fix(gui): tail history page carries the full-log todo projection

The client's todos projection derived only from the paged display window,
so reopening a session whose last todo/write preceded the tail page showed
an empty plan until the user paged back — session-level state cannot be
reconstructed from an arbitrary window. The host owns the full log, so the
tail history response now attaches todos (latest todo/write backscan, the
same posture as the view pairing); installWindow seeds it, window rebuilds
preserve it, and any in-window or live write keeps overwriting it. The
fixture mirrors the host; docs and both Agent Notes record the mechanism.

packages/client/runtime/README.md

@@ -1,6 +1,6 @@
 # @deepseek-ai/dsh-client-runtime
 
-Client cordis boot + core services: SlotsService (Service wrapper over SlotCore + 'slots/changed' bridge), SessionsService (list store projection, scope tree, bindings, ancestry), the Session object layer (exported as a type; instances are owned and handed out by SessionsService — the manager/paging internals stay package-internal, tests reach them via src), ClientLoader (`./loader` subpath, statically held by the shell). Contract: api-contracts v3 §4. `ConversationSnapshot` carries `todos` — the latest `todo/write` whole-list snapshot in the window, consumed as a per-event side effect (last write wins) and reset on every window rebuild.
+Client cordis boot + core services: SlotsService (Service wrapper over SlotCore + 'slots/changed' bridge), SessionsService (list store projection, scope tree, bindings, ancestry), the Session object layer (exported as a type; instances are owned and handed out by SessionsService — the manager/paging internals stay package-internal, tests reach them via src), ClientLoader (`./loader` subpath, statically held by the shell). Contract: api-contracts v3 §4. `ConversationSnapshot` carries `todos` — the session-level todo projection: seeded from the tail history page's full-log projection (`history` response `todos`), overwritten by every in-window or live `todo/write` (last write wins), and preserved across window rebuilds.
 
 ## Session title projection
 
@@ -19,4 +19,4 @@ None; this package neither assembles nor sends a provider request.
 - **`loader.unload` is a stub (throws not-implemented)** — the full chain (fiber dispose → registration cascade → style removal) lands with the HMR project.
 - **Scope teardown is stage-driven, single-occupant today** — the staged session follows `list.current` exactly (staging is the open signal: the event window opens ⟺ the session is on stage); a removed-while-staged session's scope survives frozen until the stage moves on, not until true observer count reaches zero. Resolution (`cell()`/`binding()`/`scope()`) is pure addressing, render-safe. The staged state can widen to a multi-pane list when concurrent panes land.
 - **Value imports of this package from plugin bundles must use the `/client` subpath** — the bare package name is not in the loader externals table and inlines a second module instance, whose private scope-tag Symbol never matches (the empty-state P0 postmortem).
-- **`todos` is window-scoped** — the projection scans only the paged display window, so reopening a session whose last `todo/write` precedes the tail page shows an empty plan until the user pages back to it. Restoring the tool's cold-load reconstruction promise needs the current projection independent of the window (host-attached on history, or a dedicated read).
+- **`SessionSummary.title` is a display projection** — the wire summary carries no title yet; the cwd basename stands in, then the raw id.

packages/client/runtime/src/client/sessions/session.ts

@@ -327,13 +327,13 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
         this.openError = result.error
         return
       }
-      this.installWindow(result.value.events, result.value.hasMore)
+      this.installWindow(result.value.events, result.value.hasMore, result.value.todos)
       // Gap detection (§D.3-4): baseline past the window tail and liveBuffer did not cover it -> pull the tail page once more.
       const tailSeq = this.windowTailSeq()
       if (this.subscribedLastSeq !== null && tailSeq !== null && this.subscribedLastSeq > tailSeq) {
         result = (await this.api.sessions.history({ sessionId: this.sessionId, maxMessages: PAGE_MESSAGES })).result
         if (generation !== this.openGeneration) return
-        if (result.ok) this.installWindow(result.value.events, result.value.hasMore)
+        if (result.ok) this.installWindow(result.value.events, result.value.hasMore, result.value.todos)
       }
       this.openState = 'open'
     } catch (error) {
@@ -351,11 +351,15 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
    *  Stitching MUST NOT route through acceptLiveEvent: openState is still 'loading' here
    *  (doOpen flips it after install), so recursing would push every buffered event straight
    *  back into liveBuffer where nothing ever drains it — a silent drop loop (audit S1). */
-  private installWindow(entries: HistoryEntry[], hasMore: boolean): void {
+  private installWindow(entries: HistoryEntry[], hasMore: boolean, todos?: readonly TodoItem[]): void {
     this.events = entries.map(e => e.event)
     this.views = entries.map(e => e.view)
     this.baseSeq = this.events[0]?.seq ?? 0
     this.hasMore = hasMore
+    // Session-level projection from the tail page (full-log latest todo/write,
+    // independent of the window); an in-window write below re-derives the same
+    // value, and later live events keep overwriting it.
+    if (todos !== undefined) this.todos = todos
     this.foldAdapter.reset(this.events, this.baseSeq, this.views)
     this.rebuildDerivedFromWindow()
     const buffered = this.liveBuffer
@@ -494,14 +498,16 @@ export class Session implements ObservableSnapshot<ConversationSnapshot> {
 
   /** Re-derive state (partial/openCalls/frozenNodes) from raw window events after a rebuild — keeps
    *  paging/stitching consistent, and makes the live freeze and the history replay converge on the
-   *  same interrupted nodes (chunks are logged, so the replayed sweep re-freezes identical text). */
+   *  same interrupted nodes (chunks are logged, so the replayed sweep re-freezes identical text).
+   *  todos is deliberately NOT reset: it is session-level (seeded by the tail page's full-log
+   *  projection, not derivable from an arbitrary window). The window always extends to the log
+   *  tail, so an in-window todo/write can only overwrite it with the same latest value. */
   private rebuildDerivedFromWindow(): void {
     this.partial = null
     this.openCalls.clear()
     this.callsRev++
     this.frozenNodes = []
     this.frozenRev++
-    this.todos = []
     for (let i = 0; i < this.events.length; i++) {
       const event = this.events[i]
       /* v8 ignore next -- dense-array guard: i stays within events.length, so the undefined arm needs a sparse array no caller builds. */

packages/client/runtime/tests/fake-api.ts

@@ -47,7 +47,7 @@ export class FakeApiClient implements IApiClient {
   onList: (payload: unknown) => Promise<RpcResponse<{ items: never[] }>> = () => Promise.resolve(ok({ items: [] }))
   onCreate: (payload: unknown) => Promise<RpcResponse<{ sessionId: SessionId }>> = () => Promise.resolve(ok({ sessionId: 'fk-new' as SessionId }))
   onHistory: (payload: { sessionId: SessionId; beforeSeq?: number; maxMessages?: number })
-  => Promise<RpcResponse<{ events: never[]; hasMore: boolean }>> =
+  => Promise<RpcResponse<{ events: never[]; hasMore: boolean; todos?: { content: string; status: 'pending' | 'in_progress' | 'completed' }[] }>> =
     () => Promise.resolve(ok({ events: [], hasMore: false }))
 
   onPrompt: (payload: unknown) => Promise<RpcResponse<{ accepted: true }>> = () => Promise.resolve(ok({ accepted: true as const }))

packages/client/runtime/tests/session.spec.ts

@@ -22,9 +22,9 @@ function makeSession(api = new FakeApiClient()): { api: FakeApiClient; session:
   return { api, session: new Session(SID, api) }
 }
 
-function histResponse(events: SessionEvent[], hasMore = false) {
+function histResponse(events: SessionEvent[], hasMore = false, todos?: { content: string; status: 'pending' | 'in_progress' | 'completed' }[]) {
   // history now returns HistoryEntry[] ({event, view?}); these tests are view-less.
-  return Promise.resolve(ok({ events: entries(events) as never[], hasMore }))
+  return Promise.resolve(ok({ events: entries(events) as never[], hasMore, ...todos === undefined ? {} : { todos } }))
 }
 
 describe('open', () => {
@@ -170,6 +170,25 @@ describe('live event path', () => {
     expect(replayed.session.getSnapshot().todos).toEqual(listB)
   })
 
+  it('seeds todos from the tail page projection when the last write precedes the window', async () => {
+    const list = [{ content: '窗口外的计划', status: 'in_progress' as const }]
+    // Cold open: the page window carries NO todo/write; the projection rides the response.
+    const { api, session } = makeSession()
+    api.onHistory = () => histResponse(plainTurn(100, 9, '问', '答'), true, list)
+    await session.open()
+    expect(session.getSnapshot().todos).toEqual(list)
+    // Paging an older window in must not clear the session-level projection.
+    api.onHistory = () => histResponse(plainTurn(94, 8, '旧问', '旧答'), false)
+    await session.loadOlder()
+    expect(session.getSnapshot().todos).toEqual(list)
+    // A later live write still overrides the seeded projection.
+    session.handleMuxEnvelope('r' as never, {
+      type: 'session/event', sessionId: SID,
+      event: ev.todoWrite(106, [{ content: '新计划', status: 'pending' as const }]),
+    })
+    expect(session.getSnapshot().todos).toEqual([{ content: '新计划', status: 'pending' }])
+  })
+
   it('repairs a seq gap by repulling the tail page instead of appending a hole', async () => {
     const { api, session } = await opened(plainTurn(0, 0, 'a', 'b')) // tail seq = 5
     const repaired = [...plainTurn(0, 0, 'a', 'b'), ...plainTurn(6, 1, 'c', 'd')]