fix(mobile): preserve authoritative chat state

mobile/src/session/mobile-native-chat-stream-frame.test.ts

@@ -120,6 +120,27 @@ describe('applyMobileNativeChatStreamFrame', () => {
     })
   })
 
+  it('replaces retained history when replay metadata says no earlier rows remain', () => {
+    const merger = createNativeChatMerger()
+    replaceList(merger, ['removed-1', 'removed-2', 'a', 'b'].map(message))
+
+    const replay = [message('a'), message('b')]
+    expect(
+      applyMobileNativeChatStreamFrame({
+        merger,
+        frame: { type: 'snapshot', messages: replay, hasMore: false, beforeOffset: 0 },
+        limit: 100,
+        replaceSnapshot: false
+      })
+    ).toEqual({
+      kind: 'messages',
+      messages: replay,
+      hasMore: false,
+      beforeOffset: 0,
+      windowReplaced: true
+    })
+  })
+
   it('keeps the pagination cursor when an append does not trim history', () => {
     const merger = createNativeChatMerger()
     replaceList(merger, [message('a')])

mobile/src/session/mobile-native-chat-stream-frame.ts

@@ -27,12 +27,18 @@ export type AppliedMobileNativeChatFrame =
 
 function replayExtendsRetainedTail(
   merger: NativeChatMerger,
-  messages: readonly NativeChatMessage[]
+  messages: readonly NativeChatMessage[],
+  hasMore: boolean | undefined
 ): boolean {
   const firstIndex = messages[0] ? merger.indexById.get(messages[0].id) : undefined
   if (firstIndex === undefined) {
     return false
   }
+  // `hasMore: false` is authoritative: retained rows before the replay window
+  // were removed while disconnected, even when the newest IDs still match.
+  if (hasMore === false && firstIndex > 0) {
+    return false
+  }
   let expectedIndex = firstIndex
   let sawNewMessage = false
   for (const message of messages) {
@@ -77,7 +83,7 @@ export function applyMobileNativeChatStreamFrame(args: {
     frame.type === 'snapshot' &&
     !replaceSnapshot &&
     merger.list.length > 0 &&
-    replayExtendsRetainedTail(merger, frame.messages)
+    replayExtendsRetainedTail(merger, frame.messages, frame.hasMore)
   if (frame.type === 'replacement' || (frame.type === 'snapshot' && !replayExtendsHistory)) {
     replaceList(merger, frame.messages)
     return {

mobile/src/session/use-mobile-native-chat-ask-dismiss.test.ts

@@ -104,9 +104,14 @@ describe('useMobileNativeChatAskDismiss', () => {
     // The same question on another tab is a different pending prompt.
     await update({ prompt: first, scopeKey: 'tab-2' })
     expect(state?.showAsk).toBe(true)
+    act(() => state?.dismissAsk())
+    expect(state?.showAsk).toBe(false)
 
-    // Returning to the dismissing tab keeps it hidden.
+    // Dismissing tab 2 must not overwrite tab 1's dismissal.
     await update({ prompt: first, scopeKey: 'tab-1' })
     expect(state?.showAsk).toBe(false)
+
+    await update({ prompt: first, scopeKey: 'tab-2' })
+    expect(state?.showAsk).toBe(false)
   })
 })

mobile/src/session/use-mobile-native-chat-ask-dismiss.ts

@@ -23,20 +23,28 @@ export function useMobileNativeChatAskDismiss(args: {
 } {
   const { ask, scopeKey, observing } = args
   const askKey = ask ? JSON.stringify(ask.questions) : null
-  const [dismissed, setDismissed] = useState<{ scope: string | null; key: string } | null>(null)
+  const [dismissedByScope, setDismissedByScope] = useState<Map<string | null, string>>(
+    () => new Map()
+  )
   // Once the prompt clears while observable (agent moved on), forget the
   // dismissal so a later question — even an identical one — shows again.
   const askPresent = ask != null
   useEffect(() => {
     if (observing && !askPresent) {
-      setDismissed((prev) => (prev !== null && prev.scope === scopeKey ? null : prev))
+      setDismissedByScope((previous) => {
+        if (!previous.has(scopeKey)) {
+          return previous
+        }
+        const next = new Map(previous)
+        next.delete(scopeKey)
+        return next
+      })
     }
   }, [observing, askPresent, scopeKey])
-  const showAsk =
-    askPresent && !(dismissed !== null && dismissed.scope === scopeKey && dismissed.key === askKey)
+  const showAsk = askPresent && dismissedByScope.get(scopeKey) !== askKey
   const dismissAsk = (): void => {
     if (askKey !== null) {
-      setDismissed({ scope: scopeKey, key: askKey })
+      setDismissedByScope((previous) => new Map(previous).set(scopeKey, askKey))
     }
   }
 

mobile/src/session/use-mobile-native-chat-session.test.ts

@@ -222,6 +222,36 @@ describe('useMobileNativeChatSession', () => {
     expect(state?.messages.at(-1)?.id).toBe('live-1')
   })
 
+  it('drops paged rows that an authoritative replay says were removed', async () => {
+    const sendRequest = vi.fn().mockResolvedValue({
+      ok: true,
+      result: {
+        messages: Array.from({ length: 60 }, (_unused, index) => message(`paged-${index}`)),
+        hasMore: false,
+        beforeOffset: 40
+      }
+    })
+    const window = Array.from({ length: 40 }, (_unused, index) => message(`win-${index}`))
+    const subscribe: RpcClient['subscribe'] = vi.fn((_method, _params, onData) => {
+      emit = onData
+      onData({ type: 'snapshot', messages: window, hasMore: true, beforeOffset: 100 })
+      return () => {}
+    })
+    await mount({ sendRequest, subscribe } as unknown as RpcClient)
+    await act(async () => {
+      state?.loadEarlier()
+      await Promise.resolve()
+    })
+    expect(state?.messages).toHaveLength(100)
+
+    await act(async () =>
+      emit({ type: 'snapshot', messages: window, hasMore: false, beforeOffset: 0 })
+    )
+
+    expect(state?.messages).toEqual(window)
+    expect(state?.hasMore).toBe(false)
+  })
+
   it('surfaces a failed older-history page and clears it on a retry', async () => {
     const sendRequest = vi
       .fn()