fix(desktop): drop stale inflight-journal folds that duplicate answers

apps/desktop/src/lib/inflight-turn-journal.test.ts

@@ -183,7 +183,7 @@ describe('recoverInFlightTurnJournal', () => {
     ])
 
     const base = [user('u0', 'earlier turn'), assistant('a0', 'earlier reply')]
-    const result = recoverInFlightTurnJournal('stored-1', base)
+    const result = recoverInFlightTurnJournal('stored-1', base, { keepPending: true })
 
     expect(result.applied).toBe(true)
     expect(result.messages.map(m => m.id)).toEqual(['u0', 'a0', 'u1', 'assistant-stream-1'])
@@ -283,6 +283,76 @@ describe('recoverInFlightTurnJournal', () => {
     expect(merged.id).toBe('assistant-stream-rt9')
     expect(merged.parts[1]).toMatchObject({ type: 'text', text: 'a much longer locally journaled partial answer' })
   })
+
+  // ── Scrambled-transcript regression (duplicate trailing answers) ───────────
+  // The journal can outlive the turn it recorded (reclaim/reconnect/restart
+  // races skip the settle that would clear it). On resume the fold then
+  // re-appends content that the committed transcript ALREADY holds, rendering
+  // the same answers twice at the end of the conversation. Reported on the
+  // desktop as "the answer was already there, but it was inputted again".
+
+  it('does not re-append committed answers when the journaled user row never persisted', () => {
+    // A resume projection can journal a `user-inflight-*` row that was never
+    // written to the DB (and may even belong to a different conversation).
+    // Because no base user matches it, the fold used to treat the whole tail
+    // as unknown and append it — duplicating the assistant answers below.
+    journalEntry([
+      user('user-inflight-a3c2beb1', 'a stray user bubble that never persisted'),
+      assistant('assistant-stream-1', 'the committed answer')
+    ])
+
+    const base = [user('db-u1', 'the real prompt'), assistant('db-a1', 'the committed answer')]
+    const result = recoverInFlightTurnJournal('stored-1', base, { keepPending: false })
+
+    expect(result.caughtUp).toBe(true)
+    expect(result.applied).toBe(false)
+    expect(result.messages).toBe(base)
+    expect(result.messages.map(m => m.id)).toEqual(['db-u1', 'db-a1'])
+    // The stale entry is cleared so the next resume stays clean.
+    expect(readInFlightTurnJournal('stored-1')).toBeNull()
+  })
+
+  it('does not re-append committed answers when the journal tail has no user row', () => {
+    // A tail captured after a partial hydrate can end on assistant rows with
+    // no user prompt before them. The old code appended them verbatim, so the
+    // transcript ended with a duplicate of an answer that was already settled.
+    journalEntry([assistant('assistant-stream-1', 'the committed answer')])
+
+    const base = [user('db-u1', 'the real prompt'), assistant('db-a1', 'the committed answer')]
+    const result = recoverInFlightTurnJournal('stored-1', base, { keepPending: false })
+
+    expect(result.caughtUp).toBe(true)
+    expect(result.messages).toBe(base)
+    expect(readInFlightTurnJournal('stored-1')).toBeNull()
+  })
+
+  it('keeps appending a genuinely unknown turn (crash recovery still works)', () => {
+    // The staleness check must not swallow a tail the base never saw: that is
+    // the crash-recovery path the journal exists for.
+    journalEntry([user('u1', 'the live prompt'), assistant('assistant-stream-1', 'partial answer', { pending: true })])
+
+    const base = [user('db-u0', 'an earlier turn'), assistant('db-a0', 'earlier reply')]
+    const result = recoverInFlightTurnJournal('stored-1', base, { keepPending: true })
+
+    expect(result.applied).toBe(true)
+    expect(result.caughtUp).toBe(false)
+    expect(result.messages.map(m => m.id)).toEqual(['db-u0', 'db-a0', 'u1', 'assistant-stream-1'])
+    expect(readInFlightTurnJournal('stored-1')).not.toBeNull()
+  })
+
+  it('does not resurrect the journal streamId on a not-running resume (journal self-clear)', () => {
+    // The fold used to carry the stale entry's streamId onto the resumed state
+    // even when the backend reported the session idle. persistInFlightTurnState
+    // then re-wrote the journal instead of clearing it, so the same stale tail
+    // was folded again on every open — the scramble never healed.
+    journalEntry([user('u1', 'do the thing'), assistant('assistant-stream-1', 'partial answer', { pending: true })])
+
+    const base = [user('db-u0', 'an earlier turn'), assistant('db-a0', 'earlier reply')]
+    const result = recoverInFlightTurnJournal('stored-1', base, { keepPending: false })
+
+    expect(result.applied).toBe(true)
+    expect(result.streamId).toBeNull()
+  })
 })
 
 describe('mergeInFlightMessages', () => {

apps/desktop/src/lib/inflight-turn-journal.ts

@@ -376,6 +376,32 @@ function withoutBaseIds(rows: ChatMessage[], baseMessages: ChatMessage[]): ChatM
   return rows.filter(row => !baseIds.has(row.id))
 }
 
+/** Whether every recoverable assistant row in the journal tail already exists
+ *  as committed text in the base transcript. When true, the journal outlived
+ *  the turn it recorded and appending it would re-render the same answers at
+ *  the end of the transcript (the "scrambled conversation" regression). */
+function journalTailAlreadyCommitted(tailAssistants: ChatMessage[], baseMessages: ChatMessage[]): boolean {
+  const recoverable = tailAssistants.filter(assistantHasRecoverableContent)
+
+  if (recoverable.length === 0) {
+    return false
+  }
+
+  const baseTexts = new Set(
+    baseMessages
+      .filter(message => message.role === 'assistant' && !message.hidden)
+      .map(message => normalizedText(chatMessageText(message)))
+  )
+
+  return recoverable.every(message => {
+    const text = normalizedText(chatMessageText(message))
+
+    // Error-only rows carry no text to verify against — keep the conservative
+    // append path rather than risk dropping a recoverable failure.
+    return text.length > 0 && baseTexts.has(text)
+  })
+}
+
 export function mergeInFlightMessages(
   baseMessages: ChatMessage[],
   tailMessages: ChatMessage[],
@@ -402,15 +428,27 @@ export function mergeInFlightMessages(
   const matchingUserIndex = tailUser ? baseMessages.findLastIndex(message => userMessagesMatch(message, tailUser)) : -1
 
   if (matchingUserIndex < 0) {
-    // Base doesn't know this turn at all (user row was never persisted):
-    // append the whole tail.
+    // No base user matches the tail's user row (a projected user-inflight row
+    // that never persisted, or a tail captured without its user prompt). If the
+    // tail's answers are already committed in the transcript, the journal is
+    // stale — appending it would re-render the same replies at the end of the
+    // conversation. Otherwise, the base never saw this turn at all: append the
+    // whole tail (the crash-recovery path the journal exists for).
+    if (journalTailAlreadyCommitted(tailAssistants, baseMessages)) {
+      return { ...noop, caughtUp: true }
+    }
+
     const streamId = lastJournalRow?.id ?? null
 
     return {
       applied: true,
       caughtUp: false,
       messages: [...baseMessages, ...withoutBaseIds(tail, baseMessages)],
-      streamId,
+      // Only a genuinely running turn keeps a live stream target. On an idle
+      // resume, carrying the stale streamId would keep the journal entry alive
+      // (persistInFlightTurnState only clears when streamId is null) and the
+      // same tail would be folded again on every open.
+      streamId: options.keepPending ? streamId : null,
       turnStartedAt: null
     }
   }
@@ -464,7 +502,16 @@ export function mergeInFlightMessages(
     ...baseMessages.slice(projectionIndex + 1)
   ]
 
-  return { applied: true, caughtUp: false, messages, streamId: merged.id, turnStartedAt: null }
+  return {
+    applied: true,
+    caughtUp: false,
+    messages,
+    // Same idle-resume rule as the append path: only a running turn keeps the
+    // stream target alive, so an idle resume clears the journal instead of
+    // re-folding the same tail on every open.
+    streamId: options.keepPending ? merged.id : null,
+    turnStartedAt: null
+  }
 }
 
 const persistTimers = new Map<string, ReturnType<typeof setTimeout>>()
@@ -570,7 +617,11 @@ export function recoverInFlightTurnJournal(
 
   return {
     ...recovered,
-    streamId: recovered.applied ? (recovered.streamId ?? snapshot.streamId) : null,
+    // Never resurrect a stale stream target on an idle resume: with
+    // keepPending=false the session is not running, so the recovered rows are
+    // settled history and the journal must clear on the next state update —
+    // otherwise the same stale tail is folded again on every open.
+    streamId: recovered.applied ? (recovered.streamId ?? (options.keepPending ? snapshot.streamId : null)) : null,
     turnStartedAt: recovered.applied ? snapshot.turnStartedAt : null
   }
 }

contributors/emails/nformenton@Nicolass-MacBook-Air.local

@@ -0,0 +1,2 @@
+Nicolas-Formenton
+# PR #84137 / #84021 (desktop fixes from a second machine)