perf(desktop): keep transcript state incremental

apps/desktop/e2e/streaming-remount.spec.ts

@@ -21,8 +21,10 @@ test('remounting a live surface leaves accumulated output settled', async ({
   const sidebar = page.getByRole('navigation', { name: '对话列表' });
   await sidebar.getByRole('button', { name: '扩展' }).click();
   await expect(page.locator('[data-module="skills"]')).toBeVisible();
+  await expect(liveBubble).toHaveCount(0);
   await sidebar.getByRole('button', { name: '会话', exact: true }).click();
-  await liveBubble.waitFor({ state: 'attached' });
+  await expect(liveBubble).toHaveCount(1);
+  await expect(liveBubble).toContainText(accumulatedOutput);
 
   expect((await liveBubble.textContent())?.split(accumulatedOutput)).toHaveLength(2);
   expect(
@@ -46,7 +48,8 @@ test('remounting a live surface leaves accumulated output settled', async ({
   const steering = 'trigger rewrite after returning to this conversation';
   await composer.fill(steering);
   await composer.press('Enter');
-  await expect(liveBubble).toContainText('<redacted> NEW');
+  const finalText = 'prefix <redacted> NEW streamed after the remount';
+  await expect(liveBubble).toContainText(finalText);
 
   const observed = await page.evaluate(() => (
     window as typeof window & {
@@ -55,9 +58,8 @@ test('remounting a live surface leaves accumulated output settled', async ({
       };
     }
   ).__makaStreamingRemountObserved);
-  expect(observed?.texts.some((text) =>
-    text.includes('<redacted>') && !text.includes('NEW')
-  )).toBe(true);
+  expect(observed?.texts.some((text) => text.includes('<redacted>') && !text.includes(finalText)))
+    .toBe(true);
 });
 
 test('returning to a live conversation settles output accumulated while away', async ({

apps/desktop/src/main/__tests__/app-shell-first-send-cleanup.test.ts

@@ -18,6 +18,7 @@ import { describe, it } from 'node:test';
 
 import type { SessionSummary } from '@maka/core/session';
 import type { LiveTurnProjection } from '@maka/ui';
+import type { DesktopTranscriptRangeController } from '../../renderer/desktop-transcript-range-store.js';
 import { createAppShellChatActions } from '../../renderer/app-shell-chat-actions.js';
 import { createAppShellSessionUiStateController } from '../../renderer/app-shell-session-ui-state.js';
 import { settledSessionTransientIds } from '../../renderer/settled-session-transients.js';
@@ -81,6 +82,7 @@ function createActionsDeps() {
     setMessageLoadErrorBySession: () => undefined,
     setMessageRetryPendingBySession: () => undefined,
     setMessages: () => undefined,
+    transcriptRangeRef: { current: undefined },
     setNavSelection: () => undefined,
     setLiveTurnBySession: () => undefined,
     setInteractionBySession: () => undefined,
@@ -144,7 +146,6 @@ describe('composer first-send cleanup', () => {
           attachments: [],
           skillInvocation: { loaded: [], failed: [] },
         }),
-        readMessages: async () => [],
       },
     });
 
@@ -181,7 +182,6 @@ describe('composer first-send cleanup', () => {
           attachments: [],
           skillInvocation: { loaded: [], failed: [] },
         }),
-        readMessages: async () => [],
       },
     });
 
@@ -232,7 +232,6 @@ describe('composer first-send cleanup', () => {
         remove: async (sessionId: string) => {
           removed.push(sessionId);
         },
-        readMessages: async () => [],
       },
     });
 
@@ -273,6 +272,46 @@ describe('composer first-send cleanup', () => {
 
     assert.deepEqual(removed, []);
   });
+
+  it('returns a sparse existing session to latest before sending', async () => {
+    const latest = deferred<void>();
+    const order: string[] = [];
+    const activeIdRef = { current: 'existing-session' as string | undefined };
+    const transcript = {
+      store: {
+        range: () => ({ sessionId: 'existing-session', hasNewer: true }),
+        snapshot: () => ({ messages: [] }),
+      },
+      async loadLatest() {
+        order.push('latest');
+        await latest.promise;
+      },
+    } as unknown as DesktopTranscriptRangeController;
+    const transcriptRangeRef = { current: transcript as DesktopTranscriptRangeController | undefined };
+    const restoreWindow = installWindow({
+      sessions: {
+        send: async () => {
+          order.push('send');
+          return { ok: true, attachments: [], skillInvocation: { loaded: [], failed: [] } };
+        },
+      },
+    });
+
+    try {
+      const sending = createAppShellChatActions({
+        ...createActionsDeps(),
+        activeIdRef,
+        transcriptRangeRef,
+      }).send('hello');
+      await new Promise((resolve) => setImmediate(resolve));
+      assert.deepEqual(order, ['latest']);
+      latest.resolve();
+      assert.equal(await sending, true);
+      assert.deepEqual(order, ['latest', 'send']);
+    } finally {
+      restoreWindow();
+    }
+  });
 });
 
 function deferred<T>() {
@@ -389,23 +428,15 @@ describe('composer send failure feedback', () => {
 describe('a send in flight versus a stale session list', () => {
   const sessionId = 'session-a';
 
-  // Echoes the sent turn back through `readMessages`, which is what `send()`
-  // waits on before it reports success — a window that never shows the user
-  // message would time the send out rather than exercise the race.
   function sendingWindow() {
-    let sentTurnId: string | undefined;
     return {
       sessions: {
         create: async () => ({ id: sessionId }),
-        send: async (_sessionId: string, command: { turnId: string }) => {
-          sentTurnId = command.turnId;
-          return { ok: true, attachments: [], skillInvocation: { loaded: [], failed: [] } };
-        },
-        readMessages: async () => (
-          sentTurnId
-            ? [{ type: 'user', id: `user-${sentTurnId}`, turnId: sentTurnId, ts: 1, text: 'hello' }]
-            : []
-        ),
+        send: async () => ({
+          ok: true,
+          attachments: [],
+          skillInvocation: { loaded: [], failed: [] },
+        }),
       },
     };
   }