fix: stop chat hang after misrouted themed article requests

Route themed page/article prompts to agent orchestration, reject them
from portal direct chat, and finalize regular sessions to idle when a
direct chat turn already completed.

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

direct-chat-service.test.mjs

@@ -205,6 +205,30 @@ test('direct chat rejects page generation tasks so the execution backend can han
   }), false);
 });
 
+test('direct chat rejects themed article page tasks without explicit html path', () => {
+  const service = createDirectChatService({
+    enabled: true,
+    userAuth: {},
+    llmProviderService: {},
+    sessionSnapshotService: {},
+  });
+
+  assert.equal(service.canHandle({
+    toolMode: 'chat',
+    userMessage: {
+      role: 'user',
+      content: [{ type: 'text', text: '帮我写个主题文章' }],
+    },
+  }), false);
+  assert.equal(service.explainCanHandle({
+    toolMode: 'chat',
+    userMessage: {
+      role: 'user',
+      content: [{ type: 'text', text: '帮我写个主题文章' }],
+    },
+  }).reason, 'task_execution_required');
+});
+
 test('direct chat allows llm-routed replies on regular agent sessions', () => {
   const service = createDirectChatService({
     enabled: true,