fix: rebuild trustworthy local-day evidence (#99)

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/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):
@@ -118,8 +109,16 @@ 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)")

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 +32,9 @@ class InvariantViolationError(Exception):
     pass
 
 
+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 +200,12 @@ 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 +224,7 @@ 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 +239,8 @@ 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"],
@@ -259,76 +263,44 @@ 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.
-    Returns the run outcome.
-    """
-    try:
-        # Acquire counters and thermal evidence
-        counters = acquire_from_smartctl(smartctl_data)
-        
-        # Acquire controller identity
-        identity = acquire_from_sysfs(sysfs_path)
-        
-        # Build sample with injected clock
-        sample = {
-            "ts": clock.utcnow().isoformat(),
-            "device": config["device"],
-            **counters,
-            **identity,
-        }
-        
-        # Initialize store if needed
-        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)
 
 
-        try:
+def _publish_observation(
-            # Ensure monitoring period is open (issue #73 AC2)
+    conn: sqlite3.Connection,
-            ensure_period_open(conn, clock.utcnow())
+    sample: Dict[str, Any],
-            
+    identity: Dict[str, Any],
-            # Validate invariants
+    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)
 
-            # Write sample and get segment info
+    current_id = seg_info["sample_id"]
-            seg_info = write_sample(sample, identity, conn, clock)
-            
-            # Derive hour observations from interval with previous sample
-            try:
-                # Find the sample we just wrote
-                cursor = conn.execute("SELECT id FROM samples ORDER BY id DESC LIMIT 1")
-                current_id = cursor.fetchone()[0]
-
     prev = find_previous_sample(conn, seg_info.get("segment_id"), current_id)
     if prev is not None:
-                    # Build current sample dict for derivation
         current = {
             "id": current_id,
             "ts": sample["ts"],
@@ -338,43 +310,187 @@ def run_collection(
             "temperature_c": sample["temperature_c"],
             "data_units_written": sample["data_units_written"],
             "data_units_read": sample["data_units_read"],
+            "local_tz": tz_name,
         }
         derive_hours_from_interval(conn, prev, current)
+        from .local_day import record_local_activity_interval
+        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,
+            )
 
-                # Rebuild day aggregates from hour observations
     from .day_aggregate import derive_all_days, persist_day_aggregate
-                for agg in derive_all_days(conn):
+    for aggregate in derive_all_days(conn):
-                    persist_day_aggregate(conn, agg)
+        persist_day_aggregate(conn, aggregate)
 
-                # Derive local-day summary using system timezone (issue #90)
-                try:
-                    from .tz_util import detect_system_tz
     from .local_day import derive_local_day_summary, persist_local_day
-                    tz_name = detect_system_tz()
+    local_summary = derive_local_day_summary(conn, tz_name, observed_at)
-                    clock_now = clock.utcnow()
-                    local_summary = derive_local_day_summary(conn, tz_name, clock_now)
     if local_summary is not None:
         persist_local_day(conn, local_summary)
-                except Exception:
-                    # Local-day derivation failure must not prevent publication
-                    pass
 
+
+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)
+            _publish_observation(
+                conn,
+                observation["sample"],
+                observation["identity"],
+                observation["tz_name"],
+            )
+            conn.execute("DELETE FROM pending_publications WHERE id = ?", (pending_id,))
             conn.commit()
+            recovered += 1
         except Exception:
-                # Derivation failure must not prevent sample persistence (issue #73 AC6)
+            conn.rollback()
-                pass
+            raise
 
+
+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:
+        if isinstance(exc, sqlite3.Error) and not isinstance(exc, sqlite3.IntegrityError):
+            raise
+        if isinstance(exc, InvariantViolationError):
+            raise
+        try:
+            capacity_full = _pending_count(conn) >= PENDING_PUBLICATION_LIMIT
+        except sqlite3.Error:
+            raise exc
+        if capacity_full:
+            raise RuntimeError(
+                "pending publication capacity full "
+                f"({PENDING_PUBLICATION_LIMIT} observations); no new observation acquired; "
+                f"recovery failed: {exc}"
+            ) from exc
+        raise
+
+
+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)
+
+        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_collection(conn)
+
+        # Hold the writer reservation across the capacity check and acquisition.
+        # A concurrent collector will recheck pending work before it acquires.
+        while True:
+            conn.execute("BEGIN IMMEDIATE")
+            waiting = _pending_count(conn)
+            if waiting:
+                conn.rollback()
+                published_count += _recover_pending_for_collection(conn)
+                continue
+
+            from .tz_util import detect_system_tz
+            tz_name = detect_system_tz()
+            if acquire is not None:
+                smartctl_data, sysfs_path = acquire()
+            if smartctl_data is None or sysfs_path is None:
+                raise AcquisitionError("No acquired SMART data or sysfs identity")
+
+            counters = acquire_from_smartctl(smartctl_data)
+            identity = acquire_from_sysfs(sysfs_path)
+            sample = {
+                "ts": clock.utcnow().isoformat(),
+                "device": config["device"],
+                **counters,
+                **identity,
+            }
+            validate_sample_invariants(sample, conn)
+            _stage_observation(conn, sample, identity, tz_name)
+            conn.commit()
+            break
+
+        published_count += _recover_pending_for_collection(conn)
         return {
             "ok": True,
-                "sample_count": 1,
+            "sample_count": published_count,
             "store_path": str(store_path),
         }
-        finally:
-            conn.close()
 
-    except (AcquisitionError, InvariantViolationError) as e:
+    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/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:
@@ -101,8 +101,6 @@ def _update_repair_status(conn: sqlite3.Connection, result: RepairResult) -> Non
         ("days_derived", str(days)),
     )
 
-    conn.commit()
-
 
 def get_repair_status(conn: sqlite3.Connection) -> RepairStatus:
     """Get current repair status for read-only views."""
@@ -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
@@ -408,6 +402,11 @@ def repair_derivation(
                 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
+        # interruption rolls back the in-progress marker with the repair.
+        _update_repair_status(conn, result)
+        _set_repair_in_progress(conn, False)
         conn.commit()
         
-        # Update repair status
-        _update_repair_status(conn, result)
-        
     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
+        try:
             _apply_migrations(conn, current_version)
-        conn.execute(f"PRAGMA user_version={SCHEMA_VERSION}")
+        except Exception:
-        conn.commit()
+            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 (
@@ -221,44 +231,125 @@ 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
+    Commit each version transition independently. A failed step rolls back in
-    elif branches when SCHEMA_VERSION increases.
+    full while earlier successful steps remain versioned and retryable.
-    
-    Spec: §3.6, §10.2
     """
-    # Migration 1→2: add segment_id provenance to samples,
+    migrations = {
-    # unattributed byte tracking to day_aggregates (issue #73)
+        2: _migrate_1_to_2,
-    if current_version < 2:
+        3: _migrate_2_to_3,
-        # Defensive: only ALTER if table exists (handles minimal v1 stores)
+        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:
-            # Check if column already exists (idempotent)
+        cols = {row[1] for row in conn.execute(
-            cols = {row[1] for row in conn.execute("PRAGMA table_info(samples)").fetchall()}
+            "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()}
+        cols = {row[1] for row in conn.execute(
-            if "unattributed_bytes_written" not in cols:
+            "PRAGMA table_info(day_aggregates)"
-                conn.execute("ALTER TABLE day_aggregates ADD COLUMN unattributed_bytes_written INTEGER DEFAULT 0")
+        ).fetchall()}
-            if "unattributed_bytes_read" not in cols:
+        for column in ("unattributed_bytes_written", "unattributed_bytes_read"):
-                conn.execute("ALTER TABLE day_aggregates ADD COLUMN unattributed_bytes_read INTEGER DEFAULT 0")
+            if column not in cols:
-        current_version = 2
+                conn.execute(
+                    f"ALTER TABLE day_aggregates ADD COLUMN {column} INTEGER DEFAULT 0"
+                )
 
-    # Migration 2→3: add local_days table for local-day activity totals
+
-    # (issue #90, ADR 0010).  Pure addition — no existing rows touched.
+def _migrate_2_to_3(conn: sqlite3.Connection) -> None:
-    if current_version < 3:
+    """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 IF NOT EXISTS local_days (
+            CREATE TABLE local_days (
                 id INTEGER PRIMARY KEY AUTOINCREMENT,
                 local_date TEXT NOT NULL,
                 tz_name TEXT NOT NULL,
@@ -273,7 +364,48 @@ def _apply_migrations(conn: sqlite3.Connection, current_version: int):
                 UNIQUE(local_date, tz_name)
             )
         """)
-        current_version = 3
+
+
+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
+    try:
         _apply_migrations(conn, current_version)
-    conn.execute(f"PRAGMA user_version={SCHEMA_VERSION}")
+    except Exception:
-    conn.commit()
+        conn.close()
+        raise
     conn.close()
     return steps
 

src/fenris/tui.py

@@ -1709,7 +1709,9 @@ class FenrisTuiApp(App):
             )
             tz_name = detect_system_tz()
             if self._browse_date is not None:
-                local = query_local_day_summary(conn, self._browse_date)
+                local = query_local_day_summary(
+                    conn, self._browse_date, clock_now=self._clock_now
+                )
             else:
                 local = query_current_local_day(conn, self._clock_now, tz_name)
         except Exception:
@@ -1720,7 +1722,10 @@ class FenrisTuiApp(App):
 
         if local is None:
             date = self._browse_date or self._clock_now.astimezone().date().isoformat()
-            widget.update("%s · local-day evidence unavailable\nW unavailable · R unavailable" % date)
+            widget.update(
+                "%s · local-day evidence unavailable\nW unavailable · R unavailable"
+                % date
+            )
             widget.display = True
             main_grid.remove_class("local-day")
             return
@@ -1728,23 +1733,45 @@ class FenrisTuiApp(App):
         main_grid.add_class("local-day")
         widget.styles.display = "block"
 
+        tz_display = "%s %s" % (local["tz_name"], local["tz_offset"])
+        state = local["activity_state"]
+        state_labels = {
+            "so_far": "totals so far",
+            "incomplete": "incomplete",
+            "complete": "complete",
+            "zero": "measured zero",
+            "unavailable": "local activity unavailable",
+        }
+        label = state_labels.get(state, "local activity unavailable")
         bw = local["bytes_written"]
         br = local["bytes_read"]
-        partial = "" if local["complete"] else " · totals so far"
+        if bw is None or br is None:
-        tz_display = "%s %s" % (local["tz_name"], local["tz_offset"])
+            totals = "W unavailable · R unavailable"
-
+        else:
-        text = (
+            totals = "W %.3f GB known · R %.3f GB known" % (
-            "[bold]%s[/bold] · %s%s\n"
+                bw / 1e9, br / 1e9
-            " W %.3f GB · R %.3f GB · %.0f%% coverage"
+            )
-            % (
+        lines = [
-                local["local_date"],
+            "[bold]%s[/bold] · %s · %s" % (
-                tz_display,
+                local["local_date"], tz_display, label,
-                partial,
+            ),
-                bw / 1e9,
+            totals,
-                br / 1e9,
+        ]
-                local["coverage"] * 100,
+        if local["shared_evidence_count"]:
+            lines.append(
+                "shared at midnight W %.3f GB · R %.3f GB" % (
+                    local["shared_bytes_written"] / 1e9,
+                    local["shared_bytes_read"] / 1e9,
                 )
             )
+        if local["unallocated_evidence_count"]:
+            lines.append(
+                "unallocated W %.3f GB · R %.3f GB" % (
+                    local["unallocated_bytes_written"] / 1e9,
+                    local["unallocated_bytes_read"] / 1e9,
+                )
+            )
+        text = "\n".join(lines)
         widget.update(text)
 
     def _on_graph_drill(self, day: str) -> None:

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_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_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_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_93.py

@@ -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()
 
 

tests/test_issue_97.py

@@ -0,0 +1,293 @@
+"""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
+
+    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_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_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),
     )

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"