diff --git a/backend/run_agent_background.py b/backend/run_agent_background.py
index 56eb5e23..cbae733c 100644
--- a/backend/run_agent_background.py
+++ b/backend/run_agent_background.py
@@ -68,6 +68,25 @@ async def run_agent_background(
         logger.critical(f"Failed to initialize Redis connection: {e}")
         raise e
 
+    # Idempotency check: prevent duplicate runs
+    run_lock_key = f"agent_run_lock:{agent_run_id}"
+    
+    # Try to acquire a lock for this agent run
+    lock_acquired = await redis.set(run_lock_key, instance_id, nx=True, ex=redis.REDIS_KEY_TTL)
+    
+    if not lock_acquired:
+        # Check if the run is already being handled by another instance
+        existing_instance = await redis.get(run_lock_key)
+        if existing_instance:
+            logger.info(f"Agent run {agent_run_id} is already being processed by instance {existing_instance.decode() if isinstance(existing_instance, bytes) else existing_instance}. Skipping duplicate execution.")
+            return
+        else:
+            # Lock exists but no value, try to acquire again
+            lock_acquired = await redis.set(run_lock_key, instance_id, nx=True, ex=redis.REDIS_KEY_TTL)
+            if not lock_acquired:
+                logger.info(f"Agent run {agent_run_id} is already being processed by another instance. Skipping duplicate execution.")
+                return
+
     sentry.sentry.set_tag("thread_id", thread_id)
 
     logger.info(f"Starting background agent run: {agent_run_id} for thread: {thread_id} (Instance: {instance_id})")
@@ -249,6 +268,9 @@ async def run_agent_background(
         # Remove the instance-specific active run key
         await _cleanup_redis_instance_key(agent_run_id)
 
+        # Clean up the run lock
+        await _cleanup_redis_run_lock(agent_run_id)
+
         # Wait for all pending redis operations to complete, with timeout
         try:
             await asyncio.wait_for(asyncio.gather(*pending_redis_operations), timeout=30.0)
@@ -270,6 +292,16 @@ async def _cleanup_redis_instance_key(agent_run_id: str):
     except Exception as e:
         logger.warning(f"Failed to clean up Redis key {key}: {str(e)}")
 
+async def _cleanup_redis_run_lock(agent_run_id: str):
+    """Clean up the run lock Redis key for an agent run."""
+    run_lock_key = f"agent_run_lock:{agent_run_id}"
+    logger.debug(f"Cleaning up Redis run lock key: {run_lock_key}")
+    try:
+        await redis.delete(run_lock_key)
+        logger.debug(f"Successfully cleaned up Redis run lock key: {run_lock_key}")
+    except Exception as e:
+        logger.warning(f"Failed to clean up Redis run lock key {run_lock_key}: {str(e)}")
+
 # TTL for Redis response lists (24 hours)
 REDIS_RESPONSE_LIST_TTL = 3600 * 24
 
diff --git a/backend/services/redis.py b/backend/services/redis.py
index dc956b05..67a1df0a 100644
--- a/backend/services/redis.py
+++ b/backend/services/redis.py
@@ -96,10 +96,10 @@ async def get_client():
 
 
 # Basic Redis operations
-async def set(key: str, value: str, ex: int = None):
+async def set(key: str, value: str, ex: int = None, nx: bool = False):
     """Set a Redis key."""
     redis_client = await get_client()
-    return await redis_client.set(key, value, ex=ex)
+    return await redis_client.set(key, value, ex=ex, nx=nx)
 
 
 async def get(key: str, default: str = None):