semi implemented and features implemented save checkpoint

docs/features/unchecked/web/visual-graph-diff-with-change-highlights.md

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+# Visual Graph Diff with Change Highlights
+
+## Module
+Web
+
+## Status
+IMPLEMENTED
+
+## Description
+Full graph diff component with change type highlighting (added/removed/changed), layout engine, split-view, connected element detection, and Storybook stories. Originally marked TODO in advisory but now implemented.
+
+## Implementation Details
+- **Feature directory**: `src/Web/StellaOps.Web/src/app/shared/components/graph-diff/`
+- **Components**:
+  - `graph-diff` (`src/Web/StellaOps.Web/src/app/shared/components/graph-diff/graph-diff.component.ts`)
+  - `graph-split-view` (`src/Web/StellaOps.Web/src/app/shared/components/graph-diff/graph-split-view.component.ts`)
+- **Models**:
+  - `src/Web/StellaOps.Web/src/app/shared/components/graph-diff/graph-diff.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 side-by-side comparison view renders correctly with two versions
+  - [ ] Verify additions, removals, and changes are visually highlighted
+  - [ ] Verify diff data matches the expected delta between versions
+- **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)