Init

app/services/rate_limit.py

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+from __future__ import annotations
+
+import time
+from collections import defaultdict, deque
+from threading import Lock
+
+
+class RateLimiter:
+    """In-memory sliding window limiter (per process). Good enough for single-replica / dev."""
+
+    def __init__(self) -> None:
+        self._hits: dict[str, deque[float]] = defaultdict(deque)
+        self._lock = Lock()
+
+    def allow(self, key: str, limit: int, window_seconds: int = 60) -> bool:
+        if limit <= 0:
+            return True
+        now = time.monotonic()
+        with self._lock:
+            q = self._hits[key]
+            while q and now - q[0] > window_seconds:
+                q.popleft()
+            if len(q) >= limit:
+                return False
+            q.append(now)
+            return True
+
+
+rate_limiter = RateLimiter()