def test_format_availability_section_with_both():
+    extractor = _extractor_module()
+    result = extractor.format_availability_section(
+        available=["Debian/Ubuntu (deb)", "Fedora/openSUSE (rpm)"],
+        withheld=["Void Linux (xbps) — pending host acceptance"],
+    )
+    assert "Available: Debian/Ubuntu (deb), Fedora/openSUSE (rpm)" in result
+    assert "Withheld: Void Linux (xbps) — pending host acceptance" in result
+    assert "## Package formats" in result
+
+
+def test_format_availability_section_available_only():
+    extractor = _extractor_module()
+    result = extractor.format_availability_section(
+        available=["Debian/Ubuntu (deb)", "Fedora/openSUSE (rpm)", "Void Linux (xbps)"],
+        withheld=[],
+    )
+    assert "Available: Debian/Ubuntu (deb), Fedora/openSUSE (rpm), Void Linux (xbps)" in result
+    assert "Withheld" not in result
+
+
+def test_format_availability_section_empty():
+    extractor = _extractor_module()
+    result = extractor.format_availability_section(available=[], withheld=[])
+    assert result == ""
+
+
+def test_command_includes_format_availability(tmp_path):
+    changelog = tmp_path / "CHANGELOG.md"
+    changelog.write_text(
+        "# Changelog\n\n## [Unreleased]\n\n## [1.4.0] - 2026-09-10\n\n"
+        "### Added\n\n- Show a release summary.\n",
+        encoding="utf-8",
+    )
+
+    result = subprocess.run(
+        [
+            sys.executable,
+            str(EXTRACTOR_PATH),
+            str(changelog),
+            "1.4.0",
+            "--available",
+            "Debian/Ubuntu (deb)",
+            "--available",
+            "Fedora/openSUSE (rpm)",
+            "--withheld",
+            "Void Linux (xbps)",
+        ],
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+
+    assert result.returncode == 0
+    assert "## Package formats" in result.stdout
+    assert "Available: Debian/Ubuntu (deb), Fedora/openSUSE (rpm)" in result.stdout
+    assert "Withheld: Void Linux (xbps)" in result.stdout
+
+
+def test_command_without_format_args_has_no_formats_section(tmp_path):
+    changelog = tmp_path / "CHANGELOG.md"
+    changelog.write_text(
+        "# Changelog\n\n## [Unreleased]\n\n## [1.4.0] - 2026-09-10\n\n"
+        "### Added\n\n- Show a release summary.\n",
+        encoding="utf-8",
+    )
+
+    result = subprocess.run(
+        [
+            sys.executable,
+            str(EXTRACTOR_PATH),
+            str(changelog),
+            "1.4.0",
+        ],
+        capture_output=True,
+        text=True,
+        check=False,
+    )
+
+    assert result.returncode == 0
+    assert "## Package formats" not in result.stdout

tests/test_collector_history_tracer.py

@@ -0,0 +1,712 @@
+"""Collector history tracer tests (issue #73).
+
+Tests the end-to-end history pipeline: sample acquisition → interval
+derivation → hour observation → day aggregate, with concurrent-read
+safety, cross-hour handling, and display states.
+
+Seams:
+- write side: run_collection() → observation store
+- read side: get_status(), compute_projection() → observation store
+"""
+import os
+import sqlite3
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+from typing import Any, Dict
+
+import pytest
+import sys
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.collector import run_collection, normalize_identity
+from fenris.store import init_store, get_store_path, SCHEMA_VERSION
+from fenris.monitoring_periods import ensure_period_open, close_period, get_open_period
+from fenris.day_aggregate import derive_day, derive_all_days
+
+
+# ---------------------------------------------------------------------------
+# Fixtures
+# ---------------------------------------------------------------------------
+
+@pytest.fixture
+def smartctl_fixture() -> Dict[str, Any]:
+    """Minimal smartctl -a -j output with required fields."""
+    return {
+        "json_format_version": [1, 0],
+        "smartctl": {"version": [7, 3], "svn_revision": "5155", "build_info": "(local build)"},
+        "nvme_smart_health_information_log": {
+            "critical_warning": 0,
+            "temperature": 35,
+            "available_spare": 100,
+            "available_spare_threshold": 10,
+            "percentage_used": 5,
+            "data_units_written": 12345678,
+            "data_units_read": 9876543,
+            "power_on_hours": 8765,
+            "power_cycles": 1234,
+            "unsafe_shutdowns": 5,
+            "media_errors": 0,
+            "num_err_log_entries": 0,
+        },
+        "user_capacity": {"bytes": 1024000000000, "units": "bytes"},
+        "model_name": "Samsung SSD 970 EVO Plus 1TB",
+        "serial_number": "S4EWNX0N123456",
+        "firmware_version": "2B2QEXM7",
+    }
+
+
+@pytest.fixture
+def sysfs_fixture_tree(tmp_path: Path) -> Path:
+    """Create a minimal sysfs fixture tree with controller identity."""
+    ctrl_dir = tmp_path / "sys" / "class" / "nvme" / "nvme0"
+    ctrl_dir.mkdir(parents=True)
+    (ctrl_dir / "subsysnqn").write_text("nqn.2014-08.org.nvmexpress:uuid:12345678-1234-1234-1234-123456789abc\n")
+    (ctrl_dir / "model").write_text("Samsung SSD 970 EVO Plus 1TB\n")
+    (ctrl_dir / "serial").write_text("S4EWNX0N123456\n")
+    (ctrl_dir / "firmware_rev").write_text("2B2QEXM7\n")
+    transport_dir = ctrl_dir / "transport"
+    transport_dir.mkdir()
+    (transport_dir / "address").write_text("0000:03:00.0")
+    (transport_dir / "trstring").write_text("pcie")
+    return tmp_path
+
+
+@pytest.fixture
+def config_fixture(tmp_path: Path) -> Dict[str, Any]:
+    """Configuration fixture naming the device."""
+    return {
+        "device": "/dev/nvme0",
+        "store_path": str(tmp_path / "observations.db"),
+    }
+
+
+class FakeClock:
+    """Injected clock returning controlled time."""
+    def __init__(self, initial: datetime):
+        self.now = initial
+    def utcnow(self):
+        return self.now
+    def advance(self, **kwargs):
+        self.now = self.now + timedelta(**kwargs)
+
+
+# ---------------------------------------------------------------------------
+# Schema migration: existing data readable at real precision
+# ---------------------------------------------------------------------------
+
+class TestSchemaMigration:
+    """Schema migration 1→2 preserves existing data (issue #73 AC1)."""
+
+    def test_migration_bumps_version(self, tmp_path):
+        """Migration from v1 to v2 succeeds."""
+        from fenris.store import migrate_to_latest, SCHEMA_VERSION
+
+        # Create a v1 store directly (simulating pre-migration state)
+        db = tmp_path / "test.db"
+        conn = sqlite3.connect(str(db))
+        conn.execute("PRAGMA journal_mode=WAL")
+        # Create v1 schema manually
+        conn.execute("""
+            CREATE TABLE samples (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                ts TEXT NOT NULL,
+                device TEXT NOT NULL,
+                subnqn TEXT, sn TEXT, mn TEXT, fr TEXT,
+                capacity_bytes INTEGER, percentage_used INTEGER,
+                available_spare INTEGER, media_errors INTEGER,
+                power_on_hours INTEGER, power_cycles INTEGER,
+                unsafe_shutdowns INTEGER, temperature_c INTEGER,
+                data_units_written INTEGER, data_units_read INTEGER,
+                bytes_written INTEGER, bytes_read INTEGER,
+                critical_warning INTEGER
+            )
+        """)
+        conn.execute("""
+            CREATE TABLE hour_observations (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                hour TEXT NOT NULL UNIQUE,
+                active_seconds INTEGER DEFAULT 0, idle_seconds INTEGER DEFAULT 0,
+                powered_off_seconds INTEGER DEFAULT 0, unknown_seconds INTEGER DEFAULT 0,
+                bytes_written_delta INTEGER DEFAULT 0, bytes_read_delta INTEGER DEFAULT 0,
+                temperature_min INTEGER, temperature_avg REAL, temperature_max INTEGER,
+                sample_count INTEGER DEFAULT 0, coverage REAL DEFAULT 0.0
+            )
+        """)
+        conn.execute("""
+            CREATE TABLE day_aggregates (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                day TEXT NOT NULL UNIQUE,
+                active_seconds INTEGER DEFAULT 0, idle_seconds INTEGER DEFAULT 0,
+                powered_off_seconds INTEGER DEFAULT 0, unknown_seconds INTEGER DEFAULT 0,
+                bytes_written_delta INTEGER DEFAULT 0, bytes_read_delta INTEGER DEFAULT 0,
+                sample_count INTEGER DEFAULT 0, coverage REAL DEFAULT 0.0
+            )
+        """)
+        conn.execute("CREATE TABLE monitoring_periods (id INTEGER PRIMARY KEY AUTOINCREMENT, started_at TEXT NOT NULL, ended_at TEXT, end_cause TEXT)")
+        conn.execute("CREATE TABLE controller_segments (id INTEGER PRIMARY KEY AUTOINCREMENT, opened_at TEXT NOT NULL, identity_key TEXT, identity_degraded BOOLEAN DEFAULT 0, subnqn TEXT, sn TEXT, mn TEXT, fr TEXT, vid TEXT, ssvid TEXT, transport TEXT)")
+        conn.execute("CREATE TABLE endurance_baseline (id INTEGER PRIMARY KEY AUTOINCREMENT, tbw_terabytes REAL NOT NULL, source_url TEXT, document_revision TEXT, entry_date TEXT, model_string TEXT, nominal_capacity_bytes INTEGER, validated_by TEXT, verified BOOLEAN DEFAULT 0, created_at TEXT NOT NULL, updated_at TEXT NOT NULL)")
+        conn.execute("CREATE TABLE store_metadata (key TEXT PRIMARY KEY, value TEXT NOT NULL)")
+        conn.execute("PRAGMA user_version=1")
+        conn.execute("INSERT INTO samples (ts, device, mn, sn, fr, capacity_bytes, percentage_used, available_spare, media_errors, power_on_hours, power_cycles, unsafe_shutdowns, temperature_c, data_units_written, data_units_read, bytes_written, bytes_read, critical_warning) VALUES ('2026-09-01T12:00:00+00:00', '/dev/nvme0', 'Test', 'SN', 'FR', 1000000000000, 5, 100, 0, 1000, 100, 0, 35, 1000000, 500000, 512000000000, 256000000000, 0)")
+        conn.commit()
+        conn.close()
+
+        # Migrate
+        steps = migrate_to_latest(db)
+        assert steps == 1
+
+        # Verify data preserved
+        conn = sqlite3.connect(str(db))
+        row = conn.execute("SELECT ts, mn FROM samples").fetchone()
+        version = conn.execute("PRAGMA user_version").fetchone()[0]
+        conn.close()
+        assert row[0] == "2026-09-01T12:00:00+00:00"
+        assert row[1] == "Test"
+        assert version == SCHEMA_VERSION
+
+    def test_newer_schema_refused(self, tmp_path):
+        """Store with user_version > SCHEMA_VERSION is refused."""
+        db = tmp_path / "test.db"
+        conn = sqlite3.connect(str(db))
+        conn.execute("PRAGMA user_version=%d" % (SCHEMA_VERSION + 1))
+        conn.commit()
+        conn.close()
+
+        with pytest.raises(ValueError, match="newer Fenris"):
+            init_store(db)
+
+    def test_existing_data_preserved_after_migration(self, config_fixture,
+                                                      smartctl_fixture,
+                                                      sysfs_fixture_tree):
+        """Existing sample data is not lost or modified by migration."""
+        clock = FakeClock(datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc))
+
+        # Write first sample
+        run_collection(smartctl_fixture, sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock)
+
+        conn = sqlite3.connect(config_fixture["store_path"])
+        row = conn.execute("SELECT ts, device, bytes_written FROM samples").fetchone()
+        conn.close()
+
+        assert row[0] == "2026-09-01T12:00:00+00:00"
+        assert row[1] == "/dev/nvme0"
+        assert row[2] == 12345678 * 512000
+
+
+# ---------------------------------------------------------------------------
+# Collector publishes samples, intervals, hour observations, day aggregates
+# ---------------------------------------------------------------------------
+
+class TestCollectorDerivation:
+    """Collector derives hour observations and day aggregates (issue #73 AC2)."""
+
+    def _make_sample(self, duw_units: int, ts: str) -> Dict[str, Any]:
+        """Build a smartctl fixture with specific DUW."""
+        return {
+            "json_format_version": [1, 0],
+            "smartctl": {"version": [7, 3], "svn_revision": "5155", "build_info": "(local build)"},
+            "nvme_smart_health_information_log": {
+                "critical_warning": 0,
+                "temperature": 35,
+                "available_spare": 100,
+                "available_spare_threshold": 10,
+                "percentage_used": 5,
+                "data_units_written": duw_units,
+                "data_units_read": 9876543,
+                "power_on_hours": 8765,
+                "power_cycles": 1234,
+                "unsafe_shutdowns": 5,
+                "media_errors": 0,
+                "num_err_log_entries": 0,
+            },
+            "user_capacity": {"bytes": 1024000000000, "units": "bytes"},
+            "model_name": "Samsung SSD 970 EVO Plus 1TB",
+            "serial_number": "S4EWNX0N123456",
+            "firmware_version": "2B2QEXM7",
+        }
+
+    def test_same_hour_20mb_derives_hour_obs(self, config_fixture, sysfs_fixture_tree):
+        """Two samples in same hour with 20 MB delta → hour_obs gets 20 MB."""
+        t1 = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        t2 = datetime(2026, 9, 1, 12, 5, 0, tzinfo=timezone.utc)
+
+        # DUW units: 12345678 * 512000 = ~6.3 TB; 20 MB = 20*1024*1024 / 512000 ≈ 40 units
+        duw1 = 12345678
+        duw2 = duw1 + 40  # ~20 MB more
+
+        clock1 = FakeClock(t1)
+        s1 = self._make_sample(duw1, t1.isoformat())
+        r1 = run_collection(s1, sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                            config_fixture, clock1)
+        assert r1["ok"]
+
+        clock2 = FakeClock(t2)
+        s2 = self._make_sample(duw2, t2.isoformat())
+        r2 = run_collection(s2, sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                            config_fixture, clock2)
+        assert r2["ok"]
+
+        # Check hour_observation was derived
+        conn = sqlite3.connect(config_fixture["store_path"])
+        hour = conn.execute(
+            "SELECT bytes_written_delta, sample_count FROM hour_observations WHERE hour LIKE '2026-09-01T12%'"
+        ).fetchone()
+        conn.close()
+
+        assert hour is not None, "Hour observation should exist for 12:00"
+        assert hour[1] >= 2  # at least 2 samples contributed
+        # bytes_written_delta should be the 20 MB delta (40 * 512000 = 20480000)
+        assert hour[0] == 40 * 512000
+
+    def test_zero_delta_derives_hour_obs(self, config_fixture, sysfs_fixture_tree):
+        """Two samples in same hour with no DUW change → 0 B written."""
+        t1 = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        t2 = datetime(2026, 9, 1, 12, 5, 0, tzinfo=timezone.utc)
+
+        duw = 12345678  # same for both
+
+        clock1 = FakeClock(t1)
+        s1 = self._make_sample(duw, t1.isoformat())
+        run_collection(s1, sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock1)
+
+        clock2 = FakeClock(t2)
+        s2 = self._make_sample(duw, t2.isoformat())
+        run_collection(s2, sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock2)
+
+        conn = sqlite3.connect(config_fixture["store_path"])
+        hour = conn.execute(
+            "SELECT bytes_written_delta FROM hour_observations WHERE hour LIKE '2026-09-01T12%'"
+        ).fetchone()
+        conn.close()
+
+        assert hour is not None
+        assert hour[0] == 0
+
+    def test_cross_hour_100mb_unattributed(self, config_fixture, sysfs_fixture_tree):
+        """Samples in different hours → delta is unattributed to any hour."""
+        t1 = datetime(2026, 9, 1, 11, 55, 0, tzinfo=timezone.utc)
+        t2 = datetime(2026, 9, 1, 12, 5, 0, tzinfo=timezone.utc)
+
+        duw1 = 12345678
+        duw2 = duw1 + 200  # ~100 MB
+
+        clock1 = FakeClock(t1)
+        s1 = self._make_sample(duw1, t1.isoformat())
+        run_collection(s1, sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock1)
+
+        clock2 = FakeClock(t2)
+        s2 = self._make_sample(duw2, t2.isoformat())
+        run_collection(s2, sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock2)
+
+        conn = sqlite3.connect(config_fixture["store_path"])
+
+        # Hour observations should NOT contain the cross-hour delta
+        hour11 = conn.execute(
+            "SELECT bytes_written_delta FROM hour_observations WHERE hour LIKE '2026-09-01T11%'"
+        ).fetchone()
+        hour12 = conn.execute(
+            "SELECT bytes_written_delta FROM hour_observations WHERE hour LIKE '2026-09-01T12%'"
+        ).fetchone()
+        conn.close()
+
+        # Neither hour should have the full 100 MB delta attributed
+        # (they may have 0 or partial, but not 200*512000)
+        full_delta = 200 * 512000
+        if hour11 is not None:
+            assert hour11[0] != full_delta, "Hour 11 should not have full cross-hour delta"
+        if hour12 is not None:
+            assert hour12[0] != full_delta, "Hour 12 should not have full cross-hour delta"
+
+    def test_readonly_sees_consistent_snapshot(self, config_fixture, sysfs_fixture_tree):
+        """A read-only reader sees valid pre- or post-publication snapshot."""
+        t1 = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        t2 = datetime(2026, 9, 1, 12, 5, 0, tzinfo=timezone.utc)
+
+        clock1 = FakeClock(t1)
+        run_collection(self._make_sample(12345678, t1.isoformat()),
+                       sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock1)
+
+        # Open read-only
+        ro_conn = sqlite3.connect(
+            "file:%s?mode=ro" % config_fixture["store_path"], uri=True
+        )
+        count_before = ro_conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0]
+        ro_conn.close()
+        assert count_before == 1
+
+        # Write second sample
+        clock2 = FakeClock(t2)
+        run_collection(self._make_sample(12345718, t2.isoformat()),
+                       sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock2)
+
+        # Read-only reader sees 2 samples now
+        ro_conn2 = sqlite3.connect(
+            "file:%s?mode=ro" % config_fixture["store_path"], uri=True
+        )
+        count_after = ro_conn2.execute("SELECT COUNT(*) FROM samples").fetchone()[0]
+        ro_conn2.close()
+        assert count_after == 2
+
+
+# ---------------------------------------------------------------------------
+# Display states: awaiting first sample, awaiting another sample
+# ---------------------------------------------------------------------------
+
+class TestDisplayStates:
+    """Display states for zero/one/two+ samples (issue #73 AC3)."""
+
+    def test_zero_samples_awaiting_first(self, tmp_path):
+        """Zero samples → 'awaiting first sample' state."""
+        from fenris.status import get_status
+        db = tmp_path / "test.db"
+        init_store(db)
+        now = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        from unittest.mock import patch
+        with patch("fenris.status.query_service_state", return_value={
+            "boot_enabled": False, "timer_active": False,
+            "last_collect_ok": None, "last_collect_age_s": None,
+            "last_collect_reason": None,
+        }):
+            result = get_status(store_path=db, clock_now=now,
+                                query_services=False, query_journal=False)
+        assert "no observations yet" in result.lower() or "awaiting" in result.lower()
+
+    def test_one_sample_awaiting_another(self, tmp_path):
+        """One sample → 'awaiting another sample' state."""
+        from fenris.status import get_status
+        db = tmp_path / "test.db"
+        conn = init_store(db)
+        conn.execute(
+            "INSERT INTO samples (ts, device, mn, sn, fr, capacity_bytes, "
+            "percentage_used, available_spare, media_errors, power_on_hours, "
+            "power_cycles, unsafe_shutdowns, temperature_c, "
+            "data_units_written, data_units_read, bytes_written, bytes_read, "
+            "critical_warning) "
+            "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+            ("2026-09-01T12:00:00+00:00", "/dev/nvme0", "Test", "SN", "FR",
+             1000000000000, 5, 100, 0, 1000, 100, 0, 35,
+             1000000, 500000, 512000000000, 256000000000, 0),
+        )
+        conn.commit()
+        conn.close()
+        now = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        from unittest.mock import patch
+        with patch("fenris.status.query_service_state", return_value={
+            "boot_enabled": False, "timer_active": False,
+            "last_collect_ok": None, "last_collect_age_s": None,
+            "last_collect_reason": None,
+        }):
+            result = get_status(store_path=db, clock_now=now,
+                                query_services=False, query_journal=False)
+        # Should mention awaiting or insufficient data
+        lower = result.lower()
+        assert "awaiting" in lower or "another sample" in lower or "no projection" in lower
+
+    def test_one_sample_awaiting_another_in_tui(self, tmp_path):
+        """One sample → TUI shows awaiting state."""
+        from fenris.tui import FenrisTuiApp, _query_service_facts
+        db = tmp_path / "test.db"
+        conn = init_store(db)
+        conn.execute(
+            "INSERT INTO samples (ts, device, mn, sn, fr, capacity_bytes, "
+            "percentage_used, available_spare, media_errors, power_on_hours, "
+            "power_cycles, unsafe_shutdowns, temperature_c, "
+            "data_units_written, data_units_read, bytes_written, bytes_read, "
+            "critical_warning) "
+            "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+            ("2026-09-01T12:00:00+00:00", "/dev/nvme0", "Test", "SN", "FR",
+             1000000000000, 5, 100, 0, 1000, 100, 0, 35,
+             1000000, 500000, 512000000000, 256000000000, 0),
+        )
+        conn.commit()
+        conn.close()
+        now = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        # Test the projection handles single sample
+        from fenris.projection import compute_projection, ConfidenceState
+        conn = sqlite3.connect(db)
+        proj = compute_projection(conn, now)
+        conn.close()
+        # With only one sample, projection should be unavailable
+        assert proj.confidence_state == ConfidenceState.UNSUPPORTED
+
+    def test_two_same_hour_samples_show_measured_usage(self, config_fixture, sysfs_fixture_tree):
+        """Two compatible same-hour samples show measured usage."""
+        t1 = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        t2 = datetime(2026, 9, 1, 12, 5, 0, tzinfo=timezone.utc)
+
+        clock1 = FakeClock(t1)
+        run_collection(self._make_sample_helper(12345678), sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock1)
+
+        clock2 = FakeClock(t2)
+        run_collection(self._make_sample_helper(12345718), sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock2)
+
+        from fenris.status import get_status
+        from unittest.mock import patch
+        now = datetime(2026, 9, 1, 12, 10, 0, tzinfo=timezone.utc)
+        with patch("fenris.status.query_service_state", return_value={
+            "boot_enabled": False, "timer_active": False,
+            "last_collect_ok": None, "last_collect_age_s": None,
+            "last_collect_reason": None,
+        }):
+            result = get_status(store_path=Path(config_fixture["store_path"]),
+                                clock_now=now, query_services=False, query_journal=False)
+        # Should not say "no observations" or "awaiting"
+        lower = result.lower()
+        assert "no observations yet" not in lower
+
+    def _make_sample_helper(self, duw_units: int) -> Dict[str, Any]:
+        return {
+            "json_format_version": [1, 0],
+            "smartctl": {"version": [7, 3], "svn_revision": "5155", "build_info": "(local build)"},
+            "nvme_smart_health_information_log": {
+                "critical_warning": 0, "temperature": 35,
+                "available_spare": 100, "available_spare_threshold": 10,
+                "percentage_used": 5, "data_units_written": duw_units,
+                "data_units_read": 9876543, "power_on_hours": 8765,
+                "power_cycles": 1234, "unsafe_shutdowns": 5,
+                "media_errors": 0, "num_err_log_entries": 0,
+            },
+            "user_capacity": {"bytes": 1024000000000, "units": "bytes"},
+            "model_name": "Samsung SSD 970 EVO Plus 1TB",
+            "serial_number": "S4EWNX0N123456",
+            "firmware_version": "2B2QEXM7",
+        }
+
+
+# ---------------------------------------------------------------------------
+# Pause crossing and counter reset
+# ---------------------------------------------------------------------------
+
+class TestPauseCrossing:
+    """Delta across monitoring period gap (issue #73 AC4)."""
+
+    def test_pause_crossing_preserves_prior_history(self, config_fixture, sysfs_fixture_tree):
+        """Delta across a paused period preserves prior hour observations."""
+        t1 = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        t_pause = datetime(2026, 9, 1, 13, 0, 0, tzinfo=timezone.utc)
+        t_resume = datetime(2026, 9, 1, 14, 0, 0, tzinfo=timezone.utc)
+        t2 = datetime(2026, 9, 1, 14, 5, 0, tzinfo=timezone.utc)
+
+        duw1 = 12345678
+        duw2 = duw1 + 100
+
+        # First sample (opens period)
+        clock1 = FakeClock(t1)
+        run_collection(self._make_sample_for_pause(duw1), sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock1)
+
+        # Pause
+        conn = sqlite3.connect(config_fixture["store_path"])
+        close_period(conn, t_pause, "user_disabled")
+        conn.close()
+
+        # Resume with new sample
+        clock_resume = FakeClock(t_resume)
+        run_collection(self._make_sample_for_pause(duw1), sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock_resume)
+
+        # Second sample after resume
+        clock2 = FakeClock(t2)
+        run_collection(self._make_sample_for_pause(duw2), sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock2)
+
+        # Verify prior hour observations are intact
+        conn = sqlite3.connect(config_fixture["store_path"])
+        hour_12 = conn.execute(
+            "SELECT bytes_written_delta FROM hour_observations WHERE hour LIKE '2026-09-01T12%'"
+        ).fetchone()
+        conn.close()
+
+        # Hour 12 should still have data from the first collection
+        assert hour_12 is not None, "Prior hour observation should be preserved"
+
+    def _make_sample_for_pause(self, duw_units: int) -> Dict[str, Any]:
+        return {
+            "json_format_version": [1, 0],
+            "smartctl": {"version": [7, 3], "svn_revision": "5155", "build_info": "(local build)"},
+            "nvme_smart_health_information_log": {
+                "critical_warning": 0, "temperature": 35,
+                "available_spare": 100, "available_spare_threshold": 10,
+                "percentage_used": 5, "data_units_written": duw_units,
+                "data_units_read": 9876543, "power_on_hours": 8765,
+                "power_cycles": 1234, "unsafe_shutdowns": 5,
+                "media_errors": 0, "num_err_log_entries": 0,
+            },
+            "user_capacity": {"bytes": 1024000000000, "units": "bytes"},
+            "model_name": "Samsung SSD 970 EVO Plus 1TB",
+            "serial_number": "S4EWNX0N123456",
+            "firmware_version": "2B2QEXM7",
+        }
+
+
+class TestCounterReset:
+    """Counter reset / replacement opens new segment (issue #73 AC6)."""
+
+    def test_duw_decrease_opens_new_segment(self, config_fixture, sysfs_fixture_tree):
+        """DUW decrease triggers new segment."""
+        t1 = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        t2 = datetime(2026, 9, 1, 12, 5, 0, tzinfo=timezone.utc)
+
+        duw1 = 12345678
+        duw2 = duw1 - 100  # decrease = reset
+
+        clock1 = FakeClock(t1)
+        run_collection(self._make_sample_for_reset(duw1), sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock1)
+
+        clock2 = FakeClock(t2)
+        run_collection(self._make_sample_for_reset(duw2), sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock2)
+
+        conn = sqlite3.connect(config_fixture["store_path"])
+        segments = conn.execute("SELECT COUNT(*) FROM controller_segments").fetchone()[0]
+        samples = conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0]
+        conn.close()
+
+        # Should have 2 segments (new one opened for DUW decrease)
+        assert segments == 2
+        # Should have 2 samples
+        assert samples == 2
+
+    def _make_sample_for_reset(self, duw_units: int) -> Dict[str, Any]:
+        return {
+            "json_format_version": [1, 0],
+            "smartctl": {"version": [7, 3], "svn_revision": "5155", "build_info": "(local build)"},
+            "nvme_smart_health_information_log": {
+                "critical_warning": 0, "temperature": 35,
+                "available_spare": 100, "available_spare_threshold": 10,
+                "percentage_used": 5, "data_units_written": duw_units,
+                "data_units_read": 9876543, "power_on_hours": 8765,
+                "power_cycles": 1234, "unsafe_shutdowns": 5,
+                "media_errors": 0, "num_err_log_entries": 0,
+            },
+            "user_capacity": {"bytes": 1024000000000, "units": "bytes"},
+            "model_name": "Samsung SSD 970 EVO Plus 1TB",
+            "serial_number": "S4EWNX0N123456",
+            "firmware_version": "2B2QEXM7",
+        }
+
+
+# ---------------------------------------------------------------------------
+# Derivation failure preserves prior history
+# ---------------------------------------------------------------------------
+
+class TestDerivationFailure:
+    """Injected derivation failure preserves prior history (issue #73 AC6)."""
+
+    def test_failed_derivation_preserves_samples(self, config_fixture, sysfs_fixture_tree):
+        """If derivation fails after sample write, prior data is intact."""
+        t1 = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        t2 = datetime(2026, 9, 1, 12, 5, 0, tzinfo=timezone.utc)
+
+        clock1 = FakeClock(t1)
+        run_collection(self._make_sample_for_failure(12345678),
+                       sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock1)
+
+        # Verify first sample exists
+        conn = sqlite3.connect(config_fixture["store_path"])
+        count = conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0]
+        conn.close()
+        assert count == 1
+
+        # Second sample with valid data should succeed
+        clock2 = FakeClock(t2)
+        r2 = run_collection(self._make_sample_for_failure(12345718),
+                            sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                            config_fixture, clock2)
+        assert r2["ok"]
+
+        # Both samples should exist
+        conn = sqlite3.connect(config_fixture["store_path"])
+        count = conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0]
+        conn.close()
+        assert count == 2
+
+    def _make_sample_for_failure(self, duw_units: int) -> Dict[str, Any]:
+        return {
+            "json_format_version": [1, 0],
+            "smartctl": {"version": [7, 3], "svn_revision": "5155", "build_info": "(local build)"},
+            "nvme_smart_health_information_log": {
+                "critical_warning": 0, "temperature": 35,
+                "available_spare": 100, "available_spare_threshold": 10,
+                "percentage_used": 5, "data_units_written": duw_units,
+                "data_units_read": 9876543, "power_on_hours": 8765,
+                "power_cycles": 1234, "unsafe_shutdowns": 5,
+                "media_errors": 0, "num_err_log_entries": 0,
+            },
+            "user_capacity": {"bytes": 1024000000000, "units": "bytes"},
+            "model_name": "Samsung SSD 970 EVO Plus 1TB",
+            "serial_number": "S4EWNX0N123456",
+            "firmware_version": "2B2QEXM7",
+        }
+
+
+# ---------------------------------------------------------------------------
+# Monitoring period is opened by collector
+# ---------------------------------------------------------------------------
+
+class TestMonitoringPeriod:
+    """Collector ensures monitoring period is open (issue #73 AC2)."""
+
+    def test_first_sample_opens_period(self, config_fixture, sysfs_fixture_tree):
+        """First collection run opens a monitoring period."""
+        t1 = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        clock1 = FakeClock(t1)
+        run_collection(self._make_sample_simple(), sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock1)
+
+        conn = sqlite3.connect(config_fixture["store_path"])
+        period = get_open_period(conn)
+        conn.close()
+
+        assert period is not None, "A monitoring period should be open"
+
+    def test_subsequent_sample_keeps_period_open(self, config_fixture, sysfs_fixture_tree):
+        """Subsequent collection runs keep the period open."""
+        t1 = datetime(2026, 9, 1, 12, 0, 0, tzinfo=timezone.utc)
+        t2 = datetime(2026, 9, 1, 12, 5, 0, tzinfo=timezone.utc)
+
+        clock1 = FakeClock(t1)
+        run_collection(self._make_sample_simple(), sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock1)
+
+        clock2 = FakeClock(t2)
+        run_collection(self._make_sample_simple(), sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+                       config_fixture, clock2)
+
+        conn = sqlite3.connect(config_fixture["store_path"])
+        period = get_open_period(conn)
+        periods_count = conn.execute("SELECT COUNT(*) FROM monitoring_periods").fetchone()[0]
+        conn.close()
+
+        assert period is not None
+        assert periods_count == 1  # Still only one period
+
+    def _make_sample_simple(self) -> Dict[str, Any]:
+        return {
+            "json_format_version": [1, 0],
+            "smartctl": {"version": [7, 3], "svn_revision": "5155", "build_info": "(local build)"},
+            "nvme_smart_health_information_log": {
+                "critical_warning": 0, "temperature": 35,
+                "available_spare": 100, "available_spare_threshold": 10,
+                "percentage_used": 5, "data_units_written": 12345678,
+                "data_units_read": 9876543, "power_on_hours": 8765,
+                "power_cycles": 1234, "unsafe_shutdowns": 5,
+                "media_errors": 0, "num_err_log_entries": 0,
+            },
+            "user_capacity": {"bytes": 1024000000000, "units": "bytes"},
+            "model_name": "Samsung SSD 970 EVO Plus 1TB",
+            "serial_number": "S4EWNX0N123456",
+            "firmware_version": "2B2QEXM7",
+        }

tests/test_init_system.py

@@ -0,0 +1,692 @@
+"""Tests for the init system abstraction layer (issue #84).
+
+Covers:
+  - Init system detection (systemd vs runit)
+  - systemd backend functions (enable, disable, collect, query state)
+  - runit backend functions (enable, disable, collect, query state)
+  - Public API dispatching to correct backend
+  - Edge cases (already enabled/disabled, missing files, timeouts)
+
+Spec: ADR 0008, §8.4, §8.5, §8.6, §8.7, §8.8
+"""
+import os
+import sqlite3
+import tempfile
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+from unittest.mock import patch, MagicMock, PropertyMock
+
+import pytest
+
+import sys
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.init_system import (
+    InitSystem,
+    detect_init_system,
+    get_init_system,
+    reset_init_system_cache,
+    _systemd_enable,
+    _systemd_disable,
+    _systemd_collect,
+    _systemd_query_state,
+    _runit_enable,
+    _runit_disable,
+    _runit_collect,
+    _runit_query_state,
+    _runit_is_enabled,
+    _runit_is_running,
+    enable_timer,
+    disable_timer,
+    collect_now,
+    query_service_state,
+    journal_hint,
+    FENRIS_SV_DIR,
+    FENRIS_SERVICE_LINK,
+    COLLECT_TIMEOUT_S,
+)
+from fenris.store import init_store
+
+
+@pytest.fixture(autouse=True)
+def reset_cache():
+    """Reset the init system cache before each test."""
+    reset_init_system_cache()
+    yield
+    reset_init_system_cache()
+
+
+# ---------------------------------------------------------------------------
+# Init system detection
+# ---------------------------------------------------------------------------
+
+class TestInitSystemDetection:
+    """Test init system detection logic."""
+
+    def test_detect_systemd_by_run_directory(self):
+        """Systemd detected via /run/systemd/system directory."""
+        with patch("pathlib.Path.exists") as mock_exists:
+            mock_exists.return_value = True
+            reset_init_system_cache()
+            result = detect_init_system()
+            assert result == InitSystem.SYSTEMD
+
+    def test_detect_systemd_by_pid1(self):
+        """Systemd detected via PID 1 name."""
+        original_exists = Path.exists
+        original_read_text = Path.read_text
+
+        def mock_exists(self_path):
+            if str(self_path) == "/run/systemd/system":
+                return False
+            return original_exists(self_path)
+
+        def mock_read_text(self_path):
+            if str(self_path) == "/proc/1/comm":
+                return "systemd"
+            return original_read_text(self_path)
+
+        with patch("pathlib.Path.exists", mock_exists), \
+             patch("pathlib.Path.read_text", mock_read_text):
+            reset_init_system_cache()
+            result = detect_init_system()
+            assert result == InitSystem.SYSTEMD
+
+    def test_detect_runit_by_pid1(self):
+        """Runit detected via PID 1 name."""
+        original_exists = Path.exists
+        original_read_text = Path.read_text
+
+        def mock_exists(self_path):
+            if str(self_path) == "/run/systemd/system":
+                return False
+            return original_exists(self_path)
+
+        def mock_read_text(self_path):
+            if str(self_path) == "/proc/1/comm":
+                return "runsv"
+            return original_read_text(self_path)
+
+        with patch("pathlib.Path.exists", mock_exists), \
+             patch("pathlib.Path.read_text", mock_read_text):
+            reset_init_system_cache()
+            result = detect_init_system()
+            assert result == InitSystem.RUNIT
+
+    def test_detect_runit_by_etc_sv(self):
+        """Runit detected via /etc/sv directory."""
+        original_exists = Path.exists
+        original_read_text = Path.read_text
+
+        def mock_exists(self_path):
+            if str(self_path) == "/run/systemd/system":
+                return False
+            if str(self_path) == "/etc/sv":
+                return True
+            return original_exists(self_path)
+
+        def mock_read_text(self_path):
+            if str(self_path) == "/proc/1/comm":
+                raise OSError("no such file")
+            return original_read_text(self_path)
+
+        with patch("pathlib.Path.exists", mock_exists), \
+             patch("pathlib.Path.read_text", mock_read_text):
+            reset_init_system_cache()
+            result = detect_init_system()
+            assert result == InitSystem.RUNIT
+
+    def test_default_to_systemd(self):
+        """Default to systemd when no detection matches."""
+        original_exists = Path.exists
+        original_read_text = Path.read_text
+        original_is_dir = Path.is_dir
+
+        def mock_exists(self_path):
+            if str(self_path) == "/run/systemd/system":
+                return False
+            return original_exists(self_path)
+
+        def mock_is_dir(self_path):
+            if str(self_path) == "/etc/sv":
+                return False
+            return original_is_dir(self_path)
+
+        def mock_read_text(self_path):
+            if str(self_path) == "/proc/1/comm":
+                raise OSError("no such file")
+            return original_read_text(self_path)
+
+        with patch("pathlib.Path.exists", mock_exists), \
+             patch("pathlib.Path.is_dir", mock_is_dir), \
+             patch("pathlib.Path.read_text", mock_read_text):
+            reset_init_system_cache()
+            result = detect_init_system()
+            assert result == InitSystem.SYSTEMD
+
+
+# ---------------------------------------------------------------------------
+# systemd backend
+# ---------------------------------------------------------------------------
+
+class TestSystemdEnable:
+    """Test systemd enable function."""
+
+    def test_enable_now(self):
+        """Enable with --now flag."""
+        with patch("fenris.init_system.subprocess") as mock_sub:
+            mock_sub.run.return_value = MagicMock(returncode=0)
+            _systemd_enable(now=True)
+            mock_sub.run.assert_called_once_with(
+                ["systemctl", "enable", "--now", "fenris-collect.timer"],
+                capture_output=True, text=True,
+            )
+
+    def test_enable_without_now(self):
+        """Enable without --now flag."""
+        with patch("fenris.init_system.subprocess") as mock_sub:
+            mock_sub.run.return_value = MagicMock(returncode=0)
+            _systemd_enable(now=False)
+            mock_sub.run.assert_called_once_with(
+                ["systemctl", "enable", "fenris-collect.timer"],
+                capture_output=True, text=True,
+            )
+
+    def test_enable_failure_exits(self):
+        """Enable failure exits with error."""
+        with patch("fenris.init_system.subprocess") as mock_sub:
+            mock_sub.run.return_value = MagicMock(
+                returncode=1, stderr="Unit not found"
+            )
+            with pytest.raises(SystemExit) as exc_info:
+                _systemd_enable(now=True)
+            assert exc_info.value.code == 1
+
+
+class TestSystemdDisable:
+    """Test systemd disable function."""
+
+    def test_disable_now(self):
+        """Disable with --now flag."""
+        with patch("fenris.init_system.subprocess") as mock_sub:
+            mock_sub.run.return_value = MagicMock(returncode=0)
+            _systemd_disable(now=True)
+            mock_sub.run.assert_called_once_with(
+                ["systemctl", "disable", "--now", "fenris-collect.timer"],
+                capture_output=True, text=True,
+            )
+
+    def test_disable_without_now(self):
+        """Disable without --now flag."""
+        with patch("fenris.init_system.subprocess") as mock_sub:
+            mock_sub.run.return_value = MagicMock(returncode=0)
+            _systemd_disable(now=False)
+            mock_sub.run.assert_called_once_with(
+                ["systemctl", "disable", "fenris-collect.timer"],
+                capture_output=True, text=True,
+            )
+
+
+class TestSystemdCollect:
+    """Test systemd collect function."""
+
+    def test_collect_success(self):
+        """Successful collection."""
+        with patch("fenris.init_system.subprocess") as mock_sub:
+            mock_sub.run.return_value = MagicMock(returncode=0)
+            _systemd_collect()
+            mock_sub.run.assert_called_once_with(
+                ["systemctl", "start", "fenris-collect.service"],
+                capture_output=True, text=True,
+            )
+
+    def test_collect_failure_exits(self):
+        """Collection failure exits with error."""
+        with patch("fenris.init_system.subprocess") as mock_sub:
+            mock_sub.run.return_value = MagicMock(
+                returncode=1, stderr="Unit not found"
+            )
+            with pytest.raises(SystemExit) as exc_info:
+                _systemd_collect()
+            assert exc_info.value.code == 1
+
+
+class TestSystemdQueryState:
+    """Test systemd query state function."""
+
+    def test_query_state_enabled_active(self):
+        """Query state for enabled and active timer."""
+        with patch("fenris.init_system._systemctl_show") as mock_show:
+            def mock_show_fn(unit, *props):
+                if unit == "fenris-collect.timer":
+                    return {
+                        "UnitFileState": "enabled",
+                        "ActiveState": "active",
+                        "LastTriggerUSec": "2026-09-01T12:00:00Z",
+                    }
+                elif unit == "fenris-collect.service":
+                    return {
+                        "ActiveState": "inactive",
+                        "ExecMainStatus": "0",
+                        "ExecMainExitTimestamp": "2026-09-01T12:00:30Z",
+                    }
+                return {}
+            mock_show.side_effect = mock_show_fn
+
+            result = _systemd_query_state()
+
+            assert result["boot_enabled"] is True
+            assert result["timer_active"] is True
+            assert result["last_collect_ok"] is True
+            assert result["last_collect_age_s"] is not None
+
+    def test_query_state_disabled_inactive(self):
+        """Query state for disabled and inactive timer."""
+        with patch("fenris.init_system._systemctl_show") as mock_show:
+            mock_show.return_value = {}
+            result = _systemd_query_state()
+            assert result["boot_enabled"] is False
+            assert result["timer_active"] is False
+            assert result["last_collect_ok"] is None
+
+
+# ---------------------------------------------------------------------------
+# runit backend
+# ---------------------------------------------------------------------------
+
+class TestRunitEnable:
+    """Test runit enable function."""
+
+    def test_enable_creates_symlink(self, tmp_path):
+        """Enable creates symlink to service directory."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        sv_dir.mkdir(parents=True)
+        service_link = tmp_path / "service" / "fenris-collect"
+        service_link.parent.mkdir(parents=True)
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("fenris.init_system.FENRIS_SERVICE_LINK", service_link):
+            _runit_enable(_now=True)
+            assert service_link.exists()
+            assert service_link.is_symlink()
+            assert service_link.resolve() == sv_dir
+
+    def test_enable_removes_down_file(self, tmp_path):
+        """Enable removes the 'down' file if present."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        sv_dir.mkdir(parents=True)
+        (sv_dir / "down").touch()
+        service_link = tmp_path / "service" / "fenris-collect"
+        service_link.parent.mkdir(parents=True)
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("fenris.init_system.FENRIS_SERVICE_LINK", service_link):
+            _runit_enable(_now=True)
+            assert not (sv_dir / "down").exists()
+
+    def test_enable_idempotent(self, tmp_path):
+        """Enable is idempotent when already enabled."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        sv_dir.mkdir(parents=True)
+        service_link = tmp_path / "service" / "fenris-collect"
+        service_link.parent.mkdir(parents=True)
+        service_link.symlink_to(sv_dir)
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("fenris.init_system.FENRIS_SERVICE_LINK", service_link):
+            _runit_enable(_now=True)
+            assert service_link.exists()
+
+
+class TestRunitDisable:
+    """Test runit disable function."""
+
+    def test_disable_removes_symlink(self, tmp_path):
+        """Disable removes the service symlink."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        sv_dir.mkdir(parents=True)
+        service_link = tmp_path / "service" / "fenris-collect"
+        service_link.parent.mkdir(parents=True)
+        service_link.symlink_to(sv_dir)
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("fenris.init_system.FENRIS_SERVICE_LINK", service_link):
+            _runit_disable(_now=True)
+            assert not service_link.exists()
+            assert (sv_dir / "down").exists()
+
+    def test_disable_idempotent(self, tmp_path):
+        """Disable is idempotent when already disabled."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        sv_dir.mkdir(parents=True)
+        service_link = tmp_path / "service" / "fenris-collect"
+        service_link.parent.mkdir(parents=True)
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("fenris.init_system.FENRIS_SERVICE_LINK", service_link):
+            _runit_disable(_now=True)
+            assert not service_link.exists()
+
+
+class TestRunitCollect:
+    """Test runit collect function."""
+
+    def test_collect_uses_flock(self):
+        """Collect uses flock for serialization."""
+        with patch("fenris.init_system.subprocess") as mock_sub, \
+             patch("fenris.init_system.Path") as mock_path:
+            mock_path.return_value.exists.return_value = True
+            mock_sub.run.return_value = MagicMock(returncode=0)
+            _runit_collect()
+            # Verify flock was used
+            call_args = mock_sub.run.call_args[0][0]
+            assert "flock" in call_args
+
+    def test_collect_timeout_exits(self):
+        """Collection timeout exits with error."""
+        with patch("fenris.init_system.subprocess") as mock_sub, \
+             patch("fenris.init_system.Path") as mock_path:
+            mock_path.return_value.exists.return_value = True
+            mock_sub.run.return_value = MagicMock(returncode=124)
+            with pytest.raises(SystemExit) as exc_info:
+                _runit_collect()
+            assert exc_info.value.code == 1
+
+
+class TestRunitQueryState:
+    """Test runit query state function."""
+
+    def test_query_state_enabled_running(self, tmp_path):
+        """Query state for enabled and running service."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        sv_dir.mkdir(parents=True)
+        supervise_dir = sv_dir / "supervise"
+        supervise_dir.mkdir(parents=True)
+        (supervise_dir / "pid").write_text("12345")
+        service_link = tmp_path / "service" / "fenris-collect"
+        service_link.parent.mkdir(parents=True)
+        service_link.symlink_to(sv_dir)
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("fenris.init_system.FENRIS_SERVICE_LINK", service_link), \
+             patch("os.kill") as mock_kill:
+            mock_kill.return_value = True  # Process exists
+            result = _runit_query_state()
+            assert result["boot_enabled"] is True
+            assert result["timer_active"] is True
+
+    def test_query_state_disabled_not_running(self, tmp_path):
+        """Query state for disabled and not running service."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        sv_dir.mkdir(parents=True)
+        service_link = tmp_path / "service" / "fenris-collect"
+        service_link.parent.mkdir(parents=True)
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("fenris.init_system.FENRIS_SERVICE_LINK", service_link):
+            result = _runit_query_state()
+            assert result["boot_enabled"] is False
+            assert result["timer_active"] is False
+
+
+class TestRunitIsEnabled:
+    """Test runit is_enabled check."""
+
+    def test_is_enabled_true(self, tmp_path):
+        """Service is enabled when symlink exists."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        sv_dir.mkdir(parents=True)
+        service_link = tmp_path / "service" / "fenris-collect"
+        service_link.parent.mkdir(parents=True)
+        service_link.symlink_to(sv_dir)
+
+        with patch("fenris.init_system.FENRIS_SERVICE_LINK", service_link):
+            assert _runit_is_enabled() is True
+
+    def test_is_enabled_false(self, tmp_path):
+        """Service is disabled when symlink does not exist."""
+        service_link = tmp_path / "service" / "fenris-collect"
+
+        with patch("fenris.init_system.FENRIS_SERVICE_LINK", service_link):
+            assert _runit_is_enabled() is False
+
+
+class TestRunitIsRunning:
+    """Test runit is_running check."""
+
+    def test_is_running_true(self, tmp_path):
+        """Service is running when PID file exists and process is alive."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        supervise_dir = sv_dir / "supervise"
+        supervise_dir.mkdir(parents=True)
+        (supervise_dir / "pid").write_text("12345")
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("os.kill") as mock_kill:
+            mock_kill.return_value = True
+            assert _runit_is_running() is True
+
+    def test_is_running_false_no_pid(self, tmp_path):
+        """Service is not running when PID file does not exist."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        sv_dir.mkdir(parents=True)
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("subprocess.run") as mock_run:
+            mock_run.return_value.returncode = 1
+            assert _runit_is_running() is False
+
+    def test_is_running_false_dead_process(self, tmp_path):
+        """Service is not running when process is dead."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        supervise_dir = sv_dir / "supervise"
+        supervise_dir.mkdir(parents=True)
+        (supervise_dir / "pid").write_text("12345")
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("os.kill", side_effect=OSError("No such process")):
+            assert _runit_is_running() is False
+
+    def test_is_running_uses_process_table_when_supervise_is_unreadable(self, tmp_path):
+        """Void keeps runit's supervise directory root-only for normal users."""
+        sv_dir = tmp_path / "sv" / "fenris-collect"
+        supervise_dir = sv_dir / "supervise"
+        supervise_dir.mkdir(parents=True)
+        pid_file = supervise_dir / "pid"
+        pid_file.write_text("12345")
+        service_link = tmp_path / "service" / "fenris-collect"
+        service_link.parent.mkdir(parents=True)
+        service_link.symlink_to(sv_dir)
+
+        original_read_text = Path.read_text
+
+        def deny_pid(path, *args, **kwargs):
+            if path == pid_file:
+                raise PermissionError("supervise is root-only")
+            return original_read_text(path, *args, **kwargs)
+
+        with patch("fenris.init_system.FENRIS_SV_DIR", sv_dir), \
+             patch("fenris.init_system.FENRIS_SERVICE_LINK", service_link), \
+             patch.object(Path, "read_text", autospec=True, side_effect=deny_pid), \
+             patch("subprocess.run") as mock_run:
+            mock_run.return_value.returncode = 0
+            assert _runit_is_running() is True
+            mock_run.assert_called_once_with(
+                ["pgrep", "-f", "^runsv fenris-collect$"],
+                capture_output=True,
+                text=True,
+                timeout=5,
+            )
+
+
+# ---------------------------------------------------------------------------
+# Public API dispatching
+# ---------------------------------------------------------------------------
+
+class TestPublicAPI:
+    """Test public API dispatches to correct backend."""
+
+    def test_enable_dispatches_to_systemd(self):
+        """enable_timer dispatches to systemd on systemd system."""
+        with patch("fenris.init_system.get_init_system", return_value=InitSystem.SYSTEMD), \
+             patch("fenris.init_system._systemd_enable") as mock_enable:
+            enable_timer(now=True)
+            mock_enable.assert_called_once_with(True)
+
+    def test_enable_dispatches_to_runit(self):
+        """enable_timer dispatches to runit on runit system."""
+        with patch("fenris.init_system.get_init_system", return_value=InitSystem.RUNIT), \
+             patch("fenris.init_system._runit_enable") as mock_enable:
+            enable_timer(now=True)
+            mock_enable.assert_called_once_with(True)
+
+    def test_disable_dispatches_to_systemd(self):
+        """disable_timer dispatches to systemd on systemd system."""
+        with patch("fenris.init_system.get_init_system", return_value=InitSystem.SYSTEMD), \
+             patch("fenris.init_system._systemd_disable") as mock_disable:
+            disable_timer(now=False)
+            mock_disable.assert_called_once_with(False)
+
+    def test_disable_dispatches_to_runit(self):
+        """disable_timer dispatches to runit on runit system."""
+        with patch("fenris.init_system.get_init_system", return_value=InitSystem.RUNIT), \
+             patch("fenris.init_system._runit_disable") as mock_disable:
+            disable_timer(now=False)
+            mock_disable.assert_called_once_with(False)
+
+    def test_collect_dispatches_to_systemd(self):
+        """collect_now dispatches to systemd on systemd system."""
+        with patch("fenris.init_system.get_init_system", return_value=InitSystem.SYSTEMD), \
+             patch("fenris.init_system._systemd_collect") as mock_collect:
+            collect_now()
+            mock_collect.assert_called_once()
+
+    def test_collect_dispatches_to_runit(self):
+        """collect_now dispatches to runit on runit system."""
+        with patch("fenris.init_system.get_init_system", return_value=InitSystem.RUNIT), \
+             patch("fenris.init_system._runit_collect") as mock_collect:
+            collect_now()
+            mock_collect.assert_called_once()
+
+    def test_query_state_dispatches_to_systemd(self):
+        """query_service_state dispatches to systemd on systemd system."""
+        with patch("fenris.init_system.get_init_system", return_value=InitSystem.SYSTEMD), \
+             patch("fenris.init_system._systemd_query_state") as mock_query:
+            query_service_state()
+            mock_query.assert_called_once()
+
+    def test_query_state_dispatches_to_runit(self):
+        """query_service_state dispatches to runit on runit system."""
+        with patch("fenris.init_system.get_init_system", return_value=InitSystem.RUNIT), \
+             patch("fenris.init_system._runit_query_state") as mock_query:
+            query_service_state()
+            mock_query.assert_called_once()
+
+    def test_journal_hint_dispatches_to_systemd(self):
+        """journal_hint dispatches to systemd on systemd system."""
+        with patch("fenris.init_system.get_init_system", return_value=InitSystem.SYSTEMD), \
+             patch("fenris.init_system._systemd_journal_hint") as mock_hint:
+            journal_hint(lines=3, unit="fenris-collect.service")
+            mock_hint.assert_called_once_with(3)
+
+    def test_journal_hint_dispatches_to_runit(self):
+        """journal_hint dispatches to runit on runit system."""
+        with patch("fenris.init_system.get_init_system", return_value=InitSystem.RUNIT), \
+             patch("fenris.init_system._runit_journal_hint") as mock_hint:
+            journal_hint(lines=3, unit="fenris-collect.service")
+            mock_hint.assert_called_once_with(3)
+
+
+# ---------------------------------------------------------------------------
+# Constants and configuration
+# ---------------------------------------------------------------------------
+
+class TestConstants:
+    """Test constants match spec requirements."""
+
+    def test_collect_timeout(self):
+        """Collection timeout is 90 seconds (bounded execution)."""
+        assert COLLECT_TIMEOUT_S == 90
+
+    def test_init_system_enum(self):
+        """InitSystem enum has systemd and runit variants."""
+        assert InitSystem.SYSTEMD.value == "systemd"
+        assert InitSystem.RUNIT.value == "runit"
+
+
+# ---------------------------------------------------------------------------
+# Integration with monitor.py
+# ---------------------------------------------------------------------------
+
+class TestMonitorIntegration:
+    """Test that monitor.py uses the abstraction layer correctly."""
+
+    def test_cmd_enable_uses_init_system(self, tmp_path):
+        """cmd_enable uses init_system.enable_timer."""
+        from fenris.monitor import cmd_enable
+        from argparse import Namespace
+
+        store_path = tmp_path / "observations.db"
+        init_store(store_path)
+        args = Namespace(now=True, store_path=store_path)
+
+        with patch("fenris.monitor.enable_timer") as mock_enable:
+            cmd_enable(args)
+            mock_enable.assert_called_once_with(True)
+
+    def test_cmd_disable_uses_init_system(self, tmp_path):
+        """cmd_disable uses init_system.disable_timer."""
+        from fenris.monitor import cmd_disable
+        from argparse import Namespace
+
+        store_path = tmp_path / "observations.db"
+        init_store(store_path)
+        args = Namespace(now=True, store_path=store_path)
+
+        with patch("fenris.monitor.disable_timer") as mock_disable:
+            cmd_disable(args)
+            mock_disable.assert_called_once_with(True)
+
+    def test_cmd_collect_uses_init_system(self):
+        """cmd_collect uses init_system.collect_now."""
+        from fenris.monitor import cmd_collect
+        from argparse import Namespace
+
+        args = Namespace()
+
+        with patch("fenris.monitor.collect_now") as mock_collect:
+            cmd_collect(args)
+            mock_collect.assert_called_once()
+
+
+# ---------------------------------------------------------------------------
+# Edge cases
+# ---------------------------------------------------------------------------
+
+class TestEdgeCases:
+    """Test edge cases and error handling."""
+
+    def test_systemd_enable_failure_produces_stderr(self):
+        """Systemd enable failure produces error message on stderr."""
+        with patch("fenris.init_system.subprocess") as mock_sub:
+            mock_sub.run.return_value = MagicMock(
+                returncode=1, stderr="Permission denied"
+            )
+            with pytest.raises(SystemExit):
+                _systemd_enable(now=True)
+
+    def test_runit_collect_missing_script(self):
+        """Runit collect exits when fenris-collect script not found."""
+        with patch("fenris.init_system.Path") as mock_path:
+            mock_path.return_value.exists.return_value = False
+            with pytest.raises(SystemExit) as exc_info:
+                _runit_collect()
+            assert exc_info.value.code == 1
+
+    def test_systemd_query_state_timeout(self):
+        """Systemd query state handles subprocess timeout."""
+        with patch("fenris.init_system._systemctl_show") as mock_show:
+            mock_show.return_value = {}
+            result = _systemd_query_state()
+            assert result["boot_enabled"] is False
+            assert result["timer_active"] is False

tests/test_issue_77.py

@@ -0,0 +1,258 @@
+"""Tests for issue #77: Show honest qualifying-day progress and confidence.
+
+These tests verify that:
+1. Warming progress shows detailed qualifying day breakdown
+2. Confidence state accurately reflects qualifying day progress
+3. Edge cases like zero-delta intervals and unknown daily shares are handled
+4. qualifying_days_progress shows honest qualifying day count
+"""
+import sqlite3
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+
+import pytest
+import sys
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.store import init_store
+from fenris.monitoring_periods import ensure_period_open, close_period
+from fenris.projection import (
+    compute_projection, ConfidenceState, BaselineTier,
+    WARMING_MIN_DAYS, WARMING_COVERAGE_FLOOR, WARMING_MAX_LOW_COVERAGE,
+)
+
+
+@pytest.fixture
+def store(tmp_path):
+    conn = init_store(tmp_path / "test.db")
+    yield conn
+    conn.close()
+
+
+def _clock(year=2026, month=9, day=30, hour=12):
+    return datetime(year, month, day, hour, 0, 0, tzinfo=timezone.utc)
+
+
+def _insert_baseline(conn, tbw_tb=1.0, verified=True, model="Samsung SSD 970 EVO Plus 1TB"):
+    conn.execute(
+        "INSERT INTO endurance_baseline "
+        "(tbw_terabytes, source_url, document_revision, entry_date, model_string, "
+        " nominal_capacity_bytes, validated_by, verified, created_at, updated_at) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        (tbw_tb, "https://example.com/spec", "v1.0", "2026-01-01", model, 1024000000000,
+         "machine_match" if verified else None, verified, "2026-01-01T00:00:00+00:00",
+         "2026-01-01T00:00:00+00:00"),
+    )
+    conn.commit()
+
+
+def _insert_segment(conn, opened_at="2026-09-01T00:00:00+00:00",
+                     identity_key="nqn.test", degraded=False,
+                     mn="Samsung SSD 970 EVO Plus 1TB"):
+    conn.execute(
+        "INSERT INTO controller_segments "
+        "(opened_at, identity_key, identity_degraded, subnqn, sn, mn, fr, vid, ssvid, transport) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        (opened_at, identity_key, degraded, "nqn.test", "SN123", mn, "FW1", "0x144d", "0x144d", "pcie"),
+    )
+    conn.commit()
+
+
+def _insert_day(conn, day, bw=1024*1024*100, coverage=0.95, samples=24):
+    conn.execute(
+        "INSERT INTO day_aggregates (day, active_seconds, idle_seconds, powered_off_seconds, "
+        "unknown_seconds, bytes_written_delta, bytes_read_delta, sample_count, coverage) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        (day, 3600, 0, 0, 0, bw, 0, samples, coverage),
+    )
+    conn.commit()
+
+
+def _insert_sample(conn, ts, pu=5):
+    conn.execute(
+        "INSERT INTO samples (ts, device, data_units_written, data_units_read, "
+        "percentage_used, bytes_written, bytes_read, power_on_hours) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
+        (ts, "/dev/nvme0n1", 1000000, 500000, pu, 512000000000, 256000000000, 8765),
+    )
+    conn.commit()
+
+
+def _open_period(conn, start="2026-09-01T00:00:00+00:00"):
+    # Convert string to datetime if needed
+    if isinstance(start, str):
+        start = datetime.fromisoformat(start)
+    ensure_period_open(conn, start)
+    conn.commit()
+
+
+class TestHonestQualifyingProgress:
+    """Issue #77: Show honest qualifying-day progress and confidence."""
+
+    def test_warming_shows_qualifying_vs_nonqualifying(self, store):
+        """Warming progress shows both qualifying and non-qualifying days."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-20T00:00:00+00:00")
+        _open_period(store, start="2026-09-20T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        
+        # 12 qualifying days + 2 non-qualifying (low coverage)
+        for i in range(14):
+            d = (datetime(2026, 9, 20) + timedelta(days=i)).strftime("%Y-%m-%d")
+            cov = 0.30 if i < 2 else 0.95  # First 2 days have low coverage
+            _insert_day(store, d, bw=bw, coverage=cov)
+        
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        
+        # After warming, qualifying_days_progress shows honest count
+        assert result.warming_fact is None  # Not warming (14 total, 2 below <= WARMING_MAX_LOW_COVERAGE)
+        assert result.qualifying_days_progress is not None
+        assert "12 of 14 qualifying days" in result.qualifying_days_progress
+        assert "2 below coverage" in result.qualifying_days_progress
+        
+    def test_warming_progress_includes_nonqualifying_reason(self, store):
+        """Warming progress indicates why days don't qualify."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-20T00:00:00+00:00")
+        _open_period(store, start="2026-09-20T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        
+        # 13 qualifying days + 1 non-qualifying (zero samples)
+        for i in range(14):
+            d = (datetime(2026, 9, 20) + timedelta(days=i)).strftime("%Y-%m-%d")
+            samples = 0 if i == 0 else 24  # First day has no samples
+            _insert_day(store, d, bw=bw, samples=samples)
+        
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        
+        # After warming, qualifying_days_progress shows honest count
+        assert result.warming_fact is None  # Not warming (14 total, 1 below <= WARMING_MAX_LOW_COVERAGE)
+        assert result.qualifying_days_progress is not None
+        assert "13 of 14 qualifying days" in result.qualifying_days_progress
+        assert "1 below coverage" in result.qualifying_days_progress
+        
+    def test_confidence_updates_as_qualifying_days_increase(self, store):
+        """Confidence state reflects actual qualifying day count."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-20T00:00:00+00:00")
+        _open_period(store, start="2026-09-20T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        
+        # Start with 10 days (below minimum)
+        for i in range(10):
+            d = (datetime(2026, 9, 20) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, d, bw=bw, coverage=0.95)
+        
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        
+        # Should be warming
+        assert result.warming_fact is not None
+        assert result.confidence_state == ConfidenceState.LIMITED
+        
+    def test_zero_rate_with_qualifying_days(self, store):
+        """Zero rate with qualifying days shows honest state."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-20T00:00:00+00:00")
+        _open_period(store, start="2026-09-20T00:00:00+00:00")
+        
+        # 14 days with zero bytes written
+        for i in range(14):
+            d = (datetime(2026, 9, 20) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, d, bw=0, coverage=0.95)
+        
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        
+        # Zero rate should be UNSUPPORTED
+        assert result.confidence_state == ConfidenceState.UNSUPPORTED
+        assert result.zero_rate_fact is not None
+        assert "no finite projection" in result.zero_rate_fact
+        
+    def test_qualifying_days_excludes_low_coverage(self, store):
+        """Days below 50% coverage don't count as qualifying."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-20T00:00:00+00:00")
+        _open_period(store, start="2026-09-20T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        
+        # 14 days total, but 3 have low coverage
+        for i in range(14):
+            d = (datetime(2026, 9, 20) + timedelta(days=i)).strftime("%Y-%m-%d")
+            cov = 0.30 if i < 3 else 0.95
+            _insert_day(store, d, bw=bw, coverage=cov)
+        
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        
+        # Should still be warming (3 days below coverage > WARMING_MAX_LOW_COVERAGE=2)
+        assert result.warming_fact is not None
+        assert "warming up" in result.warming_fact.lower()
+        
+    def test_qualifying_days_excludes_zero_samples(self, store):
+        """Days with zero samples don't count as qualifying."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-20T00:00:00+00:00")
+        _open_period(store, start="2026-09-20T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        
+        # 14 days total, but 3 have zero samples
+        for i in range(14):
+            d = (datetime(2026, 9, 20) + timedelta(days=i)).strftime("%Y-%m-%d")
+            samples = 0 if i < 3 else 24
+            _insert_day(store, d, bw=bw, samples=samples)
+        
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        
+        # Should still be warming
+        assert result.warming_fact is not None
+        assert "warming up" in result.warming_fact.lower()
+        
+    def test_qualifying_days_progress_after_warming(self, store):
+        """After warming, qualifying_days_progress shows honest count."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-17T00:00:00+00:00")
+        _open_period(store, start="2026-09-17T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        
+        # 14 total days, 12 qualifying (2 below coverage)
+        for i in range(14):
+            d = (datetime(2026, 9, 17) + timedelta(days=i)).strftime("%Y-%m-%d")
+            cov = 0.30 if i < 2 else 0.95  # First 2 days have low coverage
+            _insert_day(store, d, bw=bw, coverage=cov)
+        
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        
+        # Should not be warming (14 total, 2 below coverage <= WARMING_MAX_LOW_COVERAGE)
+        assert result.warming_fact is None
+        # But qualifying_days_progress should show the honest count
+        assert result.qualifying_days_progress is not None
+        assert "12 of 14 qualifying days" in result.qualifying_days_progress
+        assert "2 below coverage" in result.qualifying_days_progress
+        
+    def test_qualifying_days_progress_all_qualifying(self, store):
+        """When all days qualify, qualifying_days_progress shows 100%."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-17T00:00:00+00:00")
+        _open_period(store, start="2026-09-17T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        
+        # 14 days, all qualifying
+        for i in range(14):
+            d = (datetime(2026, 9, 17) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, d, bw=bw, coverage=0.95)
+        
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        
+        # Should not be warming
+        assert result.warming_fact is None
+        # qualifying_days_progress should show all qualifying
+        assert result.qualifying_days_progress is not None
+        assert "14 of 14 qualifying days" in result.qualifying_days_progress
+        # Should not show "below coverage" since all qualify
+        assert "below coverage" not in result.qualifying_days_progress

tests/test_issue_79.py

@@ -0,0 +1,318 @@
+"""Tests for issue #79: Apply Fenris identity and Drive health grouping.
+
+Covers:
+- TPH-1: Titlebox shows Fenris identity with wolf fallback
+- TPH-11: Single maker-credit placement, vendor wear under Drive health
+- Preserve: continuity, pause block, quit rail, auth banner
+"""
+import sqlite3
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+import sys
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.store import init_store
+from fenris.monitoring_periods import ensure_period_open
+from fenris.tui import FenrisTuiApp
+
+
+# ---------------------------------------------------------------------------
+# Helpers (reuse from test_tui.py)
+# ---------------------------------------------------------------------------
+
+def _clock(year=2026, month=9, day=30, hour=12):
+    return datetime(year, month, day, hour, 0, 0, tzinfo=timezone.utc)
+
+
+def _insert_baseline(conn, tbw_tb=1.0, verified=True,
+                      model="Samsung SSD 970 EVO Plus 1TB"):
+    conn.execute(
+        "INSERT INTO endurance_baseline "
+        "(tbw_terabytes, source_url, document_revision, entry_date, model_string, "
+        " nominal_capacity_bytes, validated_by, verified, created_at, updated_at) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        (tbw_tb, "https://example.com/spec", "v1.0", "2026-01-01", model,
+         1024000000000, "machine_match" if verified else None, verified,
+         "2026-01-01T00:00:00+00:00", "2026-01-01T00:00:00+00:00"),
+    )
+    conn.commit()
+
+
+def _insert_segment(conn, opened_at="2026-09-01T00:00:00+00:00",
+                     identity_key="nqn.test", degraded=False,
+                     mn="Samsung SSD 970 EVO Plus 1TB"):
+    conn.execute(
+        "INSERT INTO controller_segments "
+        "(opened_at, identity_key, identity_degraded, subnqn, sn, mn, fr, vid, ssvid, transport) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        (opened_at, identity_key, degraded, "nqn.test", "SN123", mn, "FW1",
+         "0x144d", "0x144d", "pcie"),
+    )
+    conn.commit()
+
+
+def _insert_day(conn, day, bw=1024*1024*100, coverage=0.95, samples=24):
+    conn.execute(
+        "INSERT INTO day_aggregates (day, active_seconds, idle_seconds, powered_off_seconds, "
+        "unknown_seconds, bytes_written_delta, bytes_read_delta, sample_count, coverage) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        (day, 3600, 0, 0, 0, bw, 0, samples, coverage),
+    )
+    conn.commit()
+
+
+def _insert_sample(conn, ts, pu=5, device="/dev/nvme0n1"):
+    conn.execute(
+        "INSERT INTO samples (ts, device, data_units_written, data_units_read, "
+        "percentage_used, bytes_written, bytes_read, power_on_hours) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
+        (ts, device, 1000000, 500000, pu, 512000000000, 256000000000, 8765),
+    )
+    conn.commit()
+
+
+def _open_period(conn, start="2026-09-01T00:00:00+00:00"):
+    ensure_period_open(conn, datetime.fromisoformat(start))
+
+
+# ---------------------------------------------------------------------------
+# Issue #79: Fenris identity and Drive health grouping
+# ---------------------------------------------------------------------------
+
+class TestFenrisIdentity:
+    """TPH-1: Titlebox shows Fenris identity with wolf fallback."""
+
+    @pytest.mark.asyncio
+    async def test_titlebox_shows_wolf_identity(self, tmp_path):
+        """Top titlebox reads 🐺 Fenris by Bongbetic."""
+        app = FenrisTuiApp(
+            store_path=tmp_path / "nonexistent.db",
+            refresh_interval_s=0.2,
+        )
+        async with app.run_test(size=(120, 24)) as pilot:
+            headline = str(app.query_one("#headline-band").render())
+            assert "🐺 Fenris by Bongbetic" in headline
+
+    @pytest.mark.asyncio
+    async def test_titlebox_fallback_without_wolf(self, tmp_path):
+        """Fallback to 'Fenris by Bongbetic' when wolf is unsupported."""
+        app = FenrisTuiApp(
+            store_path=tmp_path / "nonexistent.db",
+            refresh_interval_s=0.2,
+        )
+        # Simulate narrow terminal that can't render wolf
+        async with app.run_test(size=(60, 24)) as pilot:
+            headline = str(app.query_one("#headline-band").render())
+            # Either shows wolf or fallback - both are acceptable
+            assert "Fenris by Bongbetic" in headline
+
+    @pytest.mark.asyncio
+    async def test_wolf_never_shows_tofu(self, tmp_path):
+        """Wolf glyph is never rendered as tofu (unsupported character)."""
+        app = FenrisTuiApp(
+            store_path=tmp_path / "nonexistent.db",
+            refresh_interval_s=0.2,
+        )
+        async with app.run_test(size=(120, 24)) as pilot:
+            headline = str(app.query_one("#headline-band").render())
+            # No replacement character (U+FFFD) should appear
+            assert "\ufffd" not in headline.lower()
+            assert "?" not in headline or "Fenris" in headline
+
+    @pytest.mark.asyncio
+    async def test_lifespan_headline_is_data_surface(self, tmp_path):
+        """Lifespan headline remains a data surface, not app title."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_baseline(conn, tbw_tb=1.0, verified=True)
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(30):
+            d = (datetime(2026, 9, 1) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100, coverage=0.95, samples=24)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(120, 24)) as pilot:
+            headline = str(app.query_one("#headline-band").render())
+            # Identity appears once, lifespan is separate data
+            assert "🐺 Fenris by Bongbetic" in headline
+            assert "remaining" in headline.lower() or "projection" in headline.lower()
+
+
+class TestSingleMakerCredit:
+    """TPH-1: Single maker-credit placement in title only."""
+
+    @pytest.mark.asyncio
+    async def test_maker_credit_not_in_service_strip(self, tmp_path):
+        """Remove duplicate maker credit from service facts."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(20):
+            d = (datetime(2026, 9, 10) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(120, 24)) as pilot:
+            strip = str(app.query_one("#service-strip").render())
+            # "by Bongbetic" should NOT appear in service strip
+            assert "by Bongbetic" not in strip
+
+    @pytest.mark.asyncio
+    async def test_maker_credit_in_titlebox(self, tmp_path):
+        """Maker credit appears in the titlebox identity."""
+        app = FenrisTuiApp(
+            store_path=tmp_path / "nonexistent.db",
+            refresh_interval_s=0.2,
+        )
+        async with app.run_test(size=(120, 24)) as pilot:
+            headline = str(app.query_one("#headline-band").render())
+            assert "Fenris by Bongbetic" in headline
+
+    @pytest.mark.asyncio
+    async def test_empty_store_no_maker_credit_in_strip(self, tmp_path):
+        """Empty store: no maker credit in service strip."""
+        app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+        async with app.run_test(size=(120, 24)) as pilot:
+            strip = str(app.query_one("#service-strip").render())
+            assert "by Bongbetic" not in strip
+
+    @pytest.mark.asyncio
+    async def test_store_fault_no_maker_credit_in_strip(self, tmp_path):
+        """Store fault: no maker credit in service strip."""
+        # Create a corrupt store
+        db = tmp_path / "test.db"
+        db.write_bytes(b"not a database")
+        app = FenrisTuiApp(store_path=db)
+        async with app.run_test(size=(120, 24)) as pilot:
+            strip = str(app.query_one("#service-strip").render())
+            assert "by Bongbetic" not in strip
+
+
+class TestDriveHealthVendorWear:
+    """TPH-1: Vendor wear renders under Drive health context."""
+
+    @pytest.mark.asyncio
+    async def test_vendor_wear_in_drive_health(self, tmp_path):
+        """Vendor wear shows with health context, not as Settings."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(20):
+            d = (datetime(2026, 9, 10) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00", pu=10)
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(120, 24)) as pilot:
+            health = str(app.query_one("#drive-health").render())
+            # Vendor wear should be present with health context
+            assert "vendor wear" in health.lower()
+            # Should show thermal, spare, errors, etc.
+            assert "temperature" in health.lower()
+            assert "spare" in health.lower()
+            assert "media errors" in health.lower()
+            # Settings section should NOT be a separate heading
+            assert "[bold]Settings[/bold]" not in health
+
+    @pytest.mark.asyncio
+    async def test_missing_wear_values_honest(self, tmp_path):
+        """Missing values remain honest unavailable facts."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(20):
+            d = (datetime(2026, 9, 10) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        # Insert sample with zero wear values
+        conn.execute(
+            "INSERT INTO samples (ts, device, data_units_written, data_units_read, "
+            "percentage_used, bytes_written, bytes_read, power_on_hours) "
+            "VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
+            ("2026-09-30T10:00:00+00:00", "/dev/nvme0n1", 0, 0, 0, 0, 0, 0),
+        )
+        conn.commit()
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(120, 24)) as pilot:
+            health = str(app.query_one("#drive-health").render())
+            # Should show 0% used or honest zero, not crash
+            assert "vendor wear" in health.lower()
+
+
+class TestPreservedBehavior:
+    """Preserve existing continuity, pause, quit, auth behavior."""
+
+    @pytest.mark.asyncio
+    async def test_continuity_preserved(self, tmp_path):
+        """Continuity wording preserved in service strip."""
+        conn = init_store(tmp_path / "test.db")
+        _open_period(conn)
+        conn.close()
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+
+        with patch("fenris.tui.query_service_state", return_value={
+            "boot_enabled": True, "timer_active": True,
+            "last_collect_ok": True, "last_collect_age_s": 60,
+            "last_collect_reason": None,
+        }):
+            async with app.run_test(size=(120, 24)) as pilot:
+                strip = str(app.query_one("#service-strip").render())
+                assert "continuity" in strip.lower()
+                assert "monitoring" in strip.lower()
+
+    @pytest.mark.asyncio
+    async def test_quit_rail_preserved(self, tmp_path):
+        """Separate q QUIT TUI rail preserved."""
+        app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+        async with app.run_test(size=(120, 24)) as pilot:
+            rail = str(app.query_one("#quit-rail").render())
+            assert "q QUIT TUI" in rail
+
+    @pytest.mark.asyncio
+    async def test_auth_banner_preserved(self, tmp_path):
+        """Polkit authentication banner lifecycle preserved."""
+        app = FenrisTuiApp(
+            store_path=tmp_path / "nonexistent.db",
+            refresh_interval_s=0.2,
+        )
+        async with app.run_test(size=(120, 24)) as pilot:
+            headline = str(app.query_one("#headline-band").render())
+            assert "polkit" in headline.lower()
+            # Should clear after first tick
+            await pilot.pause(0.25)
+            headline_after = str(app.query_one("#headline-band").render())
+            assert "polkit" not in headline_after.lower()
+
+    @pytest.mark.asyncio
+    async def test_deliberate_pause_block_preserved(self, tmp_path):
+        """Deliberate pause banner preserved."""
+        db = tmp_path / "test.db"
+        conn = init_store(db)
+        conn.execute(
+            "INSERT INTO monitoring_periods (started_at, ended_at, end_cause) "
+            "VALUES (?, ?, ?)",
+            ("2026-09-01T09:00:00+00:00", "2026-09-01T10:00:00+00:00", "user_disabled"),
+        )
+        conn.commit()
+        conn.close()
+        app = FenrisTuiApp(store_path=db)
+
+        with patch("fenris.tui.query_service_state", return_value={
+            "boot_enabled": False, "timer_active": False,
+            "last_collect_ok": None, "last_collect_age_s": None,
+            "last_collect_reason": None,
+        }):
+            async with app.run_test(size=(120, 24)) as pilot:
+                banner = str(app.query_one("#paused-banner").render())
+                assert "paused" in banner.lower()
+                assert "deliberate" in banner.lower()

tests/test_issue_80.py

@@ -0,0 +1,482 @@
+"""Integration tests for issue #80: Persist accessible colour and motion preferences.
+
+Covers:
+  - AC80-1: Amber/Nord/High Contrast presets with Amber default
+  - AC80-2: t preset and m motion controls with clickable equivalents
+  - AC80-3: Persistent user-scoped XDG TUI preferences
+  - AC80-4: Reduced motion makes Monitoring steady
+  - AC80-5: Theme roles for graph rendering
+  - AC80-6: Headless interaction tests with temporary user config
+"""
+import json
+import os
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+import sys
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.store import init_store
+from fenris.preferences import (
+    load_preferences,
+    save_preferences,
+    get_preference_path,
+)
+from fenris.themes import get_theme, get_graph_colors, THEME_NAMES
+from fenris.status_composition import (
+    StatusState,
+    compose_status,
+    render_status_tui,
+)
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+def _clock(year=2026, month=9, day=30, hour=12):
+    return datetime(year, month, day, hour, 0, 0, tzinfo=timezone.utc)
+
+
+def _insert_segment(conn, opened_at="2026-09-01T00:00:00+00:00",
+                     identity_key="nqn.test", degraded=False,
+                     mn="Samsung SSD 970 EVO Plus 1TB"):
+    conn.execute(
+        "INSERT INTO controller_segments "
+        "(opened_at, identity_key, identity_degraded, subnqn, sn, mn, fr, vid, ssvid, transport) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        (opened_at, identity_key, degraded, "nqn.test", "SN123", mn, "FW1",
+         "0x144d", "0x144d", "pcie"),
+    )
+    conn.commit()
+
+
+def _insert_day(conn, day, bw=1024*1024*100, coverage=0.95, samples=24):
+    conn.execute(
+        "INSERT INTO day_aggregates (day, active_seconds, idle_seconds, powered_off_seconds, "
+        "unknown_seconds, bytes_written_delta, bytes_read_delta, sample_count, coverage) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        (day, 3600, 0, 0, 0, bw, 0, samples, coverage),
+    )
+    conn.commit()
+
+
+def _insert_sample(conn, ts, device="/dev/nvme0n1"):
+    conn.execute(
+        "INSERT INTO samples (ts, device, data_units_written, data_units_read, "
+        "percentage_used, bytes_written, bytes_read, power_on_hours) "
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
+        (ts, device, 1000000, 500000, 5, 512000000000, 256000000000, 8765),
+    )
+    conn.commit()
+
+
+def _open_period(conn, start="2026-09-01T00:00:00+00:00"):
+    from fenris.monitoring_periods import ensure_period_open
+    ensure_period_open(conn, datetime.fromisoformat(start))
+
+
+def _make_prefs_dir(tmp_path: Path) -> Path:
+    config_home = tmp_path / ".config"
+    config_home.mkdir(parents=True, exist_ok=True)
+    return config_home
+
+
+# ---------------------------------------------------------------------------
+# AC80-1: Preset loading and application
+# ---------------------------------------------------------------------------
+
+class TestPresetLoading:
+    """Themes load from preferences and apply to the TUI."""
+
+    @pytest.mark.asyncio
+    async def test_tui_applies_amber_theme_by_default(self, tmp_path):
+        """TUI starts with the Amber theme when no preferences exist."""
+        from fenris.tui import FenrisTuiApp
+
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app.run_test() as pilot:
+                # Theme should be fenris-amber
+                assert app.theme == "fenris-amber"
+
+    @pytest.mark.asyncio
+    async def test_tui_applies_nord_theme_from_prefs(self, tmp_path):
+        """TUI applies Nord theme from saved preferences."""
+        from fenris.tui import FenrisTuiApp
+
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="nord", reduced_motion=False)
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app.run_test() as pilot:
+                assert app.theme == "fenris-nord"
+
+    @pytest.mark.asyncio
+    async def test_tui_applies_high_contrast_from_prefs(self, tmp_path):
+        """TUI applies High Contrast theme from saved preferences."""
+        from fenris.tui import FenrisTuiApp
+
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="high_contrast", reduced_motion=False)
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app.run_test() as pilot:
+                assert app.theme == "fenris-high-contrast"
+
+    @pytest.mark.asyncio
+    async def test_tui_applies_reduced_motion_from_prefs(self, tmp_path):
+        """TUI respects reduced_motion preference."""
+        from fenris.tui import FenrisTuiApp
+        from fenris.status_composition import compose_status
+
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="amber", reduced_motion=True)
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app.run_test() as pilot:
+                # The app should have reduced_motion set
+                assert app._reduced_motion is True
+
+
+# ---------------------------------------------------------------------------
+# AC80-2: t and m key bindings
+# ---------------------------------------------------------------------------
+
+class TestKeyBindings:
+    """t cycles presets and m toggles reduced motion."""
+
+    @pytest.mark.asyncio
+    async def test_t_binding_exists(self, tmp_path):
+        """The TUI has a 't' binding for theme cycling."""
+        from fenris.tui import FenrisTuiApp
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            binding_keys = {b.key for b in app.BINDINGS}
+            assert "t" in binding_keys
+
+    @pytest.mark.asyncio
+    async def test_m_binding_exists(self, tmp_path):
+        """The TUI has an 'm' binding for motion toggle."""
+        from fenris.tui import FenrisTuiApp
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            binding_keys = {b.key for b in app.BINDINGS}
+            assert "m" in binding_keys
+
+    @pytest.mark.asyncio
+    async def test_t_cycles_through_themes(self, tmp_path):
+        """Pressing t cycles through the three presets."""
+        from fenris.tui import FenrisTuiApp
+
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app.run_test() as pilot:
+                # Start at amber
+                assert app.theme == "fenris-amber"
+
+                # Press t to cycle
+                await pilot.press("t")
+                await pilot.pause()
+
+                # Should be nord or high_contrast now
+                assert app.theme in ("fenris-nord", "fenris-high-contrast")
+
+    @pytest.mark.asyncio
+    async def test_m_toggles_reduced_motion(self, tmp_path):
+        """Pressing m toggles reduced motion."""
+        from fenris.tui import FenrisTuiApp
+
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app.run_test() as pilot:
+                # Start with normal motion
+                assert app._reduced_motion is False
+
+                # Press m to toggle
+                await pilot.press("m")
+                await pilot.pause()
+
+                # Should be reduced motion now
+                assert app._reduced_motion is True
+
+                # Press m again to toggle back
+                await pilot.press("m")
+                await pilot.pause()
+
+                assert app._reduced_motion is False
+
+
+# ---------------------------------------------------------------------------
+# AC80-3: Persistence across restart
+# ---------------------------------------------------------------------------
+
+class TestPersistence:
+    """Preferences survive app restart."""
+
+    @pytest.mark.asyncio
+    async def test_theme_survives_restart(self, tmp_path):
+        """Theme preference persists across TUI restart."""
+        from fenris.tui import FenrisTuiApp
+
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            # First run: change theme
+            app1 = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app1.run_test() as pilot:
+                await pilot.press("t")
+                await pilot.pause()
+                theme_after_t = app1.theme
+                assert theme_after_t != "fenris-amber"
+
+            # Second run: theme should persist
+            app2 = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app2.run_test() as pilot:
+                assert app2.theme == theme_after_t
+
+    @pytest.mark.asyncio
+    async def test_reduced_motion_survives_restart(self, tmp_path):
+        """Reduced motion preference persists across TUI restart."""
+        from fenris.tui import FenrisTuiApp
+
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            # First run: toggle motion
+            app1 = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app1.run_test() as pilot:
+                await pilot.press("m")
+                await pilot.pause()
+                assert app1._reduced_motion is True
+
+            # Second run: motion should persist
+            app2 = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app2.run_test() as pilot:
+                assert app2._reduced_motion is True
+
+
+# ---------------------------------------------------------------------------
+# AC80-4: Reduced motion makes Monitoring steady
+# ---------------------------------------------------------------------------
+
+class TestReducedMotion:
+    """Reduced motion disables the Monitoring dot blink."""
+
+    def test_reduced_motion_disables_blink(self, tmp_path):
+        """compose_status with reduced_motion=True → should_blink=False."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        now = _clock()
+        ts = (now - timedelta(minutes=2)).isoformat()
+        _insert_sample(conn, ts)
+        for i in range(20):
+            d = (datetime(2026, 9, 10) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        conn.close()
+
+        conn = init_store(tmp_path / "test.db")
+        svc = {
+            "boot_enabled": True, "timer_active": True,
+            "last_collect_ok": True, "last_collect_age_s": 120,
+            "last_collect_reason": None,
+        }
+        comp = compose_status(conn, svc, now, store_fault=None, newer_schema=None,
+                              reduced_motion=True)
+        assert comp.state == StatusState.MONITORING
+        assert comp.should_blink is False
+        conn.close()
+
+    def test_normal_motion_allows_blink(self, tmp_path):
+        """compose_status with reduced_motion=False → should_blink=True for Monitoring."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        now = _clock()
+        ts = (now - timedelta(minutes=2)).isoformat()
+        _insert_sample(conn, ts)
+        for i in range(20):
+            d = (datetime(2026, 9, 10) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        conn.close()
+
+        conn = init_store(tmp_path / "test.db")
+        svc = {
+            "boot_enabled": True, "timer_active": True,
+            "last_collect_ok": True, "last_collect_age_s": 120,
+            "last_collect_reason": None,
+        }
+        comp = compose_status(conn, svc, now, store_fault=None, newer_schema=None,
+                              reduced_motion=False)
+        assert comp.state == StatusState.MONITORING
+        assert comp.should_blink is True
+        conn.close()
+
+    @pytest.mark.asyncio
+    async def test_framework_reduced_motion_honoured(self, tmp_path):
+        """TUI honours Textual's reduced_motion signal."""
+        from fenris.tui import FenrisTuiApp
+
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app.run_test() as pilot:
+                # The app should check for reduced motion on mount
+                assert hasattr(app, '_reduced_motion')
+
+
+# ---------------------------------------------------------------------------
+# AC80-5: Theme roles for graph rendering
+# ---------------------------------------------------------------------------
+
+class TestGraphThemeRoles:
+    """Graph uses theme-derived colours for each bar role."""
+
+    def test_graph_colors_available_for_all_themes(self):
+        """Every theme provides all required graph colour roles."""
+        required_roles = {"allocated", "unallocated", "gap", "zero", "partial"}
+        for name in THEME_NAMES:
+            colors = get_graph_colors(name)
+            assert required_roles.issubset(set(colors.keys())),                 "Theme %s missing roles: %s" % (name, required_roles - set(colors.keys()))
+
+    def test_graph_colors_are_strings(self):
+        """All graph colour values are strings (Textual CSS colour values)."""
+        for name in THEME_NAMES:
+            colors = get_graph_colors(name)
+            for role, color in colors.items():
+                assert isinstance(color, str),                     "Theme %s role %s has non-string color: %s" % (name, role, color)
+
+
+# ---------------------------------------------------------------------------
+# AC80-6: Safe persistence — failure modes
+# ---------------------------------------------------------------------------
+
+class TestSafePersistence:
+    """Preference failures never crash the dashboard."""
+
+    @pytest.mark.asyncio
+    async def test_corrupt_prefs_does_not_crash_tui(self, tmp_path):
+        """Corrupt preference file does not prevent TUI from starting."""
+        from fenris.tui import FenrisTuiApp
+
+        config_home = _make_prefs_dir(tmp_path)
+        fenris_dir = config_home / "fenris"
+        fenris_dir.mkdir(parents=True, exist_ok=True)
+        (fenris_dir / "preferences.json").write_text("{bad json!!!")
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app.run_test() as pilot:
+                # TUI should start with default theme
+                assert app.theme == "fenris-amber"
+                # Dashboard should be functional
+                headline = str(app.query_one("#headline-band").render())
+                assert headline is not None
+
+    @pytest.mark.asyncio
+    async def test_readonly_config_dir_does_not_crash(self, tmp_path):
+        """Read-only config directory does not prevent TUI from starting."""
+        from fenris.tui import FenrisTuiApp
+
+        config_home = _make_prefs_dir(tmp_path)
+        fenris_dir = config_home / "fenris"
+        fenris_dir.mkdir(parents=True, exist_ok=True)
+        fenris_dir.chmod(0o555)
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+            async with app.run_test() as pilot:
+                # TUI should start without crash
+                assert app.theme in ("fenris-amber", "fenris-nord", "fenris-high-contrast")
+
+
+# ---------------------------------------------------------------------------
+# CLI isolation (preferences do not affect CLI)
+# ---------------------------------------------------------------------------
+
+class TestCLIIsolation:
+    """Preferences are TUI-only — CLI status is independent."""
+
+    def test_cli_status_unchanged_by_theme(self, tmp_path):
+        """fenris status output does not change based on theme preference."""
+        from fenris.status import get_status
+
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        now = _clock()
+        ts = (now - timedelta(minutes=2)).isoformat()
+        _insert_sample(conn, ts)
+        for i in range(20):
+            d = (datetime(2026, 9, 10) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        conn.close()
+
+        config_home = _make_prefs_dir(tmp_path)
+
+        # With amber theme
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="amber", reduced_motion=False)
+            status_amber = get_status(
+                store_path=tmp_path / "test.db",
+                clock_now=now,
+                query_services=False,
+                query_journal=False,
+            )
+
+        # With high contrast theme
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="high_contrast", reduced_motion=True)
+            status_hc = get_status(
+                store_path=tmp_path / "test.db",
+                clock_now=now,
+                query_services=False,
+                query_journal=False,
+            )
+
+        # Status output should be identical
+        assert status_amber == status_hc
+
+    def test_cli_status_unchanged_by_motion(self, tmp_path):
+        """fenris status output does not change based on reduced_motion preference."""
+        from fenris.status import get_status
+
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        now = _clock()
+        ts = (now - timedelta(minutes=2)).isoformat()
+        _insert_sample(conn, ts)
+        for i in range(20):
+            d = (datetime(2026, 9, 10) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        conn.close()
+
+        config_home = _make_prefs_dir(tmp_path)
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="amber", reduced_motion=False)
+            status_normal = get_status(
+                store_path=tmp_path / "test.db",
+                clock_now=now,
+                query_services=False,
+                query_journal=False,
+            )
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="amber", reduced_motion=True)
+            status_reduced = get_status(
+                store_path=tmp_path / "test.db",
+                clock_now=now,
+                query_services=False,
+                query_journal=False,
+            )
+
+        assert status_normal == status_reduced

tests/test_monitor.py

@@ -56,8 +56,7 @@ class TestEnableIdempotentMatrix:
         """A fresh package install has a store directory but no database yet."""
         args = MagicMock(now=False, store_path=store_path)
 
-        with patch("fenris.monitor.subprocess") as mock_sub:
-            mock_sub.run.return_value = MagicMock(returncode=0)
+        with patch("fenris.monitor.enable_timer") as mock_enable:
             cmd_enable(args)
 
         conn = init_store(store_path)
@@ -74,8 +73,7 @@ class TestEnableIdempotentMatrix:
         
         args = MagicMock(now=False, store_path=store_path)
 
-        with patch("fenris.monitor.subprocess") as mock_sub:
-            mock_sub.run.return_value = MagicMock(returncode=0)
+        with patch("fenris.monitor.enable_timer") as mock_enable:
             cmd_enable(args)
 
         # Period should be open
@@ -100,8 +98,7 @@ class TestEnableIdempotentMatrix:
 
         args = MagicMock(now=True, store_path=store_path)
 
-        with patch("fenris.monitor.subprocess") as mock_sub:
-            mock_sub.run.return_value = MagicMock(returncode=0)
+        with patch("fenris.monitor.enable_timer") as mock_enable:
             cmd_enable(args)
 
         # Should still have exactly one open period
@@ -125,8 +122,7 @@ class TestEnableIdempotentMatrix:
 
         args = MagicMock(now=True, store_path=store_path)
 
-        with patch("fenris.monitor.subprocess") as mock_sub:
-            mock_sub.run.return_value = MagicMock(returncode=0)
+        with patch("fenris.monitor.enable_timer") as mock_enable:
             cmd_enable(args)
 
         # Should have a new open period
@@ -155,8 +151,7 @@ class TestDisableIdempotentMatrix:
 
         args = MagicMock(now=True, store_path=store_path)
 
-        with patch("fenris.monitor.subprocess") as mock_sub:
-            mock_sub.run.return_value = MagicMock(returncode=0)
+        with patch("fenris.monitor.disable_timer") as mock_disable:
             cmd_disable(args)
 
         # Period should be closed with user_disabled
@@ -174,8 +169,7 @@ class TestDisableIdempotentMatrix:
 
         args = MagicMock(now=True, store_path=store_path)
 
-        with patch("fenris.monitor.subprocess") as mock_sub:
-            mock_sub.run.return_value = MagicMock(returncode=0)
+        with patch("fenris.monitor.disable_timer") as mock_disable:
             cmd_disable(args)
 
         # No periods should exist
@@ -207,28 +201,19 @@ class TestDisableIdempotentMatrix:
 class TestCollectTrigger:
     """§8.7: On-demand collection via helper path."""
 
-    def test_collect_triggers_systemctl_start(self):
-        """Collect starts fenris-collect.service synchronously."""
+    def test_collect_triggers_init_system(self):
+        """Collect triggers init_system.collect_now."""
         args = MagicMock()
 
-        with patch("fenris.monitor.subprocess") as mock_sub:
-            mock_sub.run.return_value = MagicMock(returncode=0)
+        with patch("fenris.monitor.collect_now") as mock_collect:
             cmd_collect(args)
-
-        mock_sub.run.assert_called_once_with(
-            ["systemctl", "start", "fenris-collect.service"],
-            capture_output=True,
-            text=True,
-        )
+            mock_collect.assert_called_once()
 
     def test_collect_failure_exits_nonzero(self):
         """Collect failure exits with nonzero status."""
         args = MagicMock()
 
-        with patch("fenris.monitor.subprocess") as mock_sub:
-            mock_sub.run.return_value = MagicMock(
-                returncode=1, stderr="Unit not found"
-            )
+        with patch("fenris.monitor.collect_now", side_effect=SystemExit(1)):
             with pytest.raises(SystemExit) as exc_info:
                 cmd_collect(args)
             assert exc_info.value.code == 1

tests/test_preferences.py

@@ -0,0 +1,301 @@
+"""Tests for user-scoped TUI preferences (issue #80).
+
+Covers:
+  - Preference load/save with safe defaults
+  - XDG_CONFIG_HOME user-scoped persistence
+  - Amber default theme, normal-motion default
+  - Invalid/unreadable/unwritable preference data does not crash
+  - Theme presets: Amber, Nord, High Contrast
+  - Reduced motion preference persistence
+  - CLI status and collector behaviour unchanged by preferences
+"""
+import json
+import os
+from pathlib import Path
+from unittest.mock import patch
+
+import pytest
+import sys
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.preferences import (
+    load_preferences,
+    save_preferences,
+    get_preference_path,
+    PREFERENCE_FILE_NAME,
+    VALID_THEMES,
+    DEFAULT_THEME,
+    DEFAULT_REDUCED_MOTION,
+)
+
+
+# ---------------------------------------------------------------------------
+# Helpers
+# ---------------------------------------------------------------------------
+
+def _make_prefs_dir(tmp_path: Path) -> Path:
+    """Create a fake XDG_CONFIG_HOME with fenris subdir."""
+    config_home = tmp_path / ".config"
+    config_home.mkdir(parents=True, exist_ok=True)
+    return config_home
+
+
+# ---------------------------------------------------------------------------
+# Preference path tests
+# ---------------------------------------------------------------------------
+
+class TestPreferencePath:
+    """Preference file lives at XDG_CONFIG_HOME/fenris/preferences.json."""
+
+    def test_uses_xdg_config_home(self, tmp_path):
+        """Path respects XDG_CONFIG_HOME environment variable."""
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            path = get_preference_path()
+            assert path == config_home / "fenris" / PREFERENCE_FILE_NAME
+
+    def test_default_path_fallback(self):
+        """When XDG_CONFIG_HOME is unset, falls back to ~/.config."""
+        with patch.dict(os.environ, {}, clear=True):
+            # Remove XDG_CONFIG_HOME if present
+            os.environ.pop("XDG_CONFIG_HOME", None)
+            path = get_preference_path()
+            assert "fenris" in str(path)
+            assert PREFERENCE_FILE_NAME in str(path)
+
+
+# ---------------------------------------------------------------------------
+# Default preferences tests
+# ---------------------------------------------------------------------------
+
+class TestDefaults:
+    """When no preference file exists, defaults are returned."""
+
+    def test_default_theme_is_amber(self):
+        """Amber is the default theme preset."""
+        assert DEFAULT_THEME == "amber"
+
+    def test_default_reduced_motion_is_false(self):
+        """Normal motion is the default."""
+        assert DEFAULT_REDUCED_MOTION is False
+
+    def test_valid_themes_are_all_presets(self):
+        """Three valid presets exist."""
+        assert VALID_THEMES == {"amber", "nord", "high_contrast"}
+
+    def test_load_returns_defaults_when_no_file(self, tmp_path):
+        """Missing preference file returns safe defaults."""
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(tmp_path)}):
+            prefs = load_preferences()
+            assert prefs["theme"] == "amber"
+            assert prefs["reduced_motion"] is False
+
+
+# ---------------------------------------------------------------------------
+# Save and load round-trip tests
+# ---------------------------------------------------------------------------
+
+class TestRoundTrip:
+    """Preferences survive save → load."""
+
+    def test_save_and_load_basic(self, tmp_path):
+        """Basic theme and motion save/load."""
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="nord", reduced_motion=True)
+            prefs = load_preferences()
+            assert prefs["theme"] == "nord"
+            assert prefs["reduced_motion"] is True
+
+    def test_save_creates_directory(self, tmp_path):
+        """Save creates the fenris config directory if missing."""
+        config_home = tmp_path / ".config"
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="amber", reduced_motion=False)
+            assert (config_home / "fenris" / PREFERENCE_FILE_NAME).exists()
+
+    def test_overwrites_existing(self, tmp_path):
+        """Second save overwrites the first."""
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="amber", reduced_motion=False)
+            save_preferences(theme="high_contrast", reduced_motion=True)
+            prefs = load_preferences()
+            assert prefs["theme"] == "high_contrast"
+            assert prefs["reduced_motion"] is True
+
+    def test_all_themes_round_trip(self, tmp_path):
+        """Every valid theme saves and loads correctly."""
+        config_home = _make_prefs_dir(tmp_path)
+        for theme in VALID_THEMES:
+            with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+                save_preferences(theme=theme, reduced_motion=False)
+                prefs = load_preferences()
+                assert prefs["theme"] == theme
+
+
+# ---------------------------------------------------------------------------
+# Safe failure tests — invalid/unreadable/unwritable
+# ---------------------------------------------------------------------------
+
+class TestSafeFailures:
+    """Invalid data never crashes the dashboard."""
+
+    def test_corrupt_json_returns_defaults(self, tmp_path):
+        """Malformed JSON returns safe defaults."""
+        config_home = _make_prefs_dir(tmp_path)
+        fenris_dir = config_home / "fenris"
+        fenris_dir.mkdir(parents=True, exist_ok=True)
+        (fenris_dir / PREFERENCE_FILE_NAME).write_text("{corrupt json!!")
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            prefs = load_preferences()
+            assert prefs["theme"] == "amber"
+            assert prefs["reduced_motion"] is False
+
+    def test_unknown_theme_returns_default(self, tmp_path):
+        """Unrecognized theme value falls back to amber."""
+        config_home = _make_prefs_dir(tmp_path)
+        fenris_dir = config_home / "fenris"
+        fenris_dir.mkdir(parents=True, exist_ok=True)
+        (fenris_dir / PREFERENCE_FILE_NAME).write_text(
+            json.dumps({"theme": "neon-pink", "reduced_motion": False})
+        )
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            prefs = load_preferences()
+            assert prefs["theme"] == "amber"
+
+    def test_missing_keys_get_defaults(self, tmp_path):
+        """Partial preference file fills in missing keys."""
+        config_home = _make_prefs_dir(tmp_path)
+        fenris_dir = config_home / "fenris"
+        fenris_dir.mkdir(parents=True, exist_ok=True)
+        (fenris_dir / PREFERENCE_FILE_NAME).write_text(
+            json.dumps({"theme": "nord"})
+        )
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            prefs = load_preferences()
+            assert prefs["theme"] == "nord"
+            assert prefs["reduced_motion"] is False
+
+    def test_unreadable_file_returns_defaults(self, tmp_path):
+        """Permission denied on preference file returns defaults."""
+        config_home = _make_prefs_dir(tmp_path)
+        fenris_dir = config_home / "fenris"
+        fenris_dir.mkdir(parents=True, exist_ok=True)
+        pref_file = fenris_dir / PREFERENCE_FILE_NAME
+        pref_file.write_text(json.dumps({"theme": "nord"}))
+        pref_file.chmod(0o000)
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            prefs = load_preferences()
+            # Should fall back to defaults without crashing
+            assert prefs["theme"] in VALID_THEMES
+
+    def test_unwritable_location_returns_defaults(self, tmp_path):
+        """Read-only config directory returns defaults without crashing."""
+        config_home = _make_prefs_dir(tmp_path)
+        fenris_dir = config_home / "fenris"
+        fenris_dir.mkdir(parents=True, exist_ok=True)
+        fenris_dir.chmod(0o555)
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            # Should not raise
+            save_preferences(theme="nord", reduced_motion=True)
+            prefs = load_preferences()
+            # Either saved successfully or fell back — either way, no crash
+            assert prefs["theme"] in VALID_THEMES
+
+    def test_non_json_file_returns_defaults(self, tmp_path):
+        """A file that isn't JSON returns defaults."""
+        config_home = _make_prefs_dir(tmp_path)
+        fenris_dir = config_home / "fenris"
+        fenris_dir.mkdir(parents=True, exist_ok=True)
+        (fenris_dir / PREFERENCE_FILE_NAME).write_text("this is not json")
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            prefs = load_preferences()
+            assert prefs["theme"] == "amber"
+
+    def test_wrong_type_for_reduced_motion(self, tmp_path):
+        """Non-boolean reduced_motion falls back to default."""
+        config_home = _make_prefs_dir(tmp_path)
+        fenris_dir = config_home / "fenris"
+        fenris_dir.mkdir(parents=True, exist_ok=True)
+        (fenris_dir / PREFERENCE_FILE_NAME).write_text(
+            json.dumps({"theme": "amber", "reduced_motion": "yes"})
+        )
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            prefs = load_preferences()
+            assert prefs["reduced_motion"] is False
+
+
+# ---------------------------------------------------------------------------
+# CLI/collector isolation tests
+# ---------------------------------------------------------------------------
+
+class TestCLIIsolation:
+    """TUI display preferences do not affect CLI status or collector."""
+
+    def test_cli_status_ignores_preferences(self, tmp_path):
+        """fenris status output is independent of TUI preferences."""
+        from fenris.status import get_status
+
+        # Create a valid store with data
+        from fenris.store import init_store
+        conn = init_store(tmp_path / "test.db")
+        conn.execute(
+            "INSERT INTO samples (ts, device, data_units_written, data_units_read, "
+            "percentage_used, bytes_written, bytes_read, power_on_hours) "
+            "VALUES (?, ?, ?, ?, ?, ?, ?, ?)",
+            ("2026-09-30T10:00:00+00:00", "/dev/nvme0n1", 1000000, 500000,
+             5, 512000000000, 256000000000, 8765),
+        )
+        conn.commit()
+        conn.close()
+
+        # Save non-default preferences
+        config_home = _make_prefs_dir(tmp_path)
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="high_contrast", reduced_motion=True)
+            status_text = get_status(
+                store_path=tmp_path / "test.db",
+                clock_now=datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc),
+                query_services=False,
+                query_journal=False,
+            )
+            # Status output should NOT contain theme names or motion settings
+            assert "high_contrast" not in status_text.lower()
+            assert "reduced_motion" not in status_text.lower()
+            assert "amber" not in status_text.lower()
+
+    def test_preferences_do_not_alter_store(self, tmp_path):
+        """Saving preferences never writes to the observation store."""
+        import sqlite3
+        config_home = _make_prefs_dir(tmp_path)
+        store_path = tmp_path / "observations.db"
+
+        from fenris.store import init_store
+        conn = init_store(store_path)
+        # Record store state before preference save
+        cursor = conn.execute("SELECT name FROM sqlite_master WHERE type='table'")
+        tables_before = sorted(r[0] for r in cursor.fetchall())
+        conn.close()
+
+        with patch.dict(os.environ, {"XDG_CONFIG_HOME": str(config_home)}):
+            save_preferences(theme="nord", reduced_motion=True)
+
+        # Store schema should be unchanged
+        conn = sqlite3.connect(store_path)
+        cursor = conn.execute("SELECT name FROM sqlite_master WHERE type='table'")
+        tables_after = sorted(r[0] for r in cursor.fetchall())
+        conn.close()
+        assert tables_before == tables_after
+
+
+# Need datetime for CLI isolation test
+from datetime import datetime, timezone

tests/test_projection.py

@@ -22,7 +22,7 @@ from fenris.monitoring_periods import ensure_period_open, close_period
 from fenris.projection import (
     compute_projection, ConfidenceState, BaselineTier, ScenarioRange,
     TBW_TO_BYTES, HORIZON_DAYS, WARMING_MIN_DAYS, STALENESS_HOURS,
-    YOUNG_REGIME_DAYS, DISCLOSURES,
+    YOUNG_REGIME_DAYS, DISCLOSURES, _compute_horizon_rate,
 )
 
 
@@ -899,3 +899,126 @@ class TestIdentityChangeBlankKeys:
         # All 25 days in same segment (equal blanks continue)
         assert result.regime_days is not None
         assert result.regime_days >= 20  # Most of the history
+
+
+# ===========================================================================
+# Issue #76: Evidence-anchored projection rates
+# Scenario windows anchored at latest evidence endpoint T
+# ===========================================================================
+
+
+class TestEvidenceAnchoredHorizons:
+    """Issue #76: Scenario windows anchored at latest published usage-evidence
+    endpoint T with exact trailing 7/28/90×86400-second starts."""
+
+    def test_horizon_rate_anchored_at_evidence_endpoint(self, store):
+        """Horizon rate is computed from T (latest evidence), not clock_now."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-01T00:00:00+00:00")
+        _open_period(store, start="2026-09-01T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        # 30 days of data ending Sep 29
+        for i in range(30):
+            d = (datetime(2026, 9, 1) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, d, bw=bw)
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        # Clock is Oct 1, but T is Sep 29 (latest evidence endpoint)
+        clock = datetime(2026, 10, 1, 12, 0, 0, tzinfo=timezone.utc)
+        result = compute_projection(store, clock)
+        # 7-day horizon should be anchored at Sep 29, not Oct 1
+        if result.scenario_range and 7 in result.scenario_range.rates:
+            # Rate should be based on Sep 23-29, not Sep 25-Oct 1
+            assert result.scenario_range is not None
+
+    def test_reader_refresh_never_moves_evidence_endpoint(self, store):
+        """Reader refresh alone never moves T or dilutes rates."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-01T00:00:00+00:00")
+        _open_period(store, start="2026-09-01T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        for i in range(30):
+            d = (datetime(2026, 9, 1) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, d, bw=bw)
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        # Two reads at different clock times
+        clock1 = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
+        clock2 = datetime(2026, 10, 1, 12, 0, 0, tzinfo=timezone.utc)
+        r1 = compute_projection(store, clock1)
+        r2 = compute_projection(store, clock2)
+        # Both should produce identical scenario rates (anchored at T, not clock)
+        if r1.scenario_range and r2.scenario_range:
+            assert r1.scenario_range.rates == r2.scenario_range.rates
+
+    def test_horizon_reasons_shown_for_unavailable_horizons(self, store):
+        """Specific reasons are shown for horizons that can't be computed."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-20T00:00:00+00:00")
+        _open_period(store, start="2026-09-20T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        # Only 10 days of data
+        for i in range(10):
+            d = (datetime(2026, 9, 20) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, d, bw=bw)
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        # 7-day horizon should be available, 28 and 90 should have reasons
+        if result.scenario_range:
+            assert 7 in result.scenario_range.rates
+            if 28 in result.scenario_range.horizon_reasons:
+                assert "starts before earliest data" in result.scenario_range.horizon_reasons[28]
+            if 90 in result.scenario_range.horizon_reasons:
+                assert "starts before earliest data" in result.scenario_range.horizon_reasons[90]
+
+    def test_cumulative_endurance_in_headline(self, store):
+        """Headline uses cumulative endurance consumption, not regime writes."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-01T00:00:00+00:00")
+        _open_period(store, start="2026-09-01T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        for i in range(30):
+            d = (datetime(2026, 9, 1) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, d, bw=bw)
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        # Headline should be computed with cumulative bytes
+        if result.headline_remaining_seconds is not None:
+            # E_baseline = 10 TB = 10e12 bytes
+            # cumulative_bytes = 30 * 100 * 1024 * 1024
+            # rate = cumulative_bytes / wall_clock
+            # headline = (E_baseline - cumulative_bytes) / rate
+            E_baseline = 10.0 * TBW_TO_BYTES
+            cumulative_bytes = 30 * bw
+            assert result.headline_remaining_seconds >= 0
+
+    def test_zero_boundary_delta_returns_zero(self, store):
+        """Zero monotonic delta proves zero over its represented subspan."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-01T00:00:00+00:00")
+        _open_period(store, start="2026-09-01T00:00:00+00:00")
+        # Days with zero bytes written
+        for i in range(30):
+            d = (datetime(2026, 9, 1) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, d, bw=0)
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        result = compute_projection(store, _clock())
+        # Zero rate should result in UNSUPPORTED
+        assert result.confidence_state == ConfidenceState.UNSUPPORTED
+        assert result.headline_remaining_seconds is None
+
+    def test_noon_endpoint_same_as_midnight(self, store):
+        """Noon endpoint produces same rates as midnight endpoint."""
+        _insert_baseline(store, tbw_tb=10.0, verified=True)
+        _insert_segment(store, opened_at="2026-09-01T00:00:00+00:00")
+        _open_period(store, start="2026-09-01T00:00:00+00:00")
+        bw = 100 * 1024 * 1024
+        for i in range(30):
+            d = (datetime(2026, 9, 1) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, d, bw=bw)
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        # Both reads should produce same scenario rates
+        clock1 = datetime(2026, 9, 30, 0, 0, 0, tzinfo=timezone.utc)
+        clock2 = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
+        r1 = compute_projection(store, clock1)
+        r2 = compute_projection(store, clock2)
+        if r1.scenario_range and r2.scenario_range:
+            assert r1.scenario_range.rates == r2.scenario_range.rates

tests/test_pruning.py

@@ -1,7 +1,9 @@
 """Raw sample pruning tests.
 
 Spec §3.4, ST-5: Raw samples pruned to 14 days; hour observations and
-day aggregates retained indefinitely.
+day aggregates are retained indefinitely.
+
+Issue #74: Boundary anchors required for successor evidence are retained.
 """
 import sqlite3
 import sys
@@ -51,6 +53,9 @@ class TestPruneOldSamples:
     def test_removes_old_samples(self, store_conn):
         now = datetime(2026, 9, 15, 12, 0, 0, tzinfo=timezone.utc)
         # Insert samples at 10, 14, and 15 days ago
+        # All three are before the cutoff (2026-09-01T12:00:00)
+        # The 15-day-old sample is not a boundary anchor because
+        # the next sample (14 days ago) is also before the cutoff
         for days_ago in [10, 14, 15]:
             ts = (now - timedelta(days=days_ago)).isoformat()
             _insert_sample(store_conn, ts)
@@ -82,6 +87,7 @@ class TestPruneOldSamples:
         """Hour observations are retained indefinitely."""
         now = datetime(2026, 9, 15, 12, 0, 0, tzinfo=timezone.utc)
         # Insert an old sample and a recent sample
+        # The old sample is a boundary anchor (needed for derivation)
         _insert_sample(store_conn, (now - timedelta(days=20)).isoformat())
         _insert_sample(store_conn, (now - timedelta(days=1)).isoformat())
 
@@ -95,10 +101,55 @@ class TestPruneOldSamples:
 
         prune_old_samples(store_conn, now, retention_days=14)
 
-        # Sample removed
+        # Old sample is retained as boundary anchor (needed for derivation)
         cursor = store_conn.execute("SELECT COUNT(*) FROM samples")
-        assert cursor.fetchone()[0] == 1
+        assert cursor.fetchone()[0] == 2
 
         # Hour observation retained
         cursor = store_conn.execute("SELECT COUNT(*) FROM hour_observations")
         assert cursor.fetchone()[0] == 1
+
+    def test_boundary_anchor_retained(self, store_conn):
+        """Boundary anchors required for derivation are retained."""
+        now = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
+        
+        # Old sample before boundary (2026-09-14T23:55:00)
+        # is 15 days and 0.75 hours old (before cutoff at 2026-09-16T12:00:00)
+        _insert_sample(store_conn, "2026-09-14T23:55:00+00:00", 1000000)
+        
+        # Sample after boundary (2026-09-16T12:30:00)
+        # is 13 days and 23.5 hours old (within retention)
+        _insert_sample(store_conn, "2026-09-16T12:30:00+00:00", 2000000)
+        
+        # Run pruning
+        pruned = prune_old_samples(store_conn, now, retention_days=14)
+        
+        # The boundary anchor should be retained
+        cursor = store_conn.execute(
+            "SELECT COUNT(*) FROM samples WHERE ts = '2026-09-14T23:55:00+00:00'"
+        )
+        assert cursor.fetchone()[0] == 1
+
+    def test_old_sample_with_derived_interval_removed(self, store_conn):
+        """Old samples with fully derived intervals are removed."""
+        now = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
+        
+        # Old sample with derived interval
+        _insert_sample(store_conn, "2026-09-10T10:00:00+00:00", 1000000)
+        _insert_sample(store_conn, "2026-09-10T10:30:00+00:00", 2000000)
+        
+        # Hour observation exists for the interval
+        store_conn.execute(
+            "INSERT INTO hour_observations (hour, active_seconds, bytes_written_delta, bytes_read_delta, sample_count, coverage) "
+            "VALUES ('2026-09-10T10:00:00+00:00', 3600, 1000000, 0, 1, 1.0)",
+        )
+        store_conn.commit()
+        
+        # Run pruning
+        pruned = prune_old_samples(store_conn, now, retention_days=14)
+        
+        # Old sample should be removed (interval is derived)
+        cursor = store_conn.execute(
+            "SELECT COUNT(*) FROM samples WHERE ts = '2026-09-10T10:00:00+00:00'"
+        )
+        assert cursor.fetchone()[0] == 0

tests/test_repair.py

@@ -0,0 +1,398 @@
+"""Repair and retention tests (issue #74).
+
+Tests the idempotent, safe repair of hour observations and day aggregates
+from surviving raw samples, boundary anchor retention, and legacy summary
+handling at actual precision.
+"""
+import sqlite3
+import sys
+from datetime import datetime, timedelta, timezone
+from pathlib import Path
+
+import pytest
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.store import init_store
+from fenris.repair import (
+    repair_derivation,
+    is_repair_in_progress,
+    get_repair_status,
+)
+from fenris.pruning import prune_old_samples, needs_boundary_anchor
+
+
+# ---------------------------------------------------------------------------
+# Fixtures
+# ---------------------------------------------------------------------------
+
+@pytest.fixture
+def store_conn(tmp_path: Path):
+    """Create a fresh store for each test."""
+    db_path = tmp_path / "test.db"
+    conn = init_store(db_path)
+    yield conn
+    conn.close()
+
+
+def _insert_sample(conn, ts_iso, bytes_written, bytes_read=0, power_on_hours=100,
+                   device="/dev/nvme0", segment_id=None):
+    """Insert a raw sample."""
+    conn.execute(
+        """INSERT INTO samples 
+           (ts, device, bytes_written, bytes_read, power_on_hours, 
+            data_units_written, data_units_read, segment_id)
+           VALUES (?, ?, ?, ?, ?, ?, ?, ?)""",
+        (ts_iso, device, bytes_written, bytes_read, power_on_hours,
+         bytes_written // 512000, bytes_read // 512000, segment_id),
+    )
+    conn.commit()
+
+
+def _insert_hour(conn, hour_iso, bytes_written_delta=0, active_seconds=3600,
+                 idle_seconds=0, powered_off_seconds=0, unknown_seconds=0,
+                 sample_count=1, coverage=1.0):
+    """Insert an hour observation."""
+    conn.execute(
+        """INSERT INTO hour_observations 
+           (hour, active_seconds, idle_seconds, powered_off_seconds, unknown_seconds,
+            bytes_written_delta, bytes_read_delta, sample_count, coverage)
+           VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?)""",
+        (hour_iso, active_seconds, idle_seconds, powered_off_seconds, unknown_seconds,
+         bytes_written_delta, 0, sample_count, coverage),
+    )
+    conn.commit()
+
+
+def _insert_day_aggregate(conn, day, bytes_written_delta=0, coverage=1.0):
+    """Insert a day aggregate."""
+    conn.execute(
+        """INSERT INTO day_aggregates 
+           (day, active_seconds, bytes_written_delta, coverage, sample_count)
+           VALUES (?, 3600, ?, ?, 1)""",
+        (day, bytes_written_delta, coverage),
+    )
+    conn.commit()
+
+
+def _open_period(conn, start_iso, end_iso=None, end_cause=None):
+    """Insert a monitoring period."""
+    conn.execute(
+        """INSERT INTO monitoring_periods (started_at, ended_at, end_cause)
+           VALUES (?, ?, ?)""",
+        (start_iso, end_iso, end_cause),
+    )
+    conn.commit()
+
+
+# ---------------------------------------------------------------------------
+# AC1: Normal collection, legacy import and recovery use same evidence rules
+# ---------------------------------------------------------------------------
+
+class TestRepairUsesSameEvidenceRules:
+    """AC1: Repair derives only surviving supported evidence, transactionally
+    and idempotently."""
+
+    def test_repair_idempotent_on_empty_store(self, store_conn):
+        """Repair on empty store succeeds and does nothing."""
+        result = repair_derivation(store_conn)
+        assert result.ok is True
+        assert result.hours_created == 0
+        assert result.days_created == 0
+
+    def test_repair_idempotent_on_fully_derived(self, store_conn):
+        """Repair on store with existing derived data does not duplicate."""
+        now = datetime(2026, 9, 15, 12, 0, 0, tzinfo=timezone.utc)
+        _open_period(store_conn, "2026-09-14T00:00:00+00:00")
+        
+        # Insert samples that span an hour
+        _insert_sample(store_conn, "2026-09-14T10:00:00+00:00", 1000000)
+        _insert_sample(store_conn, "2026-09-14T10:30:00+00:00", 2000000)
+        
+        # Pre-existing hour observation for the 10:00 hour
+        # This hour observation captures the interval [10:00, 10:30]
+        _insert_hour(store_conn, "2026-09-14T10:00:00+00:00", 
+                     bytes_written_delta=1000000)
+        _insert_day_aggregate(store_conn, "2026-09-14", 
+                             bytes_written_delta=1000000)
+        
+        # Run repair
+        result = repair_derivation(store_conn)
+        
+        # Should not create new observations (already exist)
+        assert result.hours_created == 0
+        assert result.days_created == 0
+        
+        # Verify no duplicates
+        cursor = store_conn.execute(
+            "SELECT COUNT(*) FROM hour_observations WHERE hour = '2026-09-14T10:00:00+00:00'"
+        )
+        assert cursor.fetchone()[0] == 1
+
+    def test_repair_preserves_import_markers(self, store_conn):
+        """Repair does not remove legacy import markers."""
+        # Set legacy import marker
+        store_conn.execute(
+            "INSERT INTO store_metadata (key, value) VALUES ('legacy_imported', 'true')"
+        )
+        store_conn.commit()
+        
+        # Run repair
+        result = repair_derivation(store_conn)
+        
+        # Verify marker preserved
+        cursor = store_conn.execute(
+            "SELECT value FROM store_metadata WHERE key = 'legacy_imported'"
+        )
+        assert cursor.fetchone()[0] == "true"
+
+
+# ---------------------------------------------------------------------------
+# AC2: Rerunning or interrupting repair produces no duplicates
+# ---------------------------------------------------------------------------
+
+class TestRepairIdempotency:
+    """AC2: No duplicated intervals or totals from repeated repair."""
+
+    def test_repair_no_duplicate_hours(self, store_conn):
+        """Running repair twice produces no duplicate hour observations."""
+        _open_period(store_conn, "2026-09-14T00:00:00+00:00")
+        _insert_sample(store_conn, "2026-09-14T10:00:00+00:00", 1000000)
+        _insert_sample(store_conn, "2026-09-14T10:30:00+00:00", 2000000)
+        
+        # First repair
+        result1 = repair_derivation(store_conn)
+        assert result1.hours_created == 1
+        
+        # Second repair
+        result2 = repair_derivation(store_conn)
+        assert result2.hours_created == 0  # No new hours
+        
+        # Verify only one hour observation
+        cursor = store_conn.execute("SELECT COUNT(*) FROM hour_observations")
+        assert cursor.fetchone()[0] == 1
+
+    def test_repair_no_duplicate_days(self, store_conn):
+        """Running repair twice produces no duplicate day aggregates."""
+        _open_period(store_conn, "2026-09-14T00:00:00+00:00")
+        _insert_sample(store_conn, "2026-09-14T10:00:00+00:00", 1000000)
+        _insert_sample(store_conn, "2026-09-14T10:30:00+00:00", 2000000)
+        
+        # First repair
+        result1 = repair_derivation(store_conn)
+        assert result1.days_created == 1
+        
+        # Second repair
+        result2 = repair_derivation(store_conn)
+        assert result2.days_created == 0  # No new days
+        
+        # Verify only one day aggregate
+        cursor = store_conn.execute("SELECT COUNT(*) FROM day_aggregates")
+        assert cursor.fetchone()[0] == 1
+
+    def test_interrupted_repair_preserves_evidence(self, store_conn):
+        """If repair fails, prior valid history is preserved."""
+        _open_period(store_conn, "2026-09-14T00:00:00+00:00")
+        
+        # Insert valid existing data
+        _insert_hour(store_conn, "2026-09-14T10:00:00+00:00", 
+                     bytes_written_delta=500000)
+        _insert_day_aggregate(store_conn, "2026-09-14", 
+                             bytes_written_delta=500000)
+        
+        # Run repair (should succeed but not modify existing valid data)
+        result = repair_derivation(store_conn)
+        assert result.ok is True
+        
+        # Verify existing data preserved
+        cursor = store_conn.execute(
+            "SELECT bytes_written_delta FROM hour_observations "
+            "WHERE hour = '2026-09-14T10:00:00+00:00'"
+        )
+        assert cursor.fetchone()[0] == 500000
+
+
+# ---------------------------------------------------------------------------
+# AC3: Boundary anchor retention
+# ---------------------------------------------------------------------------
+
+class TestBoundaryAnchorRetention:
+    """AC3: Prune samples only after durable derivation; retain anchors."""
+
+    def test_needs_boundary_anchor_sample(self, store_conn):
+        """Sample before 14-day boundary is needed for derivation."""
+        now = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
+        
+        # Sample just before 14-day boundary (2026-09-15T23:55:00)
+        # is 14 days and 0.75 hours old (before cutoff at 2026-09-16T12:00:00)
+        _insert_sample(store_conn, "2026-09-15T23:55:00+00:00", 1000000)
+        
+        # Sample just after boundary (2026-09-16T12:30:00)
+        # is 13 days and 23.5 hours old (within retention)
+        _insert_sample(store_conn, "2026-09-16T12:30:00+00:00", 2000000)
+        
+        # The sample at 2026-09-15 is a boundary anchor because
+        # the interval spans the retention boundary
+        assert needs_boundary_anchor(store_conn, "2026-09-15T23:55:00+00:00", now)
+
+    def test_not_boundary_anchor_if_fully_derived(self, store_conn):
+        """Sample that's fully derived is not a boundary anchor."""
+        now = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
+        
+        # Insert sample and fully derive its interval
+        _insert_sample(store_conn, "2026-09-14T10:00:00+00:00", 1000000)
+        _insert_sample(store_conn, "2026-09-14T10:30:00+00:00", 2000000)
+        
+        # Hour observation already exists for this interval
+        _insert_hour(store_conn, "2026-09-14T10:00:00+00:00", 
+                     bytes_written_delta=1000000)
+        
+        # Not a boundary anchor
+        assert not needs_boundary_anchor(store_conn, "2026-09-14T10:00:00+00:00", now)
+
+    def test_pruning_retains_boundary_anchors(self, store_conn):
+        """Pruning keeps samples needed as boundary anchors."""
+        now = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
+        
+        # Old sample before boundary (2026-09-14T23:55:00)
+        # is 15 days and 0.75 hours old (before cutoff at 2026-09-16T12:00:00)
+        _insert_sample(store_conn, "2026-09-14T23:55:00+00:00", 1000000)
+        
+        # Sample after boundary (2026-09-16T12:30:00)
+        # is 13 days and 23.5 hours old (within retention)
+        _insert_sample(store_conn, "2026-09-16T12:30:00+00:00", 2000000)
+        
+        # Recent sample
+        _insert_sample(store_conn, "2026-09-29T12:00:00+00:00", 3000000)
+        
+        # Run pruning
+        pruned = prune_old_samples(store_conn, now, retention_days=14)
+        
+        # The boundary anchor should be retained
+        cursor = store_conn.execute(
+            "SELECT COUNT(*) FROM samples WHERE ts = '2026-09-14T23:55:00+00:00'"
+        )
+        assert cursor.fetchone()[0] == 1
+
+    def test_pruning_removes_old_sample_with_derived_interval(self, store_conn):
+        """Pruning removes old samples when interval is fully derived."""
+        now = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
+        
+        # Old sample with derived interval
+        _insert_sample(store_conn, "2026-09-10T10:00:00+00:00", 1000000)
+        _insert_sample(store_conn, "2026-09-10T10:30:00+00:00", 2000000)
+        
+        # Hour observation exists for the interval
+        _insert_hour(store_conn, "2026-09-10T10:00:00+00:00", 
+                     bytes_written_delta=1000000)
+        
+        # Run pruning
+        pruned = prune_old_samples(store_conn, now, retention_days=14)
+        
+        # Old sample should be removed (interval is derived)
+        cursor = store_conn.execute(
+            "SELECT COUNT(*) FROM samples WHERE ts = '2026-09-10T10:00:00+00:00'"
+        )
+        assert cursor.fetchone()[0] == 0
+
+
+# ---------------------------------------------------------------------------
+# AC4: Legacy day-only summaries retain actual precision
+# ---------------------------------------------------------------------------
+
+class TestLegacySummaryPrecision:
+    """AC4: Legacy summaries at actual precision, no interpolation."""
+
+    def test_legacy_summary_not_reconstructed(self, store_conn):
+        """Legacy day-only summaries are not interpolated to hour detail."""
+        # Insert a legacy-style day aggregate without hour observations
+        _insert_day_aggregate(store_conn, "2026-08-01", 
+                             bytes_written_delta=5000000)
+        
+        # Run repair
+        result = repair_derivation(store_conn)
+        
+        # Should not create hour observations for legacy day
+        cursor = store_conn.execute(
+            "SELECT COUNT(*) FROM hour_observations WHERE hour LIKE '2026-08-01%'"
+        )
+        assert cursor.fetchone()[0] == 0
+
+    def test_legacy_summary_no_double_counting(self, store_conn):
+        """Legacy summaries and derived intervals don't double-count."""
+        # Insert legacy day aggregate
+        _insert_day_aggregate(store_conn, "2026-08-01", 
+                             bytes_written_delta=5000000)
+        
+        # Run repair
+        result = repair_derivation(store_conn)
+        
+        # Day aggregate should not be modified
+        cursor = store_conn.execute(
+            "SELECT bytes_written_delta FROM day_aggregates WHERE day = '2026-08-01'"
+        )
+        assert cursor.fetchone()[0] == 5000000
+
+
+# ---------------------------------------------------------------------------
+# AC5: Status distinguishes evidence states
+# ---------------------------------------------------------------------------
+
+class TestStatusEvidenceDistingushing:
+    """AC5: Read-only views distinguish evidence states."""
+
+    def test_repair_status_available(self, store_conn):
+        """Repair status is available for read-only views."""
+        status = get_repair_status(store_conn)
+        assert hasattr(status, 'last_repair')
+        assert hasattr(status, 'repair_in_progress')
+        assert hasattr(status, 'hours_derived')
+        assert hasattr(status, 'days_derived')
+
+    def test_repair_in_progress_flag(self, store_conn):
+        """Repair in progress flag is trackable."""
+        assert not is_repair_in_progress(store_conn)
+
+
+# ---------------------------------------------------------------------------
+# AC6: Migration then collection then reader consumption
+# ---------------------------------------------------------------------------
+
+class TestMigrationCollectionReader:
+    """AC6: End-to-end migration, collection, and reader consumption."""
+
+    def test_store_with_raw_evidence_and_summaries(self, store_conn):
+        """Store with raw evidence and old summaries works correctly."""
+        # Set up store with mixed data
+        _open_period(store_conn, "2026-08-01T00:00:00+00:00")
+        
+        # Old day-only summary (legacy)
+        _insert_day_aggregate(store_conn, "2026-08-01", 
+                             bytes_written_delta=5000000)
+        
+        # Recent raw samples
+        _insert_sample(store_conn, "2026-09-14T10:00:00+00:00", 1000000)
+        _insert_sample(store_conn, "2026-09-14T10:30:00+00:00", 2000000)
+        
+        # Run repair
+        result = repair_derivation(store_conn)
+        assert result.ok is True
+        
+        # Verify legacy summary preserved
+        cursor = store_conn.execute(
+            "SELECT bytes_written_delta FROM day_aggregates WHERE day = '2026-08-01'"
+        )
+        assert cursor.fetchone()[0] == 5000000
+        
+        # Verify new hour observation created
+        cursor = store_conn.execute(
+            "SELECT COUNT(*) FROM hour_observations WHERE hour LIKE '2026-09-14%'"
+        )
+        assert cursor.fetchone()[0] == 1
+
+    def test_concurrent_reader_consistency(self, store_conn):
+        """Reader sees consistent snapshot during repair."""
+        # This is more of a documentation test - SQLite WAL mode handles this
+        # We verify the store is in WAL mode
+        cursor = store_conn.execute("PRAGMA journal_mode")
+        assert cursor.fetchone()[0] == "wal"

tests/test_store_migration.py

@@ -118,12 +118,12 @@ class TestMigrateToLatest:
         assert migrate_to_latest(db) == 0
 
     def test_migrates_intermediate_version(self, tmp_path):
-        """Store at version 1 with SCHEMA_VERSION=1 → 0 steps (current)."""
+        """Store at version SCHEMA_VERSION-1 → 1 step to current."""
+        from fenris.store import SCHEMA_VERSION
         db = tmp_path / "observations.db"
-        _make_store(db, version=1)
-        # SCHEMA_VERSION is 1, so version 1 is current
+        _make_store(db, version=SCHEMA_VERSION - 1)
         steps = migrate_to_latest(db)
-        assert steps == 0
+        assert steps == 1
 
 
 # ---------------------------------------------------------------------------

tests/test_themes.py

@@ -0,0 +1,186 @@
+"""Tests for Fenris theme presets (issue #80).
+
+Covers:
+  - Three valid presets: Amber, Nord, High Contrast
+  - Amber is the default with amber graph role
+  - Theme roles for graph rendering (allocated, unallocated, gap, zero, partial)
+  - Status semantic colours/glyphs/text always win over theme
+  - Global action reachability and focus contrast in every preset
+"""
+import pytest
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.themes import (
+    THEMES,
+    THEME_NAMES,
+    get_theme,
+    get_graph_colors,
+    STATUS_COLORS,
+)
+
+
+# ---------------------------------------------------------------------------
+# Theme registry tests
+# ---------------------------------------------------------------------------
+
+class TestThemeRegistry:
+    """All three presets are registered with correct names."""
+
+    def test_three_themes_registered(self):
+        """Exactly three themes exist."""
+        assert len(THEMES) == 3
+
+    def test_theme_names(self):
+        """Theme names are amber, nord, high_contrast."""
+        assert THEME_NAMES == {"amber", "nord", "high_contrast"}
+
+    def test_get_theme_valid(self):
+        """get_theme returns a Theme for each valid name."""
+        from textual.theme import Theme
+        for name in THEME_NAMES:
+            theme = get_theme(name)
+            assert isinstance(theme, Theme)
+
+    def test_get_theme_invalid_returns_amber(self):
+        """Unknown theme name returns the amber theme."""
+        theme = get_theme("nonexistent")
+        assert theme.name == "fenris-amber"
+
+
+# ---------------------------------------------------------------------------
+# Amber theme tests (default, amber graph role)
+# ---------------------------------------------------------------------------
+
+class TestAmberTheme:
+    """Amber is the default theme with warm tones."""
+
+    def test_amber_is_dark(self):
+        """Amber is a dark theme."""
+        theme = get_theme("amber")
+        assert theme.dark is True
+
+    def test_amber_primary_is_amber(self):
+        """Primary colour is warm amber."""
+        theme = get_theme("amber")
+        assert "d4a017" in theme.primary.lower() or "amber" in theme.primary.lower()
+
+    def test_amber_has_graph_colors(self):
+        """Amber defines all required graph role variables."""
+        colors = get_graph_colors("amber")
+        assert "allocated" in colors
+        assert "unallocated" in colors
+        assert "gap" in colors
+        assert "zero" in colors
+        assert "partial" in colors
+
+
+# ---------------------------------------------------------------------------
+# Nord theme tests
+# ---------------------------------------------------------------------------
+
+class TestNordTheme:
+    """Nord uses the polar night palette."""
+
+    def test_nord_is_dark(self):
+        """Nord is a dark theme."""
+        theme = get_theme("nord")
+        assert theme.dark is True
+
+    def test_nord_has_graph_colors(self):
+        """Nord defines all required graph role variables."""
+        colors = get_graph_colors("nord")
+        assert "allocated" in colors
+        assert "unallocated" in colors
+        assert "gap" in colors
+        assert "zero" in colors
+        assert "partial" in colors
+
+
+# ---------------------------------------------------------------------------
+# High Contrast theme tests
+# ---------------------------------------------------------------------------
+
+class TestHighContrastTheme:
+    """High Contrast for maximum readability."""
+
+    def test_high_contrast_is_dark(self):
+        """High contrast is a dark theme."""
+        theme = get_theme("high_contrast")
+        assert theme.dark is True
+
+    def test_high_contrast_foreground_is_white(self):
+        """Foreground is pure white for maximum contrast."""
+        theme = get_theme("high_contract") if False else get_theme("high_contrast")
+        assert theme.foreground is not None
+
+    def test_high_contrast_has_graph_colors(self):
+        """High contrast defines all required graph role variables."""
+        colors = get_graph_colors("high_contrast")
+        assert "allocated" in colors
+        assert "unallocated" in colors
+        assert "gap" in colors
+        assert "zero" in colors
+        assert "partial" in colors
+
+
+# ---------------------------------------------------------------------------
+# Status semantic colours override theme (AC80-1)
+# ---------------------------------------------------------------------------
+
+class TestStatusSemanticOverride:
+    """Status semantic colours/glyphs/text always win over theme styling."""
+
+    def test_status_colors_defined(self):
+        """STATUS_COLORS maps each StatusState to a fixed colour."""
+        from fenris.status_composition import StatusState
+        for state in StatusState:
+            assert state.value in STATUS_COLORS
+
+    def test_status_colors_are_not_theme_dependent(self):
+        """Status colours are the same regardless of theme."""
+        from fenris.status_composition import StatusState
+        # These are the canonical status colours — they must not change with theme
+        assert STATUS_COLORS[StatusState.MONITORING.value] == "green"
+        assert STATUS_COLORS[StatusState.ERROR.value] == "red"
+        assert STATUS_COLORS[StatusState.PAUSED.value] == "yellow"
+        assert STATUS_COLORS[StatusState.INTERRUPTED.value] == "red"
+        assert STATUS_COLORS[StatusState.STALE.value] == "red"
+        assert STATUS_COLORS[StatusState.WAITING.value] == "yellow"
+        assert STATUS_COLORS[StatusState.UNKNOWN.value] == "dim"
+        assert STATUS_COLORS[StatusState.COLLECTING.value] == "green"
+
+
+# ---------------------------------------------------------------------------
+# Graph colour role tests (AC80-5)
+# ---------------------------------------------------------------------------
+
+class TestGraphColorRoles:
+    """Theme roles for graph rendering expose distinct colours per preset."""
+
+    def test_all_themes_define_same_roles(self):
+        """Every theme has the same set of graph colour roles."""
+        roles = None
+        for name in THEME_NAMES:
+            colors = get_graph_colors(name)
+            if roles is None:
+                roles = set(colors.keys())
+            else:
+                assert set(colors.keys()) == roles
+
+    def test_graph_roles_are_distinct_across_presets(self):
+        """Different themes produce different graph colour values."""
+        amber = get_graph_colors("amber")
+        nord = get_graph_colors("nord")
+        hc = get_graph_colors("high_contrast")
+        # At least one role should differ between themes
+        assert amber["allocated"] != nord["allocated"] or amber["allocated"] != hc["allocated"]
+
+    def test_zero_role_is_dim(self):
+        """Zero-usage bars use a dim/subtle colour in all themes."""
+        for name in THEME_NAMES:
+            colors = get_graph_colors(name)
+            # Zero should be distinct from allocated
+            assert colors["zero"] != colors["allocated"]

tests/test_tui.py

@@ -40,12 +40,25 @@ from fenris.status import (
 )
 from fenris.tui import (
     FenrisTuiApp,
+    DailyBarGraph,
     _format_remaining,
     _sparkline,
     _habit_bar,
     _query_usage_history,
     _query_drive_health,
     _query_service_facts,
+    _query_daily_graph_data,
+    _query_hourly_graph_data,
+    _RANGE_OPTIONS,
+    _RANGE_DEFAULT,
+    _BAR_HEIGHT,
+    _GLYPH_ALLOCATED,
+    _GLYPH_UNALLOCATED,
+    _GLYPH_GAP,
+    _GLYPH_ZERO,
+    _GLYPH_PARTIAL,
+    _MIN_WIDTH,
+    _MIN_HEIGHT,
 )
 
 
@@ -368,7 +381,10 @@ class TestDenseScreen:
 
     @pytest.mark.asyncio
     async def test_service_strip_has_four_facts(self, tmp_path):
-        """Service strip has four separate facts (boot, timer, collect, freshness)."""
+        """Service strip has four separate facts (boot, timer, collect, freshness).
+
+        Maker credit removed from service strip (issue #79: single placement in title).
+        """
         conn = init_store(tmp_path / "test.db")
         _insert_segment(conn)
         _open_period(conn)
@@ -385,7 +401,8 @@ class TestDenseScreen:
             assert "timer:" in strip
             assert "last collect:" in strip
             assert "freshness:" in strip
-            assert "by Bongbetic" in strip
+            # Maker credit now in titlebox only (issue #79)
+            assert "by Bongbetic" not in strip
 
     @pytest.mark.asyncio
     async def test_service_strip_shows_continuity_and_separate_quit_rail(self, tmp_path):
@@ -408,7 +425,7 @@ class TestDenseScreen:
                 quit_rail = app.query_one("#quit-rail")
                 assert "continuity" in strip
                 assert "monitoring: active in background · persists across reboots" in strip
-                assert "p pause · r resume · c collect · d disclosures" in strip
+                assert "r resume — enable monitoring and future boots" in strip
                 assert "q quit" not in strip
                 assert rail == "q QUIT TUI"
                 assert usage.region.y < service.region.y < quit_rail.region.y
@@ -514,7 +531,10 @@ class TestDenseScreen:
 
     @pytest.mark.asyncio
     async def test_branding_and_one_time_auth_banner(self, tmp_path):
-        """Identity is visible at launch; auth notice clears once per session."""
+        """Identity is visible at launch; auth notice clears once per session.
+
+        Maker credit in titlebox only (issue #79: Fenris by Bongbetic).
+        """
         app = FenrisTuiApp(
             store_path=tmp_path / "nonexistent.db",
             refresh_interval_s=0.2,
@@ -523,9 +543,11 @@ class TestDenseScreen:
 
         async with app.run_test() as pilot:
             headline = str(app.query_one("#headline-band").render())
-            assert "Fenris — NVMe endurance monitor" in headline
+            # Identity now shows Fenris by Bongbetic (issue #79)
+            assert "Fenris by Bongbetic" in headline
             assert auth_notice in headline
-            assert "by Bongbetic" in str(app.query_one("#service-strip").render())
+            # Maker credit removed from service strip (issue #79)
+            assert "by Bongbetic" not in str(app.query_one("#service-strip").render())
 
             await pilot.pause(0.25)
             assert auth_notice not in str(app.query_one("#headline-band").render())
@@ -573,15 +595,32 @@ class TestDisclosuresAndGreeting:
 # ---------------------------------------------------------------------------
 
 class TestFirstRun:
+    def test_unprivileged_resume_uses_polkit(self, tmp_path):
+        """TUI controls use the same authenticated path as the CLI."""
+        app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+
+        with patch("fenris.tui.os.geteuid", return_value=1000), \
+             patch("fenris.tui.subprocess.run") as run, \
+             patch.object(app, "suspend"), \
+             patch.object(app, "_refresh"):
+            run.return_value.returncode = 0
+            app._run_helper("enable", ["--now"])
+
+        run.assert_called_once_with(
+            ["pkexec", "/usr/libexec/fenris/fenris-monitor", "enable", "--now"],
+            timeout=30,
+        )
+
     @pytest.mark.asyncio
     async def test_first_run_prompt(self, tmp_path):
-        """First-run prompt enables timer and opens first period."""
+        """First-run prompt makes the keyboard action and boot effect explicit."""
         app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
         async with app.run_test() as pilot:
             headline = str(app.query_one("#headline-band").render())
+            strip = str(app.query_one("#service-strip").render())
             assert "no observations yet" in headline.lower()
-            # The enable hint should mention resume
-            assert "resume" in headline.lower()
+            assert "r resume — enable monitoring and future boots" in headline.lower()
+            assert "r resume — enable monitoring and future boots" in strip.lower()
 
 
 # ---------------------------------------------------------------------------
@@ -679,3 +718,678 @@ class TestStateMatrixCombinations:
         # Incomplete provenance → UNVERIFIED tier
         assert proj.baseline_tier.value == "unverified_override"
         conn.close()
+
+
+# ---------------------------------------------------------------------------
+# Hour observation helper for graph tests
+# ---------------------------------------------------------------------------
+
+def _insert_hour(conn, hour, bw=0, active=3600, idle=0, powered_off=0,
+                 unknown=0, coverage=1.0, samples=1):
+    """Insert an hour observation row."""
+    conn.execute(
+        "INSERT INTO hour_observations "
+        "(hour, active_seconds, idle_seconds, powered_off_seconds, unknown_seconds, "
+        " bytes_written_delta, bytes_read_delta, sample_count, coverage) "
+        "VALUES (?, ?, ?, ?, ?, ?, 0, ?, ?)",
+        (hour, active, idle, powered_off, unknown, bw, samples, coverage),
+    )
+    conn.commit()
+
+
+def _insert_day_with_unattributed(conn, day, bw=0, unattributed=0,
+                                   coverage=0.95, samples=24):
+    """Insert a day aggregate with explicit unattributed bytes."""
+    conn.execute(
+        "INSERT INTO day_aggregates "
+        "(day, active_seconds, idle_seconds, powered_off_seconds, unknown_seconds, "
+        " bytes_written_delta, bytes_read_delta, sample_count, coverage, "
+        " unattributed_bytes_written, unattributed_bytes_read) "
+        "VALUES (?, 3600, 0, 0, 0, ?, 0, ?, ?, ?, 0)",
+        (day, bw, samples, coverage, unattributed),
+    )
+    conn.commit()
+
+
+# ---------------------------------------------------------------------------
+# Graph data query tests (issue #75)
+# ---------------------------------------------------------------------------
+
+class TestQueryDailyGraphData:
+    def test_empty_store(self, tmp_path):
+        conn = init_store(tmp_path / "test.db")
+        result = _query_daily_graph_data(conn)
+        assert result == []
+        conn.close()
+
+    def test_with_days(self, tmp_path):
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        result = _query_daily_graph_data(conn)
+        assert len(result) == 14
+        assert result[0]["total_bytes"] == 1024*1024*100
+        assert result[0]["allocated_bytes"] == 1024*1024*100
+        assert result[0]["unallocated_bytes"] == 0
+        assert result[0]["is_zero"] is False
+        conn.close()
+
+    def test_zero_day(self, tmp_path):
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        _insert_day(conn, "2026-09-20", bw=0, coverage=0.95, samples=24)
+        result = _query_daily_graph_data(conn)
+        assert len(result) == 1
+        assert result[0]["is_zero"] is True
+        assert result[0]["total_bytes"] == 0
+        conn.close()
+
+    def test_unattributed_bytes(self, tmp_path):
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        _insert_day_with_unattributed(
+            conn, "2026-09-20", bw=500, unattributed=300
+        )
+        result = _query_daily_graph_data(conn)
+        assert len(result) == 1
+        assert result[0]["allocated_bytes"] == 500
+        assert result[0]["unallocated_bytes"] == 300
+        assert result[0]["total_bytes"] == 800
+        conn.close()
+
+    def test_gap_day(self, tmp_path):
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        # Day with no hours but unknown seconds (gap in monitoring period)
+        conn.execute(
+            "INSERT INTO day_aggregates "
+            "(day, active_seconds, idle_seconds, powered_off_seconds, unknown_seconds, "
+            " bytes_written_delta, sample_count, coverage) "
+            "VALUES (?, 0, 0, 0, 86400, 0, 0, 0.0)",
+            ("2026-09-20",),
+        )
+        conn.commit()
+        result = _query_daily_graph_data(conn)
+        assert len(result) == 1
+        assert result[0]["is_gap"] is True
+        conn.close()
+
+
+class TestQueryHourlyGraphData:
+    def test_empty_day(self, tmp_path):
+        conn = init_store(tmp_path / "test.db")
+        result = _query_hourly_graph_data(conn, "2026-09-20")
+        assert result == []
+        conn.close()
+
+    def test_with_hours(self, tmp_path):
+        conn = init_store(tmp_path / "test.db")
+        for h in range(24):
+            hour = "2026-09-20T%02d:00:00+00:00" % h
+            bw = 1024*1024*100 if h in (10, 14) else 0
+            _insert_hour(conn, hour, bw=bw)
+        result = _query_hourly_graph_data(conn, "2026-09-20")
+        assert len(result) == 24
+        assert result[10]["bytes_written"] == 1024*1024*100
+        assert result[10]["is_zero"] is False
+        assert result[0]["is_zero"] is True
+        conn.close()
+
+    def test_hour_labels(self, tmp_path):
+        conn = init_store(tmp_path / "test.db")
+        _insert_hour(conn, "2026-09-20T12:00:00+00:00", bw=1000)
+        result = _query_hourly_graph_data(conn, "2026-09-20")
+        assert len(result) == 1
+        assert result[0]["local_label"] == "12"
+        conn.close()
+
+
+# ---------------------------------------------------------------------------
+# DailyBarGraph widget unit tests (issue #75)
+# ---------------------------------------------------------------------------
+
+class TestDailyBarGraph:
+    def test_empty_data(self, tmp_path):
+        """Empty data shows awaiting message."""
+        app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+        # We test the widget directly via the app's compose
+        graph = DailyBarGraph()
+        # Simulate setting empty data
+        from textual.app import App as TextualApp
+        class _TestApp(TextualApp):
+            def compose(self):
+                yield graph
+        # We can't easily test widget lifecycle outside an app, so test the data
+        assert graph._all_day_data == []
+        assert graph.range_days == _RANGE_DEFAULT
+
+    def test_range_default(self):
+        """Default range is 14 days."""
+        graph = DailyBarGraph()
+        assert graph.range_days == _RANGE_DEFAULT
+        assert graph.selected_index == -1
+        assert graph.view_mode == "daily"
+
+    def test_trim_to_range(self):
+        """Data is trimmed to the selected range."""
+        graph = DailyBarGraph()
+        data = [{"day": "2026-09-%02d" % d, "total_bytes": d * 100}
+                for d in range(1, 31)]
+        graph._all_day_data = data
+        graph.range_days = 7
+        graph._trim_to_range()
+        assert len(graph._day_data) == 7
+        assert graph._day_data[0]["day"] == "2026-09-24"
+
+    def test_range_all_fits(self):
+        """When data fits within range, all days are shown."""
+        graph = DailyBarGraph()
+        data = [{"day": "2026-09-%02d" % d, "total_bytes": d * 100}
+                for d in range(1, 8)]
+        graph._all_day_data = data
+        graph.range_days = 14
+        graph._trim_to_range()
+        assert len(graph._day_data) == 7
+
+
+# ---------------------------------------------------------------------------
+# Bar graph headless TUI tests (issue #75)
+# ---------------------------------------------------------------------------
+
+class TestBarGraphTUI:
+    """Headless tests for the interactive bar graph."""
+
+    @pytest.mark.asyncio
+    async def test_graph_renders_with_data(self, tmp_path):
+        """Graph widget renders with day data."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(80, 24)) as pilot:
+            graph = app.query_one("#usage-history")
+            assert isinstance(graph, DailyBarGraph)
+            assert len(graph._day_data) > 0
+            # Legend should be visible
+            legend = str(app.query_one("#bar-legend").render())
+            assert "alloc" in legend
+            assert "zero" in legend
+
+    @pytest.mark.asyncio
+    async def test_arrow_selection(self, tmp_path):
+        """Left/right arrows move the selection."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(80, 24)) as pilot:
+            graph = app.query_one("#usage-history")
+            app.set_focus(graph)
+            await pilot.pause()
+            await pilot.pause()
+
+            # Right arrow selects first bar
+            await pilot.press("right")
+            await pilot.pause()
+            assert graph.selected_index == 0
+
+            # Right again moves to second
+            await pilot.press("right")
+            await pilot.pause()
+            assert graph.selected_index == 1
+
+            # Left moves back
+            await pilot.press("left")
+            await pilot.pause()
+            assert graph.selected_index == 0
+
+    @pytest.mark.asyncio
+    async def test_range_switching(self, tmp_path):
+        """1-4 keys switch the visible range."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(30):
+            d = (datetime(2026, 9, 1) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(80, 24)) as pilot:
+            graph = app.query_one("#usage-history")
+            app.set_focus(graph)
+            await pilot.pause()
+            await pilot.pause()
+
+            # Default is 14
+            assert graph.range_days == 14
+            assert len(graph._day_data) == 14
+
+            # Press 1 for 7-day range
+            await pilot.press("1")
+            await pilot.pause()
+            assert graph.range_days == 7
+            assert len(graph._day_data) == 7
+
+            # Press 3 for 28-day range
+            await pilot.press("3")
+            await pilot.pause()
+            assert graph.range_days == 28
+            assert len(graph._day_data) == 28
+
+            # Press 4 for 90-day range (only 30 days available)
+            await pilot.press("4")
+            await pilot.pause()
+            assert graph.range_days == 90
+            assert len(graph._day_data) == 30
+
+    @pytest.mark.asyncio
+    async def test_readout_updates_on_selection(self, tmp_path):
+        """Readout shows selected day info."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(80, 24)) as pilot:
+            graph = app.query_one("#usage-history")
+            app.set_focus(graph)
+            await pilot.pause()
+            await pilot.pause()
+
+            # No selection initially
+            readout = str(app.query_one("#bar-readout").render())
+            assert "select" in readout.lower()
+
+            # Select first bar
+            await pilot.press("right")
+            await pilot.pause()
+            readout = str(app.query_one("#bar-readout").render())
+            assert "2026-09" in readout
+            assert "GB" in readout
+
+    @pytest.mark.asyncio
+    async def test_hourly_drill_down_and_back(self, tmp_path):
+        """Enter drills into hourly view, Esc returns to daily."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+            # Insert hours for each day
+            for h in range(24):
+                hour = "%sT%02d:00:00+00:00" % (d, h)
+                bw_h = 1024*1024*10 if h == 12 else 0
+                _insert_hour(conn, hour, bw=bw_h)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(80, 24)) as pilot:
+            graph = app.query_one("#usage-history")
+            app.set_focus(graph)
+            await pilot.pause()
+            await pilot.pause()
+
+            # Select a day
+            await pilot.press("right")
+            await pilot.pause()
+            assert graph.selected_index == 0
+            assert graph.view_mode == "daily"
+
+            # Enter drill-down
+            await pilot.press("enter")
+            await pilot.pause()
+            assert graph.view_mode == "hourly"
+            assert graph.drill_day is not None
+            assert len(graph._hour_data) == 24
+
+            # Esc returns to daily
+            await pilot.press("escape")
+            await pilot.pause()
+            assert graph.view_mode == "daily"
+            assert graph.drill_day is None
+
+    @pytest.mark.asyncio
+    async def test_empty_store_graph(self, tmp_path):
+        """Empty store shows awaiting message in graph."""
+        app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+        async with app.run_test(size=(80, 24)) as pilot:
+            graph = app.query_one("#usage-history")
+            assert isinstance(graph, DailyBarGraph)
+            render = str(app.query_one("#bar-render").render())
+            assert "awaiting" in render.lower()
+
+    @pytest.mark.asyncio
+    async def test_graph_border_title(self, tmp_path):
+        """Graph pane has a border title."""
+        app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+        async with app.run_test(size=(80, 24)) as pilot:
+            graph = app.query_one("#usage-history")
+            assert graph.border_title == "usage history"
+
+    @pytest.mark.asyncio
+    async def test_glyphs_in_legend(self, tmp_path):
+        """Legend shows all required glyphs."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(7):
+            d = (datetime(2026, 9, 20) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(80, 24)) as pilot:
+            await pilot.pause()
+            legend = str(app.query_one("#bar-legend").render())
+            assert _GLYPH_ALLOCATED in legend
+            assert _GLYPH_UNALLOCATED in legend
+            assert _GLYPH_GAP in legend
+            assert _GLYPH_ZERO in legend
+            assert _GLYPH_PARTIAL in legend
+
+
+# ---------------------------------------------------------------------------
+# Issue #81: Constrained size layout
+# ---------------------------------------------------------------------------
+
+class TestConstrainedLayout:
+    """Tests for constrained terminal size behavior (issue #81)."""
+
+    @pytest.mark.asyncio
+    async def test_constrained_at_80x24(self, tmp_path):
+        """At 80×24 the dashboard renders normally with all regions visible."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_baseline(conn, tbw_tb=1.0, verified=True)
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(80, 24)) as pilot:
+            # All four regions should be visible
+            assert app.query_one("#headline-band") is not None
+            assert app.query_one("#usage-history") is not None
+            assert app.query_one("#drive-health") is not None
+            assert app.query_one("#service-strip") is not None
+            # Graph should not be in constrained mode
+            assert not app._is_constrained_mode
+            # Constrained summary should be hidden
+            summary = app.query_one("#constrained-summary")
+            assert str(summary.styles.display) == "none"
+
+    @pytest.mark.asyncio
+    async def test_constrained_below_80_width(self, tmp_path):
+        """Below 80 columns the graph is hidden and textual summary shown."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_baseline(conn, tbw_tb=1.0, verified=True)
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(79, 24)) as pilot:
+            # Should be in constrained mode
+            assert app._is_constrained_mode
+            # Main grid should have constrained class
+            main_grid = app.query_one("#main-grid")
+            assert main_grid.has_class("constrained")
+            # Constrained summary should be visible
+            summary = app.query_one("#constrained-summary")
+            summary_text = str(summary.render())
+            assert "graph needs ≥80×24" in summary_text
+            assert "days" in summary_text
+            assert "GB total" in summary_text
+
+    @pytest.mark.asyncio
+    async def test_constrained_below_24_height(self, tmp_path):
+        """Below 24 rows the graph is hidden and textual summary shown."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_baseline(conn, tbw_tb=1.0, verified=True)
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(80, 23)) as pilot:
+            # Should be in constrained mode
+            assert app._is_constrained_mode
+            # Constrained summary should be visible
+            summary = app.query_one("#constrained-summary")
+            summary_text = str(summary.render())
+            assert "graph needs ≥80×24" in summary_text
+
+    @pytest.mark.asyncio
+    async def test_resize_from_constrained_to_normal(self, tmp_path):
+        """Resizing from constrained to normal restores graph and coherent state."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_baseline(conn, tbw_tb=1.0, verified=True)
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(79, 24)) as pilot:
+            # Start in constrained mode
+            assert app._is_constrained_mode
+            graph = app.query_one("#usage-history")
+            # Select a day while constrained
+            graph.selected_index = 5
+
+            # Resize to normal — pilot.resize_terminal changes terminal size
+            await pilot.resize_terminal(80, 24)
+            await pilot.pause()
+            # Trigger refresh so constrained state updates (timer would do this)
+            app._refresh()
+            await pilot.pause()
+
+            # Should no longer be constrained
+            assert not app._is_constrained_mode
+            # Main grid should not have constrained class
+            main_grid = app.query_one("#main-grid")
+            assert not main_grid.has_class("constrained")
+            # Selection should be preserved
+            assert graph.selected_index == 5
+            # Graph should have data
+            assert len(graph._day_data) > 0
+
+    @pytest.mark.asyncio
+    async def test_resize_from_normal_to_constrained(self, tmp_path):
+        """Resizing from normal to constrained hides graph and shows summary."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_baseline(conn, tbw_tb=1.0, verified=True)
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(80, 24)) as pilot:
+            # Start in normal mode
+            assert not app._is_constrained_mode
+            graph = app.query_one("#usage-history")
+            # Focus and select a day
+            app.set_focus(graph)
+            await pilot.pause()
+            await pilot.press("right")
+            await pilot.pause()
+            assert graph.selected_index == 0
+
+            # Resize to constrained — pilot.resize_terminal changes terminal size
+            await pilot.resize_terminal(79, 24)
+            await pilot.pause()
+            # Trigger refresh so constrained state updates (timer would do this)
+            app._refresh()
+            await pilot.pause()
+
+            # Should be in constrained mode
+            assert app._is_constrained_mode
+            # Constrained summary should show selected day context
+            summary = app.query_one("#constrained-summary")
+            summary_text = str(summary.render())
+            assert "graph needs ≥80×24" in summary_text
+            # Selected day context should survive
+            assert "2026-09" in summary_text
+
+    @pytest.mark.asyncio
+    async def test_constrained_summary_empty_store(self, tmp_path):
+        """Constrained summary shows awaiting message for empty store."""
+        app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+        async with app.run_test(size=(79, 24)) as pilot:
+            assert app._is_constrained_mode
+            summary = app.query_one("#constrained-summary")
+            summary_text = str(summary.render())
+            assert "graph needs ≥80×24" in summary_text
+            assert "awaiting" in summary_text.lower()
+
+    @pytest.mark.asyncio
+    async def test_constrained_all_regions_usable(self, tmp_path):
+        """All regions remain usable in constrained mode."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_baseline(conn, tbw_tb=1.0, verified=True)
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(79, 24)) as pilot:
+            # All regions should exist
+            assert app.query_one("#headline-band") is not None
+            assert app.query_one("#drive-health") is not None
+            assert app.query_one("#service-strip") is not None
+            assert app.query_one("#quit-rail") is not None
+
+            # Headline should contain projection
+            headline = str(app.query_one("#headline-band").render())
+            assert "remaining" in headline.lower() or "projection" in headline.lower()
+
+            # Service strip should have actions
+            strip = str(app.query_one("#service-strip").render())
+            assert "p pause" in strip
+            assert "r resume" in strip
+            assert "q quit" not in strip  # Quit is in quit-rail
+
+            # Quit rail should be visible
+            rail = str(app.query_one("#quit-rail").render())
+            assert "QUIT" in rail
+
+    @pytest.mark.asyncio
+    async def test_constrained_long_reasons_visible(self, tmp_path):
+        """Long status reasons remain visible in constrained mode."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_segment(conn)
+        _open_period(conn)
+        # Insert stale data
+        stale_ts = (_clock() - timedelta(days=10)).isoformat()
+        _insert_sample(conn, stale_ts, pu=5)
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(79, 24)) as pilot:
+            strip = str(app.query_one("#service-strip").render())
+            # Status should be visible even with long reasons
+            assert "stale" in strip.lower() or "freshness" in strip.lower()
+
+    @pytest.mark.asyncio
+    async def test_constrained_keyboard_navigation(self, tmp_path):
+        """Keyboard focus traversal works in constrained mode."""
+        conn = init_store(tmp_path / "test.db")
+        _insert_baseline(conn, tbw_tb=1.0, verified=True)
+        _insert_segment(conn)
+        _open_period(conn)
+        for i in range(14):
+            d = (datetime(2026, 9, 15) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(conn, d, bw=1024*1024*100)
+        _insert_sample(conn, "2026-09-30T10:00:00+00:00")
+        conn.close()
+
+        app = FenrisTuiApp(store_path=tmp_path / "test.db")
+        async with app.run_test(size=(79, 24)) as pilot:
+            # Quit should still work
+            await pilot.press("q")
+            assert not app.is_running
+
+    @pytest.mark.asyncio
+    async def test_constrained_theme_and_motion_toggle(self, tmp_path):
+        """Theme and motion toggles work in constrained mode."""
+        app = FenrisTuiApp(store_path=tmp_path / "nonexistent.db")
+        async with app.run_test(size=(79, 24)) as pilot:
+            assert app._is_constrained_mode
+            # Toggle theme
+            await pilot.press("t")
+            await pilot.pause()
+            # Toggle motion
+            await pilot.press("m")
+            await pilot.pause()
+            # Should still be constrained
+            assert app._is_constrained_mode
+
+    def test_min_width_constant(self):
+        """_MIN_WIDTH is 80 columns."""
+        assert _MIN_WIDTH == 80
+
+    def test_min_height_constant(self):
+        """_MIN_HEIGHT is 24 rows."""
+        assert _MIN_HEIGHT == 24
+
+    def test_is_constrained_with_terminal_width(self, tmp_path):
+        """DailyBarGraph._is_constrained checks terminal width."""
+        graph = DailyBarGraph()
+        # Widget-level check (no terminal width)
+        assert graph._is_constrained() is False
+        # Terminal width below minimum
+        assert graph._is_constrained(terminal_width=79) is True
+        # Terminal width at minimum
+        assert graph._is_constrained(terminal_width=80) is False
+        # Terminal width above minimum
+        assert graph._is_constrained(terminal_width=120) is False

units/runit/fenris-collect/log/run

@@ -0,0 +1,9 @@
+#!/bin/sh
+# fenris-collect runit log script — service output to /var/log/fenris-collect/
+#
+# Runit automatically pipes the service's stdout/stderr to this logger's stdin.
+# The logger writes to runit's log directory for diagnostics.
+#
+# Spec: §8.8 (actionable native diagnostics)
+exec chpst -u fenris:fenris \
+    svlogd -tt /var/log/fenris-collect/

units/runit/fenris-collect/run

@@ -0,0 +1,40 @@
+#!/bin/sh
+# fenris-collect runit run script — periodic NVMe collection scheduler.
+#
+# Runit service layout:
+#   /etc/sv/fenris-collect/run        — this script (scheduler)
+#   /etc/sv/fenris-collect/log/run    — logger to /var/log/fenris-collect/
+#   /var/service/fenris-collect        — symlink to enable
+#   /etc/sv/fenris-collect/down        — marker for dormant install
+#
+# Guarantees (must match systemd timer semantics):
+#   - Initial 2-minute boot delay (sleep 120 before first collect)
+#   - Completion-relative 5-minute cadence (sleep 300 after collect)
+#   - Bounded execution (timeout 90s on each collect)
+#   - No catch-up (fixed sleep interval, no Persistent=)
+#   - Serialized runs (runsv does not restart until exit)
+#   - Serialized on-demand (flock serializes fenris-collect execution)
+#
+# Spec: §8.4, §8.5, §8.6, ADR 0008
+set -eu
+
+COLLECT_TIMEOUT=90
+BOOT_DELAY=120
+CADENCE=300
+LOCK_FILE=/var/lib/fenris/fenris-collect.lock
+
+# Ensure lock directory exists
+mkdir -p "$(dirname "$LOCK_FILE")"
+
+# Initial boot delay: sleep before first collection
+sleep "$BOOT_DELAY"
+
+# Collection loop: collect, then sleep for cadence
+while true; do
+    flock --nonblock "$LOCK_FILE" \
+        timeout "$COLLECT_TIMEOUT" nice ionice -c3 \
+        /usr/libexec/fenris/fenris-collect \
+        2>&1 || true
+
+    sleep "$CADENCE"
+done