Update app/memory/redis_checkpointer.py

app/memory/redis_checkpointer.py

@@ -1,5 +1,8 @@
 from __future__ import annotations
 
+import asyncio
+import logging
+
 from redis.asyncio import Redis
 from redis.asyncio.retry import Retry
 from redis.backoff import ExponentialBackoff
@@ -9,17 +12,19 @@ from langgraph.checkpoint.redis.aio import AsyncRedisSaver
 
 from app.config import get_settings
 
+logger = logging.getLogger(__name__)
+
 _checkpointer_cm = None
 _checkpointer: AsyncRedisSaver | None = None
 _redis_client: Redis | None = None
+_heartbeat_task: asyncio.Task | None = None
 
 
 def _build_redis_client(redis_url: str) -> Redis:
     return Redis.from_url(
         redis_url,
-        # Detect and replace dead connections proactively
-        health_check_interval=30,          # ping idle connections every 30s
-        socket_keepalive=True,             # TCP-level keepalive
+        health_check_interval=15,
+        socket_keepalive=True,
         socket_connect_timeout=5,
         socket_timeout=10,
         retry_on_timeout=True,
@@ -28,8 +33,23 @@ def _build_redis_client(redis_url: str) -> Redis:
     )
 
 
+async def _redis_heartbeat(interval: int = 15):
+    """Keeps the pooled Redis connection alive by sending real traffic
+    through it periodically — Railway's proxy kills idle connections,
+    and OS-level TCP keepalive alone doesn't count as activity to it."""
+    while True:
+        try:
+            await asyncio.sleep(interval)
+            if _redis_client is not None:
+                await _redis_client.ping()
+        except asyncio.CancelledError:
+            break
+        except Exception as e:
+            logger.warning("Redis heartbeat ping failed: %s", e)
+
+
 async def get_checkpointer() -> AsyncRedisSaver:
-    global _checkpointer_cm, _checkpointer, _redis_client
+    global _checkpointer_cm, _checkpointer, _redis_client, _heartbeat_task
     if _checkpointer is None:
         settings = get_settings()
         ttl_minutes = max(1, settings.chat_session_ttl_seconds // 60)
@@ -42,15 +62,20 @@ async def get_checkpointer() -> AsyncRedisSaver:
         )
         _checkpointer = await _checkpointer_cm.__aenter__()
         await _checkpointer.asetup()
+
+        _heartbeat_task = asyncio.create_task(_redis_heartbeat())
     return _checkpointer
 
 
 async def close_checkpointer() -> None:
-    global _checkpointer_cm, _checkpointer, _redis_client
+    global _checkpointer_cm, _checkpointer, _redis_client, _heartbeat_task
+    if _heartbeat_task is not None:
+        _heartbeat_task.cancel()
     if _checkpointer_cm is not None:
         await _checkpointer_cm.__aexit__(None, None, None)
     if _redis_client is not None:
         await _redis_client.aclose()
     _checkpointer = None
     _checkpointer_cm = None
-    _redis_client = None
+    _redis_client = None
+    _heartbeat_task = None