refactor(v2): use Chat SDK webhooks proxy and clean up webhook server

Route webhook requests through chat.webhooks[name]() instead of calling
adapter.handleWebhook() directly, getting proper auto-initialization and
signature verification. Extract Node↔Web Request/Response conversion
into reusable helpers, parse URL pathname properly for query string
safety, and support all HTTP methods (not just POST).

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src/channels/chat-sdk-bridge.ts

@@ -307,7 +307,7 @@ export function createChatSdkBridge(config: ChatSdkBridgeConfig): ChannelAdapter
       } else {
         // Non-gateway adapters (Slack, Teams, GitHub, etc.) — register on the shared webhook server
         const webhookPath = `/api/webhooks/${adapter.name}`;
-        registerWebhookAdapter(webhookPath, adapter);
+        registerWebhookAdapter(webhookPath, chat, adapter.name);
         log.info('Webhook adapter registered', { adapter: adapter.name, path: webhookPath });
       }
 
@@ -536,55 +536,86 @@ async function handleForwardedEvent(
 }
 
 /**
- * Shared public webhook server for all webhook-based adapters.
+ * Shared webhook server for all webhook-based adapters.
  * Each adapter registers a path (e.g. /api/webhooks/slack, /api/webhooks/teams).
- * The server listens on a single port (default 3000, configurable via WEBHOOK_PORT env var).
+ * Listens on a single port (default 3000, configurable via WEBHOOK_PORT env var).
+ *
+ * Routes incoming requests to the Chat SDK's `chat.webhooks[name]()` handler,
+ * which auto-initializes the adapter and handles signature verification.
  */
-const webhookAdapters = new Map<string, Adapter>();
+interface WebhookEntry {
+  chat: Chat;
+  adapterName: string;
+}
+const webhookRoutes = new Map<string, WebhookEntry>();
 let sharedWebhookServer: http.Server | null = null;
+/** Placeholder base for URL parsing — Node's http.IncomingMessage only has a path, not a full URL. */
+const URL_BASE = 'http://0.0.0.0';
 
-function registerWebhookAdapter(path: string, adapter: Adapter): void {
-  webhookAdapters.set(path, adapter);
+/** Convert a Node http.IncomingMessage into a Web API Request. */
+function nodeToWebRequest(req: http.IncomingMessage): Promise<Request> {
+  return new Promise((resolve, reject) => {
+    const chunks: Buffer[] = [];
+    req.on('data', (chunk: Buffer) => chunks.push(chunk));
+    req.on('error', reject);
+    req.on('end', () => {
+      const body = Buffer.concat(chunks);
+      const headers = new Headers();
+      for (const [key, val] of Object.entries(req.headers)) {
+        if (typeof val === 'string') headers.set(key, val);
+        else if (Array.isArray(val)) for (const v of val) headers.append(key, v);
+      }
+      const hasBody = req.method !== 'GET' && req.method !== 'HEAD';
+      resolve(
+        new Request(`${URL_BASE}${req.url}`, {
+          method: req.method,
+          headers,
+          body: hasBody ? body : undefined,
+        }),
+      );
+    });
+  });
+}
+
+/** Write a Web API Response back to a Node http.ServerResponse. */
+async function writeWebResponse(webRes: Response, nodeRes: http.ServerResponse): Promise<void> {
+  const responseHeaders: Record<string, string> = {};
+  webRes.headers.forEach((v, k) => {
+    responseHeaders[k] = v;
+  });
+  nodeRes.writeHead(webRes.status, responseHeaders);
+  nodeRes.end(await webRes.text());
+}
+
+function registerWebhookAdapter(urlPath: string, chat: Chat, adapterName: string): void {
+  webhookRoutes.set(urlPath, { chat, adapterName });
   if (!sharedWebhookServer) {
     const port = parseInt(process.env.WEBHOOK_PORT || '3000', 10);
-    sharedWebhookServer = http.createServer((req, res) => {
-      const matchedAdapter = req.url ? webhookAdapters.get(req.url) : undefined;
-      if (req.method === 'POST' && matchedAdapter) {
-        const chunks: Buffer[] = [];
-        req.on('data', (chunk: Buffer) => chunks.push(chunk));
-        req.on('end', async () => {
-          try {
-            const body = Buffer.concat(chunks).toString();
-            const headers: Record<string, string> = {};
-            for (const [key, val] of Object.entries(req.headers)) {
-              if (typeof val === 'string') headers[key] = val;
-            }
-            const request = new Request(`http://localhost${req.url}`, {
-              method: 'POST',
-              headers,
-              body,
-            });
-            const response = await matchedAdapter.handleWebhook!(request, {
-              waitUntil: (p: Promise<unknown>) => { p.catch(() => {}); },
-            });
-            const responseBody = await response.text();
-            const responseHeaders: Record<string, string> = { 'Content-Type': 'application/json' };
-            response.headers.forEach((v, k) => { responseHeaders[k] = v; });
-            res.writeHead(response.status, responseHeaders);
-            res.end(responseBody);
-          } catch (err) {
-            log.error('Webhook handler error', { url: req.url, err });
-            res.writeHead(500);
-            res.end('{"error":"internal"}');
-          }
-        });
-      } else {
+    sharedWebhookServer = http.createServer(async (req, res) => {
+      const pathname = new URL(req.url || '/', URL_BASE).pathname;
+      const entry = webhookRoutes.get(pathname);
+      if (!entry) {
         res.writeHead(404);
         res.end('Not found');
+        return;
+      }
+      try {
+        const webReq = await nodeToWebRequest(req);
+        // eslint-disable-next-line @typescript-eslint/no-explicit-any
+        const webhooks = entry.chat.webhooks as Record<string, (req: Request, opts?: any) => Promise<Response>>;
+        const handler = webhooks[entry.adapterName];
+        const webRes = await handler(webReq, {
+          waitUntil: (p: Promise<unknown>) => { p.catch(() => {}); },
+        });
+        await writeWebResponse(webRes, res);
+      } catch (err) {
+        log.error('Webhook handler error', { url: req.url, err });
+        res.writeHead(500);
+        res.end('{"error":"internal"}');
       }
     });
     sharedWebhookServer.listen(port, '0.0.0.0', () => {
-      log.info('Shared webhook server started', { port, paths: [...webhookAdapters.keys()] });
+      log.info('Shared webhook server started', { port, paths: [...webhookRoutes.keys()] });
     });
   }
 }

src/db/session-db.ts

@@ -197,7 +197,17 @@ export function insertRecurrence(
   db.prepare(
     `INSERT INTO messages_in (id, seq, kind, timestamp, status, process_after, recurrence, platform_id, channel_type, thread_id, content)
      VALUES (?, ?, ?, datetime('now'), 'pending', ?, ?, ?, ?, ?, ?)`,
-  ).run(newId, nextEvenSeq(db), msg.kind, nextRun, msg.recurrence, msg.platform_id, msg.channel_type, msg.thread_id, msg.content);
+  ).run(
+    newId,
+    nextEvenSeq(db),
+    msg.kind,
+    nextRun,
+    msg.recurrence,
+    msg.platform_id,
+    msg.channel_type,
+    msg.thread_id,
+    msg.content,
+  );
 }
 
 export function clearRecurrence(db: Database.Database, messageId: string): void {