fix(chat): 阻止同会话并发 Agent Run 导致消息错乱

前端 submit 改用 chatStateRef 同步拦截连发；后端 createRun 检测同 session 活跃任务并返回 409，避免多条回复交错落库。

Co-authored-by: Cursor <cursoragent@cursor.com>

agent-run-gateway.test.mjs

@@ -1,4 +1,5 @@
 import assert from 'node:assert/strict';
+import crypto from 'node:crypto';
 import fs from 'node:fs/promises';
 import os from 'node:os';
 import path from 'node:path';
@@ -29,6 +30,13 @@ function createFakePool() {
         const [userId, requestId] = params;
         return [[...runs.values()].filter((row) => row.user_id === userId && row.request_id === requestId)];
       }
+      if (sql.includes('agent_session_id = ?') && sql.includes("status NOT IN ('succeeded', 'failed')")) {
+        const [sessionId] = params;
+        const active = [...runs.values()].filter(
+          (row) => row.agent_session_id === sessionId && !['succeeded', 'failed'].includes(row.status),
+        );
+        return [active.slice(0, 1).map((row) => ({ id: row.id }))];
+      }
       if (sql.includes('SELECT * FROM h5_agent_runs WHERE id = ? LIMIT 1')) {
         return [[runs.get(params[0])].filter(Boolean)];
       }
@@ -1571,3 +1579,87 @@ test('markRun appends run_snapshot when MEMIND_RUN_STREAM_REPLAY=1', async () =>
     else process.env.MEMIND_RUN_STREAM_REPLAY = previous;
   }
 });
+
+test('createRun rejects with SESSION_RUN_CONFLICT when same session already has active run', async () => {
+  const pool = createFakePool();
+  const gateway = createAgentRunGateway({
+    pool,
+    userAuth: {},
+    tkmindProxy: {},
+    autoDispatch: false,
+  });
+
+  const activeRunId = crypto.randomUUID();
+  const now = Date.now();
+  pool.runs.set(activeRunId, {
+    id: activeRunId,
+    user_id: 'user-1',
+    agent_session_id: 'sess-conflict-1',
+    request_id: 'req-active',
+    status: 'running',
+    attempts: 1,
+    user_message_json: '{}',
+    error_message: null,
+    created_at: now,
+    updated_at: now,
+    started_at: now,
+    completed_at: null,
+  });
+
+  let conflictErr = null;
+  try {
+    await gateway.createRun('user-1', {
+      sessionId: 'sess-conflict-1',
+      requestId: 'req-conflict-2',
+      userMessage: { role: 'user', content: [{ type: 'text', text: 'second' }] },
+    });
+  } catch (err) {
+    conflictErr = err;
+  }
+  assert.ok(conflictErr, 'expected an error for duplicate active session run');
+  assert.equal(conflictErr.code, 'SESSION_RUN_CONFLICT');
+  assert.equal(conflictErr.status, 409);
+
+  pool.runs.get(activeRunId).status = 'succeeded';
+  const run3 = await gateway.createRun('user-1', {
+    sessionId: 'sess-conflict-1',
+    requestId: 'req-conflict-3',
+    userMessage: { role: 'user', content: [{ type: 'text', text: 'third' }] },
+  });
+  assert.equal(run3.requestId, 'req-conflict-3');
+});
+
+test('createRun does not apply per-session conflict check for direct-chat sessions', async () => {
+  const pool = createFakePool();
+  const gateway = createAgentRunGateway({
+    pool,
+    userAuth: {},
+    tkmindProxy: {},
+    autoDispatch: false,
+  });
+
+  const activeRunId = crypto.randomUUID();
+  const now = Date.now();
+  pool.runs.set(activeRunId, {
+    id: activeRunId,
+    user_id: 'user-1',
+    agent_session_id: 'h5direct_abc',
+    request_id: 'req-active-dc',
+    status: 'running',
+    attempts: 1,
+    user_message_json: '{}',
+    error_message: null,
+    created_at: now,
+    updated_at: now,
+    started_at: now,
+    completed_at: null,
+  });
+
+  const run2 = await gateway.createRun('user-1', {
+    sessionId: 'h5direct_abc',
+    requestId: 'req-dc-2',
+    userMessage: { role: 'user', content: [{ type: 'text', text: 'hi2' }] },
+  });
+
+  assert.equal(run2.requestId, 'req-dc-2');
+});