# Nova Metrics Directory


This directory holds Nova's telemetry/observability artifacts. The
metrics layer is **Nova-native** (D-120): JSONL event log + SQLite cold
store + hash-chained Decision Ledger. No Kafka, Prometheus, ClickHouse,
or QLDB.

## Artifact inventory

| Artifact | Type | Regenerable? | Description |
|----------|------|-------------|-------------|
| `events.jsonl` | Append-only event log | No (append-only state) | CloudEvents 1.0 envelopes from all emitters (REQ-187) |
| `decision_ledger.db` | SQLite append-only hash-chain | No (append-only state) | Decision Ledger: `ai.decision.made` + `attestation.recorded` events (REQ-188, D-121) |
| `nova_metrics.db` | SQLite cold store | Yes (regenerate via collector) | Normalized fact/dimension tables (REQ-189, P2) |
| `runs/<run_id>.json` | Per-run manifest | Yes (regenerate from events) | Run lifecycle: stages, durations, exit, confidence, HITL (REQ-187) |
| `runs/<run_id>/` | Durable run artifacts | Yes (regenerate from $WORK) | Persisted copies of pcr.json, signal.json, event.json, etc. (REQ-187) |
| `lifecycle/<module>-<env>.json` | Lifecycle report | Yes (regenerate from lifecycle runs) | Per-module apply/modify/destroy results (REQ-205) |
| `test-results.xml` | JUnit XML | Yes (regenerate via pytest) | Test results (REQ-187, P1 addopts) |
| `test-report.json` | JSON test report | Yes (regenerate via pytest) | Test results in JSON (REQ-187, P1 addopts) |
| `coverage.json` | Coverage report | Yes (regenerate via pytest) | Code coverage (REQ-206, P1 addopts) |
| `powerbi/` | PowerBI export | Yes (regenerate via powerbi_export) | CSV/JSON views for PowerBI ingestion (REQ-190, P3) |
| `TRUST_SNAPSHOT.md` | Trust snapshot report | Yes (regenerate via trust_snapshot) | 5 trust metrics + chain-integrity verdict (REQ-211, P4) |

## Backup + restore

**Append-only state** (`events.jsonl`, `decision_ledger.db`): these are
the source of truth. They should be committed to git (events.jsonl) or
snapshotted (decision_ledger.db). If lost, they CANNOT be regenerated —
the events they captured are gone.

**Regenerable artifacts** (`nova_metrics.db`, `runs/`, `lifecycle/`,
`test-results.xml`, `coverage.json`, `powerbi/`): these are derived from
the append-only state + the source signals (REGRESSION_REPORT.json,
$WORK/*.json, junit XML). If lost, re-run the collector
(`core/metrics/collector.py`, P2) to rebuild `nova_metrics.db`, then
re-run the PowerBI export (`core/metrics/powerbi_export.py`, P3) to
rebuild `powerbi/`.

**Restore procedure:**
1. Recover `events.jsonl` + `decision_ledger.db` from git/snapshot.
2. `python3 core/metrics/collector.py` → rebuilds `nova_metrics.db`.
3. `python3 core/metrics/powerbi_export.py` → rebuilds `powerbi/`.
4. `python3 core/metrics/trust_snapshot.py` → rebuilds `TRUST_SNAPSHOT.md`.

## Concurrency model

Single-writer per run: the run manifest writer is the only writer per
run. SQLite WAL mode + `BEGIN IMMEDIATE` prevents concurrent-write
corruption on the Decision Ledger (P1 risk mitigation).