fix: store session bytes as base64 to avoid invalid encoding errors

src/google/adk/sessions/redis_memory_session_service.py

@@ -31,6 +31,8 @@
 from .session import Session
 from .state import State
 
+import base64
+
 logger = logging.getLogger('google_adk.' + __name__)
 
 DEFAULT_EXPIRATION = 60 * 60  # 1 hour
@@ -46,7 +48,7 @@ def _json_serializer(obj):
         return list(obj)
     if isinstance(obj, bytes):
         try:
-            return obj.decode("utf-8")
+            return base64.b64encode(obj).decode("ascii")
         except Exception:
             return repr(obj)
     if isinstance(obj, (datetime.datetime, datetime.date)):
@@ -62,6 +64,19 @@ def _json_serializer(obj):
             return "Infinity" if obj > 0 else "-Infinity"
     return str(obj)
 
+def _restore_bytes(obj):
+    if isinstance(obj, dict):
+        return {k: _restore_bytes(v) for k, v in obj.items()}
+    elif isinstance(obj, list):
+        return [_restore_bytes(v) for v in obj]
+    elif isinstance(obj, str):
+        try:
+            # intenta decodificar base64
+            data = base64.b64decode(obj, validate=True)
+            return data
+        except Exception:
+            return obj
+    return obj
 
 class RedisMemorySessionService(BaseSessionService):
     """A Redis-backed implementation of the session service."""
@@ -315,7 +330,8 @@ async def _load_sessions(self, app_name: str, user_id: str) -> dict[str, dict]:
         raw = await self.cache.get(key)
         if not raw:
             return {}
-        return json.loads(raw.decode())
+        raw_data = json.loads(raw.decode())
+        return raw_data
 
     async def _save_sessions(self, app_name: str, user_id: str, sessions: dict[str, Any]):
         key = f"{State.APP_PREFIX}{app_name}:{user_id}"