refactor: enhance type hinting and casting for improved type safety across multiple files

app/core/cache.py

@@ -6,7 +6,7 @@ import asyncio
 import json
 import logging
 from collections.abc import Awaitable, Callable
-from typing import Any
+from typing import Any, cast
 
 import redis.asyncio as redis
 from app.core.config import settings
@@ -45,10 +45,13 @@ class RedisCacheManager:
         async with self._lock:
             if self._client is not None:
                 return
-            self._client = redis.from_url(
-                settings.redis_url,
-                encoding="utf-8",
-                decode_responses=False,
+            self._client = cast(
+                Redis,
+                redis.from_url(  # type: ignore[no-untyped-call]
+                    settings.redis_url,
+                    encoding="utf-8",
+                    decode_responses=False,
+                ),
             )
             await self._refresh_availability()
 
@@ -64,10 +67,13 @@ class RedisCacheManager:
             return
         async with self._lock:
             if self._client is None:
-                self._client = redis.from_url(
-                    settings.redis_url,
-                    encoding="utf-8",
-                    decode_responses=False,
+                self._client = cast(
+                    Redis,
+                    redis.from_url(  # type: ignore[no-untyped-call]
+                        settings.redis_url,
+                        encoding="utf-8",
+                        decode_responses=False,
+                    ),
                 )
             await self._refresh_availability()
 
@@ -76,7 +82,7 @@ class RedisCacheManager:
             self._available = False
             return
         try:
-            await self._client.ping()
+            await cast(Awaitable[Any], self._client.ping())
         except RedisError as exc:  # pragma: no cover - logging only
             self._available = False
             logger.warning("Redis ping failed: %s", exc)
@@ -140,8 +146,8 @@ async def write_json(
     """Serialize data to JSON and store it with TTL using retry/backoff."""
     payload = json.dumps(value, separators=(",", ":"), ensure_ascii=True).encode("utf-8")
 
-    async def _operation() -> Any:
-        return await client.set(name=key, value=payload, ex=ttl_seconds)
+    async def _operation() -> None:
+        await client.set(name=key, value=payload, ex=ttl_seconds)
 
     await _run_with_retry(_operation, backoff_ms)
 
@@ -151,8 +157,8 @@ async def delete_keys(client: Redis, keys: list[str], backoff_ms: int) -> None:
     if not keys:
         return
 
-    async def _operation() -> Any:
-        return await client.delete(*keys)
+    async def _operation() -> None:
+        await client.delete(*keys)
 
     await _run_with_retry(_operation, backoff_ms)