Health states are events. A HealthMonitor polls registered HealthProbes on an
interval and appends HealthDegraded/HealthRestored only on a status transition
(hysteresis), so health is observable, replayable, and renderable like every
other fact in the log. The probe reads nondeterministic environment state and
records it at observe-time (Invariant #9); HealthProjection rebuilds current
health by replay, never re-probing (Invariant #8). Monitor is live-only, started
in ServerModule.start alongside narration; seeded from the projection so a
restart does not re-emit a degraded the log already records.
First concrete probe: DiskWatermarkProbe — event-log + CAS size and growth rate,
warning before the 2am surprise. Read surface mirrors `correx stats`:
GET /health/checks replays the system session and `correx health` renders it.
Health events ride the reserved __system__ session, filtered from operator
session listings.
LLAMA_SERVER (liveness + tokens/sec trend) and EVENT_STORE (append/fsync latency)
probes plug into the same HealthProbe framework as follow-ups.
Implements observability-spec §2 + §3-tier-1: metrics as a pure fold over the
event log, no third pillar, no OTel. Every metric is replayable over the full
historical log because it derives from events other contexts already emit — no
new EventPayload subclasses, so no serialization registry change.
- MetricsProjection: Projection<MetricsState> folding inference/tool/approval/
stage/workflow events into raw sums; approval request→decision latency is
correlated in-fold via a transient pending-request map.
- MetricsInspectionService: rebuilds via DefaultEventReplayer, derives read-side
ratios (token throughput, avg approval wait, session wall-time accounting split
into inference / tool / approval-wait / other) into MetricsReport.
- GET /sessions/{id}/metrics route, mirroring the replay endpoint.
- `correx stats <sessionId>` CLI client (--json passthrough), mirroring replay.
- Tests: seeded-event fold correctness with controlled timestamps (7) + CLI
render smoke tests (4).
kami