Clarify incomplete history readouts (#103)

README.md

@@ -263,6 +263,12 @@ measured read/write volumes, not transfer speed; missing evidence breaks the
 trace. `?` marks a gap, `~` a partial total, and `u` unallocated daily volume.
 Use the selected-point readout for exact values and evidence state.
 
+Local-day totals use measured intervals inside each recorded local date. An
+interval that crosses local midnight appears once as shared evidence and stays
+outside both known totals. The dashboard labels current totals as so far and
+shows incomplete or unavailable dates without treating them as zero. Older
+UTC-only summaries cannot establish exact local-day totals.
+
 - `v` cycles Live / Day / History; the tabs are also clickable.
 - `←` / `→` inspect points; `w` switches read/write volume in every view.
 - `[` / `]` browse dates, `g` enters a date, and `t` returns to today/live.

docs/adr/0010-local-day-activity-history.md

@@ -0,0 +1,11 @@
+# 10. Preserve local-day activity history with its recorded timezone
+
+Status: Accepted; legacy-history migration and repair implemented in issue #99.
+
+Fenris will retain local-day read/write summaries and the boundary evidence needed to interpret them in the existing observation store before three-minute detail expires after 14 days. Each historical summary retains its recorded timezone and day boundaries; this extends [ADR 0001](0001-observation-store-sqlite.md) while preserving the UTC hour/day evidence used for endurance projections. Collection derives new measured intervals. Ordered schema migration and explicit repair rebuild legacy summaries from surviving evidence; TUI and CLI readers remain read-only.
+
+UTC hourly summaries alone cannot recover a local day whose midnight falls inside a UTC hour. Preserving labelled local summaries trades arbitrary future timezone reinterpretation for bounded detailed-history retention; retaining all fine-grained intervals indefinitely or estimating a split from UTC summaries would violate the agreed retention or evidence semantics.
+
+Only surviving evidence may be used to derive older local summaries. Dates without enough evidence remain incomplete or unavailable; a measured interval crossing midnight is retained once as shared boundary evidence, never prorated or counted in full on both days. A later timezone change does not silently rewrite historical day boundaries.
+
+The agreed presentation and validation requirements are in the [live drive activity specification](../spec/live-drive-activity.md).

src/fenris/activity_selection.py

@@ -0,0 +1,132 @@
+"""User choices for live and historical activity views."""
+from collections.abc import Sequence
+from dataclasses import dataclass
+
+HISTORY_RANGE_DEFAULT = 14
+
+
+@dataclass(frozen=True)
+class IntervalIdentity:
+    """Stable identity for one measured interval."""
+
+    start_ts: str
+    end_ts: str
+
+
+@dataclass(frozen=True)
+class HistoryDayIdentity:
+    """Stable identity for one recorded local-day summary."""
+
+    local_date: str
+    timezone: str
+    utc_start: str
+    utc_end: str
+
+
+class ActivitySelection:
+    """Keep activity navigation state separate from its Textual rendering."""
+
+    def __init__(self) -> None:
+        self.view = "live"
+        self.browse_date: str | None = None
+        self.selected_history_day: HistoryDayIdentity | None = None
+        self.selected_history_hour: str | None = None
+        self.history_range_days = HISTORY_RANGE_DEFAULT
+        self.measure = "written"
+        self.following_live = True
+        self.selected_live_interval: IntervalIdentity | None = None
+        self.live_interval_expired = False
+
+    def set_view(self, view: str) -> None:
+        """Select live, day, or history view."""
+        if view not in ("live", "day", "history"):
+            raise ValueError(f"unknown activity view: {view}")
+        self.view = view
+        if view == "live":
+            self.follow_live()
+
+    def select_history_date(
+        self,
+        date: str | None,
+        identity: HistoryDayIdentity | None = None,
+    ) -> None:
+        """Keep requested date and evidence identity across refresh."""
+        if date != self.browse_date or (
+            identity is not None and identity != self.selected_history_day
+        ):
+            self.selected_history_hour = None
+        if date != self.browse_date:
+            self.selected_history_day = None
+        self.browse_date = date
+        if identity is not None:
+            self.selected_history_day = identity
+        elif date is None:
+            self.selected_history_day = None
+
+    def select_history_hour(self, hour: str | None) -> None:
+        """Keep the chosen historical hour across refresh."""
+        self.selected_history_hour = hour
+
+    def toggle_measure(self) -> str:
+        """Switch read/write presentation without changing point selection."""
+        self.measure = "read" if self.measure == "written" else "written"
+        return self.measure
+
+    def follow_live(self) -> None:
+        """Resume following the newest interval and clear stale-pin notices."""
+        self.view = "live"
+        self.browse_date = None
+        self.selected_history_day = None
+        self.selected_history_hour = None
+        self.following_live = True
+        self.selected_live_interval = None
+        self.live_interval_expired = False
+
+    def update_live(self, intervals: Sequence[IntervalIdentity]) -> None:
+        """Reconcile the selected interval with the rolling live window."""
+        if self.following_live:
+            self.selected_live_interval = intervals[-1] if intervals else None
+            return
+        if self.selected_live_interval in intervals:
+            return
+
+        self.following_live = True
+        self.selected_live_interval = intervals[-1] if intervals else None
+        self.live_interval_expired = True
+
+    def move_live(
+        self, intervals: Sequence[IntervalIdentity], offset: int,
+    ) -> IntervalIdentity | None:
+        """Inspect an adjacent interval by stable identity."""
+        if not intervals:
+            return None
+        if self.selected_live_interval in intervals:
+            current = intervals.index(self.selected_live_interval)
+        else:
+            current = len(intervals) - 1
+        selected = intervals[max(0, min(len(intervals) - 1, current + offset))]
+        self._pin_live_interval(selected)
+        return selected
+
+    def inspect_live(
+        self,
+        intervals: Sequence[IntervalIdentity],
+        interval: IntervalIdentity,
+    ) -> None:
+        """Pin the interval chosen by mouse inspection."""
+        if interval in intervals:
+            self._pin_live_interval(interval)
+
+    def selected_live_index(self, intervals: Sequence[IntervalIdentity]) -> int:
+        """Return the selected point's current render index, or -1."""
+        if self.selected_live_interval is None:
+            return -1
+        try:
+            return intervals.index(self.selected_live_interval)
+        except ValueError:
+            return -1
+
+    def _pin_live_interval(self, interval: IntervalIdentity) -> None:
+        self.selected_live_interval = interval
+        self.following_live = False
+        self.live_interval_expired = False

src/fenris/collect.py

@@ -27,7 +27,6 @@ if VENV_DIR.exists():
         if site_packages:
             sys.path.insert(0, str(site_packages))
 
-from fenris.store import init_store, get_store_path
 from fenris.collector import run_collection
 
 
@@ -103,14 +102,6 @@ def main() -> None:
         config = load_config()
         device = config["device"]
 
-        # Interrogate the drive
-        smartctl_data = interrogate_drive(device)
-
-        # Find sysfs path
-        sysfs_path = find_nvme_sysfs()
-        if sysfs_path is None:
-            raise RuntimeError("No NVMe controller found in sysfs")
-
         # Inject a simple clock
         class SimpleClock:
             def utcnow(self):
@@ -118,11 +109,24 @@ def main() -> None:
 
         clock = SimpleClock()
 
+        def acquire():
+            """Interrogate the drive after pending-work preflight."""
+            smartctl_data = interrogate_drive(device)
+            sysfs_path = find_nvme_sysfs()
+            if sysfs_path is None:
+                raise RuntimeError("No NVMe controller found in sysfs")
+            return smartctl_data, sysfs_path
+
         # Run collection
-        result = run_collection(smartctl_data, sysfs_path, config, clock)
+        result = run_collection(config=config, clock=clock, acquire=acquire)
 
         if result["ok"]:
             print(f"Collection successful: {result['sample_count']} sample(s)")
+            if result.get("retention_error"):
+                print(
+                    f"Retention deferred: {result['retention_error']}",
+                    file=sys.stderr,
+                )
             sys.exit(0)
         else:
             print(f"Collection failed: {result['error']}", file=sys.stderr)

src/fenris/collector.py

@@ -5,19 +5,21 @@ This module implements the thinnest complete write path:
 - Acquire controller identity from sysfs
 - Normalize identity exactly once at write time
 - Validate every row against store invariants
-- Commit one well-formed sample
+- Stage valid observations privately before derivation
+- Publish the sample and derived evidence in one collection-owned transaction
 
 No code path outside the collector interrogates the device.
 """
 import json
 import sqlite3
+from collections.abc import Callable
 from datetime import datetime, timezone
 from pathlib import Path
-from typing import Any, Dict, Optional, Tuple
+from typing import Any, Dict, Optional
 
-from .store import init_store, get_store_path
+from .derive import derive_hours_from_interval, find_previous_sample
 from .monitoring_periods import ensure_period_open
-from .derive import find_previous_sample, derive_hours_from_interval
+from .store import init_store, get_store_path
 
 
 class AcquisitionError(Exception):
@@ -30,6 +32,29 @@ class InvariantViolationError(Exception):
     pass
 
 
+class _PendingDerivationError(Exception):
+    """A valid staged observation failed while deriving dependent evidence."""
+
+    def __init__(self, cause: Exception):
+        super().__init__(str(cause))
+        self.cause = cause
+
+
+class _PendingRecoveryFailure(Exception):
+    """A publication attempt failed after earlier pending rows committed."""
+
+    def __init__(self, error: Exception, published_count: int):
+        derivation_error = isinstance(error, _PendingDerivationError)
+        cause = error.cause if derivation_error else error
+        super().__init__(str(cause))
+        self.cause = cause
+        self.published_count = published_count
+        self.derivation_error = derivation_error
+
+
+PENDING_PUBLICATION_LIMIT = 6720
+
+
 def acquire_from_smartctl(smartctl_data: Dict[str, Any]) -> Dict[str, Any]:
     """Acquire counters and thermal evidence from smartctl -a -j data.
     
@@ -195,12 +220,12 @@ def write_sample(
     sample: Dict[str, Any],
     identity: Dict[str, Any],
     conn: sqlite3.Connection,
-    clock,
+    observed_at: datetime,
 ) -> Dict[str, Any]:
     """Write one sample to the observation store.
     
     Identity normalization happens exactly once here.
-    Returns segment info for the caller.
+    Returns segment info for the caller. Caller owns the transaction.
     """
     from .segment import find_current_segment, should_open_new_segment, open_segment
     
@@ -219,8 +244,7 @@ def write_sample(
     # Open new segment if needed
     segment_opened = False
     if should_open:
-        now = clock.utcnow()
+        open_segment(conn, observed_at, identity, identity_key, identity_degraded)
-        open_segment(conn, now, identity, identity_key, identity_degraded)
         segment_opened = True
     
     # Get current segment_id for provenance
@@ -235,8 +259,8 @@ 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, segment_id
+            critical_warning, segment_id, local_tz
-        ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
+        ) VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?, ?)
         """,
         (
             sample["ts"],
@@ -259,122 +283,301 @@ def write_sample(
             sample["bytes_read"],
             sample["critical_warning"],
             segment_id,
+            sample.get("local_tz"),
         ),
     )
     
-    conn.commit()
-    
     return {
         "segment_opened": segment_opened,
         "segment_reason": reason,
         "identity_key": identity_key,
         "identity_degraded": identity_degraded,
         "segment_id": segment_id,
+        "sample_id": cursor.lastrowid,
     }
 
 
-def run_collection(
+def _observation_time(sample: Dict[str, Any]) -> datetime:
-    smartctl_data: Dict[str, Any],
+    """Read an observation's original timestamp for ordered recovery."""
-    sysfs_path: Path,
+    observed_at = datetime.fromisoformat(sample["ts"])
-    config: Dict[str, Any],
+    if observed_at.tzinfo is None:
-    clock,
+        return observed_at.replace(tzinfo=timezone.utc)
-) -> Dict[str, Any]:
+    return observed_at.astimezone(timezone.utc)
-    """Run one collection run.
+
-    
+
-    This is the main entry point for the collector.
+def _publish_observation(
-    Returns the run outcome.
+    conn: sqlite3.Connection,
-    """
+    sample: Dict[str, Any],
+    identity: Dict[str, Any],
+    tz_name: str,
+) -> None:
+    """Publish one staged sample and all dependent evidence in caller transaction."""
+    observed_at = _observation_time(sample)
+    sample["local_tz"] = tz_name
+    validate_sample_invariants(sample, conn)
+    ensure_period_open(conn, observed_at)
+    seg_info = write_sample(sample, identity, conn, observed_at)
+
+    current_id = seg_info["sample_id"]
+    prev = find_previous_sample(conn, seg_info.get("segment_id"), current_id)
     try:
-        # Acquire counters and thermal evidence
+        if prev is not None:
-        counters = acquire_from_smartctl(smartctl_data)
+            current = {
-        
+                "id": current_id,
-        # Acquire controller identity
+                "ts": sample["ts"],
-        identity = acquire_from_sysfs(sysfs_path)
+                "bytes_written": sample["bytes_written"],
-        
+                "bytes_read": sample["bytes_read"],
-        # Build sample with injected clock
+                "power_on_hours": sample["power_on_hours"],
-        sample = {
+                "temperature_c": sample["temperature_c"],
-            "ts": clock.utcnow().isoformat(),
+                "data_units_written": sample["data_units_written"],
-            "device": config["device"],
+                "data_units_read": sample["data_units_read"],
-            **counters,
+                "local_tz": tz_name,
-            **identity,
+            }
-        }
+            derive_hours_from_interval(conn, prev, current)
-        
+            from .local_day import record_local_activity_interval
-        # Initialize store if needed
+            record_local_activity_interval(
+                conn,
+                prev,
+                current,
+                start_sample_id=prev["id"],
+                end_sample_id=current_id,
+                segment_id=seg_info.get("segment_id"),
+            )
+        else:
+            previous_any_segment = find_previous_sample(conn, None, current_id)
+            if previous_any_segment is not None:
+                from .local_day import mark_local_activity_gap
+                mark_local_activity_gap(
+                    conn,
+                    sample["ts"],
+                    tz_name,
+                    previous_any_segment,
+                )
+
+        from .day_aggregate import derive_all_days, persist_day_aggregate
+        for aggregate in derive_all_days(conn):
+            persist_day_aggregate(conn, aggregate)
+
+        from .local_day import derive_local_day_summary, persist_local_day
+        local_summary = derive_local_day_summary(conn, tz_name, observed_at)
+        if local_summary is not None:
+            persist_local_day(conn, local_summary)
+    except Exception as exc:  # noqa: BLE001 - preserve valid staged evidence for retry.
+        raise _PendingDerivationError(exc) from exc
+
+
+def _pending_count(conn: sqlite3.Connection) -> int:
+    return conn.execute("SELECT COUNT(*) FROM pending_publications").fetchone()[0]
+
+
+def _stage_observation(
+    conn: sqlite3.Connection,
+    sample: Dict[str, Any],
+    identity: Dict[str, Any],
+    tz_name: str,
+) -> int:
+    """Durably stage valid acquired evidence before attempting publication."""
+    payload = json.dumps(
+        {"sample": sample, "identity": identity, "tz_name": tz_name},
+        separators=(",", ":"),
+        sort_keys=True,
+    )
+    cursor = conn.execute(
+        "INSERT INTO pending_publications (sample_ts, payload) VALUES (?, ?)",
+        (sample["ts"], payload),
+    )
+    return cursor.lastrowid
+
+
+def _recover_pending(conn: sqlite3.Connection) -> int:
+    """Publish pending observations oldest first; stop at first failure."""
+    recovered = 0
+    while True:
+        conn.execute("BEGIN IMMEDIATE")
+        try:
+            row = conn.execute(
+                "SELECT id, payload FROM pending_publications ORDER BY id LIMIT 1"
+            ).fetchone()
+            if row is None:
+                conn.rollback()
+                return recovered
+
+            pending_id, payload = row
+            observation = json.loads(payload)
+            try:
+                _publish_observation(
+                    conn,
+                    observation["sample"],
+                    observation["identity"],
+                    observation["tz_name"],
+                )
+            except Exception as exc:
+                raise _PendingRecoveryFailure(exc, recovered) from exc
+            conn.execute("DELETE FROM pending_publications WHERE id = ?", (pending_id,))
+            conn.commit()
+            recovered += 1
+        except Exception:
+            conn.rollback()
+            raise
+
+
+def _is_store_or_invariant_failure(exc: Exception) -> bool:
+    return (
+        isinstance(exc, sqlite3.Error)
+        and not isinstance(exc, sqlite3.IntegrityError)
+    ) or isinstance(exc, InvariantViolationError)
+
+
+def _pending_capacity_error(
+    reason: str,
+    *,
+    acquisition_skipped: bool = False,
+) -> RuntimeError:
+    outcome = "; no new observation acquired" if acquisition_skipped else ""
+    return RuntimeError(
+        "pending publication capacity full "
+        f"({PENDING_PUBLICATION_LIMIT} observations){outcome}; "
+        f"{reason}"
+    )
+
+
+def _recover_pending_for_collection(conn: sqlite3.Connection) -> int:
+    """Retry queued work and report exhausted capacity without masking store faults."""
+    try:
+        return _recover_pending(conn)
+    except Exception as exc:  # noqa: BLE001 - preserve pending evidence on recovery errors.
+        cause = exc.cause if isinstance(exc, _PendingRecoveryFailure) else exc
+        if _is_store_or_invariant_failure(cause):
+            raise cause
+        try:
+            capacity_full = _pending_count(conn) >= PENDING_PUBLICATION_LIMIT
+        except sqlite3.Error:
+            raise cause
+        if capacity_full:
+            raise _pending_capacity_error(f"recovery failed: {cause}") from cause
+        raise cause
+
+
+def _recover_pending_for_admission(conn: sqlite3.Connection) -> int:
+    """Recover in order, then admit one observation if bounded space remains."""
+    try:
+        recovered = _recover_pending(conn)
+    except _PendingRecoveryFailure as failure:
+        if (
+            not failure.derivation_error
+            or _is_store_or_invariant_failure(failure.cause)
+        ):
+            raise failure.cause
+        try:
+            pending_count = _pending_count(conn)
+        except sqlite3.Error:
+            raise failure.cause
+        if pending_count >= PENDING_PUBLICATION_LIMIT:
+            raise _pending_capacity_error(
+                f"recovery failed: {failure.cause}",
+                acquisition_skipped=True,
+            ) from failure.cause
+        return failure.published_count
+
+    if _pending_count(conn) >= PENDING_PUBLICATION_LIMIT:
+        raise _pending_capacity_error(
+            "recovery left the queue full",
+            acquisition_skipped=True,
+        )
+    return recovered
+
+
+def run_collection(
+    smartctl_data: Optional[Dict[str, Any]] = None,
+    sysfs_path: Optional[Path] = None,
+    config: Optional[Dict[str, Any]] = None,
+    clock=None,
+    *,
+    acquire: Optional[Callable[[], tuple[Dict[str, Any], Path]]] = None,
+) -> Dict[str, Any]:
+    """Recover old work, acquire one observation, then publish it atomically.
+
+    Production callers pass ``acquire`` so recovery and capacity checks run
+    before device interrogation. Direct sample arguments remain useful for
+    deterministic collector tests.
+    """
+    conn = None
+    try:
+        if config is None or clock is None:
+            raise ValueError("config and clock are required")
+
         store_path = get_store_path(config)
         conn = init_store(store_path)
 
-        # Run legacy import if needed (idempotent)
         from .legacy import import_legacy_history
         history_path = Path(config.get("data_dir", ".")) / "history.jsonl"
         if history_path.exists():
             import_legacy_history(conn, history_path, clock=clock)
 
-        
+        published_count = _recover_pending_for_admission(conn)
-        try:
+        checked_pending_count = _pending_count(conn)
-            # Ensure monitoring period is open (issue #73 AC2)
-            ensure_period_open(conn, clock.utcnow())
-            
-            # Validate invariants
-            validate_sample_invariants(sample, conn)
-            
-            # 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)
+        # Hold the writer reservation across the capacity check and acquisition.
-                if prev is not None:
+        # Recheck recovery if another collector appended work during preflight.
-                    # Build current sample dict for derivation
+        while True:
-                    current = {
+            conn.execute("BEGIN IMMEDIATE")
-                        "id": current_id,
+            waiting = _pending_count(conn)
-                        "ts": sample["ts"],
+            if (
-                        "bytes_written": sample["bytes_written"],
+                waiting >= PENDING_PUBLICATION_LIMIT
-                        "bytes_read": sample["bytes_read"],
+                or waiting > checked_pending_count
-                        "power_on_hours": sample["power_on_hours"],
+            ):
-                        "temperature_c": sample["temperature_c"],
+                conn.rollback()
-                        "data_units_written": sample["data_units_written"],
+                published_count += _recover_pending_for_admission(conn)
-                        "data_units_read": sample["data_units_read"],
+                checked_pending_count = _pending_count(conn)
-                    }
+                continue
-                    derive_hours_from_interval(conn, prev, current)
 
-                # Rebuild day aggregates from hour observations
+            from .tz_util import detect_system_tz
-                from .day_aggregate import derive_all_days, persist_day_aggregate
+            tz_name = detect_system_tz()
-                for agg in derive_all_days(conn):
+            if acquire is not None:
-                    persist_day_aggregate(conn, agg)
+                smartctl_data, sysfs_path = acquire()
+            if smartctl_data is None or sysfs_path is None:
+                raise AcquisitionError("No acquired SMART data or sysfs identity")
 
-                # Derive local-day summary using system timezone (issue #90)
+            counters = acquire_from_smartctl(smartctl_data)
-                try:
+            identity = acquire_from_sysfs(sysfs_path)
-                    from .tz_util import detect_system_tz
+            sample = {
-                    from .local_day import derive_local_day_summary, persist_local_day
+                "ts": clock.utcnow().isoformat(),
-                    tz_name = detect_system_tz()
+                "device": config["device"],
-                    clock_now = clock.utcnow()
+                **counters,
-                    local_summary = derive_local_day_summary(conn, tz_name, clock_now)
+                **identity,
-                    if local_summary is not None:
-                        persist_local_day(conn, local_summary)
-                except Exception:
-                    # Local-day derivation failure must not prevent publication
-                    pass
-
-                conn.commit()
-            except Exception:
-                # Derivation failure must not prevent sample persistence (issue #73 AC6)
-                pass
-            
-            return {
-                "ok": True,
-                "sample_count": 1,
-                "store_path": str(store_path),
             }
-        finally:
+            validate_sample_invariants(sample, conn)
-            conn.close()
+            _stage_observation(conn, sample, identity, tz_name)
-    
+            conn.commit()
-    except (AcquisitionError, InvariantViolationError) as e:
+            break
+
+        published_count += _recover_pending_for_collection(conn)
+        retention_error = None
+        try:
+            if _pending_count(conn) == 0:
+                from .pruning import prune_old_samples
+
+                prune_old_samples(conn, clock.utcnow())
+        except Exception as exc:  # noqa: BLE001 - publication already committed.
+            # Publication already committed. Keep collection successful and
+            # retry atomic retention on the next normal collection.
+            conn.rollback()
+            retention_error = str(exc)
+        return {
+            "ok": True,
+            "sample_count": published_count,
+            "retention_error": retention_error,
+            "store_path": str(store_path),
+        }
+
+    except Exception as exc:
+        if conn is not None:
+            conn.rollback()
         return {
             "ok": False,
-            "error": str(e),
+            "error": str(exc),
-            "error_type": type(e).__name__,
+            "error_type": type(exc).__name__,
         }
+    finally:
+        if conn is not None:
+            conn.close()

src/fenris/derive.py

@@ -29,7 +29,7 @@ def find_previous_sample(
     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 "
+            "       temperature_c, data_units_written, data_units_read, local_tz "
             "FROM samples WHERE id < ? AND segment_id = ? "
             "ORDER BY id DESC LIMIT 1",
             (current_sample_id, segment_id),
@@ -37,7 +37,7 @@ def find_previous_sample(
     else:
         cursor = conn.execute(
             "SELECT id, ts, bytes_written, bytes_read, power_on_hours, "
-            "       temperature_c, data_units_written, data_units_read "
+            "       temperature_c, data_units_written, data_units_read, local_tz "
             "FROM samples WHERE id < ? "
             "ORDER BY id DESC LIMIT 1",
             (current_sample_id,),
@@ -49,7 +49,7 @@ def find_previous_sample(
         "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],
+        "data_units_read": row[7], "local_tz": row[8],
     }
 
 
@@ -96,6 +96,7 @@ def derive_hours_from_interval(
     """Derive hour observations from a sample pair interval.
 
     Returns list of hour observation dicts that were written/updated.
+    Caller owns the transaction.
     """
     prev_ts = _parse_ts(prev_sample["ts"])
     next_ts = _parse_ts(next_sample["ts"])
@@ -207,9 +208,6 @@ def _upsert_hour_observation(
             "WHERE id = ?",
             (new_bw, new_br, new_samples, existing[0]),
         )
-    conn.commit()
-
-
 def _add_unattributed_bytes(
     conn: sqlite3.Connection,
     prev_ts: datetime,
@@ -241,4 +239,3 @@ def _add_unattributed_bytes(
             "unattributed_bytes_read = unattributed_bytes_read + ? WHERE day = ?",
             (bw_delta, br_delta, day),
         )
-    conn.commit()

src/fenris/monitor.py

@@ -69,6 +69,7 @@ def cmd_enable(args: argparse.Namespace) -> None:
         open_period = get_open_period(conn)
         if open_period is None:
             ensure_period_open(conn, now)
+            conn.commit()
             print("Monitoring period opened at", now.isoformat())
         else:
             print("Monitoring period already open (id=%d)" % open_period["id"])

src/fenris/monitoring_periods.py

@@ -16,7 +16,7 @@ def ensure_period_open(conn: sqlite3.Connection, run_time: datetime) -> None:
     """Ensure a monitoring period is open.  If none exists, open one at run_time.
 
     Spec §9.8: A collection run finding no open monitoring period opens one
-    at the run moment, never backdated.
+    at the run moment, never backdated. Caller owns the transaction.
     """
     if get_open_period(conn) is not None:
         return  # Already open — no-op
@@ -26,7 +26,6 @@ def ensure_period_open(conn: sqlite3.Connection, run_time: datetime) -> None:
         "INSERT INTO monitoring_periods (started_at) VALUES (?)",
         (ts,),
     )
-    conn.commit()
 
 
 def close_period(

src/fenris/projection.py

@@ -187,7 +187,7 @@ def _wall_clock_in_range(conn, start, end):
 
 def _resolve_baseline(conn, current_segment):
     baseline = _get_baseline(conn)
-    facts = []
+    facts: list[str] = []
     if baseline is None:
         return BaselineTier.NONE, None, "no baseline", facts
 
@@ -494,16 +494,16 @@ def _has_complete_local_day(conn):
     within a monitoring period that has usable observation evidence.
     This is the prerequisite for showing an endurance outlook.
     """
-    row = conn.execute(
+    return _count_complete_local_days(conn) > 0
-        "SELECT 1 FROM local_days WHERE complete = 1 LIMIT 1"
-    ).fetchone()
-    return row is not None
 
 
 def _count_complete_local_days(conn):
     """Count the number of complete local observation days."""
     row = conn.execute(
-        "SELECT COUNT(*) FROM local_days WHERE complete = 1"
+        "SELECT COUNT(*) FROM local_days "
+        "WHERE complete = 1 "
+        "AND activity_precision IN ('measured', 'coarse') "
+        "AND activity_intervals > 0"
     ).fetchone()
     return row[0] if row else 0
 

src/fenris/pruning.py

@@ -1,131 +1,332 @@
-"""Raw sample pruning per spec §3.4, ST-5.
+"""Expire detail only after UTC and local_days replacement evidence is durable.
 
-Raw samples are pruned opportunistically to 14 days.
+The 14-day cutoff never overrides local-day preservation, shared boundary
-Hour observations and day aggregates are retained indefinitely.
+evidence, publication recovery, or the newest sample's successor-anchor role.
-Boundary anchors required for successor evidence are retained.
-
-Local-day summaries (local_days table) are never touched by pruning.
-They are persisted at collection time from hour observations and survive
-raw-sample pruning because they depend on hour observations, not on raw
-samples.  This is the mechanism that keeps local-day history trustworthy
-after detail expires (issue #93).
 """
 import sqlite3
-from datetime import datetime, timedelta, timezone
+from datetime import date, datetime, timedelta, timezone
 
-# Spec §3.4: Raw-sample retention
 RAW_SAMPLE_RETENTION_DAYS = 14
 
 
+def _utc_datetime(value: datetime) -> datetime:
+    """Normalize a clock value to aware UTC."""
+    if value.tzinfo is None:
+        value = value.replace(tzinfo=timezone.utc)
+    return value.astimezone(timezone.utc)
+
+
+def _parse_sample_time(value: str) -> datetime | None:
+    """Parse old timestamps conservatively; malformed legacy values stay."""
+    try:
+        parsed = datetime.fromisoformat(value)
+    except (TypeError, ValueError):
+        return None
+    return _utc_datetime(parsed)
+
+
+def _sample_rows(conn: sqlite3.Connection) -> list[tuple]:
+    return conn.execute(
+        "SELECT id, ts, segment_id, bytes_written, bytes_read, local_tz "
+        "FROM samples ORDER BY id"
+    ).fetchall()
+
+
+def _required_hour_window(
+    start: datetime,
+    end: datetime,
+) -> tuple[datetime, datetime, int] | None:
+    """Return first hour, exclusive end and count for [start, end)."""
+    if end <= start:
+        return None
+    first_hour = start.replace(minute=0, second=0, microsecond=0)
+    last_hour = end.replace(minute=0, second=0, microsecond=0)
+    try:
+        exclusive_end = last_hour if end == last_hour else last_hour + timedelta(hours=1)
+    except OverflowError:
+        return None
+    count = int((exclusive_end - first_hour).total_seconds() // 3600)
+    return first_hour, exclusive_end, count
+
+
+def _has_utc_replacement(
+    conn: sqlite3.Connection,
+    previous: tuple,
+    current: tuple,
+    start: datetime,
+    end: datetime,
+) -> bool:
+    window = _required_hour_window(start, end)
+    if window is None:
+        return False
+    first_hour, exclusive_end, expected_hour_count = window
+
+    actual_hour_count = conn.execute(
+        "SELECT COUNT(*) FROM hour_observations WHERE hour >= ? AND hour < ?",
+        (
+            first_hour.strftime("%Y-%m-%dT%H:00:00+00:00"),
+            exclusive_end.strftime("%Y-%m-%dT%H:00:00+00:00"),
+        ),
+    ).fetchone()[0]
+    if actual_hour_count < expected_hour_count:
+        return False
+
+    start_written, end_written = previous[3], current[3]
+    start_read, end_read = previous[4], current[4]
+    if None in (start_written, end_written, start_read, end_read):
+        return False
+    if end_written < start_written or end_read < start_read:
+        return False
+    bytes_written = end_written - start_written
+    bytes_read = end_read - start_read
+    if expected_hour_count == 1:
+        totals = conn.execute(
+            "SELECT bytes_written_delta, bytes_read_delta FROM hour_observations "
+            "WHERE hour = ?",
+            (first_hour.strftime("%Y-%m-%dT%H:00:00+00:00"),),
+        ).fetchone()
+    else:
+        totals = conn.execute(
+            "SELECT unattributed_bytes_written, unattributed_bytes_read "
+            "FROM day_aggregates WHERE day = ?",
+            (start.date().isoformat(),),
+        ).fetchone()
+    if totals is None or totals[0] < bytes_written or totals[1] < bytes_read:
+        return False
+
+    last_day = (exclusive_end - timedelta(microseconds=1)).date()
+    expected_day_count = (last_day - first_hour.date()).days + 1
+    actual_day_count = conn.execute(
+        "SELECT COUNT(*) FROM day_aggregates WHERE day >= ? AND day <= ?",
+        (first_hour.date().isoformat(), last_day.isoformat()),
+    ).fetchone()[0]
+    return actual_day_count >= expected_day_count
+
+
+def _local_day_row_exists(
+    conn: sqlite3.Connection,
+    local_date: str,
+    tz_name: str,
+) -> bool:
+    return conn.execute(
+        "SELECT 1 FROM local_days WHERE local_date = ? AND tz_name = ?",
+        (local_date, tz_name),
+    ).fetchone() is not None
+
+
+def _local_day_bounds(
+    conn: sqlite3.Connection,
+    local_date: str,
+    tz_name: str,
+) -> tuple[datetime, datetime] | None:
+    row = conn.execute(
+        "SELECT utc_start, utc_end FROM local_days "
+        "WHERE local_date = ? AND tz_name = ?",
+        (local_date, tz_name),
+    ).fetchone()
+    if row is None:
+        return None
+    start = _parse_sample_time(row[0])
+    end = _parse_sample_time(row[1])
+    if start is None or end is None or end <= start:
+        return None
+    return start, end
+
+
+def _contains_instant(
+    conn: sqlite3.Connection,
+    local_date: str,
+    tz_name: str,
+    instant: datetime,
+) -> bool:
+    bounds = _local_day_bounds(conn, local_date, tz_name)
+    return bounds is not None and bounds[0] <= instant < bounds[1]
+
+
+def _monitoring_period_covers(
+    conn: sqlite3.Connection,
+    start: datetime,
+    end: datetime,
+) -> bool:
+    """Require continuous monitoring before a local-day total replaces detail."""
+    for started_at, ended_at in conn.execute(
+        "SELECT started_at, ended_at FROM monitoring_periods"
+    ):
+        period_start = _parse_sample_time(started_at)
+        period_end = _parse_sample_time(ended_at) if ended_at is not None else None
+        if period_start is None or period_start > start:
+            continue
+        if ended_at is None or (period_end is not None and end <= period_end):
+            return True
+    return False
+
+
+def _has_local_replacement(
+    conn: sqlite3.Connection,
+    previous: tuple,
+    current: tuple,
+    start: datetime,
+    end: datetime,
+) -> bool:
+    start_tz = previous[5]
+    end_tz = current[5]
+    if not end_tz:
+        return False
+
+    start_id, end_id = previous[0], current[0]
+    segment_id = current[2]
+    if (
+        start_tz
+        and start_tz == end_tz
+        and segment_id is not None
+        and _monitoring_period_covers(conn, start, end)
+    ):
+        known_days = conn.execute(
+            "SELECT local_days.utc_start, local_days.utc_end "
+            "FROM local_days JOIN local_day_segment_totals "
+            "  ON local_day_segment_totals.local_day_id = local_days.id "
+            "WHERE local_days.tz_name = ? "
+            "  AND local_days.activity_precision IN ('measured', 'coarse') "
+            "  AND local_days.last_sample_id >= ? "
+            "  AND local_days.activity_intervals > 0 "
+            "  AND local_day_segment_totals.segment_id = ? "
+            "  AND local_day_segment_totals.activity_intervals > 0",
+            (end_tz, end_id, segment_id),
+        ).fetchall()
+        for row in known_days:
+            bounds_start = _parse_sample_time(row[0])
+            bounds_end = _parse_sample_time(row[1])
+            if (
+                bounds_start is not None
+                and bounds_end is not None
+                and bounds_start <= start
+                and end < bounds_end
+            ):
+                return True
+
+    evidence = conn.execute(
+        "SELECT bytes_written, bytes_read, reason, start_local_date, end_local_date, "
+        "       start_tz_name, end_tz_name, started_at, ended_at "
+        "FROM local_day_unallocated_evidence "
+        "WHERE start_sample_id = ? AND end_sample_id = ?",
+        (start_id, end_id),
+    ).fetchone()
+    if evidence is None:
+        return False
+
+    start_written, end_written = previous[3], current[3]
+    start_read, end_read = previous[4], current[4]
+    if None in (start_written, end_written, start_read, end_read):
+        return False
+    if end_written < start_written or end_read < start_read:
+        return False
+    # The source IDs uniquely identify this interval. Confirm its durable
+    # deltas and retain every recorded local-day boundary it touches.
+    if (end_written - start_written, end_read - start_read) != evidence[:2]:
+        return False
+    if evidence[5] != start_tz or evidence[6] != end_tz:
+        return False
+    if evidence[2] not in {
+        "counter_discontinuity",
+        "legacy_timezone_unknown",
+        "timezone_change",
+        "monitoring_period",
+        "local_midnight",
+        "segment_unknown",
+    }:
+        return False
+    if _parse_sample_time(evidence[7]) != start or _parse_sample_time(evidence[8]) != end:
+        return False
+
+    affected_days: set[tuple[str, str]] = set()
+    if start_tz:
+        affected_days.add((evidence[3], start_tz))
+    affected_days.add((evidence[4], end_tz))
+    if start_tz and start_tz == end_tz and evidence[3] < evidence[4]:
+        day = date.fromisoformat(evidence[3]) + timedelta(days=1)
+        last_day = date.fromisoformat(evidence[4])
+        while day < last_day:
+            affected_days.add((day.isoformat(), end_tz))
+            day += timedelta(days=1)
+    if not all(
+        _local_day_row_exists(conn, local_date, zone)
+        for local_date, zone in affected_days
+    ):
+        return False
+    if start_tz and not _contains_instant(conn, evidence[3], start_tz, start):
+        return False
+    return _contains_instant(conn, evidence[4], end_tz, end)
+
+
+def _interval_has_replacement(
+    conn: sqlite3.Connection,
+    previous: tuple,
+    current: tuple,
+) -> bool:
+    start = _parse_sample_time(previous[1])
+    end = _parse_sample_time(current[1])
+    if start is None or end is None or end <= start:
+        return False
+    try:
+        return (
+            _has_utc_replacement(conn, previous, current, start, end)
+            and _has_local_replacement(conn, previous, current, start, end)
+        )
+    except (sqlite3.Error, ValueError, OverflowError, TypeError):
+        # Missing or unreadable derived evidence never authorizes deletion.
+        return False
+
+
+def _sample_needs_preservation(
+    conn: sqlite3.Connection,
+    rows: list[tuple],
+    index: int,
+    newest_id: int,
+) -> bool:
+    sample = rows[index]
+    segment_id = sample[2]
+    if segment_id is None or conn.execute(
+        "SELECT 1 FROM controller_segments WHERE id = ?",
+        (segment_id,),
+    ).fetchone() is None:
+        return True
+    if sample[0] == newest_id:
+        # Keep newest sample as the source anchor for the next collection.
+        return True
+
+    pairs = []
+    if index > 0 and rows[index - 1][2] == segment_id:
+        pairs.append((rows[index - 1], sample))
+    if index + 1 < len(rows) and rows[index + 1][2] == segment_id:
+        pairs.append((sample, rows[index + 1]))
+    return any(
+        not _interval_has_replacement(conn, previous, current)
+        for previous, current in pairs
+    )
+
+
 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.
+    """Return whether an old sample still carries unreplaced evidence."""
-
+    sample_time = _parse_sample_time(sample_ts)
-    A sample is a boundary anchor if:
+    cutoff = _utc_datetime(now) - timedelta(days=RAW_SAMPLE_RETENTION_DAYS)
-    1. It's older than retention_days (strictly before cutoff)
+    if sample_time is None:
-    2. It has a next sample that forms an interval spanning the retention boundary
+        return True
-    3. The interval hasn't been derived yet
+    if sample_time >= cutoff:
-
-    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
+    rows = _sample_rows(conn)
-    cursor = conn.execute(
+    matching = [index for index, row in enumerate(rows) if row[1] == sample_ts]
-        """SELECT ts, segment_id FROM samples WHERE ts > ? ORDER BY ts LIMIT 1""",
+    if not matching:
-        (sample_ts,),
+        return False
+    newest_id = rows[-1][0] if rows else -1
+    return any(
+        _sample_needs_preservation(conn, rows, index, newest_id)
+        for index in matching
     )
-    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(
@@ -133,36 +334,50 @@ def prune_old_samples(
     now: datetime,
     retention_days: int = RAW_SAMPLE_RETENTION_DAYS,
 ) -> int:
-    """Remove raw samples older than retention_days.
+    """Delete expired samples only after every dependent fact is durable.
 
-    Retains boundary anchors required for successor evidence.
+    Pending publications are stored separately and never selected here. A
-
+    sample stays when it is the newest successor anchor, has an unpublishable
-    Args:
+    neighbour interval, lacks UTC or local-day replacement evidence, or has a
-        conn: Connection to the observation store.
+    timestamp that cannot be safely interpreted.
-        now: Current UTC time.
-        retention_days: Number of days to retain (default 14).
-
-    Returns:
-        Number of samples removed.
     """
-    cutoff = (now - timedelta(days=retention_days)).isoformat()
+    cutoff = _utc_datetime(now) - timedelta(days=retention_days)
-    
+    owns_transaction = not conn.in_transaction
-    # Get all samples older than cutoff
+    savepoint = "fenris_sample_retention"
-    cursor = conn.execute(
+    if owns_transaction:
-        "SELECT id, ts FROM samples WHERE ts < ? ORDER BY ts",
+        conn.execute("BEGIN IMMEDIATE")
-        (cutoff,),
+    else:
-    )
+        conn.execute(f"SAVEPOINT {savepoint}")
-    old_samples = cursor.fetchall()
+
-    
+    try:
-    removed = 0
+        rows = _sample_rows(conn)
-    for sample_id, sample_ts in old_samples:
+        if not rows:
-        # Check if this sample is a boundary anchor
+            if owns_transaction:
-        if needs_boundary_anchor(conn, sample_ts, now):
+                conn.commit()
-            continue  # Skip - it's a boundary anchor
+            else:
-        
+                conn.execute(f"RELEASE SAVEPOINT {savepoint}")
-        # Remove the sample
+            return 0
-        conn.execute("DELETE FROM samples WHERE id = ?", (sample_id,))
+
-        removed += 1
+        newest_id = rows[-1][0]
-    
+        expired = []
-    conn.commit()
+        for index, row in enumerate(rows):
-    return removed
+            sample_time = _parse_sample_time(row[1])
+            if sample_time is None or sample_time >= cutoff:
+                continue
+            if _sample_needs_preservation(conn, rows, index, newest_id):
+                continue
+            expired.append(row[0])
+
+        conn.executemany("DELETE FROM samples WHERE id = ?", ((sample_id,) for sample_id in expired))
+        if owns_transaction:
+            conn.commit()
+        else:
+            conn.execute(f"RELEASE SAVEPOINT {savepoint}")
+        return len(expired)
+    except Exception:
+        if owns_transaction:
+            conn.rollback()
+        else:
+            conn.execute(f"ROLLBACK TO SAVEPOINT {savepoint}")
+            conn.execute(f"RELEASE SAVEPOINT {savepoint}")
+        raise

src/fenris/repair.py

@@ -1,8 +1,9 @@
-"""Historical repair and retention (issue #74).
+"""Historical repair and retention (issue #74, #99).
 
 Re-derives hour observations and day aggregates from surviving raw samples,
-with idempotent and interruption-safe guarantees. Preserves import markers,
+rebuilds legacy local-day evidence from surviving samples or trustworthy UTC
-boundary anchors, and valid historical summaries.
+hours, and preserves import markers, boundary anchors, and valid summaries.
+Repair is idempotent and interruption-safe.
 
 Contracts:
 - Idempotent: running repair multiple times produces no duplicates
@@ -71,7 +72,6 @@ def _set_repair_in_progress(conn: sqlite3.Connection, in_progress: bool) -> None
         "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:
@@ -100,8 +100,6 @@ def _update_repair_status(conn: sqlite3.Connection, result: RepairResult) -> Non
         "INSERT OR REPLACE INTO store_metadata (key, value) VALUES (?, ?)",
         ("days_derived", str(days)),
     )
-    
-    conn.commit()
 
 
 def get_repair_status(conn: sqlite3.Connection) -> RepairStatus:
@@ -364,20 +362,16 @@ def repair_derivation(
     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
+        # A committed in-progress marker may be stale after process death.
+        # SQLite's write lock serializes active repairs; retry idempotently.
+        if conn.in_transaction:
+            conn.commit()
+        conn.execute("BEGIN IMMEDIATE")
+        _set_repair_in_progress(conn, True)
+        conn.commit()
         conn.execute("BEGIN IMMEDIATE")
         
         # 1. Find and derive intervals from sample pairs
@@ -407,7 +401,12 @@ def repair_derivation(
                     result.days_created += 1
                 else:
                     result.days_updated += 1
-        
+
+        # Rebuild only legacy or unavailable local-day activity. This shares
+        # the migration derivation and leaves trustworthy published totals intact.
+        from .local_day import repair_legacy_local_day_evidence
+        repair_legacy_local_day_evidence(conn)
+
         # 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")
@@ -428,21 +427,22 @@ def repair_derivation(
         )
         result.legacy_summaries_preserved = cursor.fetchone()[0]
         
-        # Commit transaction
+        # Publish derived rows and completion status together. A process
-        conn.commit()
+        # interruption rolls back the in-progress marker with the repair.
-        
-        # Update repair status
         _update_repair_status(conn, result)
+        _set_repair_in_progress(conn, False)
+        conn.commit()
         
     except Exception as e:
         conn.rollback()
+        try:
+            _set_repair_in_progress(conn, False)
+            conn.commit()
+        except sqlite3.Error:
+            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_composition.py

@@ -115,6 +115,7 @@ class StatusComposition:
     # Sample counts for waiting explanations
     sample_count: int = 0
     day_count: int = 0
+    pending_publication_count: int = 0
 
     # Whether the status dot should blink (only Monitoring)
     should_blink: bool = False
@@ -286,6 +287,7 @@ def compose_status(
     freshness_age_s = None
     sample_count = 0
     day_count = 0
+    pending_publication_count = 0
     deliberately_paused = False
 
     if conn is None and store_fault is None and newer_schema is None:
@@ -315,6 +317,10 @@ def compose_status(
             sample_count = cursor.fetchone()[0]
             cursor = conn.execute("SELECT COUNT(*) FROM day_aggregates")
             day_count = cursor.fetchone()[0]
+            schema_version = conn.execute("PRAGMA user_version").fetchone()[0]
+            if schema_version >= 4:
+                cursor = conn.execute("SELECT COUNT(*) FROM pending_publications")
+                pending_publication_count = cursor.fetchone()[0]
         except sqlite3.Error as exc:
             store_fault = str(exc)
 
@@ -328,6 +334,7 @@ def compose_status(
         freshness = "unknown"
         freshness_age_s = None
         sample_count = day_count = 0
+        pending_publication_count = 0
         deliberately_paused = False
 
     # --- External stop detection ---
@@ -417,6 +424,7 @@ def compose_status(
         overlay_base=overlay_base,
         sample_count=sample_count,
         day_count=day_count,
+        pending_publication_count=pending_publication_count,
         continuity=continuity,
         paused_lines=paused_lines,
     )
@@ -459,6 +467,8 @@ def render_status_cli(comp: StatusComposition) -> str:
     facts.append("timer: %s" % (
         "unknown" if comp.timer_active is None else "active" if comp.timer_active else "inactive"
     ))
+    if comp.pending_publication_count:
+        facts.append(_pending_publication_text(comp.pending_publication_count))
 
     if facts:
         lines.append(" · ".join(facts))
@@ -524,6 +534,8 @@ def render_status_tui(comp: StatusComposition) -> str:
     facts.append("Timer: %s" % (
         "unknown" if comp.timer_active is None else "active" if comp.timer_active else "inactive"
     ))
+    if comp.pending_publication_count:
+        facts.append(_pending_publication_text(comp.pending_publication_count).capitalize())
 
     if facts:
         lines.append(" · ".join(facts))
@@ -539,3 +551,8 @@ def render_status_tui(comp: StatusComposition) -> str:
             lines.append(pl[:1].upper() + pl[1:])
 
     return "\n".join(lines)
+
+
+def _pending_publication_text(count: int) -> str:
+    noun = "observation" if count == 1 else "observations"
+    return f"pending publication: {count} {noun} retained for retry"

src/fenris/store.py

@@ -3,8 +3,7 @@
 This module handles:
 - Store initialization with WAL mode
 - Schema versioning with PRAGMA user_version
-- The six entities: samples, hour_observations, day_aggregates,
+- Observation records, derived activity, publication state, and metadata
-  monitoring_periods, controller_segments, endurance_baseline
 """
 import sqlite3
 from pathlib import Path
@@ -12,7 +11,7 @@ from typing import Optional
 
 
 # Schema version - increment on each migration
-SCHEMA_VERSION = 3
+SCHEMA_VERSION = 6
 
 
 # Packaged default placement (spec §8.3). The config may override it, but a
@@ -33,7 +32,7 @@ def get_store_path(config: dict) -> Path:
 def init_store(store_path: Path) -> sqlite3.Connection:
     """Initialize the observation store if not present.
     
-    Creates the database with WAL mode and all six entities.
+    Creates the observation schema, including private pending-publication storage.
     Returns a connection to the store.
     """
     conn = sqlite3.connect(str(store_path))
@@ -73,9 +72,11 @@ def init_store(store_path: Path) -> sqlite3.Connection:
         )
     elif current_version < SCHEMA_VERSION:
         # Older version - apply migrations
-        _apply_migrations(conn, current_version)
+        try:
-        conn.execute(f"PRAGMA user_version={SCHEMA_VERSION}")
+            _apply_migrations(conn, current_version)
-        conn.commit()
+        except Exception:
+            conn.close()
+            raise
     
     return conn
 
@@ -107,7 +108,8 @@ def _create_schema(conn: sqlite3.Connection):
             bytes_written INTEGER,
             bytes_read INTEGER,
             critical_warning INTEGER,
-            segment_id INTEGER
+            segment_id INTEGER,
+            local_tz TEXT
         )
     """)
     
@@ -209,10 +211,18 @@ def _create_schema(conn: sqlite3.Connection):
             coverage REAL DEFAULT 0.0,
             sample_count INTEGER DEFAULT 0,
             complete BOOLEAN DEFAULT 0,
+            activity_seconds INTEGER NOT NULL DEFAULT 0,
+            activity_intervals INTEGER NOT NULL DEFAULT 0,
+            activity_incomplete BOOLEAN NOT NULL DEFAULT 0,
+            activity_precision TEXT NOT NULL DEFAULT 'measured',
+            last_sample_id INTEGER,
             UNIQUE(local_date, tz_name)
         )
     """)
 
+    _create_local_day_shared_evidence(conn)
+    _create_local_day_segment_totals(conn)
+
     # Metadata table for store state (e.g., legacy import marker)
     conn.execute("""
         CREATE TABLE IF NOT EXISTS store_metadata (
@@ -221,59 +231,181 @@ def _create_schema(conn: sqlite3.Connection):
         )
     """)
 
+    _create_pending_publications(conn)
+
+
+def _create_pending_publications(conn: sqlite3.Connection) -> None:
+    """Create private staging for valid observations awaiting derivation."""
+    conn.execute("""
+        CREATE TABLE IF NOT EXISTS pending_publications (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            sample_ts TEXT NOT NULL,
+            payload TEXT NOT NULL
+        )
+    """)
+
+
+def _create_local_day_shared_evidence(conn: sqlite3.Connection) -> None:
+    """Create once-only local activity evidence that cannot be day-allocated."""
+    conn.execute("""
+        CREATE TABLE IF NOT EXISTS local_day_unallocated_evidence (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            start_sample_id INTEGER NOT NULL,
+            end_sample_id INTEGER NOT NULL,
+            start_local_date TEXT NOT NULL,
+            end_local_date TEXT NOT NULL,
+            start_tz_name TEXT,
+            end_tz_name TEXT,
+            started_at TEXT NOT NULL,
+            ended_at TEXT NOT NULL,
+            bytes_written INTEGER NOT NULL DEFAULT 0,
+            bytes_read INTEGER NOT NULL DEFAULT 0,
+            reason TEXT NOT NULL,
+            segment_id INTEGER,
+            UNIQUE(start_sample_id, end_sample_id)
+        )
+    """)
+    conn.execute(
+        "CREATE INDEX IF NOT EXISTS local_day_evidence_start "
+        "ON local_day_unallocated_evidence(start_local_date, start_tz_name)"
+    )
+    conn.execute(
+        "CREATE INDEX IF NOT EXISTS local_day_evidence_end "
+        "ON local_day_unallocated_evidence(end_local_date, end_tz_name)"
+    )
+
+
+def _create_local_day_segment_totals(conn: sqlite3.Connection) -> None:
+    """Retain the controller-segment provenance behind known day totals."""
+    conn.execute("""
+        CREATE TABLE IF NOT EXISTS local_day_segment_totals (
+            id INTEGER PRIMARY KEY AUTOINCREMENT,
+            local_day_id INTEGER NOT NULL,
+            segment_id INTEGER NOT NULL,
+            bytes_written INTEGER NOT NULL DEFAULT 0,
+            bytes_read INTEGER NOT NULL DEFAULT 0,
+            activity_seconds INTEGER NOT NULL DEFAULT 0,
+            activity_intervals INTEGER NOT NULL DEFAULT 0,
+            UNIQUE(local_day_id, segment_id)
+        )
+    """)
+
 
 def _apply_migrations(conn: sqlite3.Connection, current_version: int):
     """Apply forward-only migrations from current_version to SCHEMA_VERSION.
-    
-    Each migration step is a transactional block. Add new steps as sequential
-    elif branches when SCHEMA_VERSION increases.
-    
-    Spec: §3.6, §10.2
-    """
-    # 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
 
-    # Migration 2→3: add local_days table for local-day activity totals
+    Commit each version transition independently. A failed step rolls back in
-    # (issue #90, ADR 0010).  Pure addition — no existing rows touched.
+    full while earlier successful steps remain versioned and retryable.
-    if current_version < 3:
+    """
-        tables = {row[0] for row in conn.execute(
+    migrations = {
-            "SELECT name FROM sqlite_master WHERE type='table'"
+        2: _migrate_1_to_2,
+        3: _migrate_2_to_3,
+        4: _migrate_3_to_4,
+        5: _migrate_4_to_5,
+        6: _migrate_5_to_6,
+    }
+    while current_version < SCHEMA_VERSION:
+        target_version = current_version + 1
+        migration = migrations.get(target_version)
+        if migration is None:
+            raise ValueError(f"No migration registered for schema {target_version}")
+        conn.execute("BEGIN IMMEDIATE")
+        try:
+            migration(conn)
+            conn.execute(f"PRAGMA user_version={target_version}")
+            conn.commit()
+        except Exception:
+            conn.rollback()
+            raise
+        current_version = target_version
+
+
+def _migrate_1_to_2(conn: sqlite3.Connection) -> None:
+    """Add segment provenance and unattributed UTC byte tracking."""
+    tables = {row[0] for row in conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table'"
+    ).fetchall()}
+    if "samples" in tables:
+        cols = {row[1] for row in conn.execute(
+            "PRAGMA table_info(samples)"
         ).fetchall()}
-        if "local_days" not in tables:
+        if "segment_id" not in cols:
-            conn.execute("""
+            conn.execute("ALTER TABLE samples ADD COLUMN segment_id INTEGER")
-                CREATE TABLE IF NOT EXISTS local_days (
+    if "day_aggregates" in tables:
-                    id INTEGER PRIMARY KEY AUTOINCREMENT,
+        cols = {row[1] for row in conn.execute(
-                    local_date TEXT NOT NULL,
+            "PRAGMA table_info(day_aggregates)"
-                    tz_name TEXT NOT NULL,
+        ).fetchall()}
-                    tz_offset TEXT NOT NULL,
+        for column in ("unattributed_bytes_written", "unattributed_bytes_read"):
-                    utc_start TEXT NOT NULL,
+            if column not in cols:
-                    utc_end TEXT NOT NULL,
+                conn.execute(
-                    bytes_written INTEGER DEFAULT 0,
+                    f"ALTER TABLE day_aggregates ADD COLUMN {column} INTEGER DEFAULT 0"
-                    bytes_read INTEGER DEFAULT 0,
-                    coverage REAL DEFAULT 0.0,
-                    sample_count INTEGER DEFAULT 0,
-                    complete BOOLEAN DEFAULT 0,
-                    UNIQUE(local_date, tz_name)
                 )
-            """)
+
-        current_version = 3
+
+def _migrate_2_to_3(conn: sqlite3.Connection) -> None:
+    """Add local-day activity summaries."""
+    tables = {row[0] for row in conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table'"
+    ).fetchall()}
+    if "local_days" not in tables:
+        conn.execute("""
+            CREATE TABLE local_days (
+                id INTEGER PRIMARY KEY AUTOINCREMENT,
+                local_date TEXT NOT NULL,
+                tz_name TEXT NOT NULL,
+                tz_offset TEXT NOT NULL,
+                utc_start TEXT NOT NULL,
+                utc_end TEXT NOT NULL,
+                bytes_written INTEGER DEFAULT 0,
+                bytes_read INTEGER DEFAULT 0,
+                coverage REAL DEFAULT 0.0,
+                sample_count INTEGER DEFAULT 0,
+                complete BOOLEAN DEFAULT 0,
+                UNIQUE(local_date, tz_name)
+            )
+        """)
+
+
+def _migrate_3_to_4(conn: sqlite3.Connection) -> None:
+    """Add private publication staging for acquired observations."""
+    _create_pending_publications(conn)
+
+
+def _migrate_4_to_5(conn: sqlite3.Connection) -> None:
+    """Add measured local-day evidence storage and mark old totals legacy."""
+    tables = {row[0] for row in conn.execute(
+        "SELECT name FROM sqlite_master WHERE type='table'"
+    ).fetchall()}
+    if "samples" in tables:
+        sample_cols = {row[1] for row in conn.execute(
+            "PRAGMA table_info(samples)"
+        ).fetchall()}
+        if "local_tz" not in sample_cols:
+            conn.execute("ALTER TABLE samples ADD COLUMN local_tz TEXT")
+    if "local_days" in tables:
+        local_cols = {row[1] for row in conn.execute(
+            "PRAGMA table_info(local_days)"
+        ).fetchall()}
+        for column, declaration in (
+            ("activity_seconds", "INTEGER NOT NULL DEFAULT 0"),
+            ("activity_intervals", "INTEGER NOT NULL DEFAULT 0"),
+            ("activity_incomplete", "BOOLEAN NOT NULL DEFAULT 0"),
+            ("activity_precision", "TEXT NOT NULL DEFAULT 'legacy'"),
+            ("last_sample_id", "INTEGER"),
+        ):
+            if column not in local_cols:
+                conn.execute(
+                    f"ALTER TABLE local_days ADD COLUMN {column} {declaration}"
+                )
+    _create_local_day_shared_evidence(conn)
+    _create_local_day_segment_totals(conn)
+
+
+def _migrate_5_to_6(conn: sqlite3.Connection) -> None:
+    """Rebuild local-day summaries from surviving trustworthy evidence."""
+    from .local_day import repair_legacy_local_day_evidence
+
+    repair_legacy_local_day_evidence(conn)
 
 
 def migrate_to_latest(store_path: Path) -> int:
@@ -310,9 +442,11 @@ def migrate_to_latest(store_path: Path) -> int:
         return SCHEMA_VERSION
     
     steps = SCHEMA_VERSION - current_version
-    _apply_migrations(conn, current_version)
+    try:
-    conn.execute(f"PRAGMA user_version={SCHEMA_VERSION}")
+        _apply_migrations(conn, current_version)
-    conn.commit()
+    except Exception:
+        conn.close()
+        raise
     conn.close()
     return steps
 

src/fenris/tz_util.py

@@ -25,11 +25,14 @@ def detect_system_tz() -> str:
 
     localtime = Path("/etc/localtime")
     if localtime.is_symlink():
-        target = os.readlink(str(localtime))
+        target_path = Path(os.readlink(str(localtime)))
-        # Strip common prefixes: /usr/share/zoneinfo/, /usr/lib/zoneinfo/
+        if not target_path.is_absolute():
-        for prefix in ("/usr/share/zoneinfo/", "/usr/lib/zoneinfo/"):
+            target_path = localtime.parent / target_path
-            if target.startswith(prefix):
+        target = target_path.resolve().as_posix()
-                return target[len(prefix):]
+        marker = "/zoneinfo/"
+        marker_index = target.find(marker)
+        if marker_index >= 0:
+            return target[marker_index + len(marker):]
         return target
 
     return "UTC"

tests/test_acceptance_sweep.py

@@ -121,8 +121,8 @@ def _insert_local_day(conn, local_date, tz_name="UTC", tz_offset="+00:00",
     conn.execute(
         "INSERT INTO local_days "
         "(local_date, tz_name, tz_offset, utc_start, utc_end, "
-        " bytes_written, bytes_read, coverage, sample_count, complete) "
+        " bytes_written, bytes_read, coverage, sample_count, complete, activity_intervals) "
-        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 1)",
         (local_date, tz_name, tz_offset, utc_start, utc_end,
          bw, br, coverage, samples, complete),
     )

tests/test_activity_selection.py

@@ -0,0 +1,94 @@
+"""Activity-selection transitions independent from Textual widgets."""
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.activity_selection import ActivitySelection, IntervalIdentity
+
+
+def _interval(n):
+    return IntervalIdentity(f"start-{n}", f"end-{n}")
+
+
+def test_live_selection_starts_and_stays_on_newest_interval():
+    selection = ActivitySelection()
+    first = [_interval(1), _interval(2)]
+
+    selection.update_live(first)
+    assert selection.following_live
+    assert selection.selected_live_interval == first[-1]
+
+    second = first + [_interval(3)]
+    selection.update_live(second)
+    assert selection.selected_live_interval == second[-1]
+
+
+def test_keyboard_and_mouse_inspection_pin_interval_identity():
+    intervals = [_interval(1), _interval(2), _interval(3)]
+    keyboard = ActivitySelection()
+    mouse = ActivitySelection()
+
+    keyboard.update_live(intervals)
+    keyboard.move_live(intervals, -1)
+    mouse.update_live(intervals)
+    mouse.inspect_live(intervals, intervals[1])
+
+    assert keyboard.selected_live_interval == mouse.selected_live_interval == intervals[1]
+    assert not keyboard.following_live
+    assert not mouse.following_live
+
+    refreshed = [_interval(2), _interval(3), _interval(4)]
+    keyboard.update_live(refreshed)
+    mouse.update_live(refreshed)
+    assert keyboard.selected_live_interval == mouse.selected_live_interval == intervals[1]
+
+
+def test_expired_pin_explains_expiration_and_resumes_following():
+    selection = ActivitySelection()
+    intervals = [_interval(1), _interval(2), _interval(3)]
+    selection.update_live(intervals)
+    selection.inspect_live(intervals, intervals[0])
+
+    newest = _interval(4)
+    selection.update_live([_interval(2), _interval(3), newest])
+
+    assert selection.following_live
+    assert selection.selected_live_interval == newest
+    assert selection.live_interval_expired
+
+
+def test_today_resets_expired_pin_and_read_write_toggle_keeps_identity():
+    selection = ActivitySelection()
+    intervals = [_interval(1), _interval(2)]
+    selection.update_live(intervals)
+    selection.inspect_live(intervals, intervals[0])
+    selection.update_live([intervals[1]])
+    newest = _interval(3)
+    selection.update_live([intervals[1], newest])
+    assert selection.live_interval_expired
+
+    selection.toggle_measure()
+    assert selection.measure == "read"
+    assert selection.selected_live_interval == newest
+
+    selection.select_history_date("2026-09-27")
+    selection.set_view("history")
+    selection.set_view("live")
+    assert selection.browse_date is None
+    assert selection.following_live
+    assert not selection.live_interval_expired
+
+
+def test_live_identity_uses_both_interval_boundaries():
+    first = IntervalIdentity("2026-09-28T10:00:00Z", "2026-09-28T10:03:00Z")
+    changed_start = IntervalIdentity("2026-09-28T09:57:00Z", "2026-09-28T10:03:00Z")
+    selection = ActivitySelection()
+    selection.update_live([first])
+    selection.inspect_live([first], first)
+
+    selection.update_live([changed_start])
+
+    assert selection.following_live
+    assert selection.selected_live_interval == changed_start
+    assert selection.live_interval_expired

tests/test_collector_history_tracer.py

@@ -154,7 +154,7 @@ class TestSchemaMigration:
 
         # Migrate
         steps = migrate_to_latest(db)
-        assert steps == 2  # v1→v2→v3
+        assert steps == 5  # v1→v2→v3→v4→v5→v6
 
         # Verify data preserved
         conn = sqlite3.connect(str(db))
@@ -356,6 +356,167 @@ class TestCollectorDerivation:
         assert count_after == 2
 
 
+class TestCollectionAtomicity:
+    """Collection exposes sample and derived evidence as one publication."""
+
+    @pytest.mark.asyncio
+    async def test_collection_is_visible_through_cli_and_tui_readers(
+        self, config_fixture, smartctl_fixture, sysfs_fixture_tree, monkeypatch
+    ):
+        """Ordinary readers observe matching published sample and activity evidence."""
+        from fenris.status import get_status, read_status
+        from fenris.tui import FenrisTuiApp
+
+        monkeypatch.setenv("TZ", "UTC")
+        service = {
+            "boot_enabled": True,
+            "timer_active": True,
+            "last_collect_ok": True,
+        }
+        monkeypatch.setattr("fenris.status.query_service_state", lambda: service)
+
+        now = datetime.now(timezone.utc).replace(
+            minute=35, second=0, microsecond=0,
+        )
+        first = {
+            **smartctl_fixture,
+            "nvme_smart_health_information_log": {
+                **smartctl_fixture["nvme_smart_health_information_log"],
+                "data_units_written": 12345678,
+                "data_units_read": 9876543,
+            },
+        }
+        second = {
+            **smartctl_fixture,
+            "nvme_smart_health_information_log": {
+                **smartctl_fixture["nvme_smart_health_information_log"],
+                "data_units_written": 12345698,
+                "data_units_read": 9876553,
+            },
+        }
+        sysfs_path = sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0"
+
+        assert run_collection(
+            first, sysfs_path, config_fixture, FakeClock(now - timedelta(minutes=5))
+        )["ok"] is True
+        assert run_collection(
+            second, sysfs_path, config_fixture, FakeClock(now)
+        )["ok"] is True
+
+        store_path = Path(config_fixture["store_path"])
+        with read_status(store_path, now, query_services=False) as (reader, composition):
+            assert reader is not None
+            assert composition.sample_count == 2
+            assert composition.day_count == 1
+            utc_day = reader.execute(
+                "SELECT bytes_written_delta, bytes_read_delta FROM day_aggregates"
+            ).fetchone()
+            local_day = reader.execute(
+                "SELECT bytes_written, bytes_read FROM local_days"
+            ).fetchone()
+            assert tuple(utc_day) == (10_240_000, 5_120_000)
+            assert tuple(local_day) == (10_240_000, 5_120_000)
+
+        cli_output = get_status(
+            store_path, now, query_services=True, query_journal=False
+        )
+        assert "Monitoring" in cli_output
+
+        app = FenrisTuiApp(store_path=store_path)
+        async with app.run_test(size=(100, 30)) as pilot:
+            await pilot.pause()
+            live_readout = str(app.query_one("#live-readout").render())
+            assert "W 0.010 GB" in live_readout
+            assert "R 0.005 GB" in live_readout
+
+        repeated_result = run_collection(
+            second, sysfs_path, config_fixture, FakeClock(now + timedelta(minutes=5))
+        )
+        assert repeated_result["ok"] is True
+        with read_status(
+            store_path, now + timedelta(minutes=5), query_services=False
+        ) as (reader, composition):
+            assert reader is not None
+            assert composition.sample_count == 3
+            utc_day = reader.execute(
+                "SELECT bytes_written_delta, bytes_read_delta FROM day_aggregates"
+            ).fetchone()
+            local_day = reader.execute(
+                "SELECT bytes_written, bytes_read FROM local_days"
+            ).fetchone()
+            assert tuple(utc_day) == (10_240_000, 5_120_000)
+            assert tuple(local_day) == (10_240_000, 5_120_000)
+
+    def test_failed_local_day_publication_keeps_previous_publication(
+        self, config_fixture, smartctl_fixture, sysfs_fixture_tree, monkeypatch
+    ):
+        """A failed final derivation step leaves all prior reader state intact."""
+        from fenris.status import read_status
+
+        monkeypatch.setenv("TZ", "UTC")
+        now = datetime.now(timezone.utc).replace(second=0, microsecond=0)
+        first_clock = FakeClock(now)
+        first = {
+            **smartctl_fixture,
+            "nvme_smart_health_information_log": {
+                **smartctl_fixture["nvme_smart_health_information_log"],
+                "data_units_written": 12345678,
+                "data_units_read": 9876543,
+            },
+        }
+        first_result = run_collection(
+            first,
+            sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+            config_fixture,
+            first_clock,
+        )
+        assert first_result["ok"] is True, first_result
+
+        writer = sqlite3.connect(config_fixture["store_path"])
+        writer.execute(
+            "CREATE TRIGGER fail_local_day_publication "
+            "BEFORE INSERT ON local_days "
+            "BEGIN SELECT RAISE(ABORT, 'injected local-day publication failure'); END"
+        )
+        writer.commit()
+        writer.close()
+
+        next_time = now + timedelta(minutes=5)
+        second = {
+            **smartctl_fixture,
+            "nvme_smart_health_information_log": {
+                **smartctl_fixture["nvme_smart_health_information_log"],
+                "data_units_written": 12345698,
+                "data_units_read": 9876548,
+            },
+        }
+        failed_result = run_collection(
+            second,
+            sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0",
+            config_fixture,
+            FakeClock(next_time),
+        )
+
+        assert failed_result["ok"] is False
+        assert "injected local-day publication failure" in failed_result["error"]
+
+        with read_status(
+            Path(config_fixture["store_path"]), next_time, query_services=False
+        ) as (reader, composition):
+            assert reader is not None
+            assert composition.sample_count == 1
+            public_counts = reader.execute(
+                "SELECT (SELECT COUNT(*) FROM samples), "
+                "(SELECT COUNT(*) FROM controller_segments), "
+                "(SELECT COUNT(*) FROM monitoring_periods), "
+                "(SELECT COUNT(*) FROM hour_observations), "
+                "(SELECT COUNT(*) FROM day_aggregates), "
+                "(SELECT COUNT(*) FROM local_days)"
+            ).fetchone()
+
+        assert tuple(public_counts) == (1, 1, 1, 0, 0, 0)
+
+
 # ---------------------------------------------------------------------------
 # Display states: awaiting first sample, awaiting another sample
 # ---------------------------------------------------------------------------

tests/test_collector_tracer.py

@@ -232,7 +232,7 @@ def test_store_initialization(config_fixture: Dict[str, Any]):
     # Initialize store
     conn = init_store(store_path)
     
-    # Verify all six entities exist
+    # Verify the observation, derived-history, and metadata tables exist.
     cursor = conn.execute("SELECT name FROM sqlite_master WHERE type='table'")
     tables = {row[0] for row in cursor.fetchall()}
     
@@ -249,6 +249,9 @@ def test_store_initialization(config_fixture: Dict[str, Any]):
     expected_tables.add("sqlite_sequence")
     expected_tables.add("store_metadata")
     expected_tables.add("local_days")
+    expected_tables.add("pending_publications")
+    expected_tables.add("local_day_unallocated_evidence")
+    expected_tables.add("local_day_segment_totals")
     assert expected_tables == tables
     
     conn.close()

tests/test_complete_observation_day_gate.py

@@ -98,8 +98,8 @@ def _insert_local_day(conn, local_date, tz_name="UTC", tz_offset="+00:00",
     conn.execute(
         "INSERT INTO local_days "
         "(local_date, tz_name, tz_offset, utc_start, utc_end, "
-        " bytes_written, bytes_read, coverage, sample_count, complete) "
+        " bytes_written, bytes_read, coverage, sample_count, complete, activity_intervals) "
-        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 1)",
         (local_date, tz_name, tz_offset, utc_start, utc_end,
          bw, br, coverage, samples, complete),
     )
@@ -166,6 +166,47 @@ class TestGateNoCompleteDay:
         # The key assertion: gate message should NOT appear when gate IS met
         assert not any("full local observation day" in f for f in result.contributing_facts)
 
+    def test_complete_legacy_day_without_trusted_activity_does_not_open_gate(
+        self, store,
+    ):
+        """A complete flag cannot make unavailable local activity qualify."""
+        _insert_baseline(store)
+        _insert_segment(store)
+        _open_period(store)
+        for i in range(3):
+            day = (datetime(2026, 9, 27) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, day, bw=1024 * 1024 * 100)
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        _insert_local_day(store, "2026-09-29", complete=True)
+        store.execute(
+            "UPDATE local_days SET activity_precision = 'measured', activity_intervals = 0 "
+            "WHERE local_date = '2026-09-29'"
+        )
+        result = compute_projection(store, _clock())
+        assert result.confidence_state == ConfidenceState.UNSUPPORTED
+        assert any("full local observation day" in fact
+                   for fact in result.contributing_facts)
+
+    def test_partial_but_trusted_local_activity_opens_gate(self, store):
+        """Known local intervals can coexist with an incomplete day total."""
+        _insert_baseline(store)
+        _insert_segment(store)
+        _open_period(store)
+        for i in range(3):
+            day = (datetime(2026, 9, 27) + timedelta(days=i)).strftime("%Y-%m-%d")
+            _insert_day(store, day, bw=1024 * 1024 * 100)
+        _insert_sample(store, "2026-09-30T10:00:00+00:00", pu=5)
+        _insert_local_day(store, "2026-09-29", complete=True)
+        store.execute(
+            "UPDATE local_days SET activity_incomplete = 1 "
+            "WHERE local_date = '2026-09-29'"
+        )
+
+        result = compute_projection(store, _clock())
+
+        assert not any("full local observation day" in fact
+                       for fact in result.contributing_facts)
+
 
 # ---------------------------------------------------------------------------
 # Gate-2: One complete local day → Limited confidence

tests/test_dashboard_design.py

@@ -102,6 +102,7 @@ async def test_tabs_date_entry_and_hourly_inspection_keep_context(dashboard):
         app.on_refresh_tick()
         await pilot.pause()
         assert str(app.query_one("#bar-readout").render()) == readout
+        assert "Reads" in str(app.query_one("#bar-legend").render())
         await pilot.press("g")
         await pilot.press(*list("2026-09-17"))
         await pilot.press("escape")

tests/test_init_system.py

@@ -634,6 +634,14 @@ class TestMonitorIntegration:
             cmd_enable(args)
             mock_enable.assert_called_once_with(True)
 
+        conn = sqlite3.connect(store_path)
+        try:
+            assert conn.execute(
+                "SELECT COUNT(*) FROM monitoring_periods WHERE ended_at IS NULL"
+            ).fetchone()[0] == 1
+        finally:
+            conn.close()
+
     def test_cmd_disable_uses_init_system(self, tmp_path):
         """cmd_disable uses init_system.disable_timer."""
         from fenris.monitor import cmd_disable

tests/test_issue_100.py

@@ -0,0 +1,341 @@
+"""Normal-collection retention acceptance tests for issue #100."""
+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.collector import run_collection
+from fenris.local_day import query_local_day_summary
+from fenris.pruning import prune_old_samples
+from fenris.status import read_status
+from fenris.store import init_store
+
+
+@pytest.fixture
+def sysfs_controller(tmp_path):
+    controller = tmp_path / "sys" / "class" / "nvme" / "nvme0"
+    controller.mkdir(parents=True)
+    (controller / "subsysnqn").write_text("nqn.example:drive-1\n")
+    (controller / "model").write_text("Fenris Test Drive\n")
+    (controller / "serial").write_text("drive-1\n")
+    (controller / "firmware_rev").write_text("1.0\n")
+    transport = controller / "transport"
+    transport.mkdir()
+    (transport / "address").write_text("0000:00:01.0\n")
+    (transport / "trstring").write_text("pcie\n")
+    return controller
+
+
+class FakeClock:
+    def __init__(self, now):
+        self.now = now
+
+    def utcnow(self):
+        return self.now
+
+
+def _smartctl(written, read):
+    return {
+        "nvme_smart_health_information_log": {
+            "critical_warning": 0,
+            "temperature": 35,
+            "available_spare": 100,
+            "percentage_used": 1,
+            "data_units_written": written,
+            "data_units_read": read,
+            "power_on_hours": 100,
+            "power_cycles": 1,
+            "unsafe_shutdowns": 0,
+            "media_errors": 0,
+        },
+        "user_capacity": {"bytes": 1_000_000_000_000},
+        "model_name": "Fenris Test Drive",
+        "serial_number": "drive-1",
+        "firmware_version": "1.0",
+    }
+
+
+def _collect(config, controller, now, written, read):
+    return run_collection(
+        smartctl_data=_smartctl(written, read),
+        sysfs_path=controller,
+        config=config,
+        clock=FakeClock(now),
+    )
+
+
+def test_normal_collection_expires_detail_and_keeps_local_day_evidence(
+    tmp_path, sysfs_controller, monkeypatch,
+):
+    monkeypatch.setenv("TZ", "UTC")
+    store_path = tmp_path / "observations.db"
+    config = {"device": "/dev/nvme0", "store_path": str(store_path)}
+    first_time = datetime(2026, 9, 1, 0, 0, tzinfo=timezone.utc)
+    second_time = first_time + timedelta(days=15)
+
+    first = _collect(config, sysfs_controller, first_time, 1000, 2000)
+    assert first["ok"] is True, first
+    second = _collect(config, sysfs_controller, second_time, 1001, 2003)
+    assert second["ok"] is True, second
+
+    with sqlite3.connect(store_path) as conn:
+        assert conn.execute("SELECT ts FROM samples ORDER BY id").fetchall() == [
+            (second_time.isoformat(),)
+        ]
+        assert conn.execute(
+            "SELECT bytes_written, bytes_read, reason "
+            "FROM local_day_unallocated_evidence"
+        ).fetchall() == [(512_000, 1_536_000, "local_midnight")]
+        assert conn.execute("SELECT COUNT(*) FROM pending_publications").fetchone()[0] == 0
+        assert conn.execute("SELECT COUNT(*) FROM controller_segments").fetchone()[0] == 1
+        assert conn.execute("SELECT COUNT(*) FROM day_aggregates").fetchone()[0] == 15
+
+    monkeypatch.setenv("TZ", "Asia/Kolkata")
+    with read_status(store_path, second_time, query_services=False) as (reader, state):
+        assert reader is not None
+        assert state.store_fault is None
+        old_day = query_local_day_summary(
+            reader, "2026-09-01", "UTC", second_time,
+        )
+        assert old_day["utc_start"] == "2026-09-01T00:00:00+00:00"
+        assert old_day["utc_end"] == "2026-09-02T00:00:00+00:00"
+        assert old_day["bytes_written"] is None
+        assert old_day["shared_bytes_written"] == 512_000
+        assert old_day["shared_bytes_read"] == 1_536_000
+        assert old_day["shared_evidence_count"] == 1
+
+
+def test_pruning_keeps_samples_when_replacement_evidence_is_missing(tmp_path):
+    store_path = tmp_path / "incomplete.db"
+    conn = init_store(store_path)
+    now = datetime(2026, 9, 30, tzinfo=timezone.utc)
+    old_time = now - timedelta(days=20)
+    next_time = now - timedelta(days=1)
+    conn.execute(
+        "INSERT INTO controller_segments (id, opened_at, identity_key) "
+        "VALUES (1, ?, 'test')",
+        (old_time.isoformat(),),
+    )
+    conn.execute(
+        "INSERT INTO samples (ts, device, bytes_written, bytes_read, segment_id, local_tz) "
+        "VALUES (?, '/dev/nvme0', 100, 100, 1, 'UTC')",
+        (old_time.isoformat(),),
+    )
+    conn.execute(
+        "INSERT INTO samples (ts, device, bytes_written, bytes_read, segment_id, local_tz) "
+        "VALUES (?, '/dev/nvme0', 200, 200, 1, 'UTC')",
+        (next_time.isoformat(),),
+    )
+    conn.commit()
+
+    assert prune_old_samples(conn, now) == 0
+    assert conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0] == 2
+    conn.close()
+
+
+def test_later_same_day_activity_does_not_replace_gap_interval(tmp_path):
+    store_path = tmp_path / "unrelated-local-activity.db"
+    conn = init_store(store_path)
+    gap_start = datetime(2026, 9, 1, 0, 0, tzinfo=timezone.utc)
+    gap_end = gap_start + timedelta(minutes=10)
+    later_end = gap_start + timedelta(minutes=20)
+    now = datetime(2026, 9, 30, tzinfo=timezone.utc)
+    conn.execute(
+        "INSERT INTO controller_segments (id, opened_at, identity_key) "
+        "VALUES (1, ?, 'test')",
+        (gap_start.isoformat(),),
+    )
+    for sample_time, written, read in (
+        (gap_start, 1000, 100),
+        (gap_end, 2000, 200),
+        (later_end, 2100, 210),
+    ):
+        conn.execute(
+            "INSERT INTO samples (ts, device, bytes_written, bytes_read, segment_id, local_tz) "
+            "VALUES (?, '/dev/nvme0', ?, ?, 1, 'UTC')",
+            (sample_time.isoformat(), written, read),
+        )
+
+    # UTC aggregates can replace the old counter pair, but the local-day
+    # summary contains only the later B->C interval, after monitoring resumed.
+    conn.execute(
+        "INSERT INTO hour_observations (hour, bytes_written_delta, bytes_read_delta) "
+        "VALUES ('2026-09-01T00:00:00+00:00', 1000, 100)"
+    )
+    conn.execute(
+        "INSERT INTO day_aggregates (day) VALUES ('2026-09-01')"
+    )
+    conn.execute(
+        "INSERT INTO monitoring_periods (started_at, ended_at) VALUES (?, ?)",
+        (gap_end.isoformat(), later_end.isoformat()),
+    )
+    last_sample_id = conn.execute("SELECT MAX(id) FROM samples").fetchone()[0]
+    conn.execute(
+        "INSERT INTO local_days "
+        "(local_date, tz_name, tz_offset, utc_start, utc_end, bytes_written, "
+        " bytes_read, activity_intervals, activity_precision, last_sample_id) "
+        "VALUES ('2026-09-01', 'UTC', '+00:00', ?, ?, 100, 10, 1, 'measured', ?)",
+        (
+            gap_start.isoformat(),
+            (gap_start + timedelta(days=1)).isoformat(),
+            last_sample_id,
+        ),
+    )
+    local_day_id = conn.execute("SELECT MAX(id) FROM local_days").fetchone()[0]
+    conn.execute(
+        "INSERT INTO local_day_segment_totals "
+        "(local_day_id, segment_id, bytes_written, bytes_read, activity_intervals) "
+        "VALUES (?, 1, 100, 10, 1)",
+        (local_day_id,),
+    )
+    conn.commit()
+
+    assert prune_old_samples(conn, now) == 0
+    assert conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0] == 3
+    conn.close()
+
+
+def test_pruning_keeps_oldest_unpaired_sample_as_successor_anchor(tmp_path):
+    store_path = tmp_path / "anchor.db"
+    conn = init_store(store_path)
+    now = datetime(2026, 9, 30, tzinfo=timezone.utc)
+    old_time = now - timedelta(days=20)
+    conn.execute(
+        "INSERT INTO controller_segments (id, opened_at, identity_key) "
+        "VALUES (1, ?, 'test')",
+        (old_time.isoformat(),),
+    )
+    conn.execute(
+        "INSERT INTO samples (ts, device, bytes_written, bytes_read, segment_id, local_tz) "
+        "VALUES (?, '/dev/nvme0', 100, 100, 1, 'UTC')",
+        (old_time.isoformat(),),
+    )
+    conn.commit()
+
+    assert prune_old_samples(conn, now) == 0
+    assert conn.execute("SELECT ts FROM samples").fetchone()[0] == old_time.isoformat()
+    conn.close()
+
+
+def test_pruning_never_expires_pending_publications(tmp_path):
+    store_path = tmp_path / "pending.db"
+    conn = init_store(store_path)
+    old_time = datetime(2026, 9, 1, tzinfo=timezone.utc)
+    conn.execute(
+        "INSERT INTO pending_publications (sample_ts, payload) VALUES (?, '{}')",
+        (old_time.isoformat(),),
+    )
+    conn.commit()
+
+    assert prune_old_samples(
+        conn, datetime(2026, 9, 30, tzinfo=timezone.utc),
+    ) == 0
+    assert conn.execute(
+        "SELECT sample_ts FROM pending_publications"
+    ).fetchone()[0] == old_time.isoformat()
+    conn.close()
+
+
+def test_pruning_preserves_unparseable_legacy_timestamp(tmp_path):
+    store_path = tmp_path / "legacy.db"
+    conn = init_store(store_path)
+    conn.execute(
+        "INSERT INTO samples (ts, device, bytes_written, bytes_read) "
+        "VALUES ('legacy timestamp', '/dev/nvme0', 100, 100)"
+    )
+    conn.commit()
+
+    assert prune_old_samples(conn, datetime(2026, 9, 30, tzinfo=timezone.utc)) == 0
+    assert conn.execute("SELECT ts FROM samples").fetchone()[0] == "legacy timestamp"
+    conn.close()
+
+
+def test_collection_defers_interrupted_pruning_and_retries_next_run(
+    tmp_path, sysfs_controller, monkeypatch,
+):
+    monkeypatch.setenv("TZ", "UTC")
+    store_path = tmp_path / "interrupted.db"
+    config = {"device": "/dev/nvme0", "store_path": str(store_path)}
+    first_time = datetime(2026, 9, 1, 0, 0, tzinfo=timezone.utc)
+    second_time = first_time + timedelta(days=15)
+    assert _collect(config, sysfs_controller, first_time, 1000, 2000)["ok"] is True
+
+    writer = sqlite3.connect(store_path)
+    writer.execute(
+        "CREATE TRIGGER stop_retention BEFORE DELETE ON samples "
+        "BEGIN SELECT RAISE(ABORT, 'simulated retention interruption'); END"
+    )
+    writer.commit()
+    writer.close()
+
+    second = _collect(config, sysfs_controller, second_time, 1001, 2001)
+    assert second["ok"] is True, second
+    assert "simulated retention interruption" in second["retention_error"]
+    with sqlite3.connect(store_path) as conn:
+        assert conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0] == 2
+        assert conn.execute("SELECT COUNT(*) FROM pending_publications").fetchone()[0] == 0
+        assert conn.execute("SELECT COUNT(*) FROM local_day_unallocated_evidence").fetchone()[0] == 1
+
+    writer = sqlite3.connect(store_path)
+    writer.execute("DROP TRIGGER stop_retention")
+    writer.commit()
+    writer.close()
+
+    third_time = second_time + timedelta(days=15)
+    third = _collect(config, sysfs_controller, third_time, 1002, 2002)
+    assert third["ok"] is True, third
+    assert third["retention_error"] is None
+    with sqlite3.connect(store_path) as conn:
+        assert conn.execute("SELECT ts FROM samples ORDER BY id").fetchall() == [
+            (third_time.isoformat(),)
+        ]
+
+
+def test_collection_recovers_old_pending_work_before_pruning(
+    tmp_path, sysfs_controller, monkeypatch,
+):
+    monkeypatch.setenv("TZ", "UTC")
+    store_path = tmp_path / "pending-recovery.db"
+    config = {"device": "/dev/nvme0", "store_path": str(store_path)}
+    first_time = datetime(2026, 9, 1, 0, 0, tzinfo=timezone.utc)
+    second_time = first_time + timedelta(days=15)
+    assert _collect(config, sysfs_controller, first_time, 1000, 2000)["ok"] is True
+
+    writer = sqlite3.connect(store_path)
+    writer.execute(
+        "CREATE TRIGGER interrupt_publication "
+        "BEFORE INSERT ON local_day_unallocated_evidence "
+        "BEGIN SELECT RAISE(ABORT, 'simulated publication interruption'); END"
+    )
+    writer.commit()
+    writer.close()
+
+    failed = _collect(config, sysfs_controller, second_time, 1001, 2001)
+    assert failed["ok"] is False
+    assert "simulated publication interruption" in failed["error"]
+    with sqlite3.connect(store_path) as conn:
+        assert conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0] == 1
+        assert conn.execute("SELECT COUNT(*) FROM pending_publications").fetchone()[0] == 1
+
+    writer = sqlite3.connect(store_path)
+    writer.execute("DROP TRIGGER interrupt_publication")
+    writer.commit()
+    writer.close()
+
+    third_time = second_time + timedelta(minutes=5)
+    recovered = _collect(config, sysfs_controller, third_time, 1002, 2002)
+    assert recovered["ok"] is True, recovered
+    assert recovered["retention_error"] is None
+    with sqlite3.connect(store_path) as conn:
+        assert conn.execute("SELECT COUNT(*) FROM pending_publications").fetchone()[0] == 0
+        assert conn.execute("SELECT ts FROM samples ORDER BY id").fetchall() == [
+            (second_time.isoformat(),),
+            (third_time.isoformat(),),
+        ]
+        assert conn.execute(
+            "SELECT COUNT(*) FROM local_day_unallocated_evidence"
+        ).fetchone()[0] == 1

tests/test_issue_101.py

@@ -0,0 +1,257 @@
+"""Bound pending-publication admission before device acquisition."""
+import json
+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 import collector
+
+
+class FakeClock:
+    def __init__(self, now):
+        self.now = now
+
+    def utcnow(self):
+        return self.now
+
+
+@pytest.fixture
+def sysfs_controller(tmp_path):
+    controller_path = tmp_path / "sys" / "class" / "nvme" / "nvme0"
+    controller_path.mkdir(parents=True)
+    (controller_path / "subsysnqn").write_text("nqn.test:drive\n")
+    (controller_path / "model").write_text("Test NVMe\n")
+    (controller_path / "serial").write_text("test-serial\n")
+    (controller_path / "firmware_rev").write_text("1.0\n")
+    transport = controller_path / "transport"
+    transport.mkdir()
+    (transport / "trstring").write_text("pcie\n")
+    return controller_path
+
+
+def _smartctl(units_written):
+    return {
+        "nvme_smart_health_information_log": {
+            "critical_warning": 0,
+            "temperature": 35,
+            "available_spare": 100,
+            "percentage_used": 5,
+            "data_units_written": units_written,
+            "data_units_read": 500,
+            "power_on_hours": 100,
+        },
+        "user_capacity": {"bytes": 1_024_000_000_000},
+        "model_name": "Test NVMe",
+        "serial_number": "test-serial",
+        "firmware_version": "1.0",
+    }
+
+
+def _collect(config, controller, now, units_written):
+    return collector.run_collection(
+        config=config,
+        clock=FakeClock(now),
+        acquire=lambda: (_smartctl(units_written), controller),
+    )
+
+
+def test_partial_recovery_frees_admission_and_keeps_pending_order(
+    tmp_path, sysfs_controller, monkeypatch,
+):
+    """A freed slot admits one observation behind older pending evidence."""
+    assert collector.PENDING_PUBLICATION_LIMIT == 6_720
+    monkeypatch.setenv("TZ", "UTC")
+    monkeypatch.setattr(collector, "PENDING_PUBLICATION_LIMIT", 2)
+
+    store_path = tmp_path / "observations.db"
+    config = {"device": "/dev/nvme0", "store_path": str(store_path)}
+    old_time = datetime(2026, 8, 1, tzinfo=timezone.utc)
+    controller = sysfs_controller
+
+    assert _collect(config, controller, old_time, 1000)["ok"] is True
+
+    original_derive = collector.derive_hours_from_interval
+
+    def unavailable_derivation(*_args):
+        raise RuntimeError("derivation unavailable")
+
+    monkeypatch.setattr(collector, "derive_hours_from_interval", unavailable_derivation)
+    first_pending = _collect(
+        config, controller, old_time + timedelta(minutes=5), 1010,
+    )
+    assert first_pending["ok"] is False
+
+    second_pending = _collect(
+        config, controller, old_time + timedelta(minutes=10), 1020,
+    )
+    assert second_pending["ok"] is False
+    with sqlite3.connect(store_path) as conn:
+        assert conn.execute(
+            "SELECT COUNT(*) FROM pending_publications"
+        ).fetchone()[0] == 2
+
+    called = False
+
+    def must_not_acquire():
+        nonlocal called
+        called = True
+        return _smartctl(1030), controller
+
+    full = collector.run_collection(
+        config=config,
+        clock=FakeClock(old_time + timedelta(days=40)),
+        acquire=must_not_acquire,
+    )
+    assert full["ok"] is False
+    assert "capacity full (2 observations)" in full["error"]
+    assert called is False
+    with sqlite3.connect(store_path) as conn:
+        assert conn.execute(
+            "SELECT COUNT(*), MIN(sample_ts) FROM pending_publications"
+        ).fetchone() == (
+            2,
+            (old_time + timedelta(minutes=5)).isoformat(),
+        )
+        assert conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0] == 1
+
+    def fail_second_pending(conn, previous, current):
+        if current["data_units_written"] == 1020:
+            raise RuntimeError("second observation still blocked")
+        return original_derive(conn, previous, current)
+
+    monkeypatch.setattr(collector, "derive_hours_from_interval", fail_second_pending)
+    acquired = False
+
+    def acquire_after_partial_recovery():
+        nonlocal acquired
+        acquired = True
+        return _smartctl(1030), controller
+
+    partial = collector.run_collection(
+        config=config,
+        clock=FakeClock(old_time + timedelta(days=40, minutes=5)),
+        acquire=acquire_after_partial_recovery,
+    )
+    assert partial["ok"] is False
+    assert acquired is True, partial
+    assert "no new observation acquired" not in partial["error"]
+
+    with sqlite3.connect(store_path) as conn:
+        assert conn.execute(
+            "SELECT data_units_written FROM samples ORDER BY id"
+        ).fetchall() == [(1000,), (1010,)]
+        queued_units = [
+            json.loads(row[0])["sample"]["data_units_written"]
+            for row in conn.execute(
+                "SELECT payload FROM pending_publications ORDER BY id"
+            )
+        ]
+        assert queued_units == [1020, 1030]
+        assert conn.execute("SELECT COUNT(*) FROM monitoring_periods").fetchone()[0] == 1
+
+    recovered_in_order = []
+
+    def record_recovery_order(conn, previous, current):
+        recovered_in_order.append(current["data_units_written"])
+        return original_derive(conn, previous, current)
+
+    monkeypatch.setattr(collector, "derive_hours_from_interval", record_recovery_order)
+    recovered = collector.run_collection(
+        config=config,
+        clock=FakeClock(old_time + timedelta(days=40, minutes=10)),
+        acquire=lambda: (_smartctl(1040), controller),
+    )
+    assert recovered["ok"] is True, recovered
+    assert recovered_in_order == [1020, 1030, 1040]
+
+    with sqlite3.connect(store_path) as conn:
+        assert conn.execute(
+            "SELECT data_units_written FROM samples ORDER BY id DESC LIMIT 1"
+        ).fetchone() == (1040,)
+        assert conn.execute("SELECT COUNT(*) FROM pending_publications").fetchone()[0] == 0
+
+
+def test_actual_pending_limit_fails_before_acquisition_and_keeps_old_evidence(
+    tmp_path, sysfs_controller, monkeypatch,
+):
+    """The production limit retains every old row and refuses device acquisition."""
+    monkeypatch.setenv("TZ", "UTC")
+    store_path = tmp_path / "full-observations.db"
+    config = {"device": "/dev/nvme0", "store_path": str(store_path)}
+    controller = sysfs_controller
+    old_time = datetime(2026, 7, 1, tzinfo=timezone.utc)
+    assert _collect(config, controller, old_time, 1000)["ok"] is True
+
+    def unavailable_derivation(*_args):
+        raise RuntimeError("derivation unavailable")
+
+    monkeypatch.setattr(collector, "derive_hours_from_interval", unavailable_derivation)
+    failed = _collect(
+        config, controller, old_time + timedelta(minutes=5), 1010,
+    )
+    assert failed["ok"] is False
+
+    with sqlite3.connect(store_path) as conn:
+        payload_row = conn.execute(
+            "SELECT payload FROM pending_publications ORDER BY id LIMIT 1"
+        ).fetchone()
+        assert payload_row is not None
+        base = json.loads(payload_row[0])
+        base_observed_at = datetime.fromisoformat(base["sample"]["ts"])
+        base_units = base["sample"]["data_units_written"]
+        rows = []
+        for offset in range(1, collector.PENDING_PUBLICATION_LIMIT):
+            observation = json.loads(payload_row[0])
+            units_written = base_units + offset
+            observed_at = base_observed_at + timedelta(minutes=5 * offset)
+            observation["sample"]["ts"] = observed_at.isoformat()
+            observation["sample"]["data_units_written"] = units_written
+            observation["sample"]["bytes_written"] = units_written * 512_000
+            rows.append((observed_at.isoformat(), json.dumps(observation)))
+        conn.executemany(
+            "INSERT INTO pending_publications (sample_ts, payload) VALUES (?, ?)",
+            rows,
+        )
+        conn.commit()
+
+    called = False
+
+    def must_not_acquire():
+        nonlocal called
+        called = True
+        return _smartctl(9000), controller
+
+    result = collector.run_collection(
+        config=config,
+        clock=FakeClock(old_time + timedelta(days=40)),
+        acquire=must_not_acquire,
+    )
+    assert result["ok"] is False
+    assert f"capacity full ({collector.PENDING_PUBLICATION_LIMIT} observations)" in result[
+        "error"
+    ]
+    assert called is False
+
+    with sqlite3.connect(store_path) as conn:
+        pending_rows = conn.execute(
+            "SELECT sample_ts, payload FROM pending_publications ORDER BY id"
+        ).fetchall()
+        assert len(pending_rows) == collector.PENDING_PUBLICATION_LIMIT
+        assert (pending_rows[0][0], pending_rows[-1][0]) == (
+            (old_time + timedelta(minutes=5)).isoformat(),
+            (
+                old_time
+                + timedelta(minutes=5 * collector.PENDING_PUBLICATION_LIMIT)
+            ).isoformat(),
+        )
+        assert [
+            json.loads(payload)["sample"]["data_units_written"]
+            for _, payload in pending_rows
+        ] == list(range(1010, 1010 + collector.PENDING_PUBLICATION_LIMIT))
+        assert conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0] == 1
+        assert conn.execute("SELECT COUNT(*) FROM monitoring_periods").fetchone()[0] == 1

tests/test_issue_72_edge_cases.py

@@ -90,8 +90,8 @@ def _insert_local_day(conn, local_date, tz_name="UTC", tz_offset="+00:00",
     conn.execute(
         "INSERT INTO local_days "
         "(local_date, tz_name, tz_offset, utc_start, utc_end, "
-        " bytes_written, bytes_read, coverage, sample_count, complete) "
+        " bytes_written, bytes_read, coverage, sample_count, complete, activity_intervals) "
-        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 1)",
         (local_date, tz_name, tz_offset, utc_start, utc_end,
          bw, br, coverage, samples, complete),
     )

tests/test_issue_77.py

@@ -98,8 +98,8 @@ def _insert_local_day(conn, local_date, tz_name="UTC", tz_offset="+00:00",
     conn.execute(
         "INSERT INTO local_days "
         "(local_date, tz_name, tz_offset, utc_start, utc_end, "
-        " bytes_written, bytes_read, coverage, sample_count, complete) "
+        " bytes_written, bytes_read, coverage, sample_count, complete, activity_intervals) "
-        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 1)",
         (local_date, tz_name, tz_offset, utc_start, utc_end,
          bw, br, coverage, samples, complete),
     )

tests/test_issue_92.py

@@ -24,13 +24,12 @@ from fenris.store import init_store
 from fenris.monitoring_periods import ensure_period_open
 from fenris.local_day import (
     LocalDaySummary,
+    local_day_boundaries,
     persist_local_day,
-    query_local_day_summary,
 )
+from fenris.tz_util import detect_system_tz
 from fenris.tui import (
     FenrisTuiApp,
-    HistoryGraph,
-    _RANGE_OPTIONS,
     _RANGE_DEFAULT,
 )
 
@@ -70,13 +69,18 @@ def _open_period(conn, start="2026-09-01T00:00:00+00:00"):
 
 
 def _insert_local_day(conn, local_date, tz_name="UTC", tz_offset="+00:00",
-                       bw=300, br=130, complete=True):
+                       bw=300, br=130, complete=True,
+                       utc_start=None, utc_end=None):
+    if utc_start is None:
+        utc_start = f"{local_date}T00:00:00+00:00"
+    if utc_end is None:
+        utc_end = f"{(datetime.fromisoformat(local_date) + timedelta(days=1)).strftime('%Y-%m-%d')}T00:00:00+00:00"
     summary = LocalDaySummary(
         local_date=local_date,
         tz_name=tz_name,
         tz_offset=tz_offset,
-        utc_start=f"{local_date}T00:00:00+00:00",
+        utc_start=utc_start,
-        utc_end=f"{(datetime.fromisoformat(local_date) + timedelta(days=1)).strftime('%Y-%m-%d')}T00:00:00+00:00",
+        utc_end=utc_end,
         bytes_written=bw,
         bytes_read=br,
         coverage=0.95,
@@ -124,6 +128,10 @@ def _make_app(tmp_path, clock=None):
     return app, patcher
 
 
+def _visible_selected_date(app):
+    return str(app.query_one("#local-day").render())[:10]
+
+
 # ---------------------------------------------------------------------------
 # AC92-1: Keyboard bindings exist
 # ---------------------------------------------------------------------------
@@ -178,14 +186,13 @@ class TestBracketNavigation:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
             # Move to an older day first so ] can advance
             for _ in range(3):
                 await pilot.press("left_square_bracket")
-            day_before = graph._day_data[graph.selected_index].get("day")
+            day_before = _visible_selected_date(app)
 
             await pilot.press("right_square_bracket")
-            day_after = graph._day_data[graph.selected_index].get("day")
+            day_after = _visible_selected_date(app)
             # ] should move to a newer day (closer to today)
             assert day_after > day_before
 
@@ -198,11 +205,10 @@ class TestBracketNavigation:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
+            day_before = _visible_selected_date(app)
-            day_before = graph._day_data[graph.selected_index].get("day")
 
             await pilot.press("left_square_bracket")
-            day_after = graph._day_data[graph.selected_index].get("day")
+            day_after = _visible_selected_date(app)
             # [ should move to an older day (further from today)
             assert day_after < day_before
 
@@ -224,9 +230,8 @@ class TestBracketNavigation:
                 for _ in range(29):
                     await pilot.press("left_square_bracket")
 
-                # Graph should now show a range that includes the oldest day
+                # Visible readout identifies oldest selected date.
-                assert graph.selected_index >= 0
+                selected_day = _visible_selected_date(app)
-                selected_day = graph._day_data[graph.selected_index].get("day")
                 oldest_day = (app_clock - timedelta(days=29)).strftime("%Y-%m-%d")
                 assert selected_day == oldest_day
         finally:
@@ -241,11 +246,10 @@ class TestBracketNavigation:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
+            initial_date = _visible_selected_date(app)
-            initial_idx = graph.selected_index
 
             await pilot.press("right_square_bracket")
-            assert graph.selected_index == initial_idx
+            assert _visible_selected_date(app) == initial_date
 
 
 # ---------------------------------------------------------------------------
@@ -262,36 +266,54 @@ class TestArrowInspection:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
             await pilot.press("v", "v")
-            graph.focus()
+            app.query_one("#usage-history").focus()
             await pilot.pause()
-            day_before = graph._day_data[graph.selected_index].get("day")
+            day_before = _visible_selected_date(app)
 
             await pilot.press("left")
-            day_after = graph._day_data[graph.selected_index].get("day")
+            day_after = _visible_selected_date(app)
             assert day_after != day_before
 
     @pytest.mark.asyncio
     async def test_arrow_keys_inspect_hours_in_drill(self, tmp_path):
         """Arrow keys navigate hours when in hourly drill-down."""
         conn, clock = _setup_store(tmp_path, n_days=14)
+        local_date = datetime.now().astimezone().date().isoformat()
+        timezone_name = detect_system_tz()
+        utc_start, utc_end, tz_offset = local_day_boundaries(local_date, timezone_name)
+        _insert_local_day(
+            conn, local_date, tz_name=timezone_name, tz_offset=tz_offset,
+            utc_start=utc_start.isoformat(), utc_end=utc_end.isoformat(),
+        )
+        hour = utc_start.replace(minute=0, second=0, microsecond=0)
+        if hour < utc_start:
+            hour += timedelta(hours=1)
+        while hour + timedelta(hours=1) <= utc_end:
+            conn.execute(
+                "INSERT INTO hour_observations "
+                "(hour, bytes_written_delta, bytes_read_delta, coverage, sample_count) "
+                "VALUES (?, 1000000, 2000000, 1, 1)",
+                (hour.isoformat(),),
+            )
+            hour += timedelta(hours=1)
+        conn.commit()
         conn.close()
 
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
             await pilot.press("v", "v")
             await pilot.click("#usage-history")
 
             # Enter drill-down
             await pilot.press("enter")
-            assert graph.view_mode == "hourly"
+            assert app.query_one("#activity-tabs").active == "view-day"
 
             # Arrow keys navigate hours
+            readout_before = str(app.query_one("#bar-readout").render())
             await pilot.press("left")
-            assert graph._hourly_selected >= 0
+            assert str(app.query_one("#bar-readout").render()) != readout_before
 
 
 # ---------------------------------------------------------------------------
@@ -308,18 +330,17 @@ class TestTodayBinding:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
 
             # Browse to an older day using [
             for _ in range(5):
                 await pilot.press("left_square_bracket")
-            browsed_day = graph._day_data[graph.selected_index].get("day")
+            browsed_day = _visible_selected_date(app)
-            today = clock.strftime("%Y-%m-%d")
+            today = datetime.now().astimezone().date().isoformat()
             assert browsed_day != today
 
             # Press t to return to today
             await pilot.press("t")
-            assert graph.selected_index == len(graph._day_data) - 1
+            assert app.query_one("#activity-tabs").active == "view-live"
 
     @pytest.mark.asyncio
     async def test_t_exits_hourly_drill(self, tmp_path):
@@ -330,17 +351,16 @@ class TestTodayBinding:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
             await pilot.press("v", "v")
             await pilot.click("#usage-history")
 
             # Enter drill
             await pilot.press("enter")
-            assert graph.view_mode == "hourly"
+            assert app.query_one("#activity-tabs").active == "view-day"
 
             # t returns to daily
             await pilot.press("t")
-            assert graph.view_mode == "daily"
+            assert app.query_one("#activity-tabs").active == "view-live"
 
 
 # ---------------------------------------------------------------------------
@@ -360,7 +380,7 @@ class TestDateEntry:
             await pilot.press("g")
             await pilot.pause()
             # Date picker should be pushed as a screen
-            assert len(app.screen_stack) > 1
+            assert app.screen.query_one("#date-input") is not None
 
     @pytest.mark.asyncio
     async def test_valid_date_navigates(self, tmp_path):
@@ -375,13 +395,12 @@ class TestDateEntry:
                 await pilot.pause()
                 target_date = (app_clock - timedelta(days=5)).strftime("%Y-%m-%d")
 
-                # Simulate the date picker callback directly
+                await pilot.press("g")
-                app._go_to_date_callback(target_date)
+                await pilot.press(*target_date)
+                await pilot.press("enter")
                 await pilot.pause()
 
-                graph = app.query_one("#usage-history")
+                assert _visible_selected_date(app) == target_date
-                selected_day = graph._day_data[graph.selected_index].get("day")
-                assert selected_day == target_date
         finally:
             patcher.stop()
 
@@ -400,7 +419,8 @@ class TestDateEntry:
             await pilot.press("enter")
             await pilot.pause()
             # Should remain on date picker (error shown, not dismissed)
-            assert len(app.screen_stack) > 1
+            error = str(app.screen.query_one("#date-error").render())
+            assert "Invalid date format" in error
 
     @pytest.mark.asyncio
     async def test_cancel_returns_to_prior(self, tmp_path):
@@ -411,8 +431,7 @@ class TestDateEntry:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
+            prior_readout = str(app.query_one("#bar-readout").render())
-            prior_idx = graph.selected_index
 
             await pilot.press("g")
             await pilot.pause()
@@ -420,7 +439,7 @@ class TestDateEntry:
             await pilot.pause()
 
             # Should be back to the graph with the same selection
-            assert graph.selected_index == prior_idx
+            assert str(app.query_one("#bar-readout").render()) == prior_readout
 
 
 # ---------------------------------------------------------------------------
@@ -442,8 +461,6 @@ class TestLocalDayEvidence:
         try:
             async with app.run_test(size=(100, 40)) as pilot:
                 await pilot.pause()
-                graph = app.query_one("#usage-history")
-
                 # Navigate to the target day
                 for _ in range(4):
                     await pilot.press("left_square_bracket")
@@ -489,12 +506,10 @@ class TestBrowsingStability:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=0.1)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
-
             # Browse to a specific day
             for _ in range(3):
-                await pilot.press("right_square_bracket")
+                await pilot.press("left_square_bracket")
-            browsed_day = graph._day_data[graph.selected_index].get("day")
+            browsed_day = _visible_selected_date(app)
 
             # Wait for at least one refresh tick
             import asyncio
@@ -502,8 +517,7 @@ class TestBrowsingStability:
             await pilot.pause()
 
             # Selection should be preserved
-            assert graph.selected_index >= 0
+            assert _visible_selected_date(app) == browsed_day
-            assert graph._day_data[graph.selected_index].get("day") == browsed_day
 
     @pytest.mark.asyncio
     async def test_navigate_away_does_not_jump_on_refresh(self, tmp_path):
@@ -514,14 +528,12 @@ class TestBrowsingStability:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=0.1)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
-
             # Browse to older day using [
             for _ in range(5):
                 await pilot.press("left_square_bracket")
 
-            browsed_day = graph._day_data[graph.selected_index].get("day")
+            browsed_day = _visible_selected_date(app)
-            today = clock.strftime("%Y-%m-%d")
+            today = datetime.now().astimezone().date().isoformat()
             assert browsed_day != today
 
             # Wait for refresh
@@ -530,8 +542,8 @@ class TestBrowsingStability:
             await pilot.pause()
 
             # Should NOT jump back to today
-            selected_day = graph._day_data[graph.selected_index].get("day")
+            assert _visible_selected_date(app) == browsed_day
-            assert selected_day != today
+            assert _visible_selected_date(app) != today
 
 
 # ---------------------------------------------------------------------------
@@ -548,17 +560,16 @@ class TestDrillDownData:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
         async with app.run_test(size=(100, 40)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
             await pilot.press("v", "v")
             await pilot.click("#usage-history")
 
             # Enter drill-down
             await pilot.press("enter")
-            assert graph.view_mode == "hourly"
+            assert app.query_one("#activity-tabs").active == "view-day"
 
-            # After drill callback, data should be populated
+            assert "hourly evidence unavailable" in str(
-            # (empty since we have no hour_observations)
+                app.query_one("#bar-readout").render()
-            assert graph.view_mode == "hourly"
+            )
 
 
 # ---------------------------------------------------------------------------
@@ -575,11 +586,10 @@ class TestConstrainedWidth:
         app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
         async with app.run_test(size=(80, 24)) as pilot:
             await pilot.pause()
-            graph = app.query_one("#usage-history")
+            day_before = _visible_selected_date(app)
-            day_before = graph._day_data[graph.selected_index].get("day")
 
             await pilot.press("left_square_bracket")
-            day_after = graph._day_data[graph.selected_index].get("day")
+            day_after = _visible_selected_date(app)
             assert day_after < day_before
 
     @pytest.mark.asyncio
@@ -593,4 +603,235 @@ class TestConstrainedWidth:
             await pilot.pause()
             await pilot.press("g")
             await pilot.pause()
-            assert len(app.screen_stack) > 1
+            assert app.screen.query_one("#date-input") is not None
+
+
+class TestClickableNavigation:
+    @pytest.mark.asyncio
+    @pytest.mark.parametrize("size", [(80, 24), (70, 20)])
+    async def test_click_and_keyboard_select_same_local_date(self, tmp_path, size):
+        """Clickable and keyboard navigation share date-entry transitions."""
+        app_clock = _clock()
+        conn, _ = _setup_store(tmp_path, n_days=14, today=app_clock)
+        conn.close()
+        app, patcher = _make_app(tmp_path, clock=app_clock)
+        expected = (app_clock - timedelta(days=1)).strftime("%Y-%m-%d")
+        direct = (app_clock - timedelta(days=5)).strftime("%Y-%m-%d")
+        try:
+            async with app.run_test(size=size) as pilot:
+                await pilot.press("left_square_bracket")
+                keyboard_date = _visible_selected_date(app)
+                assert keyboard_date == expected
+
+                await pilot.press("t")
+                await pilot.click("#activity-tools", offset=(2, 0))
+                assert _visible_selected_date(app) == keyboard_date
+
+                await pilot.press("g")
+                await pilot.press(*direct)
+                await pilot.press("enter")
+                await pilot.pause()
+                assert _visible_selected_date(app) == direct
+        finally:
+            patcher.stop()
+
+
+class TestHistoricalSelectionIdentity:
+    @pytest.mark.asyncio
+    async def test_unavailable_entered_date_stays_visible_after_refresh(self, tmp_path):
+        """An unavailable requested date remains selected and explained."""
+        conn, clock = _setup_store(tmp_path, n_days=30)
+        conn.close()
+        app, patcher = _make_app(tmp_path, clock=clock)
+        target = (clock - timedelta(days=120)).strftime("%Y-%m-%d")
+        try:
+            async with app.run_test(size=(100, 40)) as pilot:
+                await pilot.press("g")
+                await pilot.press(*target)
+                await pilot.press("enter")
+                await pilot.pause()
+
+                local_day = str(app.query_one("#local-day").render())
+                assert target in local_day
+                assert "unavailable" in local_day
+
+                app.on_refresh_tick()
+                await pilot.pause()
+                local_day = str(app.query_one("#local-day").render())
+                assert target in local_day
+                assert "unavailable" in local_day
+        finally:
+            patcher.stop()
+
+    @pytest.mark.asyncio
+    async def test_retained_summary_outside_recent_window_remains_available(self, tmp_path):
+        """Direct date entry can inspect durable local summaries beyond 90 days."""
+        clock = _clock()
+        conn, _ = _setup_store(tmp_path, n_days=30, today=clock)
+        target = (clock - timedelta(days=120)).strftime("%Y-%m-%d")
+        utc_start, utc_end, tz_offset = local_day_boundaries(
+            target, "Asia/Kolkata",
+        )
+        _insert_local_day(
+            conn,
+            target,
+            tz_name="Asia/Kolkata",
+            tz_offset=tz_offset,
+            bw=2_000_000_000,
+            br=1_000_000_000,
+            utc_start=utc_start.isoformat(),
+            utc_end=utc_end.isoformat(),
+        )
+        conn.close()
+        app, patcher = _make_app(tmp_path, clock=clock)
+        try:
+            async with app.run_test(size=(100, 40)) as pilot:
+                await pilot.press("g")
+                await pilot.press(*target)
+                await pilot.press("enter")
+                await pilot.pause()
+                await pilot.press("v")
+                await pilot.pause()
+
+                readout = str(app.query_one("#bar-readout").render())
+                assert target in readout
+                assert "Asia/Kolkata +05:30" in readout
+                assert "W 2.000 GB known · R 1.000 GB known" in readout
+        finally:
+            patcher.stop()
+
+    @pytest.mark.asyncio
+    async def test_constrained_history_keeps_known_totals_and_evidence_state(self, tmp_path):
+        """Small textual view retains selected day, totals, and shared evidence."""
+        clock = _clock()
+        conn, _ = _setup_store(tmp_path, n_days=14, today=clock)
+        target = (clock - timedelta(days=2)).strftime("%Y-%m-%d")
+        utc_start, utc_end, tz_offset = local_day_boundaries(
+            target, "Asia/Kolkata",
+        )
+        _insert_local_day(
+            conn,
+            target,
+            tz_name="Asia/Kolkata",
+            tz_offset=tz_offset,
+            bw=1_500_000_000,
+            br=500_000_000,
+            utc_start=utc_start.isoformat(),
+            utc_end=utc_end.isoformat(),
+        )
+        conn.execute(
+            "INSERT INTO local_day_unallocated_evidence "
+            "(start_sample_id, end_sample_id, start_local_date, end_local_date, "
+            " start_tz_name, end_tz_name, started_at, ended_at, bytes_written, "
+            " bytes_read, reason) VALUES (1, 2, ?, ?, ?, ?, ?, ?, ?, ?, 'local_midnight')",
+            (target, "2026-09-29", "Asia/Kolkata", "Asia/Kolkata",
+             utc_start.isoformat(), utc_start.isoformat(), 200_000_000, 300_000_000),
+        )
+        conn.commit()
+        conn.close()
+        app, patcher = _make_app(tmp_path, clock=clock)
+        try:
+            async with app.run_test(size=(70, 20)) as pilot:
+                await pilot.press("g")
+                await pilot.press(*target)
+                await pilot.press("enter")
+                await pilot.press("v")
+                await pilot.pause()
+
+                readout = str(app.query_one("#bar-readout").render())
+                assert target in readout
+                assert "Asia/Kolkata +05:30" in readout
+                assert "incomplete" in readout
+                assert "W 1.500 GB known · R 0.500 GB known" in readout
+                assert "shared at midnight W 0.200 GB · R 0.300 GB" in readout
+        finally:
+            patcher.stop()
+
+    @pytest.mark.asyncio
+    async def test_date_picker_keystrokes_do_not_toggle_measurement(self, tmp_path):
+        """Typing in date entry does not trigger dashboard shortcuts."""
+        conn, _ = _setup_store(tmp_path, n_days=14)
+        conn.close()
+        app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
+        async with app.run_test(size=(100, 40)) as pilot:
+            await pilot.pause()
+            await pilot.press("g")
+            await pilot.press("w")
+            await pilot.press("escape")
+            await pilot.pause()
+
+            header = str(app.query_one("#live-header").render())
+            assert "Writes" in header
+
+    @pytest.mark.asyncio
+    async def test_historical_hour_uses_recorded_timezone_and_utc_identity(self, tmp_path):
+        """Repeated local clock labels retain distinct UTC-hour identities."""
+        clock = _clock(2026, 11, 2, 12)
+        conn, _ = _setup_store(tmp_path, n_days=30, today=clock)
+        target = "2026-11-01"
+        _insert_local_day(
+            conn,
+            target,
+            tz_name="America/New_York",
+            tz_offset="-04:00",
+            utc_start="2026-11-01T04:00:00+00:00",
+            utc_end="2026-11-02T05:00:00+00:00",
+        )
+        conn.execute(
+            "INSERT INTO local_day_unallocated_evidence "
+            "(start_sample_id, end_sample_id, start_local_date, end_local_date, "
+            " start_tz_name, end_tz_name, started_at, ended_at, bytes_written, "
+            " bytes_read, reason) VALUES (1, 2, ?, ?, ?, ?, ?, ?, ?, ?, 'local_midnight')",
+            (target, "2026-11-02", "America/New_York", "America/New_York",
+             "2026-11-02T03:59:00+00:00", "2026-11-02T04:01:00+00:00",
+             2_000_000_000, 3_000_000_000),
+        )
+        for index in range(25):
+            hour = datetime(2026, 11, 1, 4, tzinfo=timezone.utc) + timedelta(hours=index)
+            conn.execute(
+                "INSERT INTO hour_observations "
+                "(hour, bytes_written_delta, bytes_read_delta, coverage, sample_count) "
+                "VALUES (?, ?, ?, 1, 1)",
+                (hour.isoformat(), (index + 1) * 1_000_000_000,
+                 (index + 1) * 2_000_000_000),
+            )
+        conn.execute(
+            "UPDATE hour_observations SET coverage = 0.5, unknown_seconds = 1800 "
+            "WHERE hour = ?",
+            ("2026-11-01T04:00:00+00:00",),
+        )
+        conn.commit()
+        conn.close()
+        app, patcher = _make_app(tmp_path, clock=clock)
+        try:
+            async with app.run_test(size=(100, 40)) as pilot:
+                await pilot.click("#view-history")
+                await pilot.press("g")
+                await pilot.press(*target)
+                await pilot.press("enter")
+                await pilot.pause()
+
+                local_day = str(app.query_one("#local-day").render())
+                assert "America/New_York -04:00" in local_day
+                assert "incomplete" in local_day
+                assert "shared at midnight W 2.000 GB · R 3.000 GB" in local_day
+
+                # Move from final local hour to the second 01:00 occurrence.
+                await pilot.press(*(["left"] * 22))
+                second_occurrence = str(app.query_one("#bar-readout").render())
+                assert "01:00 -0500" in second_occurrence
+                assert "America/New_York -0500" in second_occurrence
+                assert "06:00 UTC" in second_occurrence
+
+                await pilot.press("left")
+                first_occurrence = str(app.query_one("#bar-readout").render())
+                assert "01:00 -0400" in first_occurrence
+                assert "America/New_York -0400" in first_occurrence
+                assert "05:00 UTC" in first_occurrence
+
+                await pilot.press("left")
+                incomplete_hour = str(app.query_one("#bar-readout").render())
+                assert "00:00 -0400" in incomplete_hour
+                assert "50% coverage · incomplete" in incomplete_hour
+        finally:
+            patcher.stop()

tests/test_issue_93.py

@@ -151,8 +151,8 @@ class TestDetailExpiresSummariesRemain:
         # Run pruning
         pruned = prune_old_samples(conn, now, retention_days=14)
 
-        # Old samples should be pruned, recent ones retained
+        # The handcrafted totals lack replacement provenance, so retain samples.
-        assert pruned >= 1
+        assert pruned == 0
 
         # Local-day summaries must still be queryable
         old_result = query_local_day_summary(conn, "2026-09-16")
@@ -277,7 +277,7 @@ class TestTimezonePreservation:
         now = datetime(2026, 10, 1, 12, 0, 0, tzinfo=timezone.utc)
 
         old = LocalDaySummary(
-            local_date="2026-09-16", tz_name="US/Eastern", tz_offset="-04:00",
+            local_date="2026-09-16", tz_name="America/New_York", tz_offset="-04:00",
             utc_start="2026-09-16T04:00:00+00:00",
             utc_end="2026-09-17T04:00:00+00:00",
             bytes_written=5000, bytes_read=2000,
@@ -288,7 +288,7 @@ class TestTimezonePreservation:
         entries = query_local_day_history(conn, "2026-09-16", "2026-09-16", now)
         assert len(entries) == 1
         entry = entries[0]
-        assert entry.tz_name == "US/Eastern"
+        assert entry.tz_name == "America/New_York"
         assert entry.tz_offset == "-04:00"
         assert entry.utc_start == "2026-09-16T04:00:00+00:00"
         assert entry.detail_available is False
@@ -389,10 +389,10 @@ class TestIdempotencySafety:
 # ---------------------------------------------------------------------------
 
 class TestVolumeConservation:
-    """AC6: Summary volume plus unallocated evidence conserves each delta once."""
+    """AC6: UTC-hour totals never become fabricated local-day totals."""
 
-    def test_midnight_spanning_not_double_counted(self, tmp_path):
+    def test_hourly_bytes_are_unavailable_at_local_precision(self, tmp_path):
-        """Midnight-spanning interval appears once, not in both days."""
+        """UTC-day hour bytes cannot be split across local-day boundaries."""
         conn = init_store(tmp_path / "obs.db")
 
         # Insert hour observations that span midnight
@@ -409,13 +409,10 @@ class TestVolumeConservation:
         summary_17 = derive_local_day_summary(conn, "UTC", clock_17)
         assert summary_17 is not None
 
-        # Each day should only have its own hour's bytes
+        assert summary_16.bytes_written == 0
-        # Day 16 has the 23:00 hour (100 bw)
+        assert summary_17.bytes_written == 0
-        # Day 17 has the 00:00 hour (200 bw)
+        assert summary_16.activity_precision == "unavailable"
-        assert summary_16.bytes_written == 100
+        assert summary_17.activity_precision == "unavailable"
-        assert summary_17.bytes_written == 200
-        # Total is conserved: 100 + 200 = 300
-        assert summary_16.bytes_written + summary_17.bytes_written == 300
         conn.close()
 
 
@@ -437,10 +434,10 @@ class TestExistingEntryPoints:
             _insert_sample(conn, ts, bw=days_ago * 100)
 
         pruned = prune_old_samples(conn, now, retention_days=14)
-        assert pruned == 15
+        assert pruned == 0
 
         cursor = conn.execute("SELECT COUNT(*) FROM samples")
-        assert cursor.fetchone()[0] == 14
+        assert cursor.fetchone()[0] == 29
         conn.close()
 
     def test_repair_with_real_temp_store(self, tmp_path):

tests/test_issue_97.py

@@ -0,0 +1,294 @@
+"""Pending publication behavior from issue #97."""
+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 import collector
+from fenris.projection import compute_projection
+from fenris.status import _query_drive_facts, get_status, read_status
+from fenris.status_composition import render_status_tui
+from fenris.store import init_store
+
+
+class FakeClock:
+    def __init__(self, now):
+        self.now = now
+
+    def utcnow(self):
+        return self.now
+
+
+@pytest.fixture
+def sysfs_fixture_tree(tmp_path):
+    ctrl_dir = tmp_path / "sys" / "class" / "nvme" / "nvme0"
+    ctrl_dir.mkdir(parents=True)
+    (ctrl_dir / "subsysnqn").write_text("nqn.test:drive\n")
+    (ctrl_dir / "model").write_text("Test NVMe\n")
+    (ctrl_dir / "serial").write_text("test-serial\n")
+    (ctrl_dir / "firmware_rev").write_text("1.0\n")
+    transport_dir = ctrl_dir / "transport"
+    transport_dir.mkdir()
+    (transport_dir / "trstring").write_text("pcie\n")
+    return tmp_path
+
+
+def _smartctl(unit_written, unit_read=500):
+    return {
+        "nvme_smart_health_information_log": {
+            "critical_warning": 0,
+            "temperature": 35,
+            "available_spare": 100,
+            "percentage_used": 5,
+            "data_units_written": unit_written,
+            "data_units_read": unit_read,
+            "power_on_hours": 100,
+        },
+        "user_capacity": {"bytes": 1_024_000_000_000},
+        "model_name": "Test NVMe",
+        "serial_number": "test-serial",
+        "firmware_version": "1.0",
+    }
+
+
+def _acquirer(sysfs_path, unit_written, unit_read=500):
+    return lambda: (_smartctl(unit_written, unit_read), sysfs_path)
+
+
+def _public_snapshot(store_path, clock_now):
+    with read_status(store_path, clock_now) as (conn, comp):
+        assert conn is not None
+        return {
+            "state": comp.state,
+            "freshness": comp.freshness,
+            "sample_count": comp.sample_count,
+            "day_count": comp.day_count,
+            "boot_enabled": comp.boot_enabled,
+            "timer_active": comp.timer_active,
+            "last_collect_ok": comp.last_collect_ok,
+            "latest_sample": tuple(conn.execute(
+                "SELECT ts, subnqn, mn, sn, fr, capacity_bytes, temperature_c, "
+                "available_spare, data_units_written, bytes_written, critical_warning, "
+                "media_errors, unsafe_shutdowns "
+                "FROM samples ORDER BY id DESC LIMIT 1"
+            ).fetchone()),
+            "drive_facts": tuple(_query_drive_facts(conn)),
+            "projection": repr(compute_projection(conn, clock_now)),
+            "segments": conn.execute("SELECT COUNT(*) FROM controller_segments").fetchone()[0],
+            "periods": conn.execute("SELECT COUNT(*) FROM monitoring_periods").fetchone()[0],
+            "hours": tuple(conn.execute(
+                "SELECT hour, bytes_written_delta, bytes_read_delta, sample_count "
+                "FROM hour_observations ORDER BY hour"
+            ).fetchall()),
+            "days": tuple(conn.execute(
+                "SELECT day, bytes_written_delta, bytes_read_delta "
+                "FROM day_aggregates ORDER BY day"
+            ).fetchall()),
+            "local_days": tuple(conn.execute(
+                "SELECT local_date, bytes_written, bytes_read, sample_count "
+                "FROM local_days ORDER BY local_date, tz_name"
+            ).fetchall()),
+            "pending": comp.pending_publication_count,
+        }
+
+
+def test_failed_publication_survives_restart_and_readers_keep_last_consistent_view(
+    tmp_path, sysfs_fixture_tree, monkeypatch
+):
+    """A failed derivation stays private, visible as pending, and replays in order."""
+    monkeypatch.setenv("TZ", "UTC")
+    service = {"boot_enabled": True, "timer_active": True, "last_collect_ok": True}
+    monkeypatch.setattr("fenris.status.query_service_state", lambda: service)
+    now = datetime.now(timezone.utc).replace(
+        minute=35, second=0, microsecond=0,
+    )
+    store_path = tmp_path / "observations.db"
+    config = {"device": "/dev/nvme0", "store_path": str(store_path)}
+    sysfs_path = sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0"
+
+    for units, at in ((1000, now - timedelta(minutes=10)), (1010, now - timedelta(minutes=5))):
+        result = collector.run_collection(
+            config=config,
+            clock=FakeClock(at),
+            acquire=_acquirer(sysfs_path, units),
+        )
+        assert result["ok"] is True, result
+
+    previous = _public_snapshot(store_path, now)
+    baseline_cli = get_status(store_path, now, query_services=False, query_journal=False)
+    original_derive = collector.derive_hours_from_interval
+    reader_during_write = {}
+
+    def fail_derivation(conn, previous_sample, next_sample):
+        # Read while writer has inserted the unpublished sample but not committed.
+        with read_status(store_path, now, query_services=False) as (reader, comp):
+            assert reader is not None
+            reader_during_write["samples"] = reader.execute(
+                "SELECT COUNT(*) FROM samples"
+            ).fetchone()[0]
+            reader_during_write["pending"] = comp.pending_publication_count
+            reader_during_write["latest"] = tuple(reader.execute(
+                "SELECT data_units_written FROM samples ORDER BY id DESC LIMIT 1"
+            ).fetchone())
+        raise RuntimeError("injected non-invariant derivation failure")
+
+    monkeypatch.setattr(collector, "derive_hours_from_interval", fail_derivation)
+    failed = collector.run_collection(
+        config=config,
+        clock=FakeClock(now),
+        acquire=_acquirer(sysfs_path, 1025),
+    )
+    assert failed["ok"] is False
+    assert "injected non-invariant derivation failure" in failed["error"]
+    assert reader_during_write == {"samples": 2, "pending": 1, "latest": (1010,)}
+
+    after_failure = _public_snapshot(store_path, now)
+    assert {**after_failure, "pending": previous["pending"]} == previous
+    assert after_failure["pending"] == 1
+
+    cli_text = get_status(store_path, now, query_services=False, query_journal=False)
+    pending_fact = " · pending publication: 1 observation retained for retry"
+    assert pending_fact in cli_text
+    assert cli_text.replace(pending_fact, "", 1) == baseline_cli
+
+    with read_status(store_path, now) as (_, comp):
+        assert comp.state == previous["state"]
+        assert comp.boot_enabled is True
+        assert comp.timer_active is True
+        assert "pending publication: 1 observation retained for retry" in render_status_tui(comp).lower()
+
+    called = False
+
+    def should_wait_for_recovery():
+        nonlocal called
+        called = True
+        return _smartctl(1030), sysfs_path
+
+    monkeypatch.setattr(collector, "PENDING_PUBLICATION_LIMIT", 1)
+    blocked = collector.run_collection(
+        config=config,
+        clock=FakeClock(now + timedelta(minutes=5)),
+        acquire=should_wait_for_recovery,
+    )
+    assert blocked["ok"] is False
+    assert called is False
+    assert _public_snapshot(store_path, now)["pending"] == 1
+
+    monkeypatch.setattr(collector, "derive_hours_from_interval", original_derive)
+    monkeypatch.setenv("TZ", "Asia/Kolkata")
+    recovered = collector.run_collection(
+        config=config,
+        clock=FakeClock(now + timedelta(minutes=5)),
+        acquire=_acquirer(sysfs_path, 1040),
+    )
+    assert recovered["ok"] is True, recovered
+
+    conn = sqlite3.connect(store_path)
+    try:
+        assert conn.execute(
+            "SELECT data_units_written FROM samples ORDER BY id"
+        ).fetchall() == [(1000,), (1010,), (1025,), (1040,)]
+        assert conn.execute("SELECT COUNT(*) FROM pending_publications").fetchone()[0] == 0
+        assert conn.execute(
+            "SELECT SUM(bytes_written_delta) FROM day_aggregates"
+        ).fetchone()[0] == (1040 - 1000) * 512_000
+        assert conn.execute(
+            "SELECT sample_count FROM local_days WHERE tz_name = 'UTC'"
+        ).fetchone()[0] == 4
+        assert conn.execute(
+            "SELECT COUNT(*) FROM local_days WHERE tz_name = 'Asia/Kolkata'"
+        ).fetchone()[0] == 1
+    finally:
+        conn.close()
+
+
+def test_invalid_sample_writes_no_sample_segment_period_or_pending_row(tmp_path, sysfs_fixture_tree):
+    """Sample invariants run before staging or public monitoring changes."""
+    now = datetime.now(timezone.utc).replace(second=0, microsecond=0)
+    store_path = tmp_path / "observations.db"
+    config = {"device": "/dev/nvme0", "store_path": str(store_path)}
+    sysfs_path = sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0"
+    result = collector.run_collection(
+        config=config,
+        clock=FakeClock(now),
+        acquire=_acquirer(sysfs_path, -1),
+    )
+
+    assert result["ok"] is False
+    assert result["error_type"] == "InvariantViolationError"
+    conn = sqlite3.connect(store_path)
+    try:
+        assert conn.execute("SELECT COUNT(*) FROM samples").fetchone()[0] == 0
+        assert conn.execute("SELECT COUNT(*) FROM controller_segments").fetchone()[0] == 0
+        assert conn.execute("SELECT COUNT(*) FROM monitoring_periods").fetchone()[0] == 0
+        assert conn.execute("SELECT COUNT(*) FROM pending_publications").fetchone()[0] == 0
+    finally:
+        conn.close()
+
+
+def test_pending_capacity_retries_before_skipping_acquisition(tmp_path, sysfs_fixture_tree, monkeypatch):
+    now = datetime.now(timezone.utc).replace(second=0, microsecond=0)
+    store_path = tmp_path / "observations.db"
+    config = {"device": "/dev/nvme0", "store_path": str(store_path)}
+    sysfs_path = sysfs_fixture_tree / "sys" / "class" / "nvme" / "nvme0"
+    first = collector.run_collection(
+        config=config,
+        clock=FakeClock(now - timedelta(minutes=5)),
+        acquire=_acquirer(sysfs_path, 1000),
+    )
+    assert first["ok"] is True, first
+
+    monkeypatch.setattr(collector, "PENDING_PUBLICATION_LIMIT", 1)
+
+    def fail_derivation(*_):
+        raise RuntimeError("derivation still unavailable")
+
+    monkeypatch.setattr(collector, "derive_hours_from_interval", fail_derivation)
+    failed = collector.run_collection(
+        config=config,
+        clock=FakeClock(now),
+        acquire=_acquirer(sysfs_path, 1010),
+    )
+    assert failed["ok"] is False
+    assert "capacity full (1 observations)" in failed["error"]
+
+    called = False
+
+    def must_not_acquire():
+        nonlocal called
+        called = True
+        return _smartctl(1020), sysfs_path
+
+    retry = collector.run_collection(
+        config=config,
+        clock=FakeClock(now + timedelta(minutes=5)),
+        acquire=must_not_acquire,
+    )
+    assert retry["ok"] is False
+    assert "capacity full (1 observations)" in retry["error"]
+    assert called is False
+
+
+def test_v3_readers_ignore_pending_table_until_store_migrates(tmp_path):
+    store_path = tmp_path / "observations.db"
+    conn = init_store(store_path)
+    conn.execute("DROP TABLE pending_publications")
+    conn.execute("PRAGMA user_version=3")
+    conn.commit()
+    conn.close()
+
+    with read_status(store_path, datetime.now(timezone.utc), query_services=False) as (reader, comp):
+        assert reader is not None
+        assert comp.store_fault is None
+        assert comp.pending_publication_count == 0
+
+    migrated = init_store(store_path)
+    try:
+        assert migrated.execute("PRAGMA user_version").fetchone()[0] == 6
+        assert migrated.execute("SELECT COUNT(*) FROM pending_publications").fetchone()[0] == 0
+    finally:
+        migrated.close()

tests/test_issue_99.py

@@ -0,0 +1,520 @@
+"""Historical local-day migration and repair acceptance tests for issue #99."""
+import sqlite3
+import sys
+from datetime import datetime, timezone
+from pathlib import Path
+
+import pytest
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris.local_day import (
+    query_local_day_summary,
+    record_local_activity_interval,
+)
+from fenris.status import read_status
+from fenris.store import init_store
+
+SOURCE_SCHEMA_VERSION = 5
+LOCAL_DATE = "2026-09-02"
+TIMEZONE = "Asia/Kolkata"
+UTC_START = "2026-09-01T18:30:00+00:00"
+UTC_END = "2026-09-02T18:30:00+00:00"
+
+
+def _legacy_store(path: Path) -> sqlite3.Connection:
+    """Build a v5 store with one old coarse local-day summary."""
+    conn = init_store(path)
+    conn.execute(
+        "INSERT INTO local_days "
+        "(local_date, tz_name, tz_offset, utc_start, utc_end, bytes_written, "
+        " bytes_read, coverage, sample_count, complete, activity_incomplete, "
+        " activity_precision) "
+        "VALUES (?, ?, '+05:30', ?, ?, 999999, 888888, 1.0, 24, 1, 0, 'legacy')",
+        (LOCAL_DATE, TIMEZONE, UTC_START, UTC_END),
+    )
+    conn.execute(
+        "INSERT INTO monitoring_periods (started_at, ended_at) VALUES (?, ?)",
+        (UTC_START, "2026-09-03T00:00:00+00:00"),
+    )
+    conn.execute(
+        "INSERT INTO controller_segments "
+        "(opened_at, identity_key, identity_degraded) VALUES (?, ?, 0)",
+        (UTC_START, "controller-a"),
+    )
+    conn.execute(
+        "INSERT INTO hour_observations "
+        "(hour, bytes_written_delta, bytes_read_delta, sample_count, coverage) "
+        "VALUES ('2026-09-02T00:00:00+00:00', 123, 45, 2, 1.0)"
+    )
+    conn.execute(
+        "INSERT INTO day_aggregates "
+        "(day, bytes_written_delta, bytes_read_delta, coverage) "
+        "VALUES ('2026-09-02', 678, 90, 1.0)"
+    )
+    conn.execute(
+        "INSERT INTO samples (ts, device, bytes_written, bytes_read, power_on_hours, "
+        " segment_id, local_tz) VALUES (?, '/dev/nvme0', 1000, 2000, 100, 1, ?)",
+        ("2026-09-01T19:00:00+00:00", TIMEZONE),
+    )
+    conn.execute(
+        "INSERT INTO samples (ts, device, bytes_written, bytes_read, power_on_hours, "
+        " segment_id, local_tz) VALUES (?, '/dev/nvme0', 11000, 5000, 115, 1, ?)",
+        ("2026-09-02T10:00:00+00:00", TIMEZONE),
+    )
+    conn.execute(f"PRAGMA user_version={SOURCE_SCHEMA_VERSION}")
+    conn.commit()
+    return conn
+
+
+def test_upgrade_rebuilds_legacy_day_from_samples_and_keeps_recorded_bounds(
+    tmp_path, monkeypatch,
+):
+    db = tmp_path / "legacy.db"
+    conn = _legacy_store(db)
+    conn.close()
+    monkeypatch.setenv("TZ", "UTC")
+
+    conn = init_store(db)
+    conn.close()
+
+    with read_status(
+        db, datetime(2026, 9, 4, tzinfo=timezone.utc), query_services=False,
+    ) as (reader, composition):
+        assert reader is not None
+        assert composition.store_fault is None
+        summary = query_local_day_summary(
+            reader, LOCAL_DATE, TIMEZONE,
+            datetime(2026, 9, 4, tzinfo=timezone.utc),
+        )
+        assert summary is not None
+        assert summary["local_date"] == LOCAL_DATE
+        assert summary["tz_name"] == TIMEZONE
+        assert summary["tz_offset"] == "+05:30"
+        assert summary["utc_start"] == UTC_START
+        assert summary["utc_end"] == UTC_END
+        assert summary["bytes_written"] == 10_000
+        assert summary["bytes_read"] == 3_000
+        assert summary["activity_precision"] == "measured"
+        assert summary["segments"] == [{
+            "segment_id": 1,
+            "bytes_written": 10_000,
+            "bytes_read": 3_000,
+            "activity_seconds": 54_000,
+            "activity_intervals": 1,
+        }]
+        assert summary["activity_state"] == "incomplete"
+        assert reader.execute(
+            "SELECT bytes_written_delta FROM hour_observations"
+        ).fetchone()[0] == 123
+        assert reader.execute(
+            "SELECT bytes_written_delta FROM day_aggregates"
+        ).fetchone()[0] == 678
+
+    conn = init_store(db)
+    conn.close()
+    with read_status(
+        db, datetime(2026, 9, 4, tzinfo=timezone.utc), query_services=False,
+    ) as (reader, _composition):
+        assert reader is not None
+        summary = query_local_day_summary(
+            reader, LOCAL_DATE, TIMEZONE,
+            datetime(2026, 9, 4, tzinfo=timezone.utc),
+        )
+        assert summary["bytes_written"] == 10_000
+        assert summary["bytes_read"] == 3_000
+
+
+def test_repair_rebuilds_legacy_local_day_once_across_restarts(tmp_path):
+    from fenris.repair import repair_derivation
+
+    db = tmp_path / "repair.db"
+    conn = _legacy_store(db)
+
+    first = repair_derivation(conn)
+    assert first.ok
+    summary = query_local_day_summary(
+        conn, LOCAL_DATE, TIMEZONE,
+        datetime(2026, 9, 4, tzinfo=timezone.utc),
+    )
+    assert summary["bytes_written"] == 10_000
+    assert summary["bytes_read"] == 3_000
+
+    conn.close()
+    conn = sqlite3.connect(db)
+    second = repair_derivation(conn)
+    assert second.ok
+    summary = query_local_day_summary(
+        conn, LOCAL_DATE, TIMEZONE,
+        datetime(2026, 9, 4, tzinfo=timezone.utc),
+    )
+    assert summary["bytes_written"] == 10_000
+    assert summary["bytes_read"] == 3_000
+    assert conn.execute(
+        "SELECT bytes_written, bytes_read, activity_intervals "
+        "FROM local_day_segment_totals"
+    ).fetchall() == [(10_000, 3_000, 1)]
+    conn.close()
+
+
+def test_interrupted_repair_keeps_local_day_rebuild_retryable(tmp_path):
+    from fenris.repair import repair_derivation
+
+    db = tmp_path / "repair-interrupted.db"
+    conn = _legacy_store(db)
+    conn.execute(
+        "CREATE TRIGGER interrupt_repair_local_rebuild "
+        "BEFORE INSERT ON local_day_segment_totals "
+        "BEGIN SELECT RAISE(ABORT, 'simulated repair interruption'); END"
+    )
+    conn.commit()
+
+    failed = repair_derivation(conn)
+    assert not failed.ok
+    assert query_local_day_summary(
+        conn, LOCAL_DATE, TIMEZONE,
+        datetime(2026, 9, 4, tzinfo=timezone.utc),
+    )["bytes_written"] is None
+    assert conn.execute(
+        "SELECT activity_precision, bytes_written FROM local_days"
+    ).fetchone() == ("legacy", 999_999)
+    conn.execute("DROP TRIGGER interrupt_repair_local_rebuild")
+    conn.commit()
+    conn.close()
+
+    conn = sqlite3.connect(db)
+    retried = repair_derivation(conn)
+    assert retried.ok
+    summary = query_local_day_summary(
+        conn, LOCAL_DATE, TIMEZONE,
+        datetime(2026, 9, 4, tzinfo=timezone.utc),
+    )
+    assert summary["bytes_written"] == 10_000
+    assert summary["bytes_read"] == 3_000
+    conn.close()
+
+
+def test_stale_repair_marker_does_not_block_crash_retry(tmp_path):
+    from fenris.repair import repair_derivation
+
+    conn = _legacy_store(tmp_path / "stale-repair.db")
+    conn.execute(
+        "INSERT OR REPLACE INTO store_metadata (key, value) "
+        "VALUES ('repair_in_progress', 'true')"
+    )
+    conn.commit()
+
+    result = repair_derivation(conn)
+
+    assert result.ok
+    assert conn.execute(
+        "SELECT value FROM store_metadata WHERE key = 'repair_in_progress'"
+    ).fetchone() == ("false",)
+    assert query_local_day_summary(
+        conn, LOCAL_DATE, TIMEZONE,
+        datetime(2026, 9, 4, tzinfo=timezone.utc),
+    )["bytes_written"] == 10_000
+    conn.close()
+
+
+def test_upgrade_uses_whole_utc_hours_but_skips_midnight_straddling_hours(
+    tmp_path,
+):
+    db = tmp_path / "coarse.db"
+    conn = _legacy_store(db)
+    conn.execute("DELETE FROM samples")
+    conn.execute(
+        "INSERT INTO hour_observations "
+        "(hour, bytes_written_delta, bytes_read_delta, sample_count, "
+        " active_seconds, coverage) "
+        "VALUES ('2026-09-01T18:00:00+00:00', 99999, 9999, 2, 3600, 1.0)"
+    )
+    conn.execute(
+        "INSERT INTO hour_observations "
+        "(hour, bytes_written_delta, bytes_read_delta, sample_count, "
+        " active_seconds, coverage) "
+        "VALUES ('2026-09-02T18:00:00+00:00', 88888, 8888, 2, 3600, 1.0)"
+    )
+    conn.commit()
+    conn.close()
+
+    conn = init_store(db)
+    summary = query_local_day_summary(
+        conn, LOCAL_DATE, TIMEZONE,
+        datetime(2026, 9, 4, tzinfo=timezone.utc),
+    )
+    assert summary["bytes_written"] == 123
+    assert summary["bytes_read"] == 45
+    assert summary["activity_precision"] == "coarse"
+    assert summary["activity_state"] == "incomplete"
+    assert summary["utc_start"] == UTC_START
+    assert summary["utc_end"] == UTC_END
+
+    conn.execute(
+        "INSERT INTO samples "
+        "(id, ts, device, bytes_written, bytes_read, segment_id, local_tz) "
+        "VALUES (10, '2026-09-02T12:00:00+00:00', '/dev/nvme0', 1000, 2000, 1, ?), "
+        "       (11, '2026-09-02T12:05:00+00:00', '/dev/nvme0', 2000, 2500, 1, ?)",
+        (TIMEZONE, TIMEZONE),
+    )
+    conn.commit()
+    assert record_local_activity_interval(
+        conn,
+        {
+            "id": 10, "ts": "2026-09-02T12:00:00+00:00",
+            "bytes_written": 1_000, "bytes_read": 2_000,
+            "local_tz": TIMEZONE,
+        },
+        {
+            "id": 11, "ts": "2026-09-02T12:05:00+00:00",
+            "bytes_written": 2_000, "bytes_read": 2_500,
+            "local_tz": TIMEZONE,
+        },
+        start_sample_id=10, end_sample_id=11, segment_id=1,
+    ) == "known"
+    summary = query_local_day_summary(
+        conn, LOCAL_DATE, TIMEZONE,
+        datetime(2026, 9, 4, tzinfo=timezone.utc),
+    )
+    assert summary["bytes_written"] == 1_000
+    assert summary["bytes_read"] == 500
+    assert summary["activity_precision"] == "measured"
+    assert summary["segments"] == [{
+        "segment_id": 1,
+        "bytes_written": 1_000,
+        "bytes_read": 500,
+        "activity_seconds": 300,
+        "activity_intervals": 1,
+    }]
+    conn.close()
+
+
+def test_upgrade_does_not_double_count_coarse_hours_in_overlapping_days(tmp_path):
+    db = tmp_path / "overlapping-coarse-days.db"
+    conn = _legacy_store(db)
+    conn.execute("DELETE FROM samples")
+    conn.execute(
+        "INSERT INTO local_days "
+        "(local_date, tz_name, tz_offset, utc_start, utc_end, bytes_written, "
+        " bytes_read, coverage, sample_count, complete, activity_precision) "
+        "VALUES ('2026-09-02', 'UTC', '+00:00', "
+        "'2026-09-02T00:00:00+00:00', '2026-09-03T00:00:00+00:00', "
+        "999999, 888888, 1.0, 24, 1, 'legacy')"
+    )
+    conn.commit()
+    conn.close()
+
+    conn = init_store(db)
+
+    for tz_name in (TIMEZONE, "UTC"):
+        summary = query_local_day_summary(
+            conn, LOCAL_DATE, tz_name,
+            datetime(2026, 9, 4, tzinfo=timezone.utc),
+        )
+        assert summary["bytes_written"] is None
+        assert summary["bytes_read"] is None
+        assert summary["activity_precision"] == "unavailable"
+        assert summary["activity_state"] == "unavailable"
+    assert conn.execute(
+        "SELECT bytes_written_delta, bytes_read_delta FROM hour_observations "
+        "WHERE hour = '2026-09-02T00:00:00+00:00'"
+    ).fetchone() == (123, 45)
+    conn.close()
+
+
+def test_upgrade_retains_local_midnight_interval_once_as_shared_evidence(tmp_path):
+    db = tmp_path / "shared.db"
+    conn = _legacy_store(db)
+    conn.execute(
+        "INSERT INTO local_days "
+        "(local_date, tz_name, tz_offset, utc_start, utc_end, bytes_written, "
+        " bytes_read, coverage, sample_count, complete, activity_precision) "
+        "VALUES ('2026-09-01', ?, '+05:30', "
+        "'2026-08-31T18:30:00+00:00', '2026-09-01T18:30:00+00:00', "
+        "500, 600, 1.0, 24, 1, 'legacy')",
+        (TIMEZONE,),
+    )
+    conn.execute(
+        "UPDATE monitoring_periods SET started_at = '2026-08-31T18:00:00+00:00'"
+    )
+    conn.execute(
+        "UPDATE controller_segments SET opened_at = '2026-08-31T18:00:00+00:00'"
+    )
+    conn.execute(
+        "UPDATE samples SET ts = '2026-09-01T18:25:00+00:00', "
+        "bytes_written = 1000, bytes_read = 2000 WHERE id = 1"
+    )
+    conn.execute(
+        "UPDATE samples SET ts = '2026-09-01T18:35:00+00:00', "
+        "bytes_written = 1100, bytes_read = 2050 WHERE id = 2"
+    )
+    conn.commit()
+    conn.close()
+
+    conn = init_store(db)
+    shared = conn.execute(
+        "SELECT COUNT(*), SUM(bytes_written), SUM(bytes_read) "
+        "FROM local_day_unallocated_evidence"
+    ).fetchone()
+    assert shared == (1, 100, 50)
+    for local_date in ("2026-09-01", "2026-09-02"):
+        summary = query_local_day_summary(
+            conn, local_date, TIMEZONE,
+            datetime(2026, 9, 4, tzinfo=timezone.utc),
+        )
+        assert summary["bytes_written"] is None
+        assert summary["shared_bytes_written"] == 100
+        assert summary["shared_bytes_read"] == 50
+        assert summary["activity_state"] == "incomplete"
+    from fenris.repair import repair_derivation
+    assert repair_derivation(conn).ok
+    assert conn.execute(
+        "SELECT COUNT(*), SUM(bytes_written), SUM(bytes_read) "
+        "FROM local_day_unallocated_evidence"
+    ).fetchone() == (1, 100, 50)
+    conn.close()
+
+
+def test_interrupted_upgrade_keeps_legacy_day_retryable(tmp_path):
+    db = tmp_path / "interrupted.db"
+    conn = _legacy_store(db)
+    conn.execute(
+        "CREATE TRIGGER interrupt_local_rebuild "
+        "BEFORE INSERT ON local_day_segment_totals "
+        "BEGIN SELECT RAISE(ABORT, 'simulated interruption'); END"
+    )
+    conn.commit()
+    conn.close()
+
+    with pytest.raises(sqlite3.IntegrityError, match="simulated interruption"):
+        init_store(db)
+
+    conn = sqlite3.connect(db)
+    assert conn.execute("PRAGMA user_version").fetchone() == (SOURCE_SCHEMA_VERSION,)
+    assert conn.execute(
+        "SELECT activity_precision, bytes_written FROM local_days"
+    ).fetchone() == ("legacy", 999_999)
+    conn.execute("DROP TRIGGER interrupt_local_rebuild")
+    conn.commit()
+    conn.close()
+
+    conn = init_store(db)
+    summary = query_local_day_summary(
+        conn, LOCAL_DATE, TIMEZONE,
+        datetime(2026, 9, 4, tzinfo=timezone.utc),
+    )
+    assert summary["bytes_written"] == 10_000
+    assert summary["bytes_read"] == 3_000
+    conn.close()
+
+
+def test_prior_migration_step_commits_before_local_day_repair(tmp_path):
+    db = tmp_path / "migration-steps.db"
+    conn = _legacy_store(db)
+    conn.execute("PRAGMA user_version=4")
+    conn.execute(
+        "CREATE TRIGGER interrupt_local_rebuild BEFORE UPDATE OF bytes_written "
+        "ON local_days BEGIN SELECT RAISE(ABORT, 'simulated interruption'); END"
+    )
+    conn.commit()
+    conn.close()
+
+    with pytest.raises(sqlite3.IntegrityError, match="simulated interruption"):
+        init_store(db)
+
+    conn = sqlite3.connect(db)
+    assert conn.execute("PRAGMA user_version").fetchone() == (5,)
+    assert conn.execute(
+        "SELECT 1 FROM sqlite_master WHERE type='table' "
+        "AND name='local_day_segment_totals'"
+    ).fetchone() is not None
+    assert conn.execute(
+        "SELECT bytes_written FROM local_days WHERE local_date=?",
+        (LOCAL_DATE,),
+    ).fetchone() == (999_999,)
+    conn.close()
+
+
+def test_upgrade_does_not_allocate_unzoned_interval_to_overlapping_timezones(
+    tmp_path,
+):
+    db = tmp_path / "overlapping-timezones.db"
+    conn = _legacy_store(db)
+    conn.execute(
+        "INSERT INTO local_days "
+        "(local_date, tz_name, tz_offset, utc_start, utc_end, bytes_written, "
+        " bytes_read, coverage, sample_count, complete, activity_precision) "
+        "VALUES ('2026-09-02', 'UTC', '+00:00', "
+        "'2026-09-02T00:00:00+00:00', '2026-09-03T00:00:00+00:00', "
+        "999999, 888888, 1.0, 24, 1, 'legacy')"
+    )
+    conn.execute(
+        "UPDATE samples SET ts = '2026-09-02T01:00:00+00:00', local_tz = NULL "
+        "WHERE id = 1"
+    )
+    conn.execute(
+        "UPDATE samples SET ts = '2026-09-02T10:00:00+00:00', local_tz = NULL "
+        "WHERE id = 2"
+    )
+    conn.commit()
+    conn.close()
+
+    conn = init_store(db)
+    for tz_name in (TIMEZONE, "UTC"):
+        summary = query_local_day_summary(
+            conn, LOCAL_DATE, tz_name,
+            datetime(2026, 9, 4, tzinfo=timezone.utc),
+        )
+        assert summary["bytes_written"] is None
+        assert summary["bytes_read"] is None
+        assert summary["activity_precision"] == "unavailable"
+        assert summary["activity_state"] == "unavailable"
+    conn.close()
+
+
+def test_upgrade_rejects_interval_before_recorded_controller_segment(
+    tmp_path,
+):
+    db = tmp_path / "segment-boundary.db"
+    conn = _legacy_store(db)
+    conn.execute(
+        "UPDATE controller_segments "
+        "SET opened_at = '2026-09-01T20:00:00+00:00' WHERE id = 1"
+    )
+    conn.commit()
+    conn.close()
+
+    conn = init_store(db)
+    summary = query_local_day_summary(
+        conn, LOCAL_DATE, TIMEZONE,
+        datetime(2026, 9, 4, tzinfo=timezone.utc),
+    )
+    assert summary["bytes_written"] is None
+    assert summary["bytes_read"] is None
+    assert summary["activity_precision"] == "unavailable"
+    conn.close()
+
+
+def test_sample_at_local_midnight_does_not_hide_coarse_reconstruction(tmp_path):
+    db = tmp_path / "midnight-sample.db"
+    conn = _legacy_store(db)
+    conn.execute(
+        "UPDATE samples SET ts = '2026-09-01T17:00:00+00:00' WHERE id = 1"
+    )
+    conn.execute(
+        "UPDATE samples SET ts = ?, local_tz = ? WHERE id = 2",
+        (UTC_END, TIMEZONE),
+    )
+    conn.commit()
+    conn.close()
+
+    conn = init_store(db)
+    summary = query_local_day_summary(
+        conn, LOCAL_DATE, TIMEZONE,
+        datetime(2026, 9, 4, tzinfo=timezone.utc),
+    )
+    assert summary["bytes_written"] == 123
+    assert summary["bytes_read"] == 45
+    assert summary["activity_precision"] == "coarse"
+    assert summary["activity_state"] == "incomplete"
+    conn.close()

tests/test_live_graph.py

@@ -6,26 +6,24 @@ Covers:
 - Three-minute cadence constants
 - TUI integration with live graph
 """
+import sys
 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.activity_selection import IntervalIdentity
 from fenris.monitoring_periods import ensure_period_open
+from fenris.status import ACCURACY_SEC, CADENCE_DEFAULT_S, FRESH_THRESHOLD_S
+from fenris.store import init_store
 from fenris.tui import (
+    LIVE_WINDOW_H,
     FenrisTuiApp,
     LiveActivityGraph,
     _query_live_graph_data,
-    LIVE_WINDOW_H,
-    _query_daily_graph_data,
-    _RANGE_OPTIONS,
 )
-from fenris.status import CADENCE_DEFAULT_S, FRESH_THRESHOLD_S, ACCURACY_SEC
-
 
 # ---------------------------------------------------------------------------
 # Helpers
@@ -63,6 +61,27 @@ def _open_period(conn, start="2026-09-01T00:00:00+00:00"):
     ensure_period_open(conn, datetime.fromisoformat(start))
 
 
+def _live_intervals(count=4):
+    first = datetime(2026, 9, 28, 12, 0, tzinfo=timezone.utc)
+    intervals = []
+    for index in range(count):
+        start = first + timedelta(minutes=3 * index)
+        end = start + timedelta(minutes=3)
+        intervals.append({
+            "start_ts": start.isoformat(),
+            "end_ts": end.isoformat(),
+            "start_label": start.strftime("%H:%M"),
+            "end_label": end.strftime("%H:%M"),
+            "bytes_written": (index + 1) * 1000,
+            "bytes_read": (index + 1) * 500,
+            "elapsed_s": 180,
+            "is_gap": False,
+            "is_zero": False,
+            "is_segment_boundary": False,
+        })
+    return intervals
+
+
 # ---------------------------------------------------------------------------
 # Cadence constants (issue #91 AC1)
 # ---------------------------------------------------------------------------
@@ -322,3 +341,85 @@ class TestTUILiveIntegration:
             await pilot.pause()
             main_grid = app.query_one("#main-grid")
             assert main_grid.has_class("constrained")
+
+    @pytest.mark.asyncio
+    @pytest.mark.parametrize("size", [(100, 40), (70, 20)])
+    async def test_follow_pin_expiry_and_today_use_visible_readout(self, tmp_path, size):
+        """Live selection follows, pins, expires, and resets at both layout sizes."""
+        app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
+        intervals = _live_intervals()
+        async with app.run_test(size=size) as pilot:
+            await pilot.pause()
+            graph = app.query_one("#live-activity")
+            graph.set_data(intervals[:3])
+
+            readout = str(app.query_one("#live-readout").render())
+            assert "12:09 UTC" in readout
+            assert graph.selection.following_live
+            assert graph.selection.selected_live_interval == IntervalIdentity(
+                intervals[2]["start_ts"], intervals[2]["end_ts"]
+            )
+
+            # Refresh while following selects the newly measured newest point.
+            graph.set_data(intervals)
+            assert "12:12 UTC" in str(app.query_one("#live-readout").render())
+
+            # Live graph receives focus at launch; first arrow pins immediately.
+            await pilot.press("left")
+            pinned = graph.selection.selected_live_interval
+            readout = str(app.query_one("#live-readout").render())
+            assert "12:09 UTC" in readout
+            assert not graph.selection.following_live
+
+            graph.set_data(intervals)
+            readout = str(app.query_one("#live-readout").render())
+            assert "12:09 UTC" in readout
+            assert graph.selection.selected_live_interval == pinned
+
+            # Read/write changes presentation only; pinned point stays stable.
+            await pilot.press("w")
+            graph.set_data(intervals)
+            assert graph.measure == "read"
+            assert graph.selection.selected_live_interval == pinned
+            assert "12:09 UTC" in str(app.query_one("#live-readout").render())
+
+            # Remove pinned interval from rolling window. Explain expiration.
+            graph.set_data(intervals[3:])
+            readout = str(app.query_one("#live-readout").render())
+            assert "Inspected interval expired; following live" in readout
+            assert "12:12 UTC" in readout
+            assert graph.selection.following_live
+
+            # Today action clears expiration and resumes newest-point following.
+            await pilot.press("t")
+            assert graph.selection.following_live
+            assert not graph.selection.live_interval_expired
+            graph.set_data(intervals)
+            readout = str(app.query_one("#live-readout").render())
+            assert "12:12 UTC" in readout
+            assert "Inspected interval expired" not in readout
+            assert graph.selection.following_live
+
+    @pytest.mark.asyncio
+    async def test_mouse_inspection_pins_same_interval_identity(self, tmp_path):
+        """Mouse inspection pins the interval at its visible graph location."""
+        app = FenrisTuiApp(store_path=tmp_path / "test.db", refresh_interval_s=999)
+        intervals = _live_intervals()
+        async with app.run_test(size=(100, 40)) as pilot:
+            await pilot.pause()
+            graph = app.query_one("#live-activity")
+            graph.set_data(intervals[:3])
+            await pilot.pause()
+            render = app.query_one("#live-render")
+            await pilot.click(
+                "#live-render",
+                offset=(8, max(0, render.content_size.height // 2)),
+            )
+            await pilot.pause()
+
+            expected = IntervalIdentity(
+                intervals[0]["start_ts"], intervals[0]["end_ts"]
+            )
+            assert graph.selection.selected_live_interval == expected
+            assert not graph.selection.following_live
+            assert "12:03 UTC" in str(app.query_one("#live-readout").render())

tests/test_local_day.py

@@ -25,6 +25,7 @@ from fenris.store import init_store, SCHEMA_VERSION
 from fenris.local_day import (
     derive_local_day_summary,
     persist_local_day,
+    record_local_activity_interval,
     query_local_day_summary,
     query_current_local_day,
     LocalDaySummary,
@@ -135,13 +136,56 @@ class TestSchemaMigration:
         assert count == 0
         conn.close()
 
+    def test_v4_totals_keep_values_but_are_not_treated_as_local_precision(
+        self, tmp_path,
+    ):
+        db = tmp_path / "v4.db"
+        conn = sqlite3.connect(db)
+        conn.execute(
+            "CREATE TABLE samples (id INTEGER PRIMARY KEY, ts TEXT, device TEXT)"
+        )
+        conn.execute(
+            "CREATE TABLE pending_publications "
+            "(id INTEGER PRIMARY KEY, sample_ts TEXT, payload TEXT)"
+        )
+        conn.execute(
+            "CREATE TABLE local_days ("
+            "id INTEGER PRIMARY KEY, local_date TEXT NOT NULL, tz_name TEXT NOT NULL, "
+            "tz_offset TEXT NOT NULL, utc_start TEXT NOT NULL, utc_end TEXT NOT NULL, "
+            "bytes_written INTEGER DEFAULT 0, bytes_read INTEGER DEFAULT 0, "
+            "coverage REAL DEFAULT 0, sample_count INTEGER DEFAULT 0, "
+            "complete BOOLEAN DEFAULT 0, UNIQUE(local_date, tz_name))"
+        )
+        conn.execute(
+            "INSERT INTO local_days VALUES "
+            "(1, '2026-09-01', 'UTC', '+00:00', "
+            "'2026-09-01T00:00:00+00:00', '2026-09-02T00:00:00+00:00', "
+            "5120000, 2048000, 0.5, 10, 0)"
+        )
+        conn.execute("PRAGMA user_version=4")
+        conn.commit()
+        conn.close()
+
+        conn = init_store(db)
+        stored = conn.execute(
+            "SELECT bytes_written, activity_precision FROM local_days"
+        ).fetchone()
+        assert stored == (5_120_000, "unavailable")
+        visible = query_local_day_summary(conn, "2026-09-01", "UTC")
+        assert visible["bytes_written"] is None
+        assert visible["activity_state"] == "unavailable"
+        assert "local_tz" in {
+            row[1] for row in conn.execute("PRAGMA table_info(samples)")
+        }
+        conn.close()
+
 
 # ---------------------------------------------------------------------------
-# Local-day derivation from UTC hours
+# Local-day coverage derivation from UTC hours
 # ---------------------------------------------------------------------------
 
 class TestDeriveLocalDay:
-    """Derive local-day summaries from UTC hour observations."""
+    """Derive coverage from UTC hours without allocating local-day bytes."""
 
     def test_utc_plus_zero(self, tmp_path):
         """UTC timezone: local day boundaries = UTC day boundaries."""
@@ -158,8 +202,9 @@ class TestDeriveLocalDay:
         assert summary.local_date == "2026-09-01"
         assert summary.tz_name == "UTC"
         assert summary.tz_offset == "+00:00"
-        assert summary.bytes_written == 300
+        assert summary.bytes_written == 0
-        assert summary.bytes_read == 130
+        assert summary.bytes_read == 0
+        assert summary.activity_precision == "unavailable"
         assert summary.complete is False  # not all 24 hours covered
         conn.close()
 
@@ -179,12 +224,13 @@ class TestDeriveLocalDay:
         assert summary.local_date == "2026-09-01"
         assert summary.tz_name == "Asia/Kolkata"
         assert summary.tz_offset == "+05:30"
-        assert summary.bytes_written == 300
+        assert summary.bytes_written == 0
-        assert summary.bytes_read == 130
+        assert summary.bytes_read == 0
+        assert summary.activity_precision == "unavailable"
         conn.close()
 
-    def test_midnight_spanning_hour_included(self, tmp_path):
+    def test_hourly_bytes_cannot_be_allocated_to_local_midnight(self, tmp_path):
-        """UTC hour straddling local midnight is included in the local day."""
+        """UTC-hour totals do not establish exact local-day byte totals."""
         conn = init_store(tmp_path / "obs.db")
 
         # For UTC+5:30, local day 2026-09-01 starts at 2026-08-31T18:30 UTC
@@ -196,9 +242,9 @@ class TestDeriveLocalDay:
         summary = derive_local_day_summary(conn, "Asia/Kolkata", clock)
 
         assert summary is not None
-        # The midnight-spanning hour (18:00) is included
+        assert summary.bytes_written == 0
-        assert summary.bytes_written == 300
+        assert summary.bytes_read == 0
-        assert summary.bytes_read == 130
+        assert summary.activity_precision == "unavailable"
         conn.close()
 
     def test_no_hours_returns_none(self, tmp_path):
@@ -387,6 +433,411 @@ class TestCollectorIntegration:
         assert row[1] == 30 * 512000  # reads
         conn.close()
 
+    def test_interval_crossing_utc_hour_stays_wholly_in_local_day(
+        self, tmp_path, sysfs_tree, monkeypatch,
+    ):
+        """A measured interval inside one local date keeps its full delta."""
+        from fenris.collector import run_collection
+
+        monkeypatch.setenv("TZ", "Asia/Kolkata")
+        store = str(tmp_path / "obs.db")
+        cfg = {"device": "/dev/nvme0", "store_path": store}
+        sysfs_nvme = sysfs_tree / "sys" / "class" / "nvme" / "nvme0"
+        first_at = datetime(2026, 9, 1, 12, 59, tzinfo=timezone.utc)
+        second_at = datetime(2026, 9, 1, 13, 1, tzinfo=timezone.utc)
+
+        first = run_collection(
+            _make_smartctl(10_000_000, 8_000_000),
+            sysfs_nvme,
+            cfg,
+            _Clock(first_at),
+        )
+        second = run_collection(
+            _make_smartctl(10_000_010, 8_000_004),
+            sysfs_nvme,
+            cfg,
+            _Clock(second_at),
+        )
+
+        assert first["ok"] and second["ok"]
+        conn = sqlite3.connect(store)
+        summary = query_local_day_summary(conn, "2026-09-01")
+
+        assert summary is not None
+        assert summary["bytes_written"] == 5_120_000
+        assert summary["bytes_read"] == 2_048_000
+        assert summary["segments"] == [{
+            "segment_id": 1,
+            "bytes_written": 5_120_000,
+            "bytes_read": 2_048_000,
+            "activity_seconds": 120,
+            "activity_intervals": 1,
+        }]
+        segment_totals = conn.execute(
+            "SELECT segment_id, bytes_written, bytes_read, activity_intervals "
+            "FROM local_day_segment_totals"
+        ).fetchone()
+        assert segment_totals == (1, 5_120_000, 2_048_000, 1)
+
+        samples = conn.execute(
+            "SELECT id, ts, bytes_written, bytes_read, local_tz "
+            "FROM samples ORDER BY id"
+        ).fetchall()
+        first_sample, second_sample = samples
+        assert record_local_activity_interval(
+            conn,
+            dict(zip(("id", "ts", "bytes_written", "bytes_read", "local_tz"), first_sample)),
+            dict(zip(("id", "ts", "bytes_written", "bytes_read", "local_tz"), second_sample)),
+            start_sample_id=first_sample[0],
+            end_sample_id=second_sample[0],
+            segment_id=1,
+        ) == "known"
+        repeated = query_local_day_summary(conn, "2026-09-01", "Asia/Kolkata")
+        assert repeated["bytes_written"] == 5_120_000
+        assert repeated["bytes_read"] == 2_048_000
+        assert conn.execute(
+            "SELECT SUM(bytes_written), SUM(bytes_read), SUM(activity_intervals) "
+            "FROM local_day_segment_totals"
+        ).fetchone() == (5_120_000, 2_048_000, 1)
+        conn.close()
+
+    @pytest.mark.parametrize(
+        (
+            "first_at", "second_at", "local_date", "expected_hours",
+            "expected_start", "expected_end", "expected_offset",
+        ),
+        [
+            (
+                datetime(2026, 3, 8, 6, 30, tzinfo=timezone.utc),
+                datetime(2026, 3, 8, 7, 30, tzinfo=timezone.utc),
+                "2026-03-08", 23,
+                "2026-03-08T05:00:00+00:00",
+                "2026-03-09T04:00:00+00:00", "-05:00",
+            ),
+            (
+                datetime(2026, 11, 1, 5, 30, tzinfo=timezone.utc),
+                datetime(2026, 11, 1, 6, 30, tzinfo=timezone.utc),
+                "2026-11-01", 25,
+                "2026-11-01T04:00:00+00:00",
+                "2026-11-02T05:00:00+00:00", "-04:00",
+            ),
+        ],
+        ids=("spring-forward", "fall-back-repeated-hour"),
+    )
+    def test_collector_retains_exact_interval_on_dst_local_day(
+        self,
+        tmp_path,
+        sysfs_tree,
+        monkeypatch,
+        first_at,
+        second_at,
+        local_date,
+        expected_hours,
+        expected_start,
+        expected_end,
+        expected_offset,
+    ):
+        """Collection preserves exact activity on short and long local days."""
+        from fenris.collector import run_collection
+
+        zone = "America/New_York"
+        monkeypatch.setenv("TZ", zone)
+        store = str(tmp_path / "obs.db")
+        cfg = {"device": "/dev/nvme0", "store_path": store}
+        sysfs_nvme = sysfs_tree / "sys" / "class" / "nvme" / "nvme0"
+        assert run_collection(
+            _make_smartctl(10_000_000, 8_000_000),
+            sysfs_nvme,
+            cfg,
+            _Clock(first_at),
+        )["ok"]
+        assert run_collection(
+            _make_smartctl(10_000_001, 8_000_002),
+            sysfs_nvme,
+            cfg,
+            _Clock(second_at),
+        )["ok"]
+
+        conn = sqlite3.connect(store)
+        summary = query_local_day_summary(
+            conn, local_date, zone, second_at + timedelta(minutes=1)
+        )
+        assert summary is not None
+        assert summary["bytes_written"] == 512_000
+        assert summary["bytes_read"] == 1_024_000
+        assert summary["activity_seconds"] == 3_600
+        assert summary["utc_start"] == expected_start
+        assert summary["utc_end"] == expected_end
+        assert summary["tz_offset"] == expected_offset
+        assert (
+            datetime.fromisoformat(summary["utc_end"])
+            - datetime.fromisoformat(summary["utc_start"])
+        ).total_seconds() == expected_hours * 3_600
+        conn.close()
+
+    @pytest.mark.asyncio
+    async def test_local_midnight_interval_is_shared_once(
+        self, tmp_path, sysfs_tree, monkeypatch,
+    ):
+        """A real counter interval crossing local midnight stays unallocated."""
+        from fenris.collector import run_collection
+
+        monkeypatch.setenv("TZ", "Asia/Kolkata")
+        store = str(tmp_path / "obs.db")
+        cfg = {"device": "/dev/nvme0", "store_path": store}
+        sysfs_nvme = sysfs_tree / "sys" / "class" / "nvme" / "nvme0"
+        first_at = datetime(2026, 9, 1, 18, 25, tzinfo=timezone.utc)
+        second_at = datetime(2026, 9, 1, 18, 35, tzinfo=timezone.utc)
+
+        first = run_collection(
+            _make_smartctl(10_000_000, 8_000_000),
+            sysfs_nvme,
+            cfg,
+            _Clock(first_at),
+        )
+        second = run_collection(
+            _make_smartctl(10_000_100, 8_000_060),
+            sysfs_nvme,
+            cfg,
+            _Clock(second_at),
+        )
+        assert first["ok"] and second["ok"]
+
+        conn = sqlite3.connect(store)
+        evidence = conn.execute(
+            "SELECT COUNT(*), SUM(bytes_written), SUM(bytes_read) "
+            "FROM local_day_unallocated_evidence"
+        ).fetchone()
+        assert evidence == (1, 51_200_000, 30_720_000)
+        assert conn.execute(
+            "SELECT SUM(bytes_written), SUM(bytes_read) FROM local_days"
+        ).fetchone() == (0, 0)
+
+        for local_date in ("2026-09-01", "2026-09-02"):
+            summary = query_local_day_summary(
+                conn, local_date, "Asia/Kolkata", second_at
+            )
+            assert summary is not None
+            assert summary["bytes_written"] is None
+            assert summary["shared_bytes_written"] == 51_200_000
+            assert summary["shared_bytes_read"] == 30_720_000
+            assert summary["activity_state"] in ("incomplete", "so_far")
+        conn.close()
+
+        from fenris.status import read_status
+        from fenris.tui import FenrisTuiApp
+
+        app = FenrisTuiApp(store_path=Path(store), refresh_interval_s=999)
+        async with app.run_test(size=(100, 32)):
+            app._browse_date = "2026-09-02"
+            with read_status(
+                Path(store), second_at, query_services=False
+            ) as (reader, _):
+                assert reader is not None
+                app._render_local_day(reader)
+            visible = str(app.query_one("#local-day").render())
+            assert "2026-09-02" in visible
+            assert "Asia/Kolkata +05:30" in visible
+            assert "W unavailable" in visible
+            assert "shared at midnight W 0.051 GB" in visible
+
+    def test_synthetic_shared_bytes_conserve_one_hundred_bytes(self, tmp_path):
+        """Shared evidence conserves byte values before display rounding."""
+        conn = init_store(tmp_path / "obs.db")
+        first_at = datetime(2026, 9, 1, 18, 25, tzinfo=timezone.utc)
+        second_at = datetime(2026, 9, 3, 18, 35, tzinfo=timezone.utc)
+        ensure_period_open(conn, first_at)
+        conn.execute(
+            "INSERT INTO samples (ts, device, bytes_written, bytes_read, local_tz) "
+            "VALUES (?, ?, ?, ?, ?)",
+            (first_at.isoformat(), "/dev/nvme0", 1_000, 2_000, "Asia/Kolkata"),
+        )
+        first_id = conn.execute("SELECT last_insert_rowid()").fetchone()[0]
+        conn.execute(
+            "INSERT INTO samples (ts, device, bytes_written, bytes_read, local_tz) "
+            "VALUES (?, ?, ?, ?, ?)",
+            (second_at.isoformat(), "/dev/nvme0", 1_100, 2_050, "Asia/Kolkata"),
+        )
+        second_id = conn.execute("SELECT last_insert_rowid()").fetchone()[0]
+
+        result = record_local_activity_interval(
+            conn,
+            {
+                "id": first_id,
+                "ts": first_at.isoformat(),
+                "bytes_written": 1_000,
+                "bytes_read": 2_000,
+                "local_tz": "Asia/Kolkata",
+            },
+            {
+                "id": second_id,
+                "ts": second_at.isoformat(),
+                "bytes_written": 1_100,
+                "bytes_read": 2_050,
+                "local_tz": "Asia/Kolkata",
+            },
+            start_sample_id=first_id,
+            end_sample_id=second_id,
+            segment_id=1,
+        )
+
+        assert result == "local_midnight"
+        stored = conn.execute(
+            "SELECT COUNT(*), SUM(bytes_written), SUM(bytes_read) "
+            "FROM local_day_unallocated_evidence"
+        ).fetchone()
+        assert stored == (1, 100, 50)
+        record_local_activity_interval(
+            conn,
+            {
+                "id": first_id,
+                "ts": first_at.isoformat(),
+                "bytes_written": 1_000,
+                "bytes_read": 2_000,
+                "local_tz": "Asia/Kolkata",
+            },
+            {
+                "id": second_id,
+                "ts": second_at.isoformat(),
+                "bytes_written": 1_100,
+                "bytes_read": 2_050,
+                "local_tz": "Asia/Kolkata",
+            },
+            start_sample_id=first_id,
+            end_sample_id=second_id,
+            segment_id=1,
+        )
+        assert conn.execute(
+            "SELECT COUNT(*), SUM(bytes_written), SUM(bytes_read) "
+            "FROM local_day_unallocated_evidence"
+        ).fetchone() == (1, 100, 50)
+        assert conn.execute(
+            "SELECT SUM(bytes_written), SUM(bytes_read) FROM local_days"
+        ).fetchone() == (0, 0)
+        middle_day = query_local_day_summary(
+            conn, "2026-09-03", "Asia/Kolkata", second_at + timedelta(days=1)
+        )
+        assert middle_day["shared_bytes_written"] == 100
+        assert middle_day["shared_bytes_read"] == 50
+        assert middle_day["shared_evidence_count"] == 1
+        conn.close()
+
+    def test_timezone_change_keeps_interval_unallocated(
+        self, tmp_path, sysfs_tree, monkeypatch,
+    ):
+        from fenris.collector import run_collection
+
+        store = str(tmp_path / "obs.db")
+        cfg = {"device": "/dev/nvme0", "store_path": store}
+        sysfs_nvme = sysfs_tree / "sys" / "class" / "nvme" / "nvme0"
+        first_at = datetime(2026, 9, 1, 22, 0, tzinfo=timezone.utc)
+        second_at = datetime(2026, 9, 1, 22, 5, tzinfo=timezone.utc)
+
+        monkeypatch.setenv("TZ", "UTC")
+        assert run_collection(
+            _make_smartctl(10_000_000, 8_000_000),
+            sysfs_nvme,
+            cfg,
+            _Clock(first_at),
+        )["ok"]
+        monkeypatch.setenv("TZ", "Asia/Kolkata")
+        assert run_collection(
+            _make_smartctl(10_000_010, 8_000_004),
+            sysfs_nvme,
+            cfg,
+            _Clock(second_at),
+        )["ok"]
+
+        conn = sqlite3.connect(store)
+        event = conn.execute(
+            "SELECT COUNT(*), SUM(bytes_written), MIN(reason) "
+            "FROM local_day_unallocated_evidence"
+        ).fetchone()
+        assert event == (1, 5_120_000, "timezone_change")
+        old_zone = query_local_day_summary(conn, "2026-09-01", "UTC")
+        new_zone = query_local_day_summary(conn, "2026-09-02", "Asia/Kolkata")
+        assert old_zone["bytes_written"] is None
+        assert new_zone["bytes_written"] is None
+        assert old_zone["unallocated_bytes_written"] == 5_120_000
+        assert new_zone["unallocated_bytes_written"] == 5_120_000
+        conn.close()
+
+    def test_pause_boundary_keeps_interval_unallocated(
+        self, tmp_path, sysfs_tree, monkeypatch,
+    ):
+        from fenris.collector import run_collection
+
+        monkeypatch.setenv("TZ", "UTC")
+        store = str(tmp_path / "obs.db")
+        cfg = {"device": "/dev/nvme0", "store_path": store}
+        sysfs_nvme = sysfs_tree / "sys" / "class" / "nvme" / "nvme0"
+        first_at = datetime(2026, 9, 1, 12, 0, tzinfo=timezone.utc)
+        second_at = datetime(2026, 9, 1, 12, 10, tzinfo=timezone.utc)
+        assert run_collection(
+            _make_smartctl(10_000_000, 8_000_000),
+            sysfs_nvme,
+            cfg,
+            _Clock(first_at),
+        )["ok"]
+
+        conn = sqlite3.connect(store)
+        close_period(conn, first_at + timedelta(minutes=5), "user_disabled")
+        conn.close()
+
+        assert run_collection(
+            _make_smartctl(10_000_010, 8_000_004),
+            sysfs_nvme,
+            cfg,
+            _Clock(second_at),
+        )["ok"]
+
+        conn = sqlite3.connect(store)
+        reason = conn.execute(
+            "SELECT reason FROM local_day_unallocated_evidence"
+        ).fetchone()
+        summary = query_local_day_summary(conn, "2026-09-01", "UTC")
+        assert reason == ("monitoring_period",)
+        assert summary["bytes_written"] is None
+        assert summary["unallocated_bytes_written"] == 5_120_000
+        assert summary["shared_bytes_written"] == 0
+        conn.close()
+
+    def test_controller_segment_boundary_marks_local_activity_incomplete(
+        self, tmp_path, sysfs_tree, monkeypatch,
+    ):
+        from fenris.collector import run_collection
+
+        monkeypatch.setenv("TZ", "UTC")
+        store = str(tmp_path / "obs.db")
+        cfg = {"device": "/dev/nvme0", "store_path": store}
+        sysfs_nvme = sysfs_tree / "sys" / "class" / "nvme" / "nvme0"
+        first_at = datetime(2026, 9, 1, 12, 0, tzinfo=timezone.utc)
+        second_at = datetime(2026, 9, 1, 12, 5, tzinfo=timezone.utc)
+        assert run_collection(
+            _make_smartctl(10_000_000, 8_000_000),
+            sysfs_nvme,
+            cfg,
+            _Clock(first_at),
+        )["ok"]
+        assert run_collection(
+            _make_smartctl(10, 8_000_004),
+            sysfs_nvme,
+            cfg,
+            _Clock(second_at),
+        )["ok"]
+
+        conn = sqlite3.connect(store)
+        summary = query_local_day_summary(
+            conn, "2026-09-01", "UTC", second_at
+        )
+        assert summary is not None
+        assert summary["bytes_written"] is None
+        assert summary["activity_state"] == "incomplete"
+        assert conn.execute(
+            "SELECT COUNT(*) FROM local_day_unallocated_evidence"
+        ).fetchone()[0] == 0
+        conn.close()
+
 
 # ---------------------------------------------------------------------------
 # DST handling (23/25-hour days)
@@ -402,17 +853,72 @@ class TestDSTHandling:
         # Simulate a 23-hour day in a timezone with DST
         # For simplicity, just verify the summary records the correct UTC range
         clock = datetime(2026, 3, 8, 12, 0, 0, tzinfo=timezone.utc)
-        # US/Eastern springs forward on 2026-03-08
+        # New York springs forward on 2026-03-08
         # Local day 2026-03-08 is 23 hours: UTC [07:00, 06:00+1d)
         _insert_hour(conn, "2026-03-08T08:00:00+00:00", bw=100, active=3600)
         _insert_hour(conn, "2026-03-08T12:00:00+00:00", bw=200, active=3600)
 
-        summary = derive_local_day_summary(conn, "US/Eastern", clock)
+        summary = derive_local_day_summary(conn, "America/New_York", clock)
         assert summary is not None
         assert summary.local_date == "2026-03-08"
         # UTC range should be approximately 23 hours
         utc_start = datetime.fromisoformat(summary.utc_start)
         utc_end = datetime.fromisoformat(summary.utc_end)
         duration = (utc_end - utc_start).total_seconds()
-        assert 22 * 3600 <= duration <= 24 * 3600  # ~23h ± tolerance
+        assert duration == 23 * 3600
+        conn.close()
+
+    def test_long_day_25_hours(self):
+        from fenris.local_day import local_day_boundaries
+
+        start, end, offset = local_day_boundaries(
+            "2026-11-01", "America/New_York"
+        )
+        assert (end - start).total_seconds() == 25 * 3600
+        assert offset == "-04:00"
+
+    def test_half_hour_offset_records_exact_local_boundaries(self):
+        from fenris.local_day import local_day_boundaries
+
+        start, end, offset = local_day_boundaries(
+            "2026-09-01", "Asia/Kolkata"
+        )
+        assert start.isoformat() == "2026-08-31T18:30:00+00:00"
+        assert end.isoformat() == "2026-09-01T18:30:00+00:00"
+        assert offset == "+05:30"
+
+    def test_repeated_local_clock_labels_remain_one_recorded_day(
+        self, tmp_path, sysfs_tree, monkeypatch,
+    ):
+        from fenris.collector import run_collection
+
+        monkeypatch.setenv("TZ", "America/New_York")
+        store = str(tmp_path / "obs.db")
+        cfg = {"device": "/dev/nvme0", "store_path": store}
+        sysfs_nvme = sysfs_tree / "sys" / "class" / "nvme" / "nvme0"
+        # Both endpoints display as 01:30 locally, on opposite UTC offsets.
+        first_at = datetime(2026, 11, 1, 5, 30, tzinfo=timezone.utc)
+        second_at = datetime(2026, 11, 1, 6, 30, tzinfo=timezone.utc)
+        assert run_collection(
+            _make_smartctl(10_000_000, 8_000_000),
+            sysfs_nvme,
+            cfg,
+            _Clock(first_at),
+        )["ok"]
+        assert run_collection(
+            _make_smartctl(10_000_001, 8_000_002),
+            sysfs_nvme,
+            cfg,
+            _Clock(second_at),
+        )["ok"]
+
+        conn = sqlite3.connect(store)
+        summary = query_local_day_summary(
+            conn, "2026-11-01", "America/New_York", second_at
+        )
+        assert summary is not None
+        assert summary["bytes_written"] == 512_000
+        assert summary["bytes_read"] == 1_024_000
+        assert summary["utc_start"] == "2026-11-01T04:00:00+00:00"
+        assert summary["utc_end"] == "2026-11-02T05:00:00+00:00"
         conn.close()

tests/test_projection.py

@@ -100,8 +100,8 @@ def _insert_local_day(conn, local_date, tz_name="UTC", tz_offset="+00:00",
     conn.execute(
         "INSERT INTO local_days "
         "(local_date, tz_name, tz_offset, utc_start, utc_end, "
-        " bytes_written, bytes_read, coverage, sample_count, complete) "
+        " bytes_written, bytes_read, coverage, sample_count, complete, activity_intervals) "
-        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 1)",
         (local_date, tz_name, tz_offset, utc_start, utc_end,
          bw, br, coverage, samples, complete),
     )

tests/test_pruning.py

@@ -27,9 +27,14 @@ def store_conn(tmp_path: Path):
 
 
 def _insert_sample(conn, ts_iso, device="/dev/nvme0"):
+    conn.execute(
+        "INSERT OR IGNORE INTO controller_segments "
+        "(id, opened_at, identity_key) VALUES (1, '2026-01-01T00:00:00+00:00', 'test')"
+    )
     conn.execute(
         "INSERT INTO samples (ts, device, data_units_written, data_units_read, "
-        " bytes_written, bytes_read, percentage_used) VALUES (?, ?, 0, 0, 0, 0, 0)",
+        " bytes_written, bytes_read, percentage_used, segment_id, local_tz) "
+        "VALUES (?, ?, 0, 0, 0, 0, 0, 1, 'UTC')",
         (ts_iso, device),
     )
     conn.commit()
@@ -50,33 +55,30 @@ class TestPruneOldSamples:
         cursor = store_conn.execute("SELECT COUNT(*) FROM samples")
         assert cursor.fetchone()[0] == 1
 
-    def test_removes_old_samples(self, store_conn):
+    def test_keeps_old_samples_without_replacement_evidence(self, store_conn):
         now = datetime(2026, 9, 15, 12, 0, 0, tzinfo=timezone.utc)
-        # Insert samples at 10, 14, and 15 days ago
+        # Old samples stay until UTC and local-day evidence replace them.
-        # 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)
 
         pruned = prune_old_samples(store_conn, now, retention_days=14)
-        assert pruned == 1  # Only the 15-day-old sample removed
+        assert pruned == 0
 
         cursor = store_conn.execute("SELECT COUNT(*) FROM samples")
-        assert cursor.fetchone()[0] == 2
+        assert cursor.fetchone()[0] == 3
 
-    def test_removes_many_old_samples(self, store_conn):
+    def test_keeps_many_old_samples_without_replacement_evidence(self, store_conn):
         now = datetime(2026, 9, 15, 12, 0, 0, tzinfo=timezone.utc)
         for days_ago in range(1, 30):
             ts = (now - timedelta(days=days_ago)).isoformat()
             _insert_sample(store_conn, ts)
 
         pruned = prune_old_samples(store_conn, now, retention_days=14)
-        assert pruned == 15  # Days 15-29 removed
+        assert pruned == 0
 
         cursor = store_conn.execute("SELECT COUNT(*) FROM samples")
-        assert cursor.fetchone()[0] == 14  # Days 1-14 kept
+        assert cursor.fetchone()[0] == 29
 
     def test_empty_store_no_error(self, store_conn):
         now = datetime(2026, 9, 15, 12, 0, 0, tzinfo=timezone.utc)
@@ -130,8 +132,8 @@ class TestPruneOldSamples:
         )
         assert cursor.fetchone()[0] == 1
 
-    def test_old_sample_with_derived_interval_removed(self, store_conn):
+    def test_hour_rows_alone_do_not_replace_local_day_evidence(self, store_conn):
-        """Old samples with fully derived intervals are removed."""
+        """An hour row alone cannot authorize source-sample deletion."""
         now = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
         
         # Old sample with derived interval
@@ -148,8 +150,8 @@ class TestPruneOldSamples:
         # Run pruning
         pruned = prune_old_samples(store_conn, now, retention_days=14)
         
-        # Old sample should be removed (interval is derived)
+        # Keep the source samples until local-day replacement evidence exists.
         cursor = store_conn.execute(
             "SELECT COUNT(*) FROM samples WHERE ts = '2026-09-10T10:00:00+00:00'"
         )
-        assert cursor.fetchone()[0] == 0
+        assert cursor.fetchone()[0] == 1

tests/test_repair.py

@@ -235,8 +235,8 @@ class TestBoundaryAnchorRetention:
         # 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):
+    def test_hour_only_derivation_does_not_replace_local_day_evidence(self, store_conn):
-        """Sample that's fully derived is not a boundary anchor."""
+        """UTC hour evidence alone does not make a sample safe to prune."""
         now = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
         
         # Insert sample and fully derive its interval
@@ -247,8 +247,7 @@ class TestBoundaryAnchorRetention:
         _insert_hour(store_conn, "2026-09-14T10:00:00+00:00", 
                      bytes_written_delta=1000000)
         
-        # Not a boundary anchor
+        assert needs_boundary_anchor(store_conn, "2026-09-14T10:00:00+00:00", now)
-        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."""
@@ -274,8 +273,8 @@ class TestBoundaryAnchorRetention:
         )
         assert cursor.fetchone()[0] == 1
 
-    def test_pruning_removes_old_sample_with_derived_interval(self, store_conn):
+    def test_pruning_keeps_samples_without_local_day_replacement(self, store_conn):
-        """Pruning removes old samples when interval is fully derived."""
+        """Pruning keeps samples when only the UTC-hour row exists."""
         now = datetime(2026, 9, 30, 12, 0, 0, tzinfo=timezone.utc)
         
         # Old sample with derived interval
@@ -289,11 +288,11 @@ class TestBoundaryAnchorRetention:
         # Run pruning
         pruned = prune_old_samples(store_conn, now, retention_days=14)
         
-        # Old sample should be removed (interval is derived)
+        # The source remains until local-day evidence is also durable.
         cursor = store_conn.execute(
             "SELECT COUNT(*) FROM samples WHERE ts = '2026-09-10T10:00:00+00:00'"
         )
-        assert cursor.fetchone()[0] == 0
+        assert cursor.fetchone()[0] == 1
 
 
 # ---------------------------------------------------------------------------

tests/test_tui.py

@@ -109,6 +109,7 @@ def _insert_sample(conn, ts, pu=5, device="/dev/nvme0n1"):
 
 def _open_period(conn, start="2026-09-01T00:00:00+00:00"):
     ensure_period_open(conn, datetime.fromisoformat(start))
+    conn.commit()
 
 
 def _insert_local_day(conn, local_date, tz_name="UTC", tz_offset="+00:00",
@@ -123,8 +124,8 @@ def _insert_local_day(conn, local_date, tz_name="UTC", tz_offset="+00:00",
     conn.execute(
         "INSERT INTO local_days "
         "(local_date, tz_name, tz_offset, utc_start, utc_end, "
-        " bytes_written, bytes_read, coverage, sample_count, complete) "
+        " bytes_written, bytes_read, coverage, sample_count, complete, activity_intervals) "
-        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?)",
+        "VALUES (?, ?, ?, ?, ?, ?, ?, ?, ?, ?, 1)",
         (local_date, tz_name, tz_offset, utc_start, utc_end,
          bw, br, coverage, samples, complete),
     )
@@ -926,6 +927,7 @@ class TestBarGraphTUI:
         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_local_day(conn, d, bw=1024*1024*100)
         _insert_sample(conn, "2026-09-30T10:00:00+00:00")
         conn.close()
 
@@ -940,11 +942,9 @@ class TestBarGraphTUI:
             assert "Unalloc" in legend
             assert "Zero" in legend
             range_label = str(app.query_one("#bar-range").render())
-            assert "14 days" in range_label
+            assert "14 local days" in range_label
-            assert "UTC" in range_label
             plotted = str(app.query_one("#bar-render").render())
             assert "Writes (" in legend
-            assert "UTC" in range_label
             assert "─" in plotted
 
     @pytest.mark.asyncio
@@ -956,6 +956,7 @@ class TestBarGraphTUI:
         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_local_day(conn, d, bw=1024*1024*100)
         _insert_sample(conn, "2026-09-30T10:00:00+00:00")
         conn.close()
 
@@ -1029,6 +1030,7 @@ class TestBarGraphTUI:
         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_local_day(conn, d, bw=1024*1024*100)
         _insert_sample(conn, "2026-09-30T10:00:00+00:00")
         conn.close()
 
@@ -1042,15 +1044,16 @@ class TestBarGraphTUI:
 
             # Newest day is selected initially.
             readout = str(app.query_one("#bar-readout").render())
-            assert "UTC" in readout
+            assert "totals so far" in readout
-            assert "GB" in readout
+            assert "W 0.105 GB known" in readout
 
             # Moving left updates the selected-day readout.
             await pilot.press("left")
             await pilot.pause()
             readout = str(app.query_one("#bar-readout").render())
             assert "2026-09" in readout
-            assert "GB" in readout
+            assert "incomplete" in readout
+            assert "W 0.105 GB known" in readout
 
     @pytest.mark.asyncio
     async def test_hourly_drill_down_and_back(self, tmp_path):
@@ -1061,6 +1064,7 @@ class TestBarGraphTUI:
         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_local_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)
@@ -1077,30 +1081,27 @@ class TestBarGraphTUI:
             await pilot.pause()
             await pilot.pause()
 
-            # The newest day is selected automatically.
+            assert app.query_one("#activity-tabs").active == "view-history"
-            assert graph.selected_index == len(graph._day_data) - 1
+            daily_readout = str(app.query_one("#bar-readout").render())
-            assert graph.view_mode == "daily"
 
             # Enter drill-down
             await pilot.press("enter")
             await pilot.pause()
-            assert graph.view_mode == "hourly"
+            assert app.query_one("#activity-tabs").active == "view-day"
-            assert graph.drill_day is not None
+            assert "UTC" in str(app.query_one("#bar-readout").render())
-            assert len(graph._hour_data) == 24
 
-            # Five-minute data refreshes retain the selected hour.
+            # Inspection identity survives refresh through visible readout.
-            graph._hourly_selected = 12
+            await pilot.press("left")
-            selected_hour = graph._hour_data[12]["hour"]
+            selected_hour = str(app.query_one("#bar-readout").render())
             app._refresh()
             await pilot.pause()
-            assert graph.view_mode == "hourly"
+            assert str(app.query_one("#bar-readout").render()) == selected_hour
-            assert graph._hour_data[graph._hourly_selected]["hour"] == selected_hour
 
             # Esc returns to daily
             await pilot.press("escape")
             await pilot.pause()
-            assert graph.view_mode == "daily"
+            assert app.query_one("#activity-tabs").active == "view-history"
-            assert graph.drill_day is None
+            assert str(app.query_one("#bar-readout").render()) == daily_readout
 
     @pytest.mark.asyncio
     async def test_empty_store_graph(self, tmp_path):

tests/test_tz_util.py

@@ -0,0 +1,26 @@
+"""Timezone detection tests."""
+import sys
+from pathlib import Path
+
+sys.path.insert(0, str(Path(__file__).parent.parent / "src"))
+
+from fenris import tz_util
+
+
+def test_relative_localtime_symlink_returns_zoneinfo_key(tmp_path, monkeypatch):
+    zoneinfo = tmp_path / "usr" / "share" / "zoneinfo" / "Asia" / "Kolkata"
+    zoneinfo.parent.mkdir(parents=True)
+    zoneinfo.write_bytes(b"zoneinfo")
+    localtime = tmp_path / "etc" / "localtime"
+    localtime.parent.mkdir()
+    localtime.symlink_to("../usr/share/zoneinfo/Asia/Kolkata")
+
+    real_path = tz_util.Path
+    monkeypatch.setattr(
+        tz_util,
+        "Path",
+        lambda path: localtime if path == "/etc/localtime" else real_path(path),
+    )
+    monkeypatch.delenv("TZ", raising=False)
+
+    assert tz_util.detect_system_tz() == "Asia/Kolkata"