# Unified Event Timeline Service

## Module
Timeline

## Status
VERIFIED

## Description
Cross-service event timeline with HLC-ordered events, deterministic event IDs (SHA-256 of correlation_id+t_hlc+service+kind), W3C Trace Context integration, PostgreSQL append-only storage with materialized critical-path views. Provides event SDK for Scheduler/AirGap/Attestor/Policy/VexLens integration, timeline query API with HLC range filtering, causal latency measurement, and forensic event export with DSSE attestation.

## Implementation Details
- **TimelineQueryService**: `src/Timeline/__Libraries/StellaOps.Timeline.Core/TimelineQueryService.cs` -- central query engine: GetByCorrelationIdAsync (HLC range, service/kind filters, limit/offset, cursor paging), GetCriticalPathAsync (stage duration analysis: consecutive event pairs with percentage of total, sorted by duration descending), GetByServiceAsync (cross-correlation service queries)
- **TimelineEndpoints**: `src/Timeline/StellaOps.Timeline.WebService/Endpoints/TimelineEndpoints.cs` -- `/api/v1/timeline`: GET /{correlationId} returns TimelineResponse (events with EventId, THlc, TsWall, Service, Kind, Payload, EngineVersion; totalCount, hasMore, nextCursor); GET /{correlationId}/critical-path returns CriticalPathResponse (totalDurationMs, stages with durationMs/percentage/fromHlc/toHlc)
- **ReplayEndpoints**: `src/Timeline/StellaOps.Timeline.WebService/Endpoints/ReplayEndpoints.cs` -- deterministic replay: POST /{correlationId}/replay (dry-run/verify modes, HLC range), GET /replay/{replayId} (progress, deterministic match verification via SHA-256 chain digest comparison)
- **ExportEndpoints**: `src/Timeline/StellaOps.Timeline.WebService/Endpoints/ExportEndpoints.cs` -- forensic export: POST /{correlationId}/export (NDJSON/JSON, optional DSSE signing), GET /export/{exportId}, GET /export/{exportId}/download
- **TimelineReplayOrchestrator**: `src/Timeline/__Libraries/StellaOps.Timeline.Core/Replay/TimelineReplayOrchestrator.cs` -- background replay execution with FakeTimeProvider for determinism, IncrementalHash chain digest, progress tracking, cancellation support
- **TimelineBundleBuilder**: `src/Timeline/__Libraries/StellaOps.Timeline.Core/Export/TimelineBundleBuilder.cs` -- NDJSON/JSON bundle building with IEventSigner integration for DSSE-attested exports; includes event_id, t_hlc, ts_wall, correlation_id, service, kind, payload_digest, engine_version, schema_version
- **ServiceCollectionExtensions**: `src/Timeline/__Libraries/StellaOps.Timeline.Core/ServiceCollectionExtensions.cs` -- DI registration for all timeline services
- **TimelineMetrics**: `src/Timeline/__Libraries/StellaOps.Timeline.Core/Telemetry/TimelineMetrics.cs` -- OpenTelemetry metrics: RecordReplay, RecordExport
- **Program.cs**: `src/Timeline/StellaOps.Timeline.WebService/Program.cs` -- maps TimelineEndpoints, ReplayEndpoints, ExportEndpoints, HealthEndpoints
- **Tests**: `src/Timeline/__Tests/StellaOps.Timeline.Core.Tests/TimelineQueryServiceTests.cs`, `src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests/TimelineApiIntegrationTests.cs`, `ReplayOrchestratorIntegrationTests.cs`
- **Source**: SPRINT_20260107_003_000_INDEX_unified_event_timeline.md

## E2E Test Plan
- [x] GET /api/v1/timeline/{correlationId} returns cross-service events ordered by HLC timestamp
- [x] Verify deterministic event IDs are SHA-256 hashes of correlation_id+t_hlc+service+kind
- [x] Test HLC range filtering returns only events within the specified window
- [x] Verify critical path analysis computes correct stage durations and percentages
- [x] Test deterministic replay: initiate -> poll status -> verify deterministicMatch=true
- [x] Verify forensic export produces NDJSON bundle with all event fields
- [x] Test DSSE-signed export bundles include valid signature attestation
- [x] Verify service and kind filters work correctly across multiple source services
- [x] Test pagination with cursor returns consistent ordered results

## Verification

**Run ID**: run-001
**Date**: 2026-02-10
**Verdict**: PASS

**Implementation Verification**:
- TimelineQueryService with HLC-ordered events, cursor paging via ToSortableString()
- TimelineEndpoints with GET /{correlationId} returning EventId, THlc, TsWall
- TimelineReplayOrchestrator with FakeTimeProvider for determinism, IncrementalHash SHA-256 chain digest
- TimelineBundleBuilder with NDJSON/JSON + DSSE signing
- ExportEndpoints has 2 stubbed follow-through methods but core builder is fully implemented

**Test Execution**:
- 20 tests across 3 files
- All tests PASS

**Build Status**:
- 0 errors
- 0 warnings
- Build: PASS

**Overall Verdict**: PASS

## Recheck (run-002)
- **Date**: 2026-02-10
- **Result**: PASS after endpoint hardening
- **Key fixes verified**:
  - Replay status lifecycle remains reachable across requests.
  - Export status/download no longer return synthetic success for unknown IDs.
  - Invalid HLC query input returns 400 instead of 500.
- **Tests**: Timeline.Core.Tests 7/7, Timeline.WebService.Tests 19/19 (26 total).
- **Evidence**: `docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-002/tier2-api-check.json`

## Recheck (run-003)
- **Date**: 2026-02-10
- **Result**: PASS
- **Verification**: follow-up API replay confirmed timeline query success, 404, and pagination contracts remain stable.
- **Tests**: Timeline.Core.Tests 7/7, Timeline.WebService.Tests 19/19 (26 total).
- **Evidence**: `docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-003/tier2-api-check.json`


## Recheck (Run-004)
- **Verified**: 2026-02-10
- **Method**: Tier 2 replay via in-process WebApplicationFactory + full suite replay.
- **Tests**: PASS (`src/Timeline/__Tests/StellaOps.Timeline.Core.Tests`: 7/7; `src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests`: 19/19).
- **Tier 2 Evidence**: `docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-004/tier2-api-check.json`
- **Outcome**: Query/replay/export API contracts remain stable under follow-up replay.

## Recheck (Run-005)
- **Verified**: 2026-02-10
- **Method**: Tier 2a API replay validated via Timeline integration suites.
- **Tests**: PASS (`src/Timeline/__Tests/StellaOps.Timeline.Core.Tests`: 7/7; `src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests`: 19/19).
- **Tier 2 Evidence**: `docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-005/tier2-api-check.json`
- **Outcome**: Unified timeline API behavior remains healthy.

## Recheck (Run-006)
- **Verified**: 2026-02-10
- **Method**: Tier 2 replay (API + integration) with deterministic suite verification.
- **Tests**: PASS (src/Timeline/__Tests/StellaOps.Timeline.Core.Tests: 7/7; src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests: 19/19).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-006/tier2-api-check.json
- **Outcome**: Checked timeline behavior remains healthy in continued replay.

## Recheck (Run-007)
- **Verified**: 2026-02-10
- **Method**: Tier 2 replay (API + integration) with deterministic suite verification.
- **Tests**: PASS (src/Timeline/__Tests/StellaOps.Timeline.Core.Tests: 7/7; src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests: 19/19).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-007/tier2-api-check.json
- **Outcome**: Checked timeline behavior remains healthy in continued replay.

## Recheck (Run-008)
- **Verified**: 2026-02-10
- **Method**: Tier 2a API replay + deterministic integration suite replay.
- **Tests**: PASS (src/Timeline/__Tests/StellaOps.Timeline.Core.Tests: 7/7, src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests: 19/19).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-008/tier2-api-check.json
- **Outcome**: Checked Timeline behavior remains healthy in continued replay.


## Recheck (Run-009)
- **Verified**: 2026-02-10
- **Method**: Tier 2a API replay + deterministic integration suite replay.
- **Tests**: PASS (src/Timeline/__Tests/StellaOps.Timeline.Core.Tests: 7/7, src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests: 19/19).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-009/tier2-api-check.json
- **Outcome**: Checked Timeline behavior remains healthy in continued replay.


## Recheck (Run-010)
- **Verified**: 2026-02-10
- **Method**: Tier 2d deterministic integration replay.
- **Tests**: PASS (Timeline.Core 7/7, Timeline.WebService 19/19; total 26/26).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-010/tier2-integration-check.json
- **Outcome**: Checked timeline behavior remains healthy in continued replay.
## Recheck (Run-011)
- **Verified**: 2026-02-10
- **Method**: Tier 2d deterministic integration replay.
- **Tests**: PASS (Timeline.Core 7/7, Timeline.WebService 19/19; total 26/26).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-011/tier2-integration-check.json
- **Outcome**: Checked timeline behavior remains healthy in continued replay.
## Recheck (Run-012)
- **Verified**: 2026-02-10
- **Method**: Tier 2 replay + deterministic integration suite replay.
- **Tests**: PASS (src/Timeline/__Tests/StellaOps.Timeline.Core.Tests: 7/7; src/Timeline/__Tests/StellaOps.Timeline.WebService.Tests: 19/19; total 26/26).
- **Tier 2 Evidence**: docs/qa/feature-checks/runs/timeline/unified-event-timeline-service/run-012/tier2-api-check.json
- **Outcome**: Checked timeline behavior remains healthy in continued replay.