# Sidebar Layout Persistence Review

## Verdict
SHIP

## Block-level findings
None. The implementation is robust and follows the established patterns for localStorage usage in this codebase.

## Ship-with-followup findings
None.

## Nits
None.

## What was checked
- **A. sidebar-storage.ts correctness**: 
    - `loadSidebarPanels` correctly handles all failure modes (missing key, malformed JSON, non-array types, and mixed-type arrays) without throwing. It returns a defensive shallow copy of the default layout.
    - `saveSidebarPanels` is best-effort and safely swallows any storage errors (e.g., QuotaExceededError or SecurityError).
    - The localStorage key `dispatch-sidebar-panels` is correctly namespaced.
- **B. SidebarPanel.svelte integration**:
    - Initialization correctly seeds the `panels` state using `loadSidebarPanels()`.
    - The `$effect` correctly captures all changes to the `panels` array (addition, removal, and selection changes) due to the reactive read in the map function.
    - Session-ephemeral `id` fields are correctly regenerated and not persisted, avoiding potential collisions across sessions.
    - The 'minimum 1 panel' invariant is preserved by the existing UI logic (`{#if idx > 0}`) and reinforced by the storage fallback.
- **C. Test coverage**:
    - The unit tests in `sidebar-storage.test.ts` are comprehensive, covering initial load, valid round-trips, corruption, malformed data, filtering, and storage exceptions.
    - Verified mutation isolation (fresh array on each load).
- **D. Regression risks**:
    - Add/remove and dropdown handlers are preserved and correctly trigger persistence via state reassignment.
    - No infinite loops or race conditions identified; the `$effect` is one-way (state -> localStorage).
- **E. Stylistic / consistency**:
    - Matches the `dispatch-` prefix pattern seen in `config.ts`.
    - Documentation and comments are thorough and clear.

## What was NOT checked
- Persistence of the `sidebarOpen` toggle (explicitly out of scope).
- Drag-to-reorder support (not implemented in the UI).
- Backend synchronization (feature designed for per-device localStorage).
