# VEX Merge Panel Three-Column Layout

## Module
Web

## Status
VERIFIED

## Description
Three-column VEX merge panel (source A / merged result / source B) with inline conflict resolution, lattice-based merge visualization, and trust provenance annotations. Enhances the existing VEX merge workflow with side-by-side comparison.

## Implementation Details
- **Feature directory**: `src/Web/StellaOps.Web/src/app/features/vex-studio/components/vex-merge-panel/`
- **Components**:
  - `vex-merge-panel` (`src/Web/StellaOps.Web/src/app/features/vex-studio/components/vex-merge-panel/vex-merge-panel.component.ts`)
- **Behavior coverage**:
  - `src/Web/StellaOps.Web/src/tests/vex_studio/vex-merge-panel-three-column-layout.behavior.spec.ts`
- **Source**: batch_38/file_16.md

## 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 panel/drawer opens on trigger (click, keyboard shortcut)
  - [ ] Verify the panel displays the correct detail data for the selected item
  - [ ] Verify the panel can be closed (X button, Escape key, backdrop click)
- **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
- Run ID: `docs/qa/feature-checks/runs/web/vex-merge-panel-three-column-layout/run-001/`
- Date (UTC): 2026-02-11
- Tier 0: PASS (component/spec paths and symbols verified; dossier path note captured for inline-template implementation).
- Tier 1: PASS (`npm run test` focused + regression include suite: 38 files / 174 tests; `npm run build` passed with baseline warnings).
- Tier 2: PASS (three-column layout rendering, deterministic row ordering/date formatting, provenance actions, and edge state behavior verified via Angular behavior harness).