fix(stores): MemoryStore/FileStore.exists() ignores expiry

exists() checked only key/file presence, unlike get() which correctly
treats an expired entry as gone (and lazily removes it). Since expired
entries are only cleared on access rather than eagerly, a key that has
passed its expires_in remains "present" in the backing dict/filesystem
until something touches it - so exists() reported True for a key that
get() would return None for, an inconsistency between two methods of
the same Store interface.

Give exists() the same load-check-expire logic get() already uses (minus
the renew_for handling, which only makes sense for get()).

Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>

Author: chuenchen309

litestar/stores/file.py

@@ -177,7 +177,16 @@ async def delete_expired(self) -> None:
     async def exists(self, key: str) -> bool:
         """Check if a given ``key`` exists."""
         path = self._path_from_key(key)
-        return await path.exists()
+        storage_obj = await self._load_from_path(path)
+
+        if not storage_obj:
+            return False
+
+        if storage_obj.expired:
+            await path.unlink(missing_ok=True)
+            return False
+
+        return True
 
     async def expires_in(self, key: str) -> int | None:
         """Get the time in seconds ``key`` expires in. If no such ``key`` exists or no

litestar/stores/memory.py

@@ -104,7 +104,17 @@ async def delete_expired(self) -> None:
 
     async def exists(self, key: str) -> bool:
         """Check if a given ``key`` exists."""
-        return key in self._store
+        async with self._lock:
+            storage_obj = self._store.get(key)
+
+            if not storage_obj:
+                return False
+
+            if storage_obj.expired:
+                self._store.pop(key)
+                return False
+
+            return True
 
     async def expires_in(self, key: str) -> int | None:
         """Get the time in seconds ``key`` expires in. If no such ``key`` exists or no

tests/unit/test_stores.py

@@ -156,6 +156,22 @@ async def test_exists(store: Store) -> None:
     assert await store.exists("foo") is True
 
 
+async def test_exists_expired(store: Store, frozen_datetime: Traveller) -> None:
+    # exists() must be consistent with get(): an expired key must report as
+    # not existing, not just be lazily cleaned up on the next get()/set() call.
+    await store.set("foo", b"bar", expires_in=1)
+
+    frozen_datetime.shift(2)
+    if isinstance(store, RedisStore):
+        # shifting time does not affect the Redis instance
+        # this is done to emulate auto-expiration
+        await store._redis.expire(f"{store.namespace}:foo", 0)
+    if isinstance(store, ValkeyStore):
+        await store._valkey.expire(f"{store.namespace}:foo", 0)
+
+    assert await store.exists("foo") is False
+
+
 async def test_expires_in_not_set(store: Store) -> None:
     assert await store.expires_in("foo") is None