# Three-Pane Layout (Categories/Items/Proof)

## Module
Web

## Status
IMPLEMENTED

## Description
The compare feature implements a three-pane layout with categories, items, and proof panes for side-by-side comparison of scans/policies.

## Implementation Details
- **Feature directory**: `src/Web/StellaOps.Web/src/app/features/triage/`
- **Components**:
  - `ai-code-guard-badge` (`src/Web/StellaOps.Web/src/app/features/triage/components/ai-code-guard-badge/ai-code-guard-badge.component.ts`)
  - `ai-recommendation-panel` (`src/Web/StellaOps.Web/src/app/features/triage/components/ai-recommendation-panel/ai-recommendation-panel.component.ts`)
  - `attestation-viewer` (`src/Web/StellaOps.Web/src/app/features/triage/components/attestation-viewer/attestation-viewer.component.ts`)
  - `bulk-action-modal` (`src/Web/StellaOps.Web/src/app/features/triage/components/bulk-action-modal/bulk-action-modal.component.ts`)
  - `case-header` (`src/Web/StellaOps.Web/src/app/features/triage/components/case-header/case-header.component.ts`)
  - `decision-drawer-enhanced` (`src/Web/StellaOps.Web/src/app/features/triage/components/decision-drawer/decision-drawer-enhanced.component.ts`)
  - `decision-drawer` (`src/Web/StellaOps.Web/src/app/features/triage/components/decision-drawer/decision-drawer.component.ts`)
  - `attestation-chain` (`src/Web/StellaOps.Web/src/app/features/triage/components/evidence-panel/attestation-chain.component.ts`)
  - `backport-verdict-badge` (`src/Web/StellaOps.Web/src/app/features/triage/components/evidence-panel/backport-verdict-badge.component.ts`)
  - `binary-diff-tab` (`src/Web/StellaOps.Web/src/app/features/triage/components/evidence-panel/binary-diff-tab.component.ts`)
  - `confidence-meter` (`src/Web/StellaOps.Web/src/app/features/triage/components/evidence-panel/confidence-meter.component.ts`)
  - `diff-tab` (`src/Web/StellaOps.Web/src/app/features/triage/components/evidence-panel/diff-tab.component.ts`)
  - `dsse-badge` (`src/Web/StellaOps.Web/src/app/features/triage/components/evidence-panel/dsse-badge.component.ts`)
  - `evidence-uri-link` (`src/Web/StellaOps.Web/src/app/features/triage/components/evidence-panel/evidence-uri-link.component.ts`)
  - `function-trace` (`src/Web/StellaOps.Web/src/app/features/triage/components/evidence-panel/function-trace.component.ts`)
  - ... and 48 more components
- **Services**:
  - `advisory-ai` (`src/Web/StellaOps.Web/src/app/features/triage/services/advisory-ai.service.ts`)
  - `binary-diff-evidence` (`src/Web/StellaOps.Web/src/app/features/triage/services/binary-diff-evidence.service.ts`)
  - `diff-evidence` (`src/Web/StellaOps.Web/src/app/features/triage/services/diff-evidence.service.ts`)
  - `display-preferences` (`src/Web/StellaOps.Web/src/app/features/triage/services/display-preferences.service.ts`)
  - `evidence-tab` (`src/Web/StellaOps.Web/src/app/features/triage/services/evidence-tab.service.ts`)
  - `gating` (`src/Web/StellaOps.Web/src/app/features/triage/services/gating.service.ts`)
  - `keyboard-shortcuts` (`src/Web/StellaOps.Web/src/app/features/triage/services/keyboard-shortcuts.service.ts`)
  - `reach-graph-slice` (`src/Web/StellaOps.Web/src/app/features/triage/services/reach-graph-slice.service.ts`)
  - `reachability` (`src/Web/StellaOps.Web/src/app/features/triage/services/reachability.service.ts`)
  - `runtime-evidence` (`src/Web/StellaOps.Web/src/app/features/triage/services/runtime-evidence.service.ts`)
- **Models**:
  - `src/Web/StellaOps.Web/src/app/features/triage/models/diff-evidence.models.ts`
  - `src/Web/StellaOps.Web/src/app/features/triage/models/evidence-panel.models.ts`
  - `src/Web/StellaOps.Web/src/app/features/triage/models/evidence.model.ts`
  - `src/Web/StellaOps.Web/src/app/features/triage/models/gating.model.ts`
  - `src/Web/StellaOps.Web/src/app/features/triage/models/reachability.models.ts`
- **Source**: Feature matrix scan

## E2E Test Plan
- **Setup**:
  - [ ] Log in with a user that has appropriate permissions
  - [ ] Navigate to `/triage/artifacts`
  - [ ] 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)