feat: replay execution context on WS reconnect

Store current execution state (prompt_id, cached nodes, executed nodes,
outputs to execute) on the server instance during execution. On WS
reconnect, replay execution_start, execution_cached, progress_state,
and executing events so the frontend can restore progress tracking.

Refactor ProgressRegistry to expose get_serialized_state() and reuse
it in WebUIProgressHandler._send_progress_state().

comfy_execution/progress.py

@@ -164,21 +164,7 @@ class WebUIProgressHandler(ProgressHandler):
         if self.server_instance is None:
             return
 
-        # Only send info for non-pending nodes
-        active_nodes = {
-            node_id: {
-                "value": state["value"],
-                "max": state["max"],
-                "state": state["state"].value,
-                "node_id": node_id,
-                "prompt_id": prompt_id,
-                "display_node_id": self.registry.dynprompt.get_display_node_id(node_id),
-                "parent_node_id": self.registry.dynprompt.get_parent_node_id(node_id),
-                "real_node_id": self.registry.dynprompt.get_real_node_id(node_id),
-            }
-            for node_id, state in nodes.items()
-            if state["state"] != NodeState.Pending
-        }
+        active_nodes = self.registry.get_serialized_state()
 
         # Send a combined progress_state message with all node states
         # Include client_id to ensure message is only sent to the initiating client
@@ -314,6 +300,24 @@ class ProgressRegistry:
             if handler.enabled:
                 handler.finish_handler(node_id, entry, self.prompt_id)
 
+    def get_serialized_state(self) -> Dict[str, dict]:
+        """Return current node progress as a dict suitable for WS progress_state."""
+        active: Dict[str, dict] = {}
+        for nid, state in self.nodes.items():
+            if state["state"] == NodeState.Pending:
+                continue
+            active[nid] = {
+                "value": state["value"],
+                "max": state["max"],
+                "state": state["state"].value,
+                "node_id": nid,
+                "prompt_id": self.prompt_id,
+                "display_node_id": self.dynprompt.get_display_node_id(nid),
+                "parent_node_id": self.dynprompt.get_parent_node_id(nid),
+                "real_node_id": self.dynprompt.get_real_node_id(nid),
+            }
+        return active
+
     def reset_handlers(self) -> None:
         """Reset all handlers"""
         for handler in self.handlers.values():

execution.py

@@ -701,6 +701,8 @@ class PromptExecutor:
         else:
             self.server.client_id = None
 
+        self.server.current_prompt_id = prompt_id
+
         self.status_messages = []
         self.add_message("execution_start", { "prompt_id": prompt_id}, broadcast=False)
 
@@ -722,10 +724,13 @@ class PromptExecutor:
             self.add_message("execution_cached",
                           { "nodes": cached_nodes, "prompt_id": prompt_id},
                           broadcast=False)
+            self.server.current_cached_nodes = cached_nodes
             pending_subgraph_results = {}
             pending_async_nodes = {} # TODO - Unify this with pending_subgraph_results
             ui_node_outputs = {}
             executed = set()
+            self.server.current_executed_nodes = executed
+            self.server.current_outputs_to_execute = list(execute_outputs)
             execution_list = ExecutionList(dynamic_prompt, self.caches.outputs)
             current_outputs = self.caches.outputs.all_node_ids()
             for node_id in list(execute_outputs):
@@ -762,6 +767,10 @@ class PromptExecutor:
                 "meta": meta_outputs,
             }
             self.server.last_node_id = None
+            self.server.current_prompt_id = None
+            self.server.current_outputs_to_execute = None
+            self.server.current_cached_nodes = None
+            self.server.current_executed_nodes = None
             if comfy.model_management.DISABLE_SMART_MEMORY:
                 comfy.model_management.unload_all_models()
 

server.py

@@ -242,6 +242,10 @@ class PromptServer():
         self.routes = routes
         self.last_node_id = None
         self.client_id = None
+        self.current_prompt_id = None
+        self.current_outputs_to_execute = None
+        self.current_cached_nodes = None
+        self.current_executed_nodes = None
 
         self.on_prompt_handlers = []
 
@@ -264,9 +268,38 @@ class PromptServer():
             try:
                 # Send initial state to the new client
                 await self.send("status", {"status": self.get_queue_info(), "sid": sid}, sid)
-                # On reconnect if we are the currently executing client send the current node
-                if self.client_id == sid and self.last_node_id is not None:
-                    await self.send("executing", { "node": self.last_node_id }, sid)
+                # On reconnect if we are the currently executing client, replay catch-up events
+                if self.client_id == sid and self.current_prompt_id is not None:
+                    await self.send("execution_start", {
+                        "prompt_id": self.current_prompt_id,
+                        "timestamp": int(time.time() * 1000),
+                        "outputs_to_execute": self.current_outputs_to_execute or [],
+                        "executed_node_ids": list(self.current_executed_nodes) if self.current_executed_nodes else [],
+                    }, sid)
+
+                    if self.current_cached_nodes:
+                        await self.send("execution_cached", {
+                            "nodes": self.current_cached_nodes,
+                            "prompt_id": self.current_prompt_id,
+                            "timestamp": int(time.time() * 1000),
+                        }, sid)
+
+                    from comfy_execution.progress import get_progress_state
+                    progress = get_progress_state()
+                    if progress.prompt_id == self.current_prompt_id:
+                        active_nodes = progress.get_serialized_state()
+                        if active_nodes:
+                            await self.send("progress_state", {
+                                "prompt_id": self.current_prompt_id,
+                                "nodes": active_nodes,
+                            }, sid)
+
+                    if self.last_node_id is not None:
+                        await self.send("executing", {
+                            "node": self.last_node_id,
+                            "display_node": self.last_node_id,
+                            "prompt_id": self.current_prompt_id,
+                        }, sid)
 
                 # Flag to track if we've received the first message
                 first_message = True