refactor: make Redis an optional dependency with better error handling

- Move redis and orjson to optional dependencies under [redis] extra
- Add clear ImportError messages guiding users to install with [redis] extra
- Reduce base package size by making Redis dependencies opt-in

Author: yvesemmanuel

pyproject.toml

@@ -28,9 +28,7 @@ dependencies = [
   "google-genai>=1.21.1, <2.0.0", # Google GenAI SDK
   "google-adk", # Google ADK
   "httpx>=0.27.0, <1.0.0", # For OpenMemory service
-  "redis >= 7.0.0", # Redis for session storage
   # go/keep-sorted end
-  "orjson>=3.11.4",
 ]
 dynamic = ["version"]
 
@@ -41,9 +39,13 @@ changelog = "https://github.com/google/adk-python-community/blob/main/CHANGELOG.
 documentation = "https://google.github.io/adk-docs/"
 
 [project.optional-dependencies]
+redis = [
+  "redis>=5.0.0", # Redis for session storage
+  "orjson>=3.11.4", # Fast JSON serialization for Redis
+]
 test = [
-    "pytest>=8.4.2",
-    "pytest-asyncio>=1.2.0",
+  "pytest>=8.4.2",
+  "pytest-asyncio>=1.2.0",
 ]
 
 
@@ -72,8 +74,8 @@ build-backend = "flit_core.buildapi"
 
 [dependency-groups]
 dev = [
-    "pytest>=8.4.2",
-    "pytest-asyncio>=1.2.0",
+  "pytest>=8.4.2",
+  "pytest-asyncio>=1.2.0",
 ]
 
 

src/google/adk_community/sessions/redis_session_service.py

@@ -20,11 +20,25 @@
 import uuid
 from typing import Any, Optional
 
-import orjson
-import redis.asyncio as redis
-from redis.crc import key_slot
 from typing_extensions import override
 
+try:
+    import redis.asyncio as redis
+    from redis.crc import key_slot
+except ImportError as exc:
+    raise ImportError(
+        "redis is required to use RedisSessionService. "
+        "Install it with: pip install google-adk-community[redis]"
+    ) from exc
+
+try:
+    import orjson
+except ImportError as exc:
+    raise ImportError(
+        "orjson is required to use RedisSessionService. "
+        "Install it with: pip install google-adk-community[redis]"
+    ) from exc
+
 from google.adk.events.event import Event
 from google.adk.sessions.base_session_service import (
     BaseSessionService,