fix(userbot): a deletion that arrives before its message is applied once the message is stored

backend/src/userbot/modules/capture/pending.py

@@ -0,0 +1,36 @@
+import time
+
+from userbot.modules.capture.repository import CHANNEL_ID_THRESHOLD
+
+PENDING_DELETE_SECONDS = 120.0
+PENDING_DELETE_LIMIT = 10_000
+
+DeleteKey = tuple[int | None, int]
+
+
+def _key(chat_id: int | None, message_id: int) -> DeleteKey:
+    if chat_id is None or chat_id > CHANNEL_ID_THRESHOLD:
+        return None, message_id
+    return chat_id, message_id
+
+
+class PendingDeletes:
+    def __init__(self) -> None:
+        self._expires: dict[DeleteKey, float] = {}
+
+    def remember(self, chat_id: int | None, message_ids: list[int]) -> None:
+        now = time.monotonic()
+        while self._expires:
+            oldest = next(iter(self._expires))
+            fresh = self._expires[oldest] > now
+            if fresh and len(self._expires) < PENDING_DELETE_LIMIT:
+                break
+            del self._expires[oldest]
+        for message_id in message_ids:
+            key = _key(chat_id, message_id)
+            self._expires.pop(key, None)
+            self._expires[key] = now + PENDING_DELETE_SECONDS
+
+    def take(self, chat_id: int, message_id: int) -> bool:
+        expires = self._expires.pop(_key(chat_id, message_id), None)
+        return expires is not None and expires > time.monotonic()