Description

The Redis session service implementation contains a bug where user session keys are generated with double colons ("::") in the key pattern. This occurs in the RedisKeys.user_sessions() method, which constructs keys used to track all sessions for a specific user within an application.

Current Behavior

The key generation in redis_session_service.py currently produces:

{APP_PREFIX}::{app_name}:{user_id}

This results in keys like: adk::my_app::user_123

Expected Behavior

The key should follow a consistent single-colon delimiter pattern:

{APP_PREFIX}{app_name}:{user_id}

Resulting in keys like: adkmy_app:user_123

Root Cause

In the RedisKeys.user_sessions() method, the APP_PREFIX constant already contains a trailing colon, but the f-string adds an additional colon separator:

return f"{State.APP_PREFIX}:{app_name}:{user_id}"  # Creates double colon