fix(native-chat): handle reordering with timestampless transcripts (#10050)

Grok transcripts carry no timestamps. Previous logic excluded these rows
from matching, leaving pending sends and launch prompts unmatched and
causing the seeded bubble to appear rank-pinned at the list tail — which
reads as conversation reordering.

Now pending sends, launch prompts, and their pruning rules treat null
timestamps as matching-eligible, allowing echo suppression and proper
cleanup of delivered messages.

src/renderer/src/components/native-chat/native-chat-pending.test.ts

@@ -134,6 +134,16 @@ describe('prunePendingSends', () => {
     expect(prunePendingSends(pending, [oldUser, oldAnswer])).toEqual(pending)
   })
 
+  it('prunes a first send against a timestampless transcript turn (grok)', () => {
+    const pending = [{ ...pendingOf('p1', 'rename it'), afterMessageId: null }]
+    const transcript = [
+      { ...userMessage('u1', 'rename it'), timestamp: null },
+      { ...assistantMessage('a1', 'done'), timestamp: null }
+    ]
+
+    expect(prunePendingSends(pending, transcript)).toEqual([])
+  })
+
   it('prunes only one of two identical pending sends for one completed turn', () => {
     const pending = [pendingOf('p1', 'repeat'), pendingOf('p2', 'repeat')]
     expect(
@@ -246,6 +256,14 @@ describe('pendingSendsAsMessages', () => {
     expect(prunePendingSends(pending, remoteTranscript)).toEqual([])
   })
 
+  it('hides a first send while its timestampless transcript turn is visible (grok)', () => {
+    const pending = [{ ...pendingOf('p1', 'rename it'), afterMessageId: null }]
+
+    expect(
+      pendingSendsAsMessages(pending, [{ ...userMessage('u1', 'rename it'), timestamp: null }])
+    ).toEqual([])
+  })
+
   it('hides only one of two identical pending sends for one real user turn', () => {
     const pending = [pendingOf('p1', 'repeat'), pendingOf('p2', 'repeat')]
     expect(pendingSendsAsMessages(pending, [userMessage('u1', 'repeat')]).map((m) => m.id)).toEqual(
@@ -340,6 +358,20 @@ describe('launchPromptAsMessage', () => {
     ).toBe(true)
   })
 
+  // Grok transcripts carry no timestamps; before the null-matchable rule the
+  // seeded bubble was never hidden or pruned and sat rank-pinned at the list
+  // tail forever, reading as the conversation reordering.
+  it('hides and prunes the launch prompt against a timestampless transcript (grok)', () => {
+    const entry = { tabId: 'tab-1', agent: 'grok' as const, text: 'rename it', createdAt: 42 }
+    const transcript = [
+      { ...userMessage('u1', 'rename it'), timestamp: null },
+      { ...assistantMessage('a1', 'done'), timestamp: null }
+    ]
+
+    expect(launchPromptAsMessage(entry, transcript)).toBeNull()
+    expect(shouldPruneLaunchPrompt(entry, transcript)).toBe(true)
+  })
+
   it('does not bind a launch prompt to an older identical completed turn', () => {
     const entry = {
       tabId: 'tab-1',

src/renderer/src/components/native-chat/native-chat-pending.ts

@@ -111,8 +111,11 @@ function messageIsAfterPendingTimestamp(
   message: NativeChatMessage,
   pending: NativeChatPendingSend
 ): boolean {
+  // Why: some transcripts (e.g. Grok) never carry timestamps. Excluding their
+  // rows would make the echo unmatchable forever, stranding a rank-pinned
+  // bubble at the list tail — which reads as the conversation reordering.
   if (message.timestamp === null) {
-    return false
+    return true
   }
   const boundary = nativeChatPendingMatchingAfter(pending)
   // A transcript-clock boundary describes an existing message, so exclude ties.
@@ -231,9 +234,11 @@ export function launchPromptAsMessage(
   if (!entry) {
     return null
   }
+  // Why: a launch prompt seeds a brand-new session, so a matching user turn
+  // with no timestamp (e.g. Grok transcripts) can only be its own delivery.
   const represented = matchingNativeChatUserContentCounts(
     existingMessages.filter(
-      (message) => message.timestamp !== null && message.timestamp >= entry.createdAt
+      (message) => message.timestamp === null || message.timestamp >= entry.createdAt
     )
   )
   if ((represented.get(nativeChatPendingContentKey(entry)) ?? 0) > 0) {
@@ -256,7 +261,7 @@ export function shouldPruneLaunchPrompt(
   messages: NativeChatMessage[]
 ): boolean {
   const relevant = messages.filter(
-    (message) => message.timestamp !== null && message.timestamp >= entry.createdAt
+    (message) => message.timestamp === null || message.timestamp >= entry.createdAt
   )
   return (
     (advancedNativeChatUserContentCounts(relevant).get(nativeChatPendingContentKey(entry)) ?? 0) > 0