fix(desktop): place steer messages before redirected replies

apps/desktop/e2e/correction-session-switch.spec.ts

@@ -26,6 +26,17 @@ async function send(page: Page, text: string): Promise<void> {
   await page.keyboard.press('Enter')
 }
 
+async function steer(page: Page, text: string): Promise<void> {
+  const composer = page.locator('[contenteditable="true"]').first()
+  const primary = page.locator('[data-slot="composer-root"] button[type="submit"]')
+
+  await composer.waitFor({ state: 'visible', timeout: 15_000 })
+  await composer.click()
+  await composer.type(text, { delay: 5 })
+  await expect(primary).toHaveAttribute('aria-label', /Steer/)
+  await primary.click()
+}
+
 async function waitForTranscriptText(page: Page, text: string): Promise<void> {
   await page.waitForFunction(
     (expected: string) => (document.querySelector('[data-slot="aui_thread-viewport"]')?.textContent ?? '').includes(expected),
@@ -61,6 +72,17 @@ async function transcriptTextOrder(page: Page): Promise<string[]> {
   })
 }
 
+async function transcriptMessageOrder(page: Page): Promise<string[]> {
+  return page.evaluate(() => {
+    const viewport = document.querySelector('[data-slot="aui_thread-viewport"]')
+    if (!viewport) return []
+
+    return Array.from(viewport.querySelectorAll<HTMLElement>('[data-role="user"], [data-role="assistant"]'))
+      .map(message => message.textContent?.trim() ?? '')
+      .filter(Boolean)
+  })
+}
+
 async function openFreshDraft(page: Page, priorSessionText: string): Promise<void> {
   await page.locator('[data-slot="sidebar"] button[aria-label="New session"]').first().click()
   await page.waitForFunction(
@@ -87,6 +109,16 @@ function relevantOrder(messages: string[]): string[] {
   return messages.filter(message => message.includes(ORIGINAL_PROMPT) || message.includes(CORRECTION))
 }
 
+function steerTurnOrder(messages: string[]): string[] {
+  return messages.flatMap(message => {
+    if (message.includes(ORIGINAL_PROMPT)) return [ORIGINAL_PROMPT]
+    if (message.includes(CORRECTION)) return [CORRECTION]
+    if (message.includes(CORRECTED_REPLY)) return [CORRECTED_REPLY]
+
+    return []
+  })
+}
+
 test.describe('correction session switch', () => {
   let fixture: MockBackendFixture | null = null
 
@@ -113,9 +145,9 @@ test.describe('correction session switch', () => {
     await waitForTranscriptText(page, TOOL_STARTED)
     await waitForTranscriptText(page, ORIGINAL_PROMPT)
 
-    // The historical session redirected while a foreground terminal task was
-    // running. Enter records the accepted correction at the next tool boundary.
-    await send(page, CORRECTION)
+    // The historical session redirects while a foreground terminal task is
+    // running. Use the visible Steer action to cover the real composer path.
+    await steer(page, CORRECTION)
     await waitForTranscriptText(page, CORRECTION)
 
     const orderBeforeSwitch = relevantOrder(await transcriptTextOrder(page))
@@ -136,5 +168,6 @@ test.describe('correction session switch', () => {
     expect(await textNodeOccurrences(page, CORRECTION)).toBe(1)
 
     await waitForTranscriptText(page, CORRECTED_REPLY)
+    expect(steerTurnOrder(await transcriptMessageOrder(page))).toEqual([ORIGINAL_PROMPT, CORRECTION, CORRECTED_REPLY])
   })
 })

apps/desktop/e2e/queue-turn-boundary.spec.ts

@@ -14,6 +14,7 @@ import { MOCK_REPLY } from './mock-server'
 
 const ACTIVE_PROMPT = 'E2E_QUEUE_TURN_BOUNDARY_ACTIVE'
 const QUEUED_PROMPT = 'E2E_QUEUE_TURN_BOUNDARY_QUEUED'
+const STEER_PROMPT = 'E2E_STEER_TURN_BOUNDARY_CORRECTION'
 
 async function send(page: Page, text: string): Promise<void> {
   const composer = page.locator('[contenteditable="true"]').first()
@@ -23,6 +24,37 @@ async function send(page: Page, text: string): Promise<void> {
   await page.keyboard.press('Enter')
 }
 
+async function steer(page: Page, text: string): Promise<void> {
+  const composer = page.locator('[contenteditable="true"]').first()
+  const primary = page.locator('[data-slot="composer-root"] button[type="submit"]')
+
+  await composer.click()
+  await composer.type(text, { delay: 5 })
+  await expect(primary).toHaveAttribute('aria-label', /Steer/)
+  await primary.click()
+}
+
+async function transcriptMessageOrder(page: Page): Promise<string[]> {
+  return page.evaluate(() => {
+    const viewport = document.querySelector('[data-slot="aui_thread-viewport"]')
+    if (!viewport) return []
+
+    return Array.from(viewport.querySelectorAll<HTMLElement>('[data-role="user"], [data-role="assistant"]'))
+      .map(message => message.textContent?.trim() ?? '')
+      .filter(Boolean)
+  })
+}
+
+function steerTurnOrder(messages: string[]): string[] {
+  return messages.flatMap(message => {
+    if (message.includes(ACTIVE_PROMPT)) return [ACTIVE_PROMPT]
+    if (message.includes(STEER_PROMPT)) return [STEER_PROMPT]
+    if (message.includes(MOCK_REPLY)) return [MOCK_REPLY]
+
+    return []
+  })
+}
+
 test.describe('queued prompt turn boundary', () => {
   let fixture: MockBackendFixture | null = null
 
@@ -66,4 +98,21 @@ test.describe('queued prompt turn boundary', () => {
     )
     await expect.poll(() => mock.receivedPrompts.filter(prompt => prompt === QUEUED_PROMPT)).toHaveLength(1)
   })
+
+  test('places a steer prompt before the reply it redirects', async () => {
+    const { mock, page } = fixture!
+
+    await send(page, ACTIVE_PROMPT)
+    await mock.waitForHeldStream()
+    await steer(page, STEER_PROMPT)
+    mock.releaseHeldStream()
+
+    await page.waitForFunction(
+      expected => (document.querySelector('[data-slot="aui_thread-viewport"]')?.textContent ?? '').includes(expected),
+      MOCK_REPLY,
+      { timeout: 60_000 }
+    )
+
+    expect(steerTurnOrder(await transcriptMessageOrder(page))).toEqual([ACTIVE_PROMPT, STEER_PROMPT, MOCK_REPLY])
+  })
 })

apps/desktop/src/app/session/hooks/use-prompt-actions/index.ts

@@ -220,7 +220,13 @@ export function usePromptActions({
   const copy = t.desktop
 
   const appendSessionTextMessage = useCallback(
-    (sessionId: string, role: ChatMessage['role'], text: string, storedSessionId?: string | null) => {
+    (
+      sessionId: string,
+      role: ChatMessage['role'],
+      text: string,
+      storedSessionId?: string | null,
+      options: { insertBeforeActiveReply?: boolean } = {}
+    ) => {
       // Strip ANSI: slash-command output from the backend worker carries SGR
       // color codes (e.g. "Unknown command" in red). The ESC byte is invisible
       // in the chat panel, so without this the `[1;31m…[0m` payload leaks as
@@ -231,21 +237,33 @@ export function usePromptActions({
         return
       }
 
+      const messageId = `${role}-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`
+
       updateSessionState(
         sessionId,
-        state => ({
-          ...state,
-          messages: [
-            ...state.messages,
-            {
-              id: `${role}-${Date.now()}-${Math.random().toString(36).slice(2, 8)}`,
-              role,
-              parts: [textPart(body)]
-            }
-          ]
-        }),
+        state => {
+          const message: ChatMessage = {
+            id: messageId,
+            role,
+            parts: [textPart(body)]
+          }
+          const streamIndex = options.insertBeforeActiveReply && state.streamId
+            ? state.messages.findIndex(candidate => candidate.id === state.streamId)
+            : -1
+          const lastAssistantIndex = options.insertBeforeActiveReply
+            ? state.messages.map(candidate => candidate.role).lastIndexOf('assistant')
+            : -1
+          const insertionIndex = streamIndex >= 0 ? streamIndex : lastAssistantIndex
+          const messages = insertionIndex >= 0
+            ? [...state.messages.slice(0, insertionIndex), message, ...state.messages.slice(insertionIndex)]
+            : [...state.messages, message]
+
+          return { ...state, messages }
+        },
         storedSessionId ?? selectedStoredSessionIdRef.current
       )
+
+      return messageId
     },
     [selectedStoredSessionIdRef, updateSessionState]
   )
@@ -620,15 +638,49 @@ export function usePromptActions({
       // message after the interrupted checkpoint, matching the durable core
       // transcript rather than a system note that changes role after reload.
       const send = async (id: string): Promise<boolean> => {
-        const result = await requestGateway<SessionRedirectResponse>('session.redirect', { session_id: id, text })
+        // Redirect aborts the model request, so the completion event can race
+        // its RPC response. Insert before the live reply *before* awaiting the
+        // gateway; appending after the response leaves the correction below a
+        // reply that the redirect has already replaced.
+        const messageId = appendSessionTextMessage(id, 'user', text, undefined, { insertBeforeActiveReply: true })
+        const discardOptimisticMessage = () =>
+          updateSessionState(id, state => ({
+            ...state,
+            messages: state.messages.filter(message => message.id !== messageId)
+          }))
+        const moveOptimisticMessageToEnd = () =>
+          updateSessionState(id, state => {
+            const message = state.messages.find(candidate => candidate.id === messageId)
+
+            return message
+              ? { ...state, messages: [...state.messages.filter(candidate => candidate.id !== messageId), message] }
+              : state
+          })
 
-        if (result?.status === 'redirected' || result?.status === 'queued') {
-          triggerHaptic('submit')
-          appendSessionTextMessage(id, 'user', text)
+        try {
+          const result = await requestGateway<SessionRedirectResponse>('session.redirect', { session_id: id, text })
+
+          if (result?.status === 'redirected') {
+            triggerHaptic('submit')
+
+            return true
+          }
 
-          return true
+          if (result?.status === 'queued') {
+            // Build-window redirects become the next turn, not part of the
+            // active reply, so retain the optimistic row at the tail.
+            moveOptimisticMessageToEnd()
+            triggerHaptic('submit')
+
+            return true
+          }
+        } catch (err) {
+          discardOptimisticMessage()
+          throw err
         }
 
+        discardOptimisticMessage()
+
         return false
       }
 
@@ -661,7 +713,7 @@ export function usePromptActions({
 
       return false
     },
-    [activeSessionId, activeSessionIdRef, appendSessionTextMessage, requestGateway, selectedStoredSessionIdRef]
+    [activeSessionId, activeSessionIdRef, appendSessionTextMessage, requestGateway, selectedStoredSessionIdRef, updateSessionState]
   )
 
   const reloadFromMessage = useCallback(