# Excititor Chunk Telemetry (Sprint 110)

## Metrics (Meter: `StellaOps.Excititor.Chunks`)
- `vex_chunks_ingested_total` (counter) — tags: `tenant`, `source`, `status` (`accepted|rejected`), `reason` (nullable for accepted). Increments per chunk submitted.
- `vex_chunks_item_count` (histogram, unit=items) — records item count per chunk.
- `vex_chunks_payload_bytes` (histogram, unit=bytes) — measured from NDJSON payload length.
- `vex_chunks_latency_ms` (histogram) — end-to-end ingestion latency per request.

## Logs
- `vex.chunk.ingest.accepted` — includes `chunk_id`, `tenant`, `source`, `item_count`, `chunk_digest`.
- `vex.chunk.ingest.rejected` — includes `chunk_id`, `tenant`, `source`, `reason`, validation errors (summarized).

## Wiring steps
1. Register `ChunkTelemetry` as singleton with shared `Meter` instance.
2. In `/vex/evidence/chunks` handler, compute `chunk_digest` deterministically from canonical JSON and emit counters/histograms via `ChunkTelemetry`.
3. Log using structured templates above; avoid request bodies in logs.
4. Expose metrics via default ASP.NET metrics export (Prometheus/OpenTelemetry) already configured in WebService.

## Determinism & offline posture
- Do not include host-specific paths or timestamps in metric dimensions.
- Histogram buckets: use standard OTEL defaults; no runtime-generated buckets.
- Keep meter name stable; adding new instruments requires version note in sprint Decisions & Risks.

## Ownership
- Implementer: Excititor Observability Guild
- Reviewers: Evidence Locker Guild (for parity with attestation metrics)