docs: add Azure Cache for Redis and Redis Enterprise configuration guide (#72)

Fixes #72 - Document proper client configuration for Azure Cache for Redis
and Redis Enterprise deployments that use proxy layers.

Changes:
- Add comprehensive Azure/Enterprise configuration section to README
- Add test demonstrating correct client configuration approach
- Clarify that standard Redis client should be used, not RedisCluster
- Explain proxy architecture and why it requires this configuration

The key is that Azure Cache for Redis and similar enterprise
deployments use a proxy layer that makes clusters appear as single
endpoints. This requires using a standard Redis client rather than
a cluster-aware client to avoid detection issues and cross-slot errors.

Author: bsbodden

README.md

@@ -40,6 +40,62 @@ If you're using a Redis version lower than 8.0, you'll need to ensure these modu
 
 Failure to have these modules available will result in errors during index creation and checkpoint operations.
 
+### Azure Cache for Redis / Redis Enterprise Configuration
+
+If you're using **Azure Cache for Redis** (especially Enterprise tier) or **Redis Enterprise**, there are important configuration considerations:
+
+#### Client Configuration
+
+Azure Cache for Redis and Redis Enterprise use a **proxy layer** that makes the cluster appear as a single endpoint. This requires using a **standard Redis client**, not a cluster-aware client:
+
+```python
+from redis import Redis
+from langgraph.checkpoint.redis import RedisSaver
+
+# ✅ CORRECT: Use standard Redis client for Azure/Enterprise
+client = Redis(
+    host="your-cache.redis.cache.windows.net",  # or your Redis Enterprise endpoint
+    port=6379,  # or 10000 for Azure Enterprise with TLS
+    password="your-access-key",
+    ssl=True,  # Azure/Enterprise typically requires SSL
+    ssl_cert_reqs="required",  # or "none" for self-signed certs
+    decode_responses=False  # RedisSaver expects bytes
+)
+
+# Pass the configured client to RedisSaver
+saver = RedisSaver(redis_client=client)
+saver.setup()
+
+# ❌ WRONG: Don't use RedisCluster client with Azure/Enterprise
+# from redis.cluster import RedisCluster
+# cluster_client = RedisCluster(...)  # This will fail with proxy-based deployments
+```
+
+#### Why This Matters
+
+- **Proxy Architecture**: Azure Cache for Redis and Redis Enterprise use a proxy layer that handles cluster operations internally
+- **Automatic Detection**: RedisSaver will correctly detect this as non-cluster mode when using the standard client
+- **No Cross-Slot Errors**: The proxy handles key distribution, avoiding cross-slot errors
+
+#### Azure Cache for Redis Specific Settings
+
+For Azure Cache for Redis Enterprise tier:
+- **Port**: Use port `10000` for Enterprise tier with TLS, or `6379` for standard
+- **Modules**: Enterprise tier includes RediSearch and RedisJSON by default
+- **SSL/TLS**: Always enabled, minimum TLS 1.2 for Enterprise
+
+Example for Azure Cache for Redis Enterprise:
+```python
+client = Redis(
+    host="your-cache.redisenterprise.cache.azure.net",
+    port=10000,  # Enterprise TLS port
+    password="your-access-key",
+    ssl=True,
+    ssl_cert_reqs="required",
+    decode_responses=False
+)
+```
+
 ## Installation
 
 Install the library using pip:

langgraph/checkpoint/redis/aio.py

@@ -709,7 +709,9 @@ async def alist(
                     if isinstance(checkpoint_data, dict)
                     else orjson.loads(checkpoint_data)
                 )
-                channel_values = self._recursive_deserialize(checkpoint_dict.get("channel_values", {}))
+                channel_values = self._recursive_deserialize(
+                    checkpoint_dict.get("channel_values", {})
+                )
             else:
                 # If checkpoint data is missing, the document is corrupted
                 # Set empty channel values rather than attempting a fallback