# Causal Timeline with Critical Path and Event Detail

## Module
Web

## Status
VERIFIED

## Description
Full-featured causal timeline view with lane-based event visualization (D3.js, one lane per service), critical path highlighting, event detail panel, evidence links, timeline export, filtering, HLC range picker, and forensic export button. Supports correlation ID-based navigation for tracing release pipeline events. (Merged with Timeline UI Component from Phase 2 (none) section.)

## Implementation Details
- **Feature directory**: `src/Web/StellaOps.Web/src/app/features/timeline/`
- **Routes**: `timeline.routes.ts`
- **Components**:
  - `causal-lanes` (`src/Web/StellaOps.Web/src/app/features/timeline/components/causal-lanes/causal-lanes.component.ts`)
  - `critical-path` (`src/Web/StellaOps.Web/src/app/features/timeline/components/critical-path/critical-path.component.ts`)
  - `event-detail-panel` (`src/Web/StellaOps.Web/src/app/features/timeline/components/event-detail-panel/event-detail-panel.component.ts`)
  - `evidence-links` (`src/Web/StellaOps.Web/src/app/features/timeline/components/evidence-links/evidence-links.component.ts`)
  - `export-button` (`src/Web/StellaOps.Web/src/app/features/timeline/components/export-button/export-button.component.ts`)
  - `timeline-filter` (`src/Web/StellaOps.Web/src/app/features/timeline/components/timeline-filter/timeline-filter.component.ts`)
  - `timeline-page` (`src/Web/StellaOps.Web/src/app/features/timeline/pages/timeline-page/timeline-page.component.ts`)
- **Services**:
  - `timeline` (`src/Web/StellaOps.Web/src/app/features/timeline/services/timeline.service.ts`)
- **Models**:
  - `src/Web/StellaOps.Web/src/app/features/timeline/models/timeline.models.ts`
- **Source**: Feature matrix scan

## E2E Test Plan
- **Setup**:
  - [ ] Log in with a user that has appropriate permissions
  - [ ] Navigate to the relevant page/section where this feature appears
  - [ ] Ensure test data exists (scanned artifacts, SBOM data, or seed data as needed)
- **Core verification**:
  - [ ] Verify the component renders correctly with sample data
  - [ ] Verify interactive elements respond to user input
  - [ ] Verify data is fetched and displayed from the correct API endpoints
- **Edge cases**:
  - [ ] Verify graceful handling when backend API is unavailable (error state)
  - [ ] Verify responsive layout at different viewport sizes
  - [ ] Verify accessibility (keyboard navigation, screen reader labels, ARIA attributes)

## Verification
- Date: 2026-02-10
- Run artifacts: docs/qa/feature-checks/runs/web/causal-timeline-with-critical-path-and-event-detail/run-001/
- Tier results:
  - tier0-source-check.json: pass
  - tier1-build-check.json: pass
  - tier2-e2e-check.json: pass