diff --git a/web/e2e/document-revision-runtime.spec.ts b/web/e2e/document-revision-runtime.spec.ts
index 05789337..aa4b85a9 100644
--- a/web/e2e/document-revision-runtime.spec.ts
+++ b/web/e2e/document-revision-runtime.spec.ts
@@ -392,20 +392,20 @@ async function waitForSquadCompletion(
   if (verdict.action === 'reject') {
     fail(`squad observation rejected: ${verdict.reason}`);
   }
+  if (verdict.action === 'accept') {
+    return Date.now() - startedAt;
+  }
+
+  await expect(assistant).toHaveAttribute('data-chat-status', ANY_TERMINAL_STATUS_RE, {
+    timeout: timeoutMs,
+  });
+  verdict = await observe();
+  if (verdict.action === 'reject') {
+    fail(`squad observation rejected: ${verdict.reason}`);
+  }
   if (verdict.action !== 'accept') {
-    await expect(assistant).toHaveAttribute('data-chat-status', ANY_TERMINAL_STATUS_RE, {
-      timeout: timeoutMs,
-    });
-    verdict = await observe();
-    if (verdict.action === 'reject') {
-      fail(`squad observation rejected: ${verdict.reason}`);
-    }
-    if (verdict.action !== 'accept') {
-      fail(`squad terminal not accepted: ${verdict.reason}`);
-    }
+    fail(`squad terminal not accepted: ${verdict.reason}`);
   }
-  // Terminal assistant status can race ahead of InputArea isStreaming; drain stop/send.
-  await ensureChatComposerIdle(page, Math.min(60_000, Math.max(5_000, timeoutMs)));
   return Date.now() - startedAt;
 }
 
@@ -521,25 +521,15 @@ async function readReviewerIntakeDuty(page: Page, docId?: string): Promise<strin
 }
 
 async function ensureChatComposerIdle(page: Page, timeoutMs = 60_000) {
-  // Squad terminal can land while InputArea isStreaming is still true; the
-  // composer then swaps "发送 (Enter)" for "停止当前生成" and blocks the next turn.
+  // Product fix: orphan streaming_status no longer locks send once runtime is idle.
+  // Still click stop if present, then wait for the send affordance.
   const stopBtn = page.getByRole('button', { name: '停止当前生成' });
-  await expect
-    .poll(
-      async () => {
-        if (await stopBtn.isVisible().catch(() => false)) {
-          await stopBtn.click();
-        }
-        const stopLeft = await stopBtn.count();
-        const streamingHint = await page
-          .getByText('生成中，点击停止按钮可中止当前回复')
-          .count();
-        const sendReady = await page.getByRole('button', { name: /发送 \(Enter\)/ }).count();
-        return stopLeft === 0 && streamingHint === 0 && sendReady > 0;
-      },
-      { timeout: timeoutMs, intervals: [200, 500, 1000] },
-    )
-    .toBe(true);
+  if (await stopBtn.isVisible().catch(() => false)) {
+    await stopBtn.click();
+  }
+  await expect(page.getByRole('button', { name: /发送 \(Enter\)/ })).toBeVisible({
+    timeout: timeoutMs,
+  });
 }
 
 async function sendChat(page: Page, text: string) {
diff --git a/web/src/App.tsx b/web/src/App.tsx
index 534fb5bc..00a3b3dd 100644
--- a/web/src/App.tsx
+++ b/web/src/App.tsx
@@ -11,6 +11,10 @@ import {
 } from './lib/createProjectSubmitGuard';
 import { mapApiMembersToProjectMembers } from './lib/projectMemberAdapter';
 import { resolveCurrentDocRole } from './lib/currentDocRole';
+import {
+  COMPOSER_INFLIGHT_STATUSES,
+  resolveChatComposerStreaming,
+} from './lib/chatComposerStreaming';
 import {
   decideModificationProposal,
 } from './api/docgov';
@@ -113,6 +117,7 @@ import { fetchChatCategories, fetchChatDates } from './api/chatWindow';
 import { ChatCategoryStat, ChatDateStat, QuotedMessage } from './types/workbench';
 import { saveFile } from './data/fileStore';
 import { cancelTaskRun, getTaskRun } from './api/taskRuns';
+import { cancelInflightAssistantMessages } from './lib/squadCompletionObservation';
 import { useRecoveredTaskPhases } from './hooks/useRecoveredTaskPhases';
 
 export {
@@ -1150,14 +1155,21 @@ export default function App() {
     setActiveQuotes((prev) => prev.filter((_, i) => i !== index));
   };
 
-  // 当前会话是否存在正在等待/流式/自动重试中的助手气泡 (驱动 InputArea 停止态)
-  const isStreamingActive = useMemo(() => {
-    return currentSessionMessages.some(
-      (m) =>
-        m.role === 'assistant' &&
-        (m.status === 'pending' || m.status === 'streaming_status' || m.status === 'auto_retrying')
-    );
-  }, [currentSessionMessages]);
+  // 当前会话是否存在正在等待/流式/自动重试中的助手气泡 (驱动 InputArea 停止态)。
+  // 孤儿 streaming_status（任务已终态但气泡未愈合）不得继续锁住发送。
+  const isStreamingActive = useMemo(
+    () =>
+      resolveChatComposerStreaming(currentSessionMessages, {
+        turnLive: turnRuntime.isThinking,
+        taskRunLive: taskRunStream.isThinking || Boolean(taskRunStream.activeTaskRunId),
+      }),
+    [
+      currentSessionMessages,
+      turnRuntime.isThinking,
+      taskRunStream.isThinking,
+      taskRunStream.activeTaskRunId,
+    ],
+  );
 
   // 处理交互卡片动作流转 (驳回门禁确认、撤回、取消与终审联动)
   const handleCardAction = useCardActions({
@@ -1203,7 +1215,7 @@ export default function App() {
     applyControlledInvalidationPlan,
   });
 
-  // 用户主动停止：仅中止当前 session 的活跃 turn
+  // 用户主动停止：仅中止当前 session 的活跃 turn，并结算仍挂在 inflight 的孤儿气泡。
   const handleStopStreaming = () => {
     turnRuntime.abortActiveSessionTurns();
     taskRunStream.abortSession(activeSessionId);
@@ -1212,6 +1224,14 @@ export default function App() {
       void cancelTaskRun(runId).catch(() => undefined);
       taskRunStream.setRunId(activeSessionId, null);
     }
+    const inflight = COMPOSER_INFLIGHT_STATUSES as readonly string[];
+    setMessages((prev) =>
+      prev.map((m) =>
+        m.role === 'assistant' && m.status && inflight.includes(m.status)
+          ? { ...m, status: 'cancelled' as const }
+          : m,
+      ),
+    );
   };
 
   const handleLogout = () => {
diff --git a/web/src/lib/chatComposerStreaming.test.ts b/web/src/lib/chatComposerStreaming.test.ts
new file mode 100644
index 00000000..e97faa53
--- /dev/null
+++ b/web/src/lib/chatComposerStreaming.test.ts
@@ -0,0 +1,52 @@
+import assert from 'node:assert/strict';
+import { describe, it } from 'node:test';
+import { resolveChatComposerStreaming } from './chatComposerStreaming';
+
+describe('resolveChatComposerStreaming', () => {
+  it('is false when no inflight assistant bubbles', () => {
+    assert.equal(
+      resolveChatComposerStreaming(
+        [
+          { role: 'user', status: 'completed' },
+          { role: 'assistant', status: 'completed' },
+        ],
+        { turnLive: true, taskRunLive: true },
+      ),
+      false,
+    );
+  });
+
+  it('is true when inflight bubble and live turn', () => {
+    assert.equal(
+      resolveChatComposerStreaming(
+        [{ role: 'assistant', status: 'streaming_status' }],
+        { turnLive: true, taskRunLive: false },
+      ),
+      true,
+    );
+  });
+
+  it('is true when inflight bubble and live task run', () => {
+    assert.equal(
+      resolveChatComposerStreaming(
+        [{ role: 'assistant', status: 'pending' }],
+        { turnLive: false, taskRunLive: true },
+      ),
+      true,
+    );
+  });
+
+  it('is false for orphan streaming_status after runtime cleared', () => {
+    assert.equal(
+      resolveChatComposerStreaming(
+        [
+          { role: 'assistant', status: 'streaming_status' },
+          { role: 'user', status: 'completed' },
+          { role: 'assistant', status: 'completed' },
+        ],
+        { turnLive: false, taskRunLive: false },
+      ),
+      false,
+    );
+  });
+});
diff --git a/web/src/lib/chatComposerStreaming.ts b/web/src/lib/chatComposerStreaming.ts
new file mode 100644
index 00000000..f26dc1be
--- /dev/null
+++ b/web/src/lib/chatComposerStreaming.ts
@@ -0,0 +1,40 @@
+/** Message statuses that historically locked the chat composer send button. */
+export const COMPOSER_INFLIGHT_STATUSES = [
+  'pending',
+  'streaming_status',
+  'auto_retrying',
+] as const;
+
+export type ComposerInflightStatus = (typeof COMPOSER_INFLIGHT_STATUSES)[number];
+
+export type ComposerStreamingMessage = {
+  role?: string;
+  status?: string;
+};
+
+export type ComposerStreamingRuntime = {
+  /** True when a turn AbortController / thinking flag is live for this session. */
+  turnLive: boolean;
+  /** True when a task-run stream is live (thinking or retained run id). */
+  taskRunLive: boolean;
+};
+
+/**
+ * Whether InputArea should show stop / block send.
+ *
+ * Orphan assistant bubbles can stay in streaming_status after the squad run
+ * already finished (live runtime cleared). Those must not keep locking send.
+ */
+export function resolveChatComposerStreaming(
+  messages: readonly ComposerStreamingMessage[],
+  runtime: ComposerStreamingRuntime,
+): boolean {
+  const hasInflightBubble = messages.some(
+    (m) =>
+      m.role === 'assistant' &&
+      typeof m.status === 'string' &&
+      (COMPOSER_INFLIGHT_STATUSES as readonly string[]).includes(m.status),
+  );
+  if (!hasInflightBubble) return false;
+  return runtime.turnLive || runtime.taskRunLive;
+}