fix(native-chat): the host-window timer waits only for windows still open

A window that had already closed while the journal was still loading would arm a zero-delay timer
that re-armed itself every tick. Only windows still open arm one now; a closed one is settled when
the journal loads. Adds a test that a Stop-outrun send comes back once its window closes.

src/renderer/src/components/native-chat/structured-agent-session-outbox-journal-settlement.ts

@@ -63,16 +63,18 @@ export function settleStructuredAgentSessionOutboxFromJournal(
   return entries
 }
 
-/** When the soonest host window closes among entries only an owed answer settles, or null. */
+/** When the soonest host window still open closes among entries only an owed answer settles, or
+ *  null. One already closed waits for the journal to load, which re-runs the settlement anyway. */
 export function nextStructuredAgentSessionHostWindowEnd(
-  entries: readonly StructuredAgentSessionOutboxEntry[]
+  entries: readonly StructuredAgentSessionOutboxEntry[],
+  now: number
 ): number | null {
   let soonest: number | null = null
   for (const entry of entries) {
     const endsAt = structuredAgentSessionEntryAwaitsSettlement(entry)
       ? structuredAgentSessionEntryHostWindowEndsAt(entry)
       : null
-    if (endsAt !== null && (soonest === null || endsAt < soonest)) {
+    if (endsAt !== null && endsAt >= now && (soonest === null || endsAt < soonest)) {
       soonest = endsAt
     }
   }

src/renderer/src/components/native-chat/use-structured-agent-session-outbox.stop-stamp.test.tsx

@@ -11,6 +11,9 @@ import type {
   AgentJournalSubmission
 } from '../../../../shared/agent-session-journal-types'
 import { createStructuredAgentSessionOutboxEntry } from '../../../../shared/structured-agent-session-outbox'
+import { createStructuredAgentSessionOperationId } from '../../../../shared/structured-agent-session-mutation'
+import { AGENT_SESSION_MAX_OPERATION_REPLAY_AGE_MS } from '../../../../shared/agent-session-host-authority'
+import { createBrowserUuid } from '@/lib/browser-uuid'
 
 type SentParams = { envelope: { clientOperationId: string }; delivery?: string }
 
@@ -260,6 +263,26 @@ describe('a Stop answered while the journal is already read through it', () => {
   })
 })
 
+describe("the host's window for a send a Stop outran", () => {
+  it('hands it back to check the chat once the window closes, though nothing else moved', async () => {
+    const id = createStructuredAgentSessionOperationId(
+      createBrowserUuid,
+      Date.now() - AGENT_SESSION_MAX_OPERATION_REPLAY_AGE_MS + 5_000
+    )
+    seedAttempted({ clientMessageId: id, stoppedBy: { operationId: 'stop-1' } })
+    const view = mount({ fence: 1, submissions: [], journalCursor: { epoch: 'e', sequence: 3 } })
+    expect(view.result.current.outbox).toHaveLength(1)
+
+    await act(async () => {
+      await vi.advanceTimersByTimeAsync(6_000)
+    })
+    expect(view.result.current.outbox).toEqual([])
+    expect(readNativeChatDraftCache(SCOPE)).toBe('follow-up')
+    expect(view.result.current.error).toBe(CHECK_THE_CHAT)
+    expect(mocks.call).not.toHaveBeenCalled()
+  })
+})
+
 describe('a send in doubt behind one a Stop outran', () => {
   it('is the one resent: the queue waits on it, not on the stamped one', async () => {
     const later = {

src/renderer/src/components/native-chat/use-structured-agent-session-outbox.ts

@@ -171,13 +171,13 @@ export function useStructuredAgentSessionOutbox(args: {
     }
     // A send only an owed answer settles must still end when the host's window for it closes,
     // though nothing else moves by then.
-    const windowEnd = nextStructuredAgentSessionHostWindowEnd(entries)
+    const windowEnd = nextStructuredAgentSessionHostWindowEnd(entries, now)
     if (windowEnd === null) {
       return
     }
     const timer = setTimeout(
       () => setHostWindowsClosed((count) => count + 1),
-      Math.min(Math.max(windowEnd - now + 1, 0), MAX_TIMER_DELAY_MS)
+      Math.min(windowEnd - now + 1, MAX_TIMER_DELAY_MS)
     )
     return () => clearTimeout(timer)
   }, [