merge: semantic WeChat session actions

chat-intent-router.mjs

@@ -543,6 +543,23 @@ function parseRouterJson(reply) {
   }
 }
 
+const WECHAT_SESSION_ACTIONS = new Set(['continue', 'reset', 'ignore_previous', 'unclear']);
+
+function buildWechatSessionActionPrompt(text) {
+  return [
+    '你是微信聊天会话动作分类器，只判断用户是否要切换上下文。',
+    '只输出 JSON，不要 markdown：',
+    '{"action":"continue|reset|ignore_previous|unclear","confidence":0.0,"reason":"一句话"}',
+    'reset：用户要开启全新会话、重新开始、换一个完全不同的对话。',
+    'ignore_previous：用户只要求不要参考之前某段内容，但不一定要创建新会话。',
+    'continue：用户明确要沿用当前话题或继续上文。',
+    'unclear：无法确定，不要擅自切换。',
+    '',
+    '[User]',
+    String(text ?? '').trim() || '(empty)',
+  ].join('\n');
+}
+
 function normalizeRoute(value) {
   const normalized = String(value ?? '').trim().toLowerCase();
   if (normalized === CHAT_INTENT_ROUTE.DIRECT_CHAT || normalized === ROUTER_DECISION_ROUTE.CHAT) {
@@ -1275,10 +1292,44 @@ export function createChatIntentRouter(options = {}) {
     }, { source: 'fallback' }));
   }
 
+  async function classifySessionAction({ text } = {}) {
+    // The general H5 router intentionally remains rule/skill-only. Session
+    // action classification is separately opt-in because it runs before every
+    // WeChat Agent request that contains a context hint.
+    if (!policy.enabled || typeof llmProviderService?.createChatCompletion !== 'function') return null;
+    try {
+      const completion = await withTimeout(
+        llmProviderService.createChatCompletion({
+          providerKeyId: policy.modelProviderKeyId || undefined,
+          model: policy.model || undefined,
+          temperature: 0,
+          messages: [
+            { role: 'system', content: buildWechatSessionActionPrompt(text) },
+          ],
+        }),
+        Math.min(policy.timeoutMs, 1200),
+        'WeChat session action classifier',
+      );
+      if (!completion?.ok) return null;
+      const parsed = parseRouterJson(completion.reply);
+      const action = String(parsed?.action ?? '').trim().toLowerCase();
+      if (!WECHAT_SESSION_ACTIONS.has(action)) return null;
+      return {
+        action,
+        confidence: Number(parsed?.confidence),
+        reason: String(parsed?.reason ?? '').trim(),
+      };
+    } catch (err) {
+      logger?.warn?.('[chat-intent-router] WeChat session action classification skipped:', err);
+      return null;
+    }
+  }
+
   return {
     getStatus,
     isEnabled,
     classify,
+    classifySessionAction,
     resolveAgentMemoryContext,
     applyAgentOrchestration: applyAgentOrchestrationToUserMessage,
   };
@@ -1374,6 +1425,11 @@ export function createManagedChatIntentRouter({
       return router.classify(input);
     },
 
+    async classifySessionAction(input = {}) {
+      const router = await ensureRouter();
+      return router.classifySessionAction(input);
+    },
+
     async resolveAgentMemoryContext(input = {}) {
       const router = await ensureRouter();
       return router.resolveAgentMemoryContext(input);