fix(native-chat): text sent to a new agent claims an empty starting chat only in its own split

Notes sent from the right-hand split could land in, and focus, an empty chat still starting in the
left-hand one. A request with text now claims an empty starting chat only in the tab group it opens
in, the same rule a request without text follows; elsewhere it opens its own chat there.

src/renderer/src/lib/structured-agent-session-empty-chat-reuse.test.ts

@@ -103,7 +103,10 @@ vi.mock('@/store', () => ({
   }
 }))
 
-import { appendStructuredAgentSessionOutboxMessage } from '@/components/native-chat/structured-agent-session-outbox-storage'
+import {
+  appendStructuredAgentSessionOutboxMessage,
+  readOutbox
+} from '@/components/native-chat/structured-agent-session-outbox-storage'
 import {
   appendNativeChatAttachmentCache,
   clearNativeChatAttachmentCacheForTests
@@ -452,6 +455,34 @@ describe('a "new chat" with text', () => {
     })
   })
 
+  it('opens its own chat in its own split beside an empty chat starting in another', () => {
+    mocks.launch.mockImplementation(() => new Promise(() => undefined))
+    const blank = pick('plus-pick-1', { group: 'group-left' })
+
+    const notes = pick('notes-send', { prompt: 'review notes', group: 'group-right' })
+
+    expect(notes.sessionId).toBe(second.sessionId)
+    expect(
+      store.state.unifiedTabsByWorktree[WORKTREE_ID]?.find(
+        (tab) => tab.entityId === second.sessionId
+      )?.groupId
+    ).toBe('group-right')
+    expect(mocks.focusGroup).not.toHaveBeenCalled()
+    expect(readOutbox(blank.sessionId)).toEqual([])
+    expect(readOutbox(second.sessionId).map((entry) => entry.body.blocks)).toEqual([
+      [{ type: 'text', text: 'review notes' }]
+    ])
+  })
+
+  it('takes an empty chat starting in its own split', () => {
+    mocks.launch.mockImplementation(() => new Promise(() => undefined))
+    const blank = pick('plus-pick-1', { group: 'group-right' })
+
+    expect(pick('notes-send', { prompt: 'review notes', group: 'group-right' }).sessionId).toBe(
+      blank.sessionId
+    )
+  })
+
   it('takes an empty chat still starting, as before', () => {
     mocks.launch.mockImplementation(() => new Promise(() => undefined))
     const blank = pick('plus-pick-1')

src/renderer/src/lib/structured-agent-session-launch-holders.ts

@@ -67,8 +67,8 @@ export function claimableStructuredLaunchAttempt(
   return request.hasText ? emptyStructuredLaunchAttempt(state) : undefined
 }
 
-/** The launch a new start of `request` joins: one it re-delivers, else an empty starting chat, which
- *  a request with text claims and one without reuses in its own tab group. The newest wins. */
+/** The launch a new start of `request` joins: one it re-delivers, else an empty starting chat in the
+ *  tab group it opens in, which a request with text claims and one without reuses. The newest wins. */
 export function getJoinableStructuredLaunchState(
   identity: string,
   request: StructuredLaunchRequest
@@ -79,8 +79,7 @@ export function getJoinableStructuredLaunchState(
     structuredLaunchesHoldingIdentity(matches).findLast(
       (state) =>
         emptyStructuredLaunchAttempt(state) &&
-        (request.hasText ||
-          !request.groupId ||
+        (!request.groupId ||
           structuredChatTabGroupId(state.intent.worktreeId, state.intent.sessionId) ===
             request.groupId)
     )