xavierk
e12f4a574c
- Change default collection cadence from 5 minutes to 3 minutes (CADENCE_DEFAULT_S=180, systemd OnUnitInactiveSec=3min, runit CADENCE=180) - Update freshness threshold to 450s (2×180 + AccuracySec + 60) - Add _query_live_graph_data(): queries raw samples from the last 3 hours and computes interval byte deltas with actual timestamps - Add LiveActivityGraph widget: vertical bar chart of interval volumes with read/write toggle (w key), arrow key inspection, and click support - Wire live graph into TUI layout (full-width row between daily graph and drive health), refresh cycle, and CSS grid - Replace t theme binding with t today/live binding; theme selection via preferences file - Add w binding for read/write toggle on live graph - Update action legend, help screen, and grid layout for new live-activity row - Add 20 tests covering cadence constants, live query, widget rendering, toggle, and TUI integration - Update all cadence documentation (README, ADR 0003, acceptance criteria LC-2, fenris-redesign constants table, CHANGELOG)
34 lines
7.3 KiB
Markdown
34 lines
7.3 KiB
Markdown
# 3. Service lifecycle: timer-driven collection with a sanctioned control path
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## Status
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Accepted — resolves [Define the collector, service, and CLI lifecycle](https://git.bongbetic.com/xavierk/Fenris/issues/8) on the [Wayfinder map](https://git.bongbetic.com/xavierk/Fenris/issues/1). Amends the toggle mechanism of [Verify systemd lifecycle and privilege constraints](https://git.bongbetic.com/xavierk/Fenris/issues/7); its spirit — scoped, explicit, authenticated, no generic `manage-unit-files` grant — is intact.
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Amended by [Define endurance-baseline provenance and validation](https://git.bongbetic.com/xavierk/Fenris/issues/12): the helper gains a `baseline` verb that persists the CLI-validated endurance-baseline row — same fixed-operation, polkit-mediated pattern.
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## Context
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Fenris's current single process combines daemonization, a PID file, an HTTP dashboard, and control (`fenris.py start/stop/status/sample`) over checkout-relative state. [ADR 0001](0001-observation-store-sqlite.md) fixed the observation store, including `monitoring_periods` whose `user_disabled` end cause records deliberate pauses, and the [systemd lifecycle research](https://git.bongbetic.com/xavierk/Fenris/src/branch/research/systemd-privilege-lifecycle/docs/research/systemd-privilege-lifecycle.md) fixed the timer + oneshot architecture, standard paths, journal diagnostics, allow-listed status reads, and polkit-mediated startup toggles — while leaving cadence mechanics, the configuration surface, CLI compatibility, staleness thresholds, and the mechanism that records a deliberate disable open. In particular, `systemctl enable`/`disable` cannot write a monitoring-period row, so a direct-systemctl toggle cannot satisfy the store's semantics.
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## Decision
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1. **Units.** Two system units only: `fenris-collect.timer` (`WantedBy=timers.target`) and `fenris-collect.service` (`Type=oneshot`, root, `ExecStart=/usr/libexec/fenris/fenris-collect`; no listener, no UI code). The TUI and CLI are ordinary unprivileged processes and never units. There is no `/run/fenris` coordination surface: systemd serializes runs, the observation store holds state, and failures go to the journal per [ADR 0001](0001-observation-store-sqlite.md).
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2. **Cadence.** Default three minutes: `OnBootSec=2min`, `OnUnitInactiveSec=3min` (measured from run completion; drift accepted because hours are the evidence grain), `AccuracySec=30s`, `Persistent=no`, no suspend catch-up (absent hours classify through power-on-hours evidence), `TimeoutStartSec=90s` so a hung interrogation fails visibly. Cadence changes are documented drop-ins on the timer unit (`systemctl edit` + daemon-reload); no interval key exists in configuration.
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3. **Configuration.** `/etc/fenris/fenris.conf` holds exactly one key: the device selector, a stable `/dev/disk/by-id/…` path (raw nodes accepted with an instability warning), validated at collection time. The oneshot re-reads it every run, so there is no reload path to design. An invalid selector is a bounded failed run — journal plus failed unit result, retried next interval; `status` and the TUI also read the world-readable file directly and surface a `configuration error: <reason>` fact.
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4. **Entry points.** Two privileged binaries: `/usr/libexec/fenris/fenris-collect` (device interrogation and store writes; the unit's `ExecStart`) and `/usr/libexec/fenris/fenris-monitor` (fixed operations `enable` and `disable` with optional `--now`, plus the collect trigger, monitoring-period bookkeeping, and `baseline set`/`baseline clear` persistence for the CLI-validated endurance baseline; the only binary the polkit policy authorizes). One unprivileged `fenris` for humans: no arguments opens the TUI; subcommands (`status`, `sample`, `monitor pause`, `monitor resume`) are the CLI.
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5. **Sanctioned toggle.** Pause = `disable --now`; Resume = `enable --now`; both executed by `fenris-monitor`, which performs the systemctl operation and the monitoring-period bookkeeping in one step, under polkit action `com.bongbetic.fenris.monitor` (`auth_admin`, covering the collect trigger too). Root invokes the helpers directly; where no polkit agent exists the operation fails cleanly and prints the root equivalent. This amends the research's direct-systemctl toggle: a period boundary cannot be recorded by systemctl, so the toggle must be Fenris's own fixed operation.
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6. **Period rows.** Idempotent matrix: a first-ever enable opens a period at the enable moment (hours before the first successful sample are unknown-but-inside, correctly so when the device errors); a resume with an open period — a raw `systemctl stop` intervened — changes no row, the gap remaining inside as unknown seconds; a resume with no open period opens a new row at the resume moment; a pause with an open period closes it `user_disabled` at the pause moment; a pause otherwise is a no-op. A raw stop or disable outside the helper is an unexplained gap, never `user_disabled`: only the sanctioned path can record intent.
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7. **On-demand collection.** `fenris sample` and the TUI's collect-now route through `fenris-monitor` → `systemctl start fenris-collect.service`, which blocks until the oneshot exits, and the outcome (freshness line or journal hint) is reported synchronously. No code path outside `fenris-collect` touches the device; the TUI never samples in-process; no confirmation is required.
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8. **TUI controls.** Pause asks for confirmation; Resume does not (benign — friction invites raw-systemctl escapes). Boot enablement and current runtime activity are always displayed as separate facts, next to last collect outcome and freshness. No bare start/stop exists anywhere.
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9. **CLI compatibility.** `status` is a pure read-only composition of the observation store and allow-listed `systemctl show` properties: projection facts, enabled/active, last collect outcome, and a `journalctl -u fenris-collect.service` hint on failure or staleness; it never auto-samples and never prompts. `sample` is retained via the helper path; `--device` is rejected with a pointer to the configuration file. `start`, `stop`, and `run` are rejected with one-line migration pointers, not aliased — an alias would silently change meaning. `fenris.sh` is retired: not shipped, removed from the repository, and the README maps its five menu options to their successors.
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10. **Freshness constants.** Documented once, consumed by TUI and CLI alike: fresh means the newest sample is within 2× cadence + `AccuracySec` + 60 s; between that and 48 h the store is missed (a contributing fact); at ≥ 48 h it is stale, matching [ADR 0002](0002-projection-model-sustained-regime.md)'s evidence gate; an empty store reads "no observations yet" with an enable hint.
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## Consequences
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- Polkit ships one Fenris-specific policy authorizing exactly one fixed-operation binary; the collector itself is never polkit-reachable.
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- Monitoring-period boundaries are exact at toggle moments; approximation never enters the habit record.
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- Interval tuning is a systemd drop-in documented in the README; `/etc/fenris` stays a one-key file.
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- Headless administration has full parity: every TUI action has a CLI twin.
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- The TUI must run privileged operations through a terminal-attached subprocess so the platform polkit agent can prompt; the TUI prototype ticket validates this in practice.
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- Nothing survives of the prototype's daemonization, PID files, or HTTP server; their commands fail with pointers instead of quiet behavior changes.
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