Add smart ACK provider for WeChat MP replies

Replace fixed ackText with a rule-based AckProvider that picks
response templates by message type and intent (translate, summary,
rewrite, poster, ppt, mindmap, code, search, schedule). Pure sync,
zero I/O, auto-falls back to config.ackText on any error.

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

session-reconcile.test.mjs

@@ -48,7 +48,7 @@ test('extensionsNeedingRefresh adds missing extensions', () => {
   assert.equal(toAdd[0].name, 'summon');
 });
 
-test('reconcileAgentSession tolerates invalid working directory during resume sync', async () => {
+test('reconcileAgentSession tolerates invalid working directory during resume sync without restart', async () => {
   const calls = [];
   const apiFetch = async (pathname) => {
     calls.push(pathname);
@@ -90,7 +90,79 @@ test('reconcileAgentSession tolerates invalid working directory during resume sy
     '/sessions/session-1',
     '/agent/update_working_dir',
     '/sessions/session-1/extensions',
+  ]);
+});
+
+test('reconcileAgentSession skips restart when extensions already match', async () => {
+  const calls = [];
+  const apiFetch = async (pathname) => {
+    calls.push(pathname);
+    if (pathname === '/sessions/session-1') {
+      return {
+        ok: true,
+        text: async () => JSON.stringify({ working_dir: '/valid/workspace' }),
+      };
+    }
+    if (pathname === '/sessions/session-1/extensions') {
+      return {
+        ok: true,
+        text: async () =>
+          JSON.stringify({
+            extensions: [{ name: 'skills', available_tools: [] }],
+          }),
+      };
+    }
+    if (pathname === '/agent/restart') {
+      return {
+        ok: true,
+        text: async () => JSON.stringify({ ok: true }),
+      };
+    }
+    throw new Error(`unexpected path: ${pathname}`);
+  };
+
+  await reconcileAgentSession(apiFetch, 'session-1', {
+    workingDir: '/valid/workspace',
+    sessionPolicy: { extensionOverrides: [{ name: 'skills', available_tools: [] }] },
+  });
+
+  assert.deepEqual(calls, ['/sessions/session-1', '/sessions/session-1/extensions']);
+});
+
+test('reconcileAgentSession restarts after adding missing extensions', async () => {
+  const calls = [];
+  const apiFetch = async (pathname) => {
+    calls.push(pathname);
+    if (pathname === '/sessions/session-1') {
+      return {
+        ok: true,
+        text: async () => JSON.stringify({ working_dir: '/valid/workspace' }),
+      };
+    }
+    if (pathname === '/sessions/session-1/extensions') {
+      return {
+        ok: true,
+        text: async () => JSON.stringify({ extensions: [] }),
+      };
+    }
+    if (pathname === '/agent/add_extension' || pathname === '/agent/restart') {
+      return {
+        ok: true,
+        text: async () => JSON.stringify({ ok: true }),
+      };
+    }
+    throw new Error(`unexpected path: ${pathname}`);
+  };
+
+  await reconcileAgentSession(apiFetch, 'session-1', {
+    workingDir: '/valid/workspace',
+    sessionPolicy: { extensionOverrides: [{ name: 'skills', available_tools: [] }] },
+  });
+
+  assert.deepEqual(calls, [
+    '/sessions/session-1',
     '/sessions/session-1/extensions',
+    '/agent/add_extension',
     '/agent/restart',
   ]);
 });