fix: refresh magic notes after external updates

Subscribe the open Magic Notes workspace to committed database changes from desktop and Agent/MCP writes. Preserve selections and unsaved drafts during refresh and external deletion.

File-level commit includes existing runtime edits in shared files; their remaining dependencies are still in the working tree.

Release note: Magic Notes now updates automatically after Agent/MCP edits while preserving your selection and unsaved drafts.

docs/features/magic-notes/README.md

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+# Magic Notes
+
+Magic Notes is the local notes, checklist and AI-comment workbench. Desktop
+actions and authorized Agent/MCP tools write to the same desktop SQLite store.
+The open workbench subscribes to successful writes so users can see external
+changes without leaving the page or clicking a refresh button.
+
+## Documents
+
+- [Technical design](./technical-design.md): database notifications, process
+  boundaries, refresh lifecycle and regression coverage.
+- [Progress](./progress.md): implementation and validation evidence.
+- [UI design system](../../../UI-DESIGN.md#137-魔法笔记): authoritative workbench
+  interaction rules, including selection and draft preservation.
+
+An entry is a saved rich-text record within a note. A todo is a checklist item
+derived from an entry. An unsaved draft belongs to the open editor; it is not
+written to storage by a background refresh.

docs/features/magic-notes/progress.md

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+# Magic Notes Progress
+
+## 2026-09-15: Automatic External Refresh
+
+- Implemented the shared-database notification and Main/preload subscription
+  described in [technical design](./technical-design.md).
+- The open workbench reloads external changes while retaining current selection
+  and unsaved drafts. Deleted notes and edited entries retain drafts with an
+  explicit explanation. The cancelled manual-refresh proposal is not implemented.
+- An initial completed `npm test` run passed 357 files and 4,201 tests, with
+  9 files and 67 tests skipped (680.45 seconds). The first invocation had exceeded
+  the command tool's 120-second limit.
+- After three additional renderer race/retry tests, the final `npm test` run
+  reported 355 files and 4,202 tests passed, 9 files and 67 tests skipped, and two
+  unrelated timeout failures: the large offline dependency inventory test in
+  `tests/agent-package.test.ts` (60 seconds), and the two-project OpenCode case in
+  `src/main/agent/local-runtime-reuse.test.ts` (40-second request timeout).
+- Rerunning those two files together passed 24 tests with one skipped in
+  103.71 seconds, without source or timeout changes. The final renderer/preload
+  focused run also passed all 38 tests. No Magic Notes regression failed.
+- `npm run typecheck` and `npm run lint`: passed. The new required subscription
+  method is also present in the application test API fixture.
+- Validation uses production SQLite and Agent/MCP gateway code, the production
+  preload with mocked Electron transport, and renderer interaction tests. An
+  interactive Electron window was not exercised. No deployed Agent code or
+  desktop-to-Agent protocol changed, so no separate Linux Host scenario applies.

docs/features/magic-notes/technical-design.md

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+# Magic Notes Technical Design
+
+## Change Notifications
+
+`AssistantDatabase` accepts `onMagicNotesChanged: () => void`. Every successful
+note/entry create, update or delete emits once after the write commits, including
+empty-note creation, initial content, title/pin updates and cascading deletion.
+Saved note analysis, todo completion, saved todo analysis and assistant-data
+clearing also emit. Revision conflicts, missing rows, rolled-back writes and
+unchanged todo completion do not emit. Startup schema migrations run before the
+workbench loads and do not publish notifications.
+
+Desktop IPC and `KnowledgeMcpGateway` use this same database instance. The latter
+also serves Agent tools; no tool-specific notification or daemon protocol change
+is needed. Raw SQL writes from an unrelated process are outside this callback
+contract.
+
+Main queues notification delivery to the live window on `magic-notes:changed`.
+The typed preload method `magicNotes.onChanged(listener)` exposes no Electron
+objects and returns a function removing that listener. The existing
+`onTodoStatusChanged` event remains the separate sidebar-count signal.
+
+## Refresh Lifecycle
+
+`MagicNotesWorkspace` subscribes on mount and coalesces notifications with a
+100 ms debounce. Pending notifications wait for an active local save or analysis
+to finish. Cleanup removes the listener, clears its timer and invalidates pending
+refresh results. This does not introduce periodic database polling.
+
+The existing list/detail loader reloads notes and todos, then the preferred note.
+Request counters reject superseded results and preserve newer user selections.
+Todo selection survives list reordering while the item exists; replacing the todo
+snapshot also reloads the selected todo's source entry. Search, filters and layout
+state are not reset.
+
+Background application of a detail reads the current draft state after the
+asynchronous fetch. A dirty title is retained, and the composer is not remounted.
+An entry editor uses its original editing content and revision for both its React
+key and save request; external revisions cannot remount it or bypass optimistic
+concurrency checks. Deleted entries remain displayed only while their editor is
+open. If an externally deleted note has a draft, its editor remains available
+with a deletion explanation instead of moving the draft to another note.
+
+Read failures use the existing retryable refresh error and retain successful
+data and drafts. Retry uses the same draft-preserving loader. Interaction rules
+are owned by [the UI design system](../../../UI-DESIGN.md#137-魔法笔记).
+
+## Validation
+
+- `assistant-database.test.ts` checks committed writes with a second SQLite
+  connection, successful mutation coverage, failures, no-op completion and reset.
+- `knowledge-mcp-gateway.test.ts` exercises real database CRUD through Agent/MCP
+  access, including revision failure without an extra notification.
+- `magic-notes-events.test.ts` executes the production preload, checking the
+  channel, payload-free callback and listener removal.
+- `MagicNotesWorkspace.test.tsx` covers external updates and deletion, selection,
+  source reload, editor identity and draft saves, coalescing, deferred writes,
+  asynchronous selection races, error retry and unmount cleanup.
+
+No schema migration, dependency, refresh control or network service is added.