fix: isolate visual tool failures from agent runs

tkmind-proxy.test.mjs

@@ -20,6 +20,7 @@ async function withFakeGoosedSession(
   const workingDir = fs.mkdtempSync(path.join(os.tmpdir(), 'memind-memory-v2-'));
   const harnessEntries = [];
   const replyBodies = [];
+  const startBodies = [];
   const updateBodies = [];
   let activeConversation = conversation;
   let server;
@@ -32,6 +33,7 @@ async function withFakeGoosedSession(
       const body = rawBody ? JSON.parse(rawBody) : {};
 
       if (req.method === 'POST' && req.url === '/agent/start') {
+        startBodies.push(body);
         res.writeHead(200, { 'Content-Type': 'application/json' });
         res.end(JSON.stringify({ id: 'session-1' }));
         return;
@@ -98,6 +100,7 @@ async function withFakeGoosedSession(
       workingDir,
       harnessEntries,
       replyBodies,
+      startBodies,
       updateBodies,
     });
   } finally {
@@ -1353,6 +1356,69 @@ test('submitSessionReplyForUser fails closed when historical image scrub is unsu
   });
 });
 
+test('visual fallback session removes read_image while preserving the text task path', async () => {
+  await withFakeGoosedSession(async ({
+    apiTarget,
+    workingDir,
+    replyBodies,
+    startBodies,
+  }) => {
+    const baseAuth = createMemoryTestUserAuth(workingDir);
+    const userAuth = {
+      ...baseAuth,
+      async getAgentSessionPolicy() {
+        return {
+          gooseMode: 'chat',
+          enableContextMemory: true,
+          extensionOverrides: [
+            { name: 'memory', available_tools: [] },
+            { name: 'developer', available_tools: ['read_image'] },
+          ],
+        };
+      },
+      async ownsSession() {
+        return true;
+      },
+      async canUseChat() {
+        return { ok: true };
+      },
+      async getUserById() {
+        return { id: 'user-1' };
+      },
+      async resolveUserPolicies() {
+        return { unrestricted: true, policies: {} };
+      },
+    };
+    const proxy = createTkmindProxy({
+      apiTarget,
+      apiSecret: 'test-secret',
+      userAuth,
+    });
+
+    await proxy.startSessionForUser(
+      'user-1',
+      { disableImageReading: true },
+    );
+    await proxy.submitSessionReplyForUser(
+      'user-1',
+      'session-1',
+      'request-visual-fallback',
+      {
+        id: 'message-visual-fallback',
+        role: 'user',
+        content: [{ type: 'text', text: '跳过视觉检查，继续修改页面' }],
+      },
+      { disableImageReading: true },
+    );
+
+    assert.deepEqual(
+      startBodies[0].extension_overrides,
+      [{ name: 'memory', available_tools: [] }],
+    );
+    assert.equal(replyBodies.length, 1);
+  });
+});
+
 test('submitSessionReplyForUser applies the shared Qwen vision preprocessing path', async () => {
   await withFakeGoosedSession(async ({ apiTarget, workingDir, replyBodies }) => {
     const proxy = createTkmindProxy({