semi implemented and features implemented save checkpoint

docs/features/unchecked/web/gate-explain-drawer.md

@@ -0,0 +1,30 @@
+# Gate Explain Drawer
+
+## Module
+Web
+
+## Status
+IMPLEMENTED
+
+## Description
+Slide-in drawer explaining why a policy gate passed or failed, showing each rule evaluation, evidence inputs, and what would need to change for a different outcome.
+
+## Implementation Details
+- **Feature directory**: `src/Web/StellaOps.Web/src/app/shared/overlays/gate-explain-drawer/`
+- **Components**:
+  - `gate-explain-drawer` (`src/Web/StellaOps.Web/src/app/shared/overlays/gate-explain-drawer/gate-explain-drawer.component.ts`)
+- **Source**: SPRINT_20260118_009_FE_route_migration_shared_components.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)