fix: use Page.loadEventFired + networkIdle instead of fixed timeout

Replace 15s polling loop with proper CDP event-based page load
detection: wait for Page.loadEventFired, then PerformanceObserver
network idle (no new resource requests for 1s). More reliable and
faster than fixed timeouts.

Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>

src/index.ts

@@ -28,6 +28,7 @@ class CdpSession {
   private ws!: WebSocket;
   private msgId = 0;
   private pending = new Map<number, { resolve: (v: any) => void; reject: (e: Error) => void }>();
+  private eventListeners = new Map<string, Array<(params: any) => void>>();
 
   static async connect(port: number): Promise<CdpSession> {
     const resp = await fetch(`http://localhost:${port}/json`);
@@ -45,13 +46,20 @@ class CdpSession {
       this.ws.onopen = () => resolve();
       this.ws.onerror = (e: any) => reject(new Error(`WebSocket error: ${e.message || e}`));
       this.ws.onmessage = (ev: MessageEvent) => {
-        const msg: CdpResult = JSON.parse(typeof ev.data === 'string' ? ev.data : ev.data.toString());
+        const msg = JSON.parse(typeof ev.data === 'string' ? ev.data : ev.data.toString());
+        // Handle command responses
         if (msg.id != null && this.pending.has(msg.id)) {
           const p = this.pending.get(msg.id)!;
           this.pending.delete(msg.id);
           if (msg.error) p.reject(new Error(msg.error.message));
           else p.resolve(msg.result);
         }
+        // Handle events
+        if (msg.method && this.eventListeners.has(msg.method)) {
+          for (const fn of this.eventListeners.get(msg.method)!) {
+            fn(msg.params);
+          }
+        }
       };
     });
   }
@@ -64,6 +72,29 @@ class CdpSession {
     });
   }
 
+  waitForEvent(event: string, timeoutMs: number = 30000): Promise<any> {
+    return new Promise((resolve, reject) => {
+      const timer = setTimeout(() => {
+        cleanup();
+        reject(new Error(`Timeout waiting for ${event}`));
+      }, timeoutMs);
+      const handler = (params: any) => {
+        cleanup();
+        resolve(params);
+      };
+      const cleanup = () => {
+        clearTimeout(timer);
+        const listeners = this.eventListeners.get(event);
+        if (listeners) {
+          const idx = listeners.indexOf(handler);
+          if (idx >= 0) listeners.splice(idx, 1);
+        }
+      };
+      if (!this.eventListeners.has(event)) this.eventListeners.set(event, []);
+      this.eventListeners.get(event)!.push(handler);
+    });
+  }
+
   async evaluate(expression: string): Promise<any> {
     const res = await this.send('Runtime.evaluate', { expression, returnByValue: true });
     return res?.result?.value;
@@ -202,40 +233,47 @@ export async function run(
       mobile: false,
     });
 
+    // Navigate and wait for page load event
+    const loadPromise = cdp.waitForEvent('Page.loadEventFired', 30000);
     await cdp.send('Page.navigate', { url });
+    await loadPromise;
 
-    // Wait for window.context.result.data to be populated (poll up to 15s)
+    // Wait for networkIdle — poll until no pending requests for 1s
+    await cdp.evaluate(`
+      new Promise(resolve => {
+        let timer;
+        const reset = () => { clearTimeout(timer); timer = setTimeout(resolve, 1000); };
+        const observer = new PerformanceObserver(() => reset());
+        observer.observe({ entryTypes: ['resource'] });
+        reset();
+      })
+    `);
+
+    // Extract window.context.result.data
     let productPackInfo: unknown = null;
     let windowContext: unknown = null;
-    for (let i = 0; i < 30; i++) {
-      await new Promise(r => setTimeout(r, 500));
-      const ctx = await cdp.evaluate(`
-        (function() {
-          try {
-            const d = window.context && window.context.result && window.context.result.data;
-            if (d && d.productPackInfo) {
-              return JSON.stringify({
-                productPackInfo: d.productPackInfo,
-                productTitle: d.productTitle || null,
-                productAttributes: d.productAttributes || null,
-                skuSelection: d.skuSelection || null,
-              });
-            }
-          } catch(e) {}
-          return null;
-        })()
-      `);
-      if (ctx) {
-        const parsed = JSON.parse(ctx);
-        productPackInfo = parsed.productPackInfo;
-        windowContext = parsed;
-        break;
-      }
+    const ctx = await cdp.evaluate(`
+      (function() {
+        try {
+          const d = window.context && window.context.result && window.context.result.data;
+          if (d && d.productPackInfo) {
+            return JSON.stringify({
+              productPackInfo: d.productPackInfo,
+              productTitle: d.productTitle || null,
+              productAttributes: d.productAttributes || null,
+              skuSelection: d.skuSelection || null,
+            });
+          }
+        } catch(e) {}
+        return null;
+      })()
+    `);
+    if (ctx) {
+      const parsed = JSON.parse(ctx);
+      productPackInfo = parsed.productPackInfo;
+      windowContext = parsed;
     }
 
-    // Extra wait for remaining dynamic content (images etc)
-    await new Promise(r => setTimeout(r, 2000));
-
     const outputDir = path.join('/tmp', '1688-logistics', offerId);
 
     // Capture full-page screenshots (scrolling)