feat: multi-browser pooling (2 Chromium instances × 8 pages)

- Launch BROWSER_COUNT separate Chromium instances (default: 2)
- Each with PAGES_PER_BROWSER pages (default: 8, 16 total)
- Round-robin distribution across browser instances
- Independent restart scheduling per browser
- Updated health endpoint to show per-browser stats
- docker-compose: added BROWSER_COUNT and PAGES_PER_BROWSER env vars

src/middleware/usage.ts

@@ -11,34 +11,27 @@ function getMonthKey(): string {
   return `${d.getFullYear()}-${String(d.getMonth() + 1).padStart(2, "0")}`;
 }
 
-// Load usage data from file on startup
 async function loadUsageData(): Promise<void> {
   try {
     const data = await fs.readFile(USAGE_FILE, "utf8");
     const usageObj = JSON.parse(data);
-    
     usage = new Map();
     for (const [key, record] of Object.entries(usageObj)) {
       usage.set(key, record as { count: number; monthKey: string });
     }
-    
     console.log(`Loaded usage data for ${usage.size} keys`);
   } catch (error) {
-    // File doesn't exist or invalid JSON - start fresh
     console.log("No existing usage data found, starting fresh");
     usage = new Map();
   }
 }
 
-// Save usage data to file
 async function saveUsageData(): Promise<void> {
   try {
     const usageObj: Record<string, { count: number; monthKey: string }> = {};
     for (const [key, record] of usage) {
       usageObj[key] = record;
     }
-    
-    // Ensure directory exists
     await fs.mkdir(path.dirname(USAGE_FILE), { recursive: true });
     await fs.writeFile(USAGE_FILE, JSON.stringify(usageObj, null, 2));
   } catch (error) {
@@ -46,21 +39,20 @@ async function saveUsageData(): Promise<void> {
   }
 }
 
-// Initialize usage data loading
 loadUsageData().catch(console.error);
 
 export function usageMiddleware(req: any, res: any, next: any): void {
-  const key = req.headers.authorization?.slice(7) || "unknown";
+  // Use apiKeyInfo attached by auth middleware (works for both Bearer and X-API-Key)
+  const keyInfo = req.apiKeyInfo;
+  const key = keyInfo?.key || "unknown";
   const monthKey = getMonthKey();
 
-  // Pro keys have no limit
   if (isProKey(key)) {
     trackUsage(key, monthKey);
     next();
     return;
   }
 
-  // Free tier limit check
   const record = usage.get(key);
   if (record && record.monthKey === monthKey && record.count >= FREE_TIER_LIMIT) {
     res.status(429).json({
@@ -83,8 +75,6 @@ function trackUsage(key: string, monthKey: string): void {
   } else {
     record.count++;
   }
-  
-  // Save to file after each update (simple approach)
   saveUsageData().catch(console.error);
 }