Task 21 review — two Criticals sharing one root cause, plus four follow-ups.
C1/C2 root cause: `OnReconnectedAsync` opened with `Births.Clear(); _trackers.Clear();`
— "not housekeeping, the correctness step" — and that reset was missing from the
other two seams where the view underneath a surviving cache changes.
- C1: the ingestor OUTLIVES a session rebuild. `SessionIdentity` is a strict
superset of `IngestIdentity`, so changing only Host/Port/ClientId/credentials/
TLS/a timeout gives `!SameSession && SameIngest` — `ReinitializeAsync` tears the
session down and re-establishes on the same instance, and `TeardownAsync` touches
no ingest state (the resilience layer re-running `InitializeAsync` is the second
path). A node that rebound alias 5 during the changeover would publish Pressure's
value under the Temperature RawPath at Good. Hoisted into `ResetSessionState`,
called from `AttachTo` (earliest seam — a persistent session can push between
CONNACK and our SUBSCRIBE), `EstablishAsync` and `OnReconnectedAsync`.
- C2: `Register` pruned trackers but not births. While a node is unauthored its
traffic is dropped at `Dispatch`, so its cached birth FREEZES rather than
refreshing; drop-then-re-add across a week mis-routes at Good, and `Births` grew
monotonically. Now evicted on edge-node departure.
Deliberately NARROWER than "absent from ByScope": a device with no authored tags
under a still-authored node keeps receiving traffic, so its birth is live, not
frozen — evicting it would discard correct state. Pinned both ways.
- I1: a birth whose seq is unreadable produced a permanent debounce-paced rebirth
loop. "A birth arrived" is now tracked separately from "the birth established a
baseline". Writing the test showed the cap belonged wider than the review scoped
it: data-before-birth and unknown-alias loop identically (20 messages → 23 NCMDs
against a cap of 3), so all three missing-metadata reasons share one per-node
consecutive cap, re-armed by any applied birth. A seq gap stays uncapped — it
self-limits.
- I2: the oversize `WarnOnce` key was the raw topic, off a group-wide `#`
subscription. `HandleMessage` now parses and filters to authored nodes BEFORE the
size check (also skipping the protobuf parse for discarded traffic), and `_warned`
carries a hard ceiling so a future bad derivation degrades to silence.
- I3: array metrics slipped the unsupported-type gate — `ToDriverDataType` returns
the ELEMENT type, so a String-typed tag published a packed `byte[]` as base64 at
Good. Gated on `IsSparkplugArray`.
- I4: driver-level Sparkplug coverage for the composition-root lines T22 left
untested — the `OnDataChange` re-raise, `ReadAsync` off the shared cache,
subscribe/unsubscribe dispatch, and both directions of the mode gate.
Minors: M1 the oversize test fed unparseable bytes and passed with the size check
deleted (now a real NBIRTH + an at-the-ceiling control); M2 answered in-place (an
absent seq is refused WITHOUT becoming the baseline, so the NCMD assertion is the
complete check); M3 `HostStateObserved` raise wrapped; M5 the legacy `STATE/{host}`
form is now subscribed, so the parser's tolerance is reachable in production; M8
`ResolveBinding` prefers the NAME over a disagreeing alias; M9 a narrowing float
conversion refuses instead of publishing ±Infinity at Good (a publisher's own
infinity still passes through). M4 was already resolved by T22.
Also fixed a race in the new tests: `publish.Topics.Clear()` after a call that
dispatches rebirths off-thread must drain first — it made the C1 sequence-baseline
pin pass vacuously in the first falsifiability run.
Falsifiability: dropping the reset from AttachTo+EstablishAsync reddens 4 (C1);
dropping the Register eviction reddens 2 (C2); widening the eviction predicate to
the reviewer's literal phrasing reddens the keep-live-births pin (C2b). 545/545 MQTT
unit tests green (was 524); whole-solution `--no-incremental` build clean under TWAE.
Claude-Session: https://claude.ai/code/session_01GASWkNEi68FSCtvr6rLoEW
Joseph Doherty
6d7a458c4d