diff --git a/agent_v0/server_v1/api_stream.py b/agent_v0/server_v1/api_stream.py
index a61d1cbf5..e3be254e3 100644
--- a/agent_v0/server_v1/api_stream.py
+++ b/agent_v0/server_v1/api_stream.py
@@ -101,10 +101,10 @@ _pending_lock = threading.Lock()
 _replay_lock = threading.Lock()
 # session_id -> liste d'actions en attente (FIFO)
 _replay_queues: Dict[str, List[Dict[str, Any]]] = defaultdict(list)
-# replay_id -> état du replay (workflow_id, session_id, status, progress)
-_replay_states: Dict[str, Dict[str, Any]] = {}
 # machine_id -> session_id (mapping pour le replay ciblé par machine)
 _machine_replay_target: Dict[str, str] = {}
+# replay_id -> état du replay (workflow_id, session_id, status, progress)
+_replay_states: Dict[str, Dict[str, Any]] = {}
 
 
 class StreamEvent(BaseModel):
diff --git a/visual_workflow_builder/frontend_v4/src/components/ExecutionControls.tsx b/visual_workflow_builder/frontend_v4/src/components/ExecutionControls.tsx
index 383dcee4a..fa4c51b50 100644
--- a/visual_workflow_builder/frontend_v4/src/components/ExecutionControls.tsx
+++ b/visual_workflow_builder/frontend_v4/src/components/ExecutionControls.tsx
@@ -39,7 +39,7 @@ export default function ExecutionControls({ execution, onStart, onStop }: Props)
         headers: { 'Content-Type': 'application/json' },
         body: JSON.stringify({
           workflow_id: workflowId,
-          session_id: `replay_${Date.now()}`,
+          session_id: '',  // vide = auto-détection de la session agent active
           actions: steps.map((step: any, i: number) => ({
             action_id: step.id || `action_${i}`,
             type: step.action_type,