fix(mcp): get_anomaly shows a quick Steward restart, not only a gap over 90 s (#5862)

A redeploy's new process ticks at once, so its once-a-minute samples never
broke for 90 s and get_anomaly showed none of the day's restarts. The first
self-monitor tick in a process now records restart_gap_secs (time since the
last process's last sample), and steward_gaps shows each one as a restart.

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

steward/alerts/service.py

@@ -28,7 +28,7 @@ CORE_METRICS: dict[str, list[str]] = {
     "dns":     ["is_up", "response_ms"],
     "http":    ["is_up", "response_ms"],
     "steward": ["ingest_posts", "ingest_failed", "ingest_slowest_ms", "db_roundtrip_ms",
-                "unwatched_secs", "cleanup_secs", "open_fds", "open_fds_pct",
+                "unwatched_secs", "restart_gap_secs", "cleanup_secs", "open_fds", "open_fds_pct",
                 "backup_age_secs", "backup_bytes"],
 }
 

steward/core/formatting.py

@@ -298,6 +298,7 @@ METRICS: dict[str, tuple[str, str]] = {
     "ingest_slowest_ms": ("Slowest agent post", "the longest report in the last minute; agents give up at 10 s"),
     "db_roundtrip_ms": ("Database round trip", "a trivial query to Steward's database, connection included"),
     "unwatched_secs": ("Time not watching", "how long Steward wasn't recording before this minute; 0 when unbroken"),
+    "restart_gap_secs": ("Restarted after", "recorded when Steward starts: how long since it last recorded"),
     "cleanup_secs": ("Hourly cleanup took", "how long the last retention and rollup run took"),
     "backup_age_secs": ("Newest backup's age", "time since Steward last sent a backup to its bucket"),
     "backup_bytes": ("Backup size", "the size of the last backup sent"),

steward/core/self_monitor.py

@@ -25,6 +25,10 @@ source and resource:
   • ``db_roundtrip_ms`` — a timed ``SELECT 1``, connection checkout included
   • ``unwatched_secs`` — how long Steward wasn't recording before this tick (a
     deploy, an outage, a stalled loop), from its own last sample; 0 when unbroken
+  • ``restart_gap_secs`` — once, on a fresh process's first tick: how long since
+    the last process's last sample, however short. A quick redeploy never
+    breaks the minute long enough to show as unwatched; this marks it anyway,
+    so get_anomaly can show Steward's own restarts beside an anomaly (#5862)
 
 ``cleanup_secs`` is recorded by the hourly cleanup itself when it finishes.
 """
@@ -51,6 +55,7 @@ except ImportError:  # pragma: no cover - non-POSIX
 FD_WARN_PCT = 80.0
 
 _warned = False  # de-dupe the WARNING so a sustained leak doesn't spam the log
+_started = False  # this process has ticked: restart_gap_secs is recorded on the first tick only
 
 
 def count_open_fds() -> int | None:
@@ -98,7 +103,7 @@ async def record_self_metrics(app) -> None:
     The open-file pair is skipped (logged at debug) where fd accounting isn't
     available, so it's safe to schedule unconditionally.
     """
-    global _warned
+    global _warned, _started
 
     from sqlalchemy import select, text
     from steward.models.metrics import PluginMetricLatest
@@ -129,11 +134,13 @@ async def record_self_metrics(app) -> None:
                     ("ingest_posts", tally.posts), ("ingest_failed", tally.failed),
                     ("ingest_slowest_ms", tally.slowest_ms), ("db_roundtrip_ms", roundtrip_ms),
                     ("unwatched_secs", unwatched_secs(last, now)),
+                    ("restart_gap_secs", None if _started or last is None else (now - last).total_seconds()),
                     ("open_fds", fds), ("open_fds_pct", pct)]:
                 if value is not None:
                     batch.add(source_module="steward", resource_name="process",
                               metric_name=metric_name, value=value, recorded_at=now)
             await batch.record(session)
+    _started = True
 
     if pct is not None and pct >= FD_WARN_PCT:
         if not _warned:

steward/mcp/tools/_events.py

@@ -152,13 +152,23 @@ async def other_anomalies(db, place: Place, anomaly_id: str, since: datetime,
     return here, elsewhere
 
 
-def gaps_in(times: list[datetime], since: datetime, until: datetime) -> list[dict]:
-    """Each break longer than STEWARD_GAP_S between consecutive samples that
-    overlaps the window, as a "steward" event lasting the break."""
+def gaps_in(times: list[datetime], since: datetime, until: datetime,
+            restarts: list[tuple[datetime, float]] = ()) -> list[dict]:
+    """Each restart (its first sample's time and how long since the last
+    one) and each other break longer than STEWARD_GAP_S between consecutive
+    samples that overlaps the window, as a "steward" event lasting the break.
+    A restart is shown however short: a quick redeploy never breaks the
+    minute, and still restarts every count Steward keeps."""
     out = []
+    for at, secs in restarts:
+        if at >= since and at - timedelta(seconds=secs) <= until:
+            out.append(event(at - timedelta(seconds=secs), "steward",
+                             f"Steward restarted, not recording for {human_duration(secs)}: "
+                             "readings either side of it can be wrong", until=at))
+    restarted = {at for at, _ in restarts}
     for before, after in zip(times, times[1:]):
         secs = (after - before).total_seconds()
-        if secs > STEWARD_GAP_S and after >= since and before <= until:
+        if secs > STEWARD_GAP_S and after >= since and before <= until and after not in restarted:
             out.append(event(before, "steward",
                              f"Steward wasn't recording for {human_duration(secs)} (a restart, a deploy or a "
                              "stall): readings either side of a gap can be wrong", until=after))
@@ -172,12 +182,13 @@ async def steward_gaps(db, since: datetime, until: datetime) -> list[dict]:
     silence (#5862). Raw samples only, so a window older than their
     retention shows none."""
     rows = (await db.execute(
-        select(PluginMetric.recorded_at).where(
+        select(PluginMetric.metric_name, PluginMetric.recorded_at, PluginMetric.value).where(
             PluginMetric.source_module == "steward", PluginMetric.resource_name == "process",
-            PluginMetric.metric_name == "db_roundtrip_ms",
+            PluginMetric.metric_name.in_(("db_roundtrip_ms", "restart_gap_secs")),
             PluginMetric.recorded_at >= since - timedelta(hours=1), PluginMetric.recorded_at <= until)
-        .order_by(PluginMetric.recorded_at))).scalars()
-    return gaps_in(list(rows), since, until)
+        .order_by(PluginMetric.recorded_at))).all()
+    return gaps_in([at for name, at, _ in rows if name == "db_roundtrip_ms"], since, until,
+                   [(at, value) for name, at, value in rows if name == "restart_gap_secs"])
 
 
 async def plugin_events(place: Place, since: datetime, until: datetime) -> list[list[dict]]: