partly or unimplemented features - now implemented

docs/features/unchecked/web/sbom-graph-reachability-overlay-with-time-slider.md

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+# SBOM Graph Reachability Overlay with Time Slider
+
+## Module
+Web
+
+## Status
+IMPLEMENTED
+
+## Description
+Reachability halo overlay on SBOM graph visualization with time slider for temporal reachability exploration and state legend. Uses deterministic stub data pending fixture bundle.
+
+## What's Implemented
+- **Existing components**:
+  - `graph-canvas` (`src/Web/StellaOps.Web/src/app/features/graph/graph-canvas.component.ts`)
+  - `graph-explorer` (`src/Web/StellaOps.Web/src/app/features/graph/graph-explorer.component.ts`)
+  - `graph-filters` (`src/Web/StellaOps.Web/src/app/features/graph/graph-filters.component.ts`)
+  - `graph-hotkey-help` (`src/Web/StellaOps.Web/src/app/features/graph/graph-hotkey-help.component.ts`)
+  - `graph-overlays` (`src/Web/StellaOps.Web/src/app/features/graph/graph-overlays.component.ts`)
+  - `graph-side-panels` (`src/Web/StellaOps.Web/src/app/features/graph/graph-side-panels.component.ts`)
+- **Existing services**:
+  - `graph-accessibility` (`src/Web/StellaOps.Web/src/app/features/graph/graph-accessibility.service.ts`)
+
+## What's Missing
+- **Reachability halo overlay**: Graph overlay components exist but no dedicated reachability state halo (color-coded rings around nodes showing lattice state: SR/SU/RO/RU/CR/CU/X)
+- **Time slider for temporal reachability**: No time slider component enabling temporal exploration of how reachability states evolved over scan/signal events
+- **Lattice state legend**: No legend component mapping halo colors to reachability lattice states
+- **Backend API for temporal reachability**: No API endpoint returning reachability state snapshots at different points in time
+- **Deterministic fixture bundle**: Currently uses stub data; pending fixture bundle with real reachability overlay data
+
+## Implementation Plan
+- Add reachability state halo overlay to graph-overlays component using lattice state colors
+- Create time slider component for temporal reachability exploration
+- Add lattice state legend component
+- Build backend API for temporal reachability snapshots
+- Wire overlay to live reachability data via graph service
+
+## E2E Test Plan
+- **Setup**:
+  - [ ] Log in with a user that has appropriate permissions
+  - [ ] Navigate to `/graph`
+  - [ ] Ensure test data exists (scanned artifacts, SBOM data, or seed data as needed)
+- **Core verification**:
+  - [ ] Verify the visualization renders correctly with sample data
+  - [ ] Verify interactive elements (hover tooltips, click-to-drill-down) work
+  - [ ] Verify the visualization handles empty/minimal data gracefully
+- **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)