chore: initialize project repository

app/infrastructure/memory_cache.py

@@ -0,0 +1,33 @@
+from typing import Any, Protocol
+
+
+class CacheClient(Protocol):
+    async def get(self, key: str) -> Any: ...
+
+    async def set(self, key: str, value: str, ex: int | None = None) -> Any: ...
+
+
+class CacheReadResult:
+    def __init__(self, value: Any, degraded: bool = False) -> None:
+        self.value = value
+        self.degraded = degraded
+
+
+class MemoryCacheAdapter:
+    """Cache is an optimization; failures must not block MySQL recall."""
+
+    def __init__(self, client: CacheClient) -> None:
+        self.client = client
+
+    async def get(self, key: str) -> CacheReadResult:
+        try:
+            return CacheReadResult(await self.client.get(key))
+        except Exception:
+            return CacheReadResult(None, degraded=True)
+
+    async def set(self, key: str, value: str, ttl_seconds: int = 300) -> bool:
+        try:
+            await self.client.set(key, value, ex=ttl_seconds)
+            return True
+        except Exception:
+            return False