security(polymarket-browse): add token bucket rate limiter for API calls

- Add RateLimiter class (token bucket algorithm)
- Thread-safe for use with ThreadPoolExecutor
- RATE_LIMIT_CALLS = 10 per RATE_LIMIT_WINDOW = 1 second
- _rate_limiter.acquire() called before each API request
- Also add MAX_RESPONSE_SIZE check in fetch_page

skills/polymarket-browse/scripts/browse.py

@@ -10,6 +10,7 @@ import time
 import argparse
 import hashlib
 import os
+import threading
 from concurrent.futures import ThreadPoolExecutor, as_completed
 from datetime import datetime, timezone, timedelta
 from typing import Any, Callable, TypedDict
@@ -97,8 +98,43 @@ class FetchResult(TypedDict):
 PAGE_SIZE = 50
 MAX_RETRIES = 5
 INITIAL_RETRY_DELAY = 2  # exponential backoff starts at 2s
+MAX_RESPONSE_SIZE = 10 * 1024 * 1024  # 10MB limit per API response
+RATE_LIMIT_CALLS = 10  # max API calls
+RATE_LIMIT_WINDOW = 1.0  # per second
 WIB = timezone(timedelta(hours=7))  # UTC+7 for Indonesian users
 
+
+class RateLimiter:
+    """Token bucket rate limiter for API calls. Thread-safe for use with ThreadPoolExecutor."""
+
+    def __init__(
+        self, calls: int = RATE_LIMIT_CALLS, window: float = RATE_LIMIT_WINDOW
+    ):
+        self.calls = calls
+        self.window = window
+        self.tokens = float(calls)
+        self.last_update = time.monotonic()
+        self._lock = threading.Lock()
+
+    def acquire(self) -> None:
+        """Block until a token is available."""
+        with self._lock:
+            now = time.monotonic()
+            elapsed = now - self.last_update
+            self.tokens = min(
+                self.calls, self.tokens + elapsed * (self.calls / self.window)
+            )
+            if self.tokens < 1:
+                wait_time = (1 - self.tokens) * (self.window / self.calls)
+                time.sleep(wait_time)
+                self.tokens = 0
+            else:
+                self.tokens -= 1
+            self.last_update = time.monotonic()
+
+
+_rate_limiter = RateLimiter()
+
 GAME_CATEGORIES = {
     "All Esports": "Esports",
     "Counter Strike": "Counter Strike",
@@ -176,9 +212,15 @@ def fetch_page(
         if attempt > 0:
             time.sleep(delay)
         try:
+            _rate_limiter.acquire()
             req = Request(url, headers={"User-Agent": "Mozilla/5.0"})
             with urlopen(req, timeout=10) as r:
-                return json.loads(r.read())
+                data = r.read()
+                if len(data) > MAX_RESPONSE_SIZE:
+                    raise ValueError(
+                        f"API response too large: {len(data)} bytes (max {MAX_RESPONSE_SIZE})"
+                    )
+                return json.loads(data)
         except Exception:
             if attempt < max_retries - 1:
                 delay *= 2