feat: route WeChat messages through SessionRouter for per-user context

Previously wechat_webhook.py sent each WeChat message as a stateless
API call to Hermes (no X-Hermes-Session-Id), so Mohe had zero memory
of previous messages. Now uses SessionRouter with SessionBridge
(same as XMPP path), which:
- Maintains per-user sessions via opencode.db
- Injects recent conversation context automatically
- Uses the same model/LLM pipeline as XMPP messages

gateway/linux/wechat_webhook.py

@@ -4,6 +4,13 @@
 import os, sys, json, logging, threading, queue, time
 from http.server import HTTPServer, BaseHTTPRequestHandler
 
+# ── MoFin session routing (shared with XMPP) ──
+_SCRIPTS_DIR = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "scripts")
+if _SCRIPTS_DIR not in sys.path:
+    sys.path.insert(0, _SCRIPTS_DIR)
+from chat_bridge import SessionBridge
+from session_router import SessionRouter
+
 HERMES_API = "http://192.168.1.246:8646/v1/chat/completions"
 HERMES_KEY = "hermes123"
 PORT = 5804
@@ -23,6 +30,12 @@ logging.basicConfig(
 )
 log = logging.getLogger("wc-webhook")
 
+# ── Session router (per-user session context via opencode.db) ──
+_router = SessionRouter(
+    bridge=SessionBridge(session_id="wechat-mohe"),
+    default_session="wechat-mohe",
+)
+
 # ── 消息队列（串行处理，防止并发打爆 Hermes）──────────────
 _msg_queue = queue.Queue()
 
@@ -42,29 +55,15 @@ def _hermes_worker():
 
 
 def _do_forward(sender, sender_id, text):
-    """实际调用 Hermes API 并回复微信。"""
-    payload = json.dumps({
-        "model": "nova-4",
-        "messages": [
-            {"role": "user", "content": f"[微信消息] 来自 {sender}({sender_id}): {text}"}
-        ]
-    }).encode()
-
+    """通过 SessionRouter 发送消息（自动带上下文 + 会话管理）。"""
     try:
-        import urllib.request as ureq
-        handler = ureq.ProxyHandler({})
-        opener = ureq.build_opener(handler)
-        req = ureq.Request(HERMES_API, data=payload,
-            headers={"Content-Type": "application/json", "Authorization": f"Bearer {HERMES_KEY}"})
-        resp = opener.open(req, timeout=600)
-        resp_data = json.loads(resp.read())
-        reply = resp_data.get('choices', [{}])[0].get('message', {}).get('content', '')
-        log.info(f"Hermes OK, reply: {reply[:60]}")
+        reply = _router.route("wechat", sender_id, text)
+        log.info(f"Router OK, reply: {reply[:60] if reply else '(empty)'}")
 
         if reply and sender:
             WebhookHandler._send_wechat_static(sender, reply)
     except Exception as e:
-        log.error(f"Hermes error: {e}")
+        log.error(f"Router error: {e}")
 
 
 # 启动 worker 线程