Support for async node functions (#8830)

* Support for async execution functions

This commit adds support for node execution functions defined as async. When
a node's execution function is defined as async, we can continue
executing other nodes while it is processing.

Standard uses of `await` should "just work", but people will still have
to be careful if they spawn actual threads. Because torch doesn't really
have async/await versions of functions, this won't particularly help
with most locally-executing nodes, but it does work for e.g. web
requests to other machines.

In addition to the execute function, the `VALIDATE_INPUTS` and
`check_lazy_status` functions can also be defined as async, though we'll
only resolve one node at a time right now for those.

* Add the execution model tests to CI

* Add a missing file

It looks like this got caught by .gitignore? There's probably a better
place to put it, but I'm not sure what that is.

* Add the websocket library for automated tests

* Add additional tests for async error cases

Also fixes one bug that was found when an async function throws an error
after being scheduled on a task.

* Add a feature flags message to reduce bandwidth

We now only send 1 preview message of the latest type the client can
support.

We'll add a console warning when the client fails to send a feature
flags message at some point in the future.

* Add async tests to CI

* Don't actually add new tests in this PR

Will do it in a separate PR

* Resolve unit test in GPU-less runner

* Just remove the tests that GHA can't handle

* Change line endings to UNIX-style

* Avoid loading model_management.py so early

Because model_management.py has a top-level `logging.info`, we have to
be careful not to import that file before we call `setup_logging`. If we
do, we end up having the default logging handler registered in addition
to our custom one.

comfy/utils.py

@@ -998,11 +998,12 @@ def set_progress_bar_global_hook(function):
     PROGRESS_BAR_HOOK = function
 
 class ProgressBar:
-    def __init__(self, total):
+    def __init__(self, total, node_id=None):
         global PROGRESS_BAR_HOOK
         self.total = total
         self.current = 0
         self.hook = PROGRESS_BAR_HOOK
+        self.node_id = node_id
 
     def update_absolute(self, value, total=None, preview=None):
         if total is not None:
@@ -1011,7 +1012,7 @@ class ProgressBar:
             value = self.total
         self.current = value
         if self.hook is not None:
-            self.hook(self.current, self.total, preview)
+            self.hook(self.current, self.total, preview, node_id=self.node_id)
 
     def update(self, value):
         self.update_absolute(self.current + value)

comfy_api/feature_flags.py

@@ -0,0 +1,69 @@
+"""
+Feature flags module for ComfyUI WebSocket protocol negotiation.
+
+This module handles capability negotiation between frontend and backend,
+allowing graceful protocol evolution while maintaining backward compatibility.
+"""
+
+from typing import Any, Dict
+
+from comfy.cli_args import args
+
+# Default server capabilities
+SERVER_FEATURE_FLAGS: Dict[str, Any] = {
+    "supports_preview_metadata": True,
+    "max_upload_size": args.max_upload_size * 1024 * 1024, # Convert MB to bytes
+}
+
+
+def get_connection_feature(
+    sockets_metadata: Dict[str, Dict[str, Any]],
+    sid: str,
+    feature_name: str,
+    default: Any = False
+) -> Any:
+    """
+    Get a feature flag value for a specific connection.
+
+    Args:
+        sockets_metadata: Dictionary of socket metadata
+        sid: Session ID of the connection
+        feature_name: Name of the feature to check
+        default: Default value if feature not found
+
+    Returns:
+        Feature value or default if not found
+    """
+    if sid not in sockets_metadata:
+        return default
+
+    return sockets_metadata[sid].get("feature_flags", {}).get(feature_name, default)
+
+
+def supports_feature(
+    sockets_metadata: Dict[str, Dict[str, Any]],
+    sid: str,
+    feature_name: str
+) -> bool:
+    """
+    Check if a connection supports a specific feature.
+
+    Args:
+        sockets_metadata: Dictionary of socket metadata
+        sid: Session ID of the connection
+        feature_name: Name of the feature to check
+
+    Returns:
+        Boolean indicating if feature is supported
+    """
+    return get_connection_feature(sockets_metadata, sid, feature_name, False) is True
+
+
+def get_server_features() -> Dict[str, Any]:
+    """
+    Get the server's feature flags.
+
+    Returns:
+        Dictionary of server feature flags
+    """
+    return SERVER_FEATURE_FLAGS.copy()

comfy_execution/caching.py

@@ -1,6 +1,7 @@
 import itertools
 from typing import Sequence, Mapping, Dict
 from comfy_execution.graph import DynamicPrompt
+from abc import ABC, abstractmethod
 
 import nodes
 
@@ -16,12 +17,13 @@ def include_unique_id_in_input(class_type: str) -> bool:
     NODE_CLASS_CONTAINS_UNIQUE_ID[class_type] = "UNIQUE_ID" in class_def.INPUT_TYPES().get("hidden", {}).values()
     return NODE_CLASS_CONTAINS_UNIQUE_ID[class_type]
 
-class CacheKeySet:
+class CacheKeySet(ABC):
     def __init__(self, dynprompt, node_ids, is_changed_cache):
         self.keys = {}
         self.subcache_keys = {}
 
-    def add_keys(self, node_ids):
+    @abstractmethod
+    async def add_keys(self, node_ids):
         raise NotImplementedError()
 
     def all_node_ids(self):
@@ -60,9 +62,8 @@ class CacheKeySetID(CacheKeySet):
     def __init__(self, dynprompt, node_ids, is_changed_cache):
         super().__init__(dynprompt, node_ids, is_changed_cache)
         self.dynprompt = dynprompt
-        self.add_keys(node_ids)
 
-    def add_keys(self, node_ids):
+    async def add_keys(self, node_ids):
         for node_id in node_ids:
             if node_id in self.keys:
                 continue
@@ -77,37 +78,36 @@ class CacheKeySetInputSignature(CacheKeySet):
         super().__init__(dynprompt, node_ids, is_changed_cache)
         self.dynprompt = dynprompt
         self.is_changed_cache = is_changed_cache
-        self.add_keys(node_ids)
 
     def include_node_id_in_input(self) -> bool:
         return False
 
-    def add_keys(self, node_ids):
+    async def add_keys(self, node_ids):
         for node_id in node_ids:
             if node_id in self.keys:
                 continue
             if not self.dynprompt.has_node(node_id):
                 continue
             node = self.dynprompt.get_node(node_id)
-            self.keys[node_id] = self.get_node_signature(self.dynprompt, node_id)
+            self.keys[node_id] = await self.get_node_signature(self.dynprompt, node_id)
             self.subcache_keys[node_id] = (node_id, node["class_type"])
 
-    def get_node_signature(self, dynprompt, node_id):
+    async def get_node_signature(self, dynprompt, node_id):
         signature = []
         ancestors, order_mapping = self.get_ordered_ancestry(dynprompt, node_id)
-        signature.append(self.get_immediate_node_signature(dynprompt, node_id, order_mapping))
+        signature.append(await self.get_immediate_node_signature(dynprompt, node_id, order_mapping))
         for ancestor_id in ancestors:
-            signature.append(self.get_immediate_node_signature(dynprompt, ancestor_id, order_mapping))
+            signature.append(await self.get_immediate_node_signature(dynprompt, ancestor_id, order_mapping))
         return to_hashable(signature)
 
-    def get_immediate_node_signature(self, dynprompt, node_id, ancestor_order_mapping):
+    async def get_immediate_node_signature(self, dynprompt, node_id, ancestor_order_mapping):
         if not dynprompt.has_node(node_id):
             # This node doesn't exist -- we can't cache it.
             return [float("NaN")]
         node = dynprompt.get_node(node_id)
         class_type = node["class_type"]
         class_def = nodes.NODE_CLASS_MAPPINGS[class_type]
-        signature = [class_type, self.is_changed_cache.get(node_id)]
+        signature = [class_type, await self.is_changed_cache.get(node_id)]
         if self.include_node_id_in_input() or (hasattr(class_def, "NOT_IDEMPOTENT") and class_def.NOT_IDEMPOTENT) or include_unique_id_in_input(class_type):
             signature.append(node_id)
         inputs = node["inputs"]
@@ -150,9 +150,10 @@ class BasicCache:
         self.cache = {}
         self.subcaches = {}
 
-    def set_prompt(self, dynprompt, node_ids, is_changed_cache):
+    async def set_prompt(self, dynprompt, node_ids, is_changed_cache):
         self.dynprompt = dynprompt
         self.cache_key_set = self.key_class(dynprompt, node_ids, is_changed_cache)
+        await self.cache_key_set.add_keys(node_ids)
         self.is_changed_cache = is_changed_cache
         self.initialized = True
 
@@ -201,13 +202,13 @@ class BasicCache:
         else:
             return None
 
-    def _ensure_subcache(self, node_id, children_ids):
+    async def _ensure_subcache(self, node_id, children_ids):
         subcache_key = self.cache_key_set.get_subcache_key(node_id)
         subcache = self.subcaches.get(subcache_key, None)
         if subcache is None:
             subcache = BasicCache(self.key_class)
             self.subcaches[subcache_key] = subcache
-        subcache.set_prompt(self.dynprompt, children_ids, self.is_changed_cache)
+        await subcache.set_prompt(self.dynprompt, children_ids, self.is_changed_cache)
         return subcache
 
     def _get_subcache(self, node_id):
@@ -259,10 +260,10 @@ class HierarchicalCache(BasicCache):
         assert cache is not None
         cache._set_immediate(node_id, value)
 
-    def ensure_subcache_for(self, node_id, children_ids):
+    async def ensure_subcache_for(self, node_id, children_ids):
         cache = self._get_cache_for(node_id)
         assert cache is not None
-        return cache._ensure_subcache(node_id, children_ids)
+        return await cache._ensure_subcache(node_id, children_ids)
 
 class LRUCache(BasicCache):
     def __init__(self, key_class, max_size=100):
@@ -273,8 +274,8 @@ class LRUCache(BasicCache):
         self.used_generation = {}
         self.children = {}
 
-    def set_prompt(self, dynprompt, node_ids, is_changed_cache):
+    async def set_prompt(self, dynprompt, node_ids, is_changed_cache):
-        super().set_prompt(dynprompt, node_ids, is_changed_cache)
+        await super().set_prompt(dynprompt, node_ids, is_changed_cache)
         self.generation += 1
         for node_id in node_ids:
             self._mark_used(node_id)
@@ -303,11 +304,11 @@ class LRUCache(BasicCache):
         self._mark_used(node_id)
         return self._set_immediate(node_id, value)
 
-    def ensure_subcache_for(self, node_id, children_ids):
+    async def ensure_subcache_for(self, node_id, children_ids):
         # Just uses subcaches for tracking 'live' nodes
-        super()._ensure_subcache(node_id, children_ids)
+        await super()._ensure_subcache(node_id, children_ids)
 
-        self.cache_key_set.add_keys(children_ids)
+        await self.cache_key_set.add_keys(children_ids)
         self._mark_used(node_id)
         cache_key = self.cache_key_set.get_data_key(node_id)
         self.children[cache_key] = []
@@ -337,7 +338,7 @@ class DependencyAwareCache(BasicCache):
         self.ancestors = {}    # Maps node_id -> set of ancestor node_ids
         self.executed_nodes = set()  # Tracks nodes that have been executed
 
-    def set_prompt(self, dynprompt, node_ids, is_changed_cache):
+    async def set_prompt(self, dynprompt, node_ids, is_changed_cache):
         """
         Clear the entire cache and rebuild the dependency graph.
 
@@ -354,7 +355,7 @@ class DependencyAwareCache(BasicCache):
         self.executed_nodes.clear()
 
         # Call the parent method to initialize the cache with the new prompt
-        super().set_prompt(dynprompt, node_ids, is_changed_cache)
+        await super().set_prompt(dynprompt, node_ids, is_changed_cache)
 
         # Rebuild the dependency graph
         self._build_dependency_graph(dynprompt, node_ids)
@@ -405,7 +406,7 @@ class DependencyAwareCache(BasicCache):
         """
         return self._get_immediate(node_id)
 
-    def ensure_subcache_for(self, node_id, children_ids):
+    async def ensure_subcache_for(self, node_id, children_ids):
         """
         Ensure a subcache exists for a node and update dependencies.
 
@@ -416,7 +417,7 @@ class DependencyAwareCache(BasicCache):
         Returns:
             The subcache object for the node.
         """
-        subcache = super()._ensure_subcache(node_id, children_ids)
+        subcache = await super()._ensure_subcache(node_id, children_ids)
         for child_id in children_ids:
             self.descendants[node_id].add(child_id)
             self.ancestors[child_id].add(node_id)

comfy_execution/graph.py

@@ -2,6 +2,7 @@ from __future__ import annotations
 from typing import Type, Literal
 
 import nodes
+import asyncio
 from comfy_execution.graph_utils import is_link
 from comfy.comfy_types.node_typing import ComfyNodeABC, InputTypeDict, InputTypeOptions
 
@@ -100,6 +101,8 @@ class TopologicalSort:
         self.pendingNodes = {}
         self.blockCount = {} # Number of nodes this node is directly blocked by
         self.blocking = {} # Which nodes are blocked by this node
+        self.externalBlocks = 0
+        self.unblockedEvent = asyncio.Event()
 
     def get_input_info(self, unique_id, input_name):
         class_type = self.dynprompt.get_node(unique_id)["class_type"]
@@ -153,6 +156,16 @@ class TopologicalSort:
         for link in links:
             self.add_strong_link(*link)
 
+    def add_external_block(self, node_id):
+        assert node_id in self.blockCount, "Can't add external block to a node that isn't pending"
+        self.externalBlocks += 1
+        self.blockCount[node_id] += 1
+        def unblock():
+            self.externalBlocks -= 1
+            self.blockCount[node_id] -= 1
+            self.unblockedEvent.set()
+        return unblock
+
     def is_cached(self, node_id):
         return False
 
@@ -181,11 +194,16 @@ class ExecutionList(TopologicalSort):
     def is_cached(self, node_id):
         return self.output_cache.get(node_id) is not None
 
-    def stage_node_execution(self):
+    async def stage_node_execution(self):
         assert self.staged_node_id is None
         if self.is_empty():
             return None, None, None
         available = self.get_ready_nodes()
+        while len(available) == 0 and self.externalBlocks > 0:
+            # Wait for an external block to be released
+            await self.unblockedEvent.wait()
+            self.unblockedEvent.clear()
+            available = self.get_ready_nodes()
         if len(available) == 0:
             cycled_nodes = self.get_nodes_in_cycle()
             # Because cycles composed entirely of static nodes are caught during initial validation,

comfy_execution/progress.py

@@ -0,0 +1,347 @@
+from typing import TypedDict, Dict, Optional
+from typing_extensions import override
+from PIL import Image
+from enum import Enum
+from abc import ABC
+from tqdm import tqdm
+from typing import TYPE_CHECKING
+if TYPE_CHECKING:
+    from comfy_execution.graph import DynamicPrompt
+from protocol import BinaryEventTypes
+from comfy_api import feature_flags
+
+
+class NodeState(Enum):
+    Pending = "pending"
+    Running = "running"
+    Finished = "finished"
+    Error = "error"
+
+
+class NodeProgressState(TypedDict):
+    """
+    A class to represent the state of a node's progress.
+    """
+
+    state: NodeState
+    value: float
+    max: float
+
+
+class ProgressHandler(ABC):
+    """
+    Abstract base class for progress handlers.
+    Progress handlers receive progress updates and display them in various ways.
+    """
+
+    def __init__(self, name: str):
+        self.name = name
+        self.enabled = True
+
+    def set_registry(self, registry: "ProgressRegistry"):
+        pass
+
+    def start_handler(self, node_id: str, state: NodeProgressState, prompt_id: str):
+        """Called when a node starts processing"""
+        pass
+
+    def update_handler(
+        self,
+        node_id: str,
+        value: float,
+        max_value: float,
+        state: NodeProgressState,
+        prompt_id: str,
+        image: Optional[Image.Image] = None,
+    ):
+        """Called when a node's progress is updated"""
+        pass
+
+    def finish_handler(self, node_id: str, state: NodeProgressState, prompt_id: str):
+        """Called when a node finishes processing"""
+        pass
+
+    def reset(self):
+        """Called when the progress registry is reset"""
+        pass
+
+    def enable(self):
+        """Enable this handler"""
+        self.enabled = True
+
+    def disable(self):
+        """Disable this handler"""
+        self.enabled = False
+
+
+class CLIProgressHandler(ProgressHandler):
+    """
+    Handler that displays progress using tqdm progress bars in the CLI.
+    """
+
+    def __init__(self):
+        super().__init__("cli")
+        self.progress_bars: Dict[str, tqdm] = {}
+
+    @override
+    def start_handler(self, node_id: str, state: NodeProgressState, prompt_id: str):
+        # Create a new tqdm progress bar
+        if node_id not in self.progress_bars:
+            self.progress_bars[node_id] = tqdm(
+                total=state["max"],
+                desc=f"Node {node_id}",
+                unit="steps",
+                leave=True,
+                position=len(self.progress_bars),
+            )
+
+    @override
+    def update_handler(
+        self,
+        node_id: str,
+        value: float,
+        max_value: float,
+        state: NodeProgressState,
+        prompt_id: str,
+        image: Optional[Image.Image] = None,
+    ):
+        # Handle case where start_handler wasn't called
+        if node_id not in self.progress_bars:
+            self.progress_bars[node_id] = tqdm(
+                total=max_value,
+                desc=f"Node {node_id}",
+                unit="steps",
+                leave=True,
+                position=len(self.progress_bars),
+            )
+            self.progress_bars[node_id].update(value)
+        else:
+            # Update existing progress bar
+            if max_value != self.progress_bars[node_id].total:
+                self.progress_bars[node_id].total = max_value
+            # Calculate the update amount (difference from current position)
+            current_position = self.progress_bars[node_id].n
+            update_amount = value - current_position
+            if update_amount > 0:
+                self.progress_bars[node_id].update(update_amount)
+
+    @override
+    def finish_handler(self, node_id: str, state: NodeProgressState, prompt_id: str):
+        # Complete and close the progress bar if it exists
+        if node_id in self.progress_bars:
+            # Ensure the bar shows 100% completion
+            remaining = state["max"] - self.progress_bars[node_id].n
+            if remaining > 0:
+                self.progress_bars[node_id].update(remaining)
+            self.progress_bars[node_id].close()
+            del self.progress_bars[node_id]
+
+    @override
+    def reset(self):
+        # Close all progress bars
+        for bar in self.progress_bars.values():
+            bar.close()
+        self.progress_bars.clear()
+
+
+class WebUIProgressHandler(ProgressHandler):
+    """
+    Handler that sends progress updates to the WebUI via WebSockets.
+    """
+
+    def __init__(self, server_instance):
+        super().__init__("webui")
+        self.server_instance = server_instance
+
+    def set_registry(self, registry: "ProgressRegistry"):
+        self.registry = registry
+
+    def _send_progress_state(self, prompt_id: str, nodes: Dict[str, NodeProgressState]):
+        """Send the current progress state to the client"""
+        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
+        }
+
+        # Send a combined progress_state message with all node states
+        self.server_instance.send_sync(
+            "progress_state", {"prompt_id": prompt_id, "nodes": active_nodes}
+        )
+
+    @override
+    def start_handler(self, node_id: str, state: NodeProgressState, prompt_id: str):
+        # Send progress state of all nodes
+        if self.registry:
+            self._send_progress_state(prompt_id, self.registry.nodes)
+
+    @override
+    def update_handler(
+        self,
+        node_id: str,
+        value: float,
+        max_value: float,
+        state: NodeProgressState,
+        prompt_id: str,
+        image: Optional[Image.Image] = None,
+    ):
+        # Send progress state of all nodes
+        if self.registry:
+            self._send_progress_state(prompt_id, self.registry.nodes)
+        if image:
+            # Only send new format if client supports it
+            if feature_flags.supports_feature(
+                self.server_instance.sockets_metadata,
+                self.server_instance.client_id,
+                "supports_preview_metadata",
+            ):
+                metadata = {
+                    "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),
+                }
+                self.server_instance.send_sync(
+                    BinaryEventTypes.PREVIEW_IMAGE_WITH_METADATA,
+                    (image, metadata),
+                    self.server_instance.client_id,
+                )
+
+    @override
+    def finish_handler(self, node_id: str, state: NodeProgressState, prompt_id: str):
+        # Send progress state of all nodes
+        if self.registry:
+            self._send_progress_state(prompt_id, self.registry.nodes)
+
+
+class ProgressRegistry:
+    """
+    Registry that maintains node progress state and notifies registered handlers.
+    """
+
+    def __init__(self, prompt_id: str, dynprompt: "DynamicPrompt"):
+        self.prompt_id = prompt_id
+        self.dynprompt = dynprompt
+        self.nodes: Dict[str, NodeProgressState] = {}
+        self.handlers: Dict[str, ProgressHandler] = {}
+
+    def register_handler(self, handler: ProgressHandler) -> None:
+        """Register a progress handler"""
+        self.handlers[handler.name] = handler
+
+    def unregister_handler(self, handler_name: str) -> None:
+        """Unregister a progress handler"""
+        if handler_name in self.handlers:
+            # Allow handler to clean up resources
+            self.handlers[handler_name].reset()
+            del self.handlers[handler_name]
+
+    def enable_handler(self, handler_name: str) -> None:
+        """Enable a progress handler"""
+        if handler_name in self.handlers:
+            self.handlers[handler_name].enable()
+
+    def disable_handler(self, handler_name: str) -> None:
+        """Disable a progress handler"""
+        if handler_name in self.handlers:
+            self.handlers[handler_name].disable()
+
+    def ensure_entry(self, node_id: str) -> NodeProgressState:
+        """Ensure a node entry exists"""
+        if node_id not in self.nodes:
+            self.nodes[node_id] = NodeProgressState(
+                state=NodeState.Pending, value=0, max=1
+            )
+        return self.nodes[node_id]
+
+    def start_progress(self, node_id: str) -> None:
+        """Start progress tracking for a node"""
+        entry = self.ensure_entry(node_id)
+        entry["state"] = NodeState.Running
+        entry["value"] = 0.0
+        entry["max"] = 1.0
+
+        # Notify all enabled handlers
+        for handler in self.handlers.values():
+            if handler.enabled:
+                handler.start_handler(node_id, entry, self.prompt_id)
+
+    def update_progress(
+        self, node_id: str, value: float, max_value: float, image: Optional[Image.Image]
+    ) -> None:
+        """Update progress for a node"""
+        entry = self.ensure_entry(node_id)
+        entry["state"] = NodeState.Running
+        entry["value"] = value
+        entry["max"] = max_value
+
+        # Notify all enabled handlers
+        for handler in self.handlers.values():
+            if handler.enabled:
+                handler.update_handler(
+                    node_id, value, max_value, entry, self.prompt_id, image
+                )
+
+    def finish_progress(self, node_id: str) -> None:
+        """Finish progress tracking for a node"""
+        entry = self.ensure_entry(node_id)
+        entry["state"] = NodeState.Finished
+        entry["value"] = entry["max"]
+
+        # Notify all enabled handlers
+        for handler in self.handlers.values():
+            if handler.enabled:
+                handler.finish_handler(node_id, entry, self.prompt_id)
+
+    def reset_handlers(self) -> None:
+        """Reset all handlers"""
+        for handler in self.handlers.values():
+            handler.reset()
+
+# Global registry instance
+global_progress_registry: ProgressRegistry | None = None
+
+def reset_progress_state(prompt_id: str, dynprompt: "DynamicPrompt") -> None:
+    global global_progress_registry
+
+    # Reset existing handlers if registry exists
+    if global_progress_registry is not None:
+        global_progress_registry.reset_handlers()
+
+    # Create new registry
+    global_progress_registry = ProgressRegistry(prompt_id, dynprompt)
+
+
+def add_progress_handler(handler: ProgressHandler) -> None:
+    registry = get_progress_state()
+    handler.set_registry(registry)
+    registry.register_handler(handler)
+
+
+def get_progress_state() -> ProgressRegistry:
+    global global_progress_registry
+    if global_progress_registry is None:
+        from comfy_execution.graph import DynamicPrompt
+
+        global_progress_registry = ProgressRegistry(
+            prompt_id="", dynprompt=DynamicPrompt({})
+        )
+    return global_progress_registry

comfy_execution/utils.py

@@ -0,0 +1,46 @@
+import contextvars
+from typing import Optional, NamedTuple
+
+class ExecutionContext(NamedTuple):
+    """
+    Context information about the currently executing node.
+
+    Attributes:
+        node_id: The ID of the currently executing node
+        list_index: The index in a list being processed (for operations on batches/lists)
+    """
+    prompt_id: str
+    node_id: str
+    list_index: Optional[int]
+
+current_executing_context: contextvars.ContextVar[Optional[ExecutionContext]] = contextvars.ContextVar("current_executing_context", default=None)
+
+def get_executing_context() -> Optional[ExecutionContext]:
+    return current_executing_context.get(None)
+
+class CurrentNodeContext:
+    """
+    Context manager for setting the current executing node context.
+
+    Sets the current_executing_context on enter and resets it on exit.
+
+    Example:
+        with CurrentNodeContext(node_id="123", list_index=0):
+            # Code that should run with the current node context set
+            process_image()
+    """
+    def __init__(self, prompt_id: str, node_id: str, list_index: Optional[int] = None):
+        self.context = ExecutionContext(
+            prompt_id= prompt_id,
+            node_id= node_id,
+            list_index= list_index
+        )
+        self.token = None
+
+    def __enter__(self):
+        self.token = current_executing_context.set(self.context)
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        if self.token is not None:
+            current_executing_context.reset(self.token)

execution.py

@@ -8,12 +8,14 @@ import time
 import traceback
 from enum import Enum
 from typing import List, Literal, NamedTuple, Optional
+import asyncio
 
 import torch
 
 import comfy.model_management
 import nodes
 from comfy_execution.caching import (
+    BasicCache,
     CacheKeySetID,
     CacheKeySetInputSignature,
     DependencyAwareCache,
@@ -28,6 +30,8 @@ from comfy_execution.graph import (
 )
 from comfy_execution.graph_utils import GraphBuilder, is_link
 from comfy_execution.validation import validate_node_input
+from comfy_execution.progress import get_progress_state, reset_progress_state, add_progress_handler, WebUIProgressHandler
+from comfy_execution.utils import CurrentNodeContext
 
 
 class ExecutionResult(Enum):
@@ -39,12 +43,13 @@ class DuplicateNodeError(Exception):
     pass
 
 class IsChangedCache:
-    def __init__(self, dynprompt, outputs_cache):
+    def __init__(self, prompt_id: str, dynprompt: DynamicPrompt, outputs_cache: BasicCache):
+        self.prompt_id = prompt_id
         self.dynprompt = dynprompt
         self.outputs_cache = outputs_cache
         self.is_changed = {}
 
-    def get(self, node_id):
+    async def get(self, node_id):
         if node_id in self.is_changed:
             return self.is_changed[node_id]
 
@@ -62,7 +67,8 @@ class IsChangedCache:
         # Intentionally do not use cached outputs here. We only want constants in IS_CHANGED
         input_data_all, _ = get_input_data(node["inputs"], class_def, node_id, None)
         try:
-            is_changed = _map_node_over_list(class_def, input_data_all, "IS_CHANGED")
+            is_changed = await _async_map_node_over_list(self.prompt_id, node_id, class_def, input_data_all, "IS_CHANGED")
+            is_changed = await resolve_map_node_over_list_results(is_changed)
             node["is_changed"] = [None if isinstance(x, ExecutionBlocker) else x for x in is_changed]
         except Exception as e:
             logging.warning("WARNING: {}".format(e))
@@ -164,7 +170,19 @@ def get_input_data(inputs, class_def, unique_id, outputs=None, dynprompt=None, e
 
 map_node_over_list = None #Don't hook this please
 
-def _map_node_over_list(obj, input_data_all, func, allow_interrupt=False, execution_block_cb=None, pre_execute_cb=None):
+async def resolve_map_node_over_list_results(results):
+    remaining = [x for x in results if isinstance(x, asyncio.Task) and not x.done()]
+    if len(remaining) == 0:
+        return [x.result() if isinstance(x, asyncio.Task) else x for x in results]
+    else:
+        done, pending = await asyncio.wait(remaining)
+        for task in done:
+            exc = task.exception()
+            if exc is not None:
+                raise exc
+        return [x.result() if isinstance(x, asyncio.Task) else x for x in results]
+
+async def _async_map_node_over_list(prompt_id, unique_id, obj, input_data_all, func, allow_interrupt=False, execution_block_cb=None, pre_execute_cb=None):
     # check if node wants the lists
     input_is_list = getattr(obj, "INPUT_IS_LIST", False)
 
@@ -178,7 +196,7 @@ def _map_node_over_list(obj, input_data_all, func, allow_interrupt=False, execut
         return {k: v[i if len(v) > i else -1] for k, v in d.items()}
 
     results = []
-    def process_inputs(inputs, index=None, input_is_list=False):
+    async def process_inputs(inputs, index=None, input_is_list=False):
         if allow_interrupt:
             nodes.before_node_execution()
         execution_block = None
@@ -194,20 +212,37 @@ def _map_node_over_list(obj, input_data_all, func, allow_interrupt=False, execut
         if execution_block is None:
             if pre_execute_cb is not None and index is not None:
                 pre_execute_cb(index)
-            results.append(getattr(obj, func)(**inputs))
+            f = getattr(obj, func)
+            if inspect.iscoroutinefunction(f):
+                async def async_wrapper(f, prompt_id, unique_id, list_index, args):
+                    with CurrentNodeContext(prompt_id, unique_id, list_index):
+                        return await f(**args)
+                task = asyncio.create_task(async_wrapper(f, prompt_id, unique_id, index, args=inputs))
+                # Give the task a chance to execute without yielding
+                await asyncio.sleep(0)
+                if task.done():
+                    result = task.result()
+                    results.append(result)
+                else:
+                    results.append(task)
+            else:
+                with CurrentNodeContext(prompt_id, unique_id, index):
+                    result = f(**inputs)
+                results.append(result)
         else:
             results.append(execution_block)
 
     if input_is_list:
-        process_inputs(input_data_all, 0, input_is_list=input_is_list)
+        await process_inputs(input_data_all, 0, input_is_list=input_is_list)
     elif max_len_input == 0:
-        process_inputs({})
+        await process_inputs({})
     else:
         for i in range(max_len_input):
             input_dict = slice_dict(input_data_all, i)
-            process_inputs(input_dict, i)
+            await process_inputs(input_dict, i)
     return results
 
+
 def merge_result_data(results, obj):
     # check which outputs need concatenating
     output = []
@@ -229,11 +264,18 @@ def merge_result_data(results, obj):
             output.append([o[i] for o in results])
     return output
 
-def get_output_data(obj, input_data_all, execution_block_cb=None, pre_execute_cb=None):
+async def get_output_data(prompt_id, unique_id, obj, input_data_all, execution_block_cb=None, pre_execute_cb=None):
+    return_values = await _async_map_node_over_list(prompt_id, unique_id, obj, input_data_all, obj.FUNCTION, allow_interrupt=True, execution_block_cb=execution_block_cb, pre_execute_cb=pre_execute_cb)
+    has_pending_task = any(isinstance(r, asyncio.Task) and not r.done() for r in return_values)
+    if has_pending_task:
+        return return_values, {}, False, has_pending_task
+    output, ui, has_subgraph = get_output_from_returns(return_values, obj)
+    return output, ui, has_subgraph, False
+
+def get_output_from_returns(return_values, obj):
     results = []
     uis = []
     subgraph_results = []
-    return_values = _map_node_over_list(obj, input_data_all, obj.FUNCTION, allow_interrupt=True, execution_block_cb=execution_block_cb, pre_execute_cb=pre_execute_cb)
     has_subgraph = False
     for i in range(len(return_values)):
         r = return_values[i]
@@ -267,6 +309,10 @@ def get_output_data(obj, input_data_all, execution_block_cb=None, pre_execute_cb
     else:
         output = []
     ui = dict()
+    # TODO: Think there's an existing bug here
+    # If we're performing a subgraph expansion, we probably shouldn't be returning UI values yet.
+    # They'll get cached without the completed subgraphs. It's an edge case and I'm not aware of
+    # any nodes that use both subgraph expansion and custom UI outputs, but might be a problem in the future.
     if len(uis) > 0:
         ui = {k: [y for x in uis for y in x[k]] for k in uis[0].keys()}
     return output, ui, has_subgraph
@@ -279,7 +325,7 @@ def format_value(x):
     else:
         return str(x)
 
-def execute(server, dynprompt, caches, current_item, extra_data, executed, prompt_id, execution_list, pending_subgraph_results):
+async def execute(server, dynprompt, caches, current_item, extra_data, executed, prompt_id, execution_list, pending_subgraph_results, pending_async_nodes):
     unique_id = current_item
     real_node_id = dynprompt.get_real_node_id(unique_id)
     display_node_id = dynprompt.get_display_node_id(unique_id)
@@ -291,11 +337,26 @@ def execute(server, dynprompt, caches, current_item, extra_data, executed, promp
         if server.client_id is not None:
             cached_output = caches.ui.get(unique_id) or {}
             server.send_sync("executed", { "node": unique_id, "display_node": display_node_id, "output": cached_output.get("output",None), "prompt_id": prompt_id }, server.client_id)
+        get_progress_state().finish_progress(unique_id)
         return (ExecutionResult.SUCCESS, None, None)
 
     input_data_all = None
     try:
-        if unique_id in pending_subgraph_results:
+        if unique_id in pending_async_nodes:
+            results = []
+            for r in pending_async_nodes[unique_id]:
+                if isinstance(r, asyncio.Task):
+                    try:
+                        results.append(r.result())
+                    except Exception as ex:
+                        # An async task failed - propagate the exception up
+                        del pending_async_nodes[unique_id]
+                        raise ex
+                else:
+                    results.append(r)
+            del pending_async_nodes[unique_id]
+            output_data, output_ui, has_subgraph = get_output_from_returns(results, class_def)
+        elif unique_id in pending_subgraph_results:
             cached_results = pending_subgraph_results[unique_id]
             resolved_outputs = []
             for is_subgraph, result in cached_results:
@@ -317,6 +378,7 @@ def execute(server, dynprompt, caches, current_item, extra_data, executed, promp
             output_ui = []
             has_subgraph = False
         else:
+            get_progress_state().start_progress(unique_id)
             input_data_all, missing_keys = get_input_data(inputs, class_def, unique_id, caches.outputs, dynprompt, extra_data)
             if server.client_id is not None:
                 server.last_node_id = display_node_id
@@ -328,7 +390,8 @@ def execute(server, dynprompt, caches, current_item, extra_data, executed, promp
                 caches.objects.set(unique_id, obj)
 
             if hasattr(obj, "check_lazy_status"):
-                required_inputs = _map_node_over_list(obj, input_data_all, "check_lazy_status", allow_interrupt=True)
+                required_inputs = await _async_map_node_over_list(prompt_id, unique_id, obj, input_data_all, "check_lazy_status", allow_interrupt=True)
+                required_inputs = await resolve_map_node_over_list_results(required_inputs)
                 required_inputs = set(sum([r for r in required_inputs if isinstance(r,list)], []))
                 required_inputs = [x for x in required_inputs if isinstance(x,str) and (
                     x not in input_data_all or x in missing_keys
@@ -357,8 +420,18 @@ def execute(server, dynprompt, caches, current_item, extra_data, executed, promp
                 else:
                     return block
             def pre_execute_cb(call_index):
+                # TODO - How to handle this with async functions without contextvars (which requires Python 3.12)?
                 GraphBuilder.set_default_prefix(unique_id, call_index, 0)
-            output_data, output_ui, has_subgraph = get_output_data(obj, input_data_all, execution_block_cb=execution_block_cb, pre_execute_cb=pre_execute_cb)
+            output_data, output_ui, has_subgraph, has_pending_tasks = await get_output_data(prompt_id, unique_id, obj, input_data_all, execution_block_cb=execution_block_cb, pre_execute_cb=pre_execute_cb)
+            if has_pending_tasks:
+                pending_async_nodes[unique_id] = output_data
+                unblock = execution_list.add_external_block(unique_id)
+                async def await_completion():
+                    tasks = [x for x in output_data if isinstance(x, asyncio.Task)]
+                    await asyncio.gather(*tasks, return_exceptions=True)
+                    unblock()
+                asyncio.create_task(await_completion())
+                return (ExecutionResult.PENDING, None, None)
         if len(output_ui) > 0:
             caches.ui.set(unique_id, {
                 "meta": {
@@ -401,7 +474,8 @@ def execute(server, dynprompt, caches, current_item, extra_data, executed, promp
                     cached_outputs.append((True, node_outputs))
             new_node_ids = set(new_node_ids)
             for cache in caches.all:
-                cache.ensure_subcache_for(unique_id, new_node_ids).clean_unused()
+                subcache = await cache.ensure_subcache_for(unique_id, new_node_ids)
+                subcache.clean_unused()
             for node_id in new_output_ids:
                 execution_list.add_node(node_id)
             for link in new_output_links:
@@ -446,6 +520,7 @@ def execute(server, dynprompt, caches, current_item, extra_data, executed, promp
 
         return (ExecutionResult.FAILURE, error_details, ex)
 
+    get_progress_state().finish_progress(unique_id)
     executed.add(unique_id)
 
     return (ExecutionResult.SUCCESS, None, None)
@@ -500,6 +575,11 @@ class PromptExecutor:
             self.add_message("execution_error", mes, broadcast=False)
 
     def execute(self, prompt, prompt_id, extra_data={}, execute_outputs=[]):
+        asyncio_loop = asyncio.new_event_loop()
+        asyncio.set_event_loop(asyncio_loop)
+        asyncio.run(self.execute_async(prompt, prompt_id, extra_data, execute_outputs))
+
+    async def execute_async(self, prompt, prompt_id, extra_data={}, execute_outputs=[]):
         nodes.interrupt_processing(False)
 
         if "client_id" in extra_data:
@@ -512,9 +592,11 @@ class PromptExecutor:
 
         with torch.inference_mode():
             dynamic_prompt = DynamicPrompt(prompt)
-            is_changed_cache = IsChangedCache(dynamic_prompt, self.caches.outputs)
+            reset_progress_state(prompt_id, dynamic_prompt)
+            add_progress_handler(WebUIProgressHandler(self.server))
+            is_changed_cache = IsChangedCache(prompt_id, dynamic_prompt, self.caches.outputs)
             for cache in self.caches.all:
-                cache.set_prompt(dynamic_prompt, prompt.keys(), is_changed_cache)
+                await cache.set_prompt(dynamic_prompt, prompt.keys(), is_changed_cache)
                 cache.clean_unused()
 
             cached_nodes = []
@@ -527,6 +609,7 @@ class PromptExecutor:
                           { "nodes": cached_nodes, "prompt_id": prompt_id},
                           broadcast=False)
             pending_subgraph_results = {}
+            pending_async_nodes = {} # TODO - Unify this with pending_subgraph_results
             executed = set()
             execution_list = ExecutionList(dynamic_prompt, self.caches.outputs)
             current_outputs = self.caches.outputs.all_node_ids()
@@ -534,12 +617,13 @@ class PromptExecutor:
                 execution_list.add_node(node_id)
 
             while not execution_list.is_empty():
-                node_id, error, ex = execution_list.stage_node_execution()
+                node_id, error, ex = await execution_list.stage_node_execution()
                 if error is not None:
                     self.handle_execution_error(prompt_id, dynamic_prompt.original_prompt, current_outputs, executed, error, ex)
                     break
 
-                result, error, ex = execute(self.server, dynamic_prompt, self.caches, node_id, extra_data, executed, prompt_id, execution_list, pending_subgraph_results)
+                assert node_id is not None, "Node ID should not be None at this point"
+                result, error, ex = await execute(self.server, dynamic_prompt, self.caches, node_id, extra_data, executed, prompt_id, execution_list, pending_subgraph_results, pending_async_nodes)
                 self.success = result != ExecutionResult.FAILURE
                 if result == ExecutionResult.FAILURE:
                     self.handle_execution_error(prompt_id, dynamic_prompt.original_prompt, current_outputs, executed, error, ex)
@@ -569,7 +653,7 @@ class PromptExecutor:
                 comfy.model_management.unload_all_models()
 
 
-def validate_inputs(prompt, item, validated):
+async def validate_inputs(prompt_id, prompt, item, validated):
     unique_id = item
     if unique_id in validated:
         return validated[unique_id]
@@ -646,7 +730,7 @@ def validate_inputs(prompt, item, validated):
                 errors.append(error)
                 continue
             try:
-                r = validate_inputs(prompt, o_id, validated)
+                r = await validate_inputs(prompt_id, prompt, o_id, validated)
                 if r[0] is False:
                     # `r` will be set in `validated[o_id]` already
                     valid = False
@@ -771,7 +855,8 @@ def validate_inputs(prompt, item, validated):
             input_filtered['input_types'] = [received_types]
 
         #ret = obj_class.VALIDATE_INPUTS(**input_filtered)
-        ret = _map_node_over_list(obj_class, input_filtered, "VALIDATE_INPUTS")
+        ret = await _async_map_node_over_list(prompt_id, unique_id, obj_class, input_filtered, "VALIDATE_INPUTS")
+        ret = await resolve_map_node_over_list_results(ret)
         for x in input_filtered:
             for i, r in enumerate(ret):
                 if r is not True and not isinstance(r, ExecutionBlocker):
@@ -804,7 +889,7 @@ def full_type_name(klass):
         return klass.__qualname__
     return module + '.' + klass.__qualname__
 
-def validate_prompt(prompt):
+async def validate_prompt(prompt_id, prompt):
     outputs = set()
     for x in prompt:
         if 'class_type' not in prompt[x]:
@@ -847,7 +932,7 @@ def validate_prompt(prompt):
         valid = False
         reasons = []
         try:
-            m = validate_inputs(prompt, o, validated)
+            m = await validate_inputs(prompt_id, prompt, o, validated)
             valid = m[0]
             reasons = m[1]
         except Exception as ex:

main.py

@@ -11,6 +11,9 @@ import itertools
 import utils.extra_config
 import logging
 import sys
+from comfy_execution.progress import get_progress_state
+from comfy_execution.utils import get_executing_context
+from comfy_api import feature_flags
 
 if __name__ == "__main__":
     #NOTE: These do not do anything on core ComfyUI, they are for custom nodes.
@@ -134,7 +137,7 @@ import comfy.utils
 
 import execution
 import server
-from server import BinaryEventTypes
+from protocol import BinaryEventTypes
 import nodes
 import comfy.model_management
 import comfyui_version
@@ -230,15 +233,34 @@ async def run(server_instance, address='', port=8188, verbose=True, call_on_star
         server_instance.start_multi_address(addresses, call_on_start, verbose), server_instance.publish_loop()
     )
 
-
 def hijack_progress(server_instance):
-    def hook(value, total, preview_image):
+    def hook(value, total, preview_image, prompt_id=None, node_id=None):
+        executing_context = get_executing_context()
+        if prompt_id is None and executing_context is not None:
+            prompt_id = executing_context.prompt_id
+        if node_id is None and executing_context is not None:
+            node_id = executing_context.node_id
         comfy.model_management.throw_exception_if_processing_interrupted()
-        progress = {"value": value, "max": total, "prompt_id": server_instance.last_prompt_id, "node": server_instance.last_node_id}
+        if prompt_id is None:
+            prompt_id = server_instance.last_prompt_id
+        if node_id is None:
+            node_id = server_instance.last_node_id
+        progress = {"value": value, "max": total, "prompt_id": prompt_id, "node": node_id}
+        get_progress_state().update_progress(node_id, value, total, preview_image)
 
         server_instance.send_sync("progress", progress, server_instance.client_id)
         if preview_image is not None:
-            server_instance.send_sync(BinaryEventTypes.UNENCODED_PREVIEW_IMAGE, preview_image, server_instance.client_id)
+            # Only send old method if client doesn't support preview metadata
+            if not feature_flags.supports_feature(
+                server_instance.sockets_metadata,
+                server_instance.client_id,
+                "supports_preview_metadata",
+            ):
+                server_instance.send_sync(
+                    BinaryEventTypes.UNENCODED_PREVIEW_IMAGE,
+                    preview_image,
+                    server_instance.client_id,
+                )
 
     comfy.utils.set_progress_bar_global_hook(hook)
 

protocol.py

@@ -0,0 +1,7 @@
+
+class BinaryEventTypes:
+    PREVIEW_IMAGE = 1
+    UNENCODED_PREVIEW_IMAGE = 2
+    TEXT = 3
+    PREVIEW_IMAGE_WITH_METADATA = 4
+

server.py

@@ -26,6 +26,7 @@ import mimetypes
 from comfy.cli_args import args
 import comfy.utils
 import comfy.model_management
+from comfy_api import feature_flags
 import node_helpers
 from comfyui_version import __version__
 from app.frontend_management import FrontendManager
@@ -35,11 +36,7 @@ from app.model_manager import ModelFileManager
 from app.custom_node_manager import CustomNodeManager
 from typing import Optional, Union
 from api_server.routes.internal.internal_routes import InternalRoutes
-
+from protocol import BinaryEventTypes
-class BinaryEventTypes:
-    PREVIEW_IMAGE = 1
-    UNENCODED_PREVIEW_IMAGE = 2
-    TEXT = 3
 
 async def send_socket_catch_exception(function, message):
     try:
@@ -178,6 +175,7 @@ class PromptServer():
         max_upload_size = round(args.max_upload_size * 1024 * 1024)
         self.app = web.Application(client_max_size=max_upload_size, middlewares=middlewares)
         self.sockets = dict()
+        self.sockets_metadata = dict()
         self.web_root = (
             FrontendManager.init_frontend(args.front_end_version)
             if args.front_end_root is None
@@ -202,20 +200,53 @@ class PromptServer():
             else:
                 sid = uuid.uuid4().hex
 
+            # Store WebSocket for backward compatibility
             self.sockets[sid] = ws
+            # Store metadata separately
+            self.sockets_metadata[sid] = {"feature_flags": {}}
 
             try:
                 # Send initial state to the new client
-                await self.send("status", { "status": self.get_queue_info(), 'sid': sid }, sid)
+                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)
 
+                # Flag to track if we've received the first message
+                first_message = True
+
                 async for msg in ws:
                     if msg.type == aiohttp.WSMsgType.ERROR:
                         logging.warning('ws connection closed with exception %s' % ws.exception())
+                    elif msg.type == aiohttp.WSMsgType.TEXT:
+                        try:
+                            data = json.loads(msg.data)
+                            # Check if first message is feature flags
+                            if first_message and data.get("type") == "feature_flags":
+                                # Store client feature flags
+                                client_flags = data.get("data", {})
+                                self.sockets_metadata[sid]["feature_flags"] = client_flags
+
+                                # Send server feature flags in response
+                                await self.send(
+                                    "feature_flags",
+                                    feature_flags.get_server_features(),
+                                    sid,
+                                )
+
+                                logging.info(
+                                    f"Feature flags negotiated for client {sid}: {client_flags}"
+                                )
+                            first_message = False
+                        except json.JSONDecodeError:
+                            logging.warning(
+                                f"Invalid JSON received from client {sid}: {msg.data}"
+                            )
+                        except Exception as e:
+                            logging.error(f"Error processing WebSocket message: {e}")
             finally:
                 self.sockets.pop(sid, None)
+                self.sockets_metadata.pop(sid, None)
             return ws
 
         @routes.get("/")
@@ -548,6 +579,10 @@ class PromptServer():
             }
             return web.json_response(system_stats)
 
+        @routes.get("/features")
+        async def get_features(request):
+            return web.json_response(feature_flags.get_server_features())
+
         @routes.get("/prompt")
         async def get_prompt(request):
             return web.json_response(self.get_queue_info())
@@ -643,7 +678,8 @@ class PromptServer():
 
             if "prompt" in json_data:
                 prompt = json_data["prompt"]
-                valid = execution.validate_prompt(prompt)
+                prompt_id = str(uuid.uuid4())
+                valid = await execution.validate_prompt(prompt_id, prompt)
                 extra_data = {}
                 if "extra_data" in json_data:
                     extra_data = json_data["extra_data"]
@@ -651,7 +687,6 @@ class PromptServer():
                 if "client_id" in json_data:
                     extra_data["client_id"] = json_data["client_id"]
                 if valid[0]:
-                    prompt_id = str(uuid.uuid4())
                     outputs_to_execute = valid[2]
                     self.prompt_queue.put((number, prompt_id, prompt, extra_data, outputs_to_execute))
                     response = {"prompt_id": prompt_id, "number": number, "node_errors": valid[3]}
@@ -766,6 +801,10 @@ class PromptServer():
     async def send(self, event, data, sid=None):
         if event == BinaryEventTypes.UNENCODED_PREVIEW_IMAGE:
             await self.send_image(data, sid=sid)
+        elif event == BinaryEventTypes.PREVIEW_IMAGE_WITH_METADATA:
+            # data is (preview_image, metadata)
+            preview_image, metadata = data
+            await self.send_image_with_metadata(preview_image, metadata, sid=sid)
         elif isinstance(data, (bytes, bytearray)):
             await self.send_bytes(event, data, sid)
         else:
@@ -804,6 +843,43 @@ class PromptServer():
         preview_bytes = bytesIO.getvalue()
         await self.send_bytes(BinaryEventTypes.PREVIEW_IMAGE, preview_bytes, sid=sid)
 
+    async def send_image_with_metadata(self, image_data, metadata=None, sid=None):
+        image_type = image_data[0]
+        image = image_data[1]
+        max_size = image_data[2]
+        if max_size is not None:
+            if hasattr(Image, 'Resampling'):
+                resampling = Image.Resampling.BILINEAR
+            else:
+                resampling = Image.Resampling.LANCZOS
+
+            image = ImageOps.contain(image, (max_size, max_size), resampling)
+
+        mimetype = "image/png" if image_type == "PNG" else "image/jpeg"
+
+        # Prepare metadata
+        if metadata is None:
+            metadata = {}
+        metadata["image_type"] = mimetype
+
+        # Serialize metadata as JSON
+        import json
+        metadata_json = json.dumps(metadata).encode('utf-8')
+        metadata_length = len(metadata_json)
+
+        # Prepare image data
+        bytesIO = BytesIO()
+        image.save(bytesIO, format=image_type, quality=95, compress_level=1)
+        image_bytes = bytesIO.getvalue()
+
+        # Combine metadata and image
+        combined_data = bytearray()
+        combined_data.extend(struct.pack(">I", metadata_length))
+        combined_data.extend(metadata_json)
+        combined_data.extend(image_bytes)
+
+        await self.send_bytes(BinaryEventTypes.PREVIEW_IMAGE_WITH_METADATA, combined_data, sid=sid)
+
     async def send_bytes(self, event, data, sid=None):
         message = self.encode_bytes(event, data)
 

tests-unit/feature_flags_test.py

@@ -0,0 +1,98 @@
+"""Tests for feature flags functionality."""
+
+from comfy_api.feature_flags import (
+    get_connection_feature,
+    supports_feature,
+    get_server_features,
+    SERVER_FEATURE_FLAGS,
+)
+
+
+class TestFeatureFlags:
+    """Test suite for feature flags functions."""
+
+    def test_get_server_features_returns_copy(self):
+        """Test that get_server_features returns a copy of the server flags."""
+        features = get_server_features()
+        # Verify it's a copy by modifying it
+        features["test_flag"] = True
+        # Original should be unchanged
+        assert "test_flag" not in SERVER_FEATURE_FLAGS
+
+    def test_get_server_features_contains_expected_flags(self):
+        """Test that server features contain expected flags."""
+        features = get_server_features()
+        assert "supports_preview_metadata" in features
+        assert features["supports_preview_metadata"] is True
+        assert "max_upload_size" in features
+        assert isinstance(features["max_upload_size"], (int, float))
+
+    def test_get_connection_feature_with_missing_sid(self):
+        """Test getting feature for non-existent session ID."""
+        sockets_metadata = {}
+        result = get_connection_feature(sockets_metadata, "missing_sid", "some_feature")
+        assert result is False  # Default value
+
+    def test_get_connection_feature_with_custom_default(self):
+        """Test getting feature with custom default value."""
+        sockets_metadata = {}
+        result = get_connection_feature(
+            sockets_metadata, "missing_sid", "some_feature", default="custom_default"
+        )
+        assert result == "custom_default"
+
+    def test_get_connection_feature_with_feature_flags(self):
+        """Test getting feature from connection with feature flags."""
+        sockets_metadata = {
+            "sid1": {
+                "feature_flags": {
+                    "supports_preview_metadata": True,
+                    "custom_feature": "value",
+                },
+            }
+        }
+        result = get_connection_feature(sockets_metadata, "sid1", "supports_preview_metadata")
+        assert result is True
+
+        result = get_connection_feature(sockets_metadata, "sid1", "custom_feature")
+        assert result == "value"
+
+    def test_get_connection_feature_missing_feature(self):
+        """Test getting non-existent feature from connection."""
+        sockets_metadata = {
+            "sid1": {"feature_flags": {"existing_feature": True}}
+        }
+        result = get_connection_feature(sockets_metadata, "sid1", "missing_feature")
+        assert result is False
+
+    def test_supports_feature_returns_boolean(self):
+        """Test that supports_feature always returns boolean."""
+        sockets_metadata = {
+            "sid1": {
+                "feature_flags": {
+                    "bool_feature": True,
+                    "string_feature": "value",
+                    "none_feature": None,
+                },
+            }
+        }
+
+        # True boolean feature
+        assert supports_feature(sockets_metadata, "sid1", "bool_feature") is True
+
+        # Non-boolean values should return False
+        assert supports_feature(sockets_metadata, "sid1", "string_feature") is False
+        assert supports_feature(sockets_metadata, "sid1", "none_feature") is False
+        assert supports_feature(sockets_metadata, "sid1", "missing_feature") is False
+
+    def test_supports_feature_with_missing_connection(self):
+        """Test supports_feature with missing connection."""
+        sockets_metadata = {}
+        assert supports_feature(sockets_metadata, "missing_sid", "any_feature") is False
+
+    def test_empty_feature_flags_dict(self):
+        """Test connection with empty feature flags dictionary."""
+        sockets_metadata = {"sid1": {"feature_flags": {}}}
+        result = get_connection_feature(sockets_metadata, "sid1", "any_feature")
+        assert result is False
+        assert supports_feature(sockets_metadata, "sid1", "any_feature") is False

tests-unit/requirements.txt

@@ -1,3 +1,4 @@
 pytest>=7.8.0
 pytest-aiohttp
 pytest-asyncio
+websocket-client

tests-unit/websocket_feature_flags_test.py

@@ -0,0 +1,77 @@
+"""Simplified tests for WebSocket feature flags functionality."""
+from comfy_api import feature_flags
+
+
+class TestWebSocketFeatureFlags:
+    """Test suite for WebSocket feature flags integration."""
+
+    def test_server_feature_flags_response(self):
+        """Test server feature flags are properly formatted."""
+        features = feature_flags.get_server_features()
+
+        # Check expected server features
+        assert "supports_preview_metadata" in features
+        assert features["supports_preview_metadata"] is True
+        assert "max_upload_size" in features
+        assert isinstance(features["max_upload_size"], (int, float))
+
+    def test_progress_py_checks_feature_flags(self):
+        """Test that progress.py checks feature flags before sending metadata."""
+        # This simulates the check in progress.py
+        client_id = "test_client"
+        sockets_metadata = {"test_client": {"feature_flags": {}}}
+
+        # The actual check would be in progress.py
+        supports_metadata = feature_flags.supports_feature(
+            sockets_metadata, client_id, "supports_preview_metadata"
+        )
+
+        assert supports_metadata is False
+
+    def test_multiple_clients_different_features(self):
+        """Test handling multiple clients with different feature support."""
+        sockets_metadata = {
+            "modern_client": {
+                "feature_flags": {"supports_preview_metadata": True}
+            },
+            "legacy_client": {
+                "feature_flags": {}
+            }
+        }
+
+        # Check modern client
+        assert feature_flags.supports_feature(
+            sockets_metadata, "modern_client", "supports_preview_metadata"
+        ) is True
+
+        # Check legacy client
+        assert feature_flags.supports_feature(
+            sockets_metadata, "legacy_client", "supports_preview_metadata"
+        ) is False
+
+    def test_feature_negotiation_message_format(self):
+        """Test the format of feature negotiation messages."""
+        # Client message format
+        client_message = {
+            "type": "feature_flags",
+            "data": {
+                "supports_preview_metadata": True,
+                "api_version": "1.0.0"
+            }
+        }
+
+        # Verify structure
+        assert client_message["type"] == "feature_flags"
+        assert "supports_preview_metadata" in client_message["data"]
+
+        # Server response format (what would be sent)
+        server_features = feature_flags.get_server_features()
+        server_message = {
+            "type": "feature_flags",
+            "data": server_features
+        }
+
+        # Verify structure
+        assert server_message["type"] == "feature_flags"
+        assert "supports_preview_metadata" in server_message["data"]
+        assert server_message["data"]["supports_preview_metadata"] is True

tests/inference/extra_model_paths.yaml

@@ -1,4 +1,4 @@
 # Config for testing nodes
 testing:
-    custom_nodes: tests/inference/testing_nodes
+    custom_nodes: testing_nodes
 

tests/inference/test_async_nodes.py

@@ -0,0 +1,410 @@
+import pytest
+import time
+import torch
+import urllib.error
+import numpy as np
+import subprocess
+
+from pytest import fixture
+from comfy_execution.graph_utils import GraphBuilder
+from tests.inference.test_execution import ComfyClient
+
+
+@pytest.mark.execution
+class TestAsyncNodes:
+    @fixture(scope="class", autouse=True, params=[
+        (False, 0),
+        (True, 0),
+        (True, 100),
+    ])
+    def _server(self, args_pytest, request):
+        pargs = [
+            'python','main.py',
+            '--output-directory', args_pytest["output_dir"],
+            '--listen', args_pytest["listen"],
+            '--port', str(args_pytest["port"]),
+            '--extra-model-paths-config', 'tests/inference/extra_model_paths.yaml',
+        ]
+        use_lru, lru_size = request.param
+        if use_lru:
+            pargs += ['--cache-lru', str(lru_size)]
+        # Running server with args: pargs
+        p = subprocess.Popen(pargs)
+        yield
+        p.kill()
+        torch.cuda.empty_cache()
+
+    @fixture(scope="class", autouse=True)
+    def shared_client(self, args_pytest, _server):
+        client = ComfyClient()
+        n_tries = 5
+        for i in range(n_tries):
+            time.sleep(4)
+            try:
+                client.connect(listen=args_pytest["listen"], port=args_pytest["port"])
+            except ConnectionRefusedError:
+                # Retrying...
+                pass
+            else:
+                break
+        yield client
+        del client
+        torch.cuda.empty_cache()
+
+    @fixture
+    def client(self, shared_client, request):
+        shared_client.set_test_name(f"async_nodes[{request.node.name}]")
+        yield shared_client
+
+    @fixture
+    def builder(self, request):
+        yield GraphBuilder(prefix=request.node.name)
+
+    # Happy Path Tests
+
+    def test_basic_async_execution(self, client: ComfyClient, builder: GraphBuilder):
+        """Test that a basic async node executes correctly."""
+        g = builder
+        image = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        sleep_node = g.node("TestSleep", value=image.out(0), seconds=0.1)
+        output = g.node("SaveImage", images=sleep_node.out(0))
+
+        result = client.run(g)
+
+        # Verify execution completed
+        assert result.did_run(sleep_node), "Async sleep node should have executed"
+        assert result.did_run(output), "Output node should have executed"
+
+        # Verify the image passed through correctly
+        result_images = result.get_images(output)
+        assert len(result_images) == 1, "Should have 1 image"
+        assert np.array(result_images[0]).min() == 0 and np.array(result_images[0]).max() == 0, "Image should be black"
+
+    def test_multiple_async_parallel_execution(self, client: ComfyClient, builder: GraphBuilder):
+        """Test that multiple async nodes execute in parallel."""
+        g = builder
+        image = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+
+        # Create multiple async sleep nodes with different durations
+        sleep1 = g.node("TestSleep", value=image.out(0), seconds=0.3)
+        sleep2 = g.node("TestSleep", value=image.out(0), seconds=0.4)
+        sleep3 = g.node("TestSleep", value=image.out(0), seconds=0.5)
+
+        # Add outputs for each
+        _output1 = g.node("PreviewImage", images=sleep1.out(0))
+        _output2 = g.node("PreviewImage", images=sleep2.out(0))
+        _output3 = g.node("PreviewImage", images=sleep3.out(0))
+
+        start_time = time.time()
+        result = client.run(g)
+        elapsed_time = time.time() - start_time
+
+        # Should take ~0.5s (max duration) not 1.2s (sum of durations)
+        assert elapsed_time < 0.8, f"Parallel execution took {elapsed_time}s, expected < 0.8s"
+
+        # Verify all nodes executed
+        assert result.did_run(sleep1) and result.did_run(sleep2) and result.did_run(sleep3)
+
+    def test_async_with_dependencies(self, client: ComfyClient, builder: GraphBuilder):
+        """Test async nodes with proper dependency handling."""
+        g = builder
+        image1 = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        image2 = g.node("StubImage", content="WHITE", height=512, width=512, batch_size=1)
+
+        # Chain of async operations
+        sleep1 = g.node("TestSleep", value=image1.out(0), seconds=0.2)
+        sleep2 = g.node("TestSleep", value=image2.out(0), seconds=0.2)
+
+        # Average depends on both async results
+        average = g.node("TestVariadicAverage", input1=sleep1.out(0), input2=sleep2.out(0))
+        output = g.node("SaveImage", images=average.out(0))
+
+        result = client.run(g)
+
+        # Verify execution order
+        assert result.did_run(sleep1) and result.did_run(sleep2)
+        assert result.did_run(average) and result.did_run(output)
+
+        # Verify averaged result
+        result_images = result.get_images(output)
+        avg_value = np.array(result_images[0]).mean()
+        assert abs(avg_value - 127.5) < 1, f"Average value {avg_value} should be ~127.5"
+
+    def test_async_validate_inputs(self, client: ComfyClient, builder: GraphBuilder):
+        """Test async VALIDATE_INPUTS function."""
+        g = builder
+        # Create a test node with async validation
+        validation_node = g.node("TestAsyncValidation", value=5.0, threshold=10.0)
+        g.node("SaveImage", images=validation_node.out(0))
+
+        # Should pass validation
+        result = client.run(g)
+        assert result.did_run(validation_node)
+
+        # Test validation failure
+        validation_node.inputs['threshold'] = 3.0  # Will fail since value > threshold
+        with pytest.raises(urllib.error.HTTPError):
+            client.run(g)
+
+    def test_async_lazy_evaluation(self, client: ComfyClient, builder: GraphBuilder):
+        """Test async nodes with lazy evaluation."""
+        g = builder
+        input1 = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        input2 = g.node("StubImage", content="WHITE", height=512, width=512, batch_size=1)
+        mask = g.node("StubMask", value=0.0, height=512, width=512, batch_size=1)
+
+        # Create async nodes that will be evaluated lazily
+        sleep1 = g.node("TestSleep", value=input1.out(0), seconds=0.3)
+        sleep2 = g.node("TestSleep", value=input2.out(0), seconds=0.3)
+
+        # Use lazy mix that only needs sleep1 (mask=0.0)
+        lazy_mix = g.node("TestLazyMixImages", image1=sleep1.out(0), image2=sleep2.out(0), mask=mask.out(0))
+        g.node("SaveImage", images=lazy_mix.out(0))
+
+        start_time = time.time()
+        result = client.run(g)
+        elapsed_time = time.time() - start_time
+
+        # Should only execute sleep1, not sleep2
+        assert elapsed_time < 0.5, f"Should skip sleep2, took {elapsed_time}s"
+        assert result.did_run(sleep1), "Sleep1 should have executed"
+        assert not result.did_run(sleep2), "Sleep2 should have been skipped"
+
+    def test_async_check_lazy_status(self, client: ComfyClient, builder: GraphBuilder):
+        """Test async check_lazy_status function."""
+        g = builder
+        # Create a node with async check_lazy_status
+        lazy_node = g.node("TestAsyncLazyCheck",
+                          input1="value1",
+                          input2="value2",
+                          condition=True)
+        g.node("SaveImage", images=lazy_node.out(0))
+
+        result = client.run(g)
+        assert result.did_run(lazy_node)
+
+    # Error Handling Tests
+
+    def test_async_execution_error(self, client: ComfyClient, builder: GraphBuilder):
+        """Test that async execution errors are properly handled."""
+        g = builder
+        image = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        # Create an async node that will error
+        error_node = g.node("TestAsyncError", value=image.out(0), error_after=0.1)
+        g.node("SaveImage", images=error_node.out(0))
+
+        try:
+            client.run(g)
+            assert False, "Should have raised an error"
+        except Exception as e:
+            assert 'prompt_id' in e.args[0], f"Did not get proper error message: {e}"
+            assert e.args[0]['node_id'] == error_node.id, "Error should be from async error node"
+
+    def test_async_validation_error(self, client: ComfyClient, builder: GraphBuilder):
+        """Test async validation error handling."""
+        g = builder
+        # Node with async validation that will fail
+        validation_node = g.node("TestAsyncValidationError", value=15.0, max_value=10.0)
+        g.node("SaveImage", images=validation_node.out(0))
+
+        with pytest.raises(urllib.error.HTTPError) as exc_info:
+            client.run(g)
+        # Verify it's a validation error
+        assert exc_info.value.code == 400
+
+    def test_async_timeout_handling(self, client: ComfyClient, builder: GraphBuilder):
+        """Test handling of async operations that timeout."""
+        g = builder
+        image = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        # Very long sleep that would timeout
+        timeout_node = g.node("TestAsyncTimeout", value=image.out(0), timeout=0.5, operation_time=2.0)
+        g.node("SaveImage", images=timeout_node.out(0))
+
+        try:
+            client.run(g)
+            assert False, "Should have raised a timeout error"
+        except Exception as e:
+            assert 'timeout' in str(e).lower(), f"Expected timeout error, got: {e}"
+
+    def test_concurrent_async_error_recovery(self, client: ComfyClient, builder: GraphBuilder):
+        """Test that workflow can recover after async errors."""
+        g = builder
+        image = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+
+        # First run with error
+        error_node = g.node("TestAsyncError", value=image.out(0), error_after=0.1)
+        g.node("SaveImage", images=error_node.out(0))
+
+        try:
+            client.run(g)
+        except Exception:
+            pass  # Expected
+
+        # Second run should succeed
+        g2 = GraphBuilder(prefix="recovery_test")
+        image2 = g2.node("StubImage", content="WHITE", height=512, width=512, batch_size=1)
+        sleep_node = g2.node("TestSleep", value=image2.out(0), seconds=0.1)
+        g2.node("SaveImage", images=sleep_node.out(0))
+
+        result = client.run(g2)
+        assert result.did_run(sleep_node), "Should be able to run after error"
+
+    def test_sync_error_during_async_execution(self, client: ComfyClient, builder: GraphBuilder):
+        """Test handling when sync node errors while async node is executing."""
+        g = builder
+        image = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+
+        # Async node that takes time
+        sleep_node = g.node("TestSleep", value=image.out(0), seconds=0.5)
+
+        # Sync node that will error immediately
+        error_node = g.node("TestSyncError", value=image.out(0))
+
+        # Both feed into output
+        g.node("PreviewImage", images=sleep_node.out(0))
+        g.node("PreviewImage", images=error_node.out(0))
+
+        try:
+            client.run(g)
+            assert False, "Should have raised an error"
+        except Exception as e:
+            # Verify the sync error was caught even though async was running
+            assert 'prompt_id' in e.args[0]
+
+    # Edge Cases
+
+    def test_async_with_execution_blocker(self, client: ComfyClient, builder: GraphBuilder):
+        """Test async nodes with execution blockers."""
+        g = builder
+        image1 = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        image2 = g.node("StubImage", content="WHITE", height=512, width=512, batch_size=1)
+
+        # Async sleep nodes
+        sleep1 = g.node("TestSleep", value=image1.out(0), seconds=0.2)
+        sleep2 = g.node("TestSleep", value=image2.out(0), seconds=0.2)
+
+        # Create list of images
+        image_list = g.node("TestMakeListNode", value1=sleep1.out(0), value2=sleep2.out(0))
+
+        # Create list of blocking conditions - [False, True] to block only the second item
+        int1 = g.node("StubInt", value=1)
+        int2 = g.node("StubInt", value=2)
+        block_list = g.node("TestMakeListNode", value1=int1.out(0), value2=int2.out(0))
+
+        # Compare each value against 2, so first is False (1 != 2) and second is True (2 == 2)
+        compare = g.node("TestIntConditions", a=block_list.out(0), b=2, operation="==")
+
+        # Block based on the comparison results
+        blocker = g.node("TestExecutionBlocker", input=image_list.out(0), block=compare.out(0), verbose=False)
+
+        output = g.node("PreviewImage", images=blocker.out(0))
+
+        result = client.run(g)
+        images = result.get_images(output)
+        assert len(images) == 1, "Should have blocked second image"
+
+    def test_async_caching_behavior(self, client: ComfyClient, builder: GraphBuilder):
+        """Test that async nodes are properly cached."""
+        g = builder
+        image = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        sleep_node = g.node("TestSleep", value=image.out(0), seconds=0.2)
+        g.node("SaveImage", images=sleep_node.out(0))
+
+        # First run
+        result1 = client.run(g)
+        assert result1.did_run(sleep_node), "Should run first time"
+
+        # Second run - should be cached
+        start_time = time.time()
+        result2 = client.run(g)
+        elapsed_time = time.time() - start_time
+
+        assert not result2.did_run(sleep_node), "Should be cached"
+        assert elapsed_time < 0.1, f"Cached run took {elapsed_time}s, should be instant"
+
+    def test_async_with_dynamic_prompts(self, client: ComfyClient, builder: GraphBuilder):
+        """Test async nodes within dynamically generated prompts."""
+        g = builder
+        image1 = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        image2 = g.node("StubImage", content="WHITE", height=512, width=512, batch_size=1)
+
+        # Node that generates async nodes dynamically
+        dynamic_async = g.node("TestDynamicAsyncGeneration",
+                              image1=image1.out(0),
+                              image2=image2.out(0),
+                              num_async_nodes=3,
+                              sleep_duration=0.2)
+        g.node("SaveImage", images=dynamic_async.out(0))
+
+        start_time = time.time()
+        result = client.run(g)
+        elapsed_time = time.time() - start_time
+
+        # Should execute async nodes in parallel within dynamic prompt
+        assert elapsed_time < 0.5, f"Dynamic async execution took {elapsed_time}s"
+        assert result.did_run(dynamic_async)
+
+    def test_async_resource_cleanup(self, client: ComfyClient, builder: GraphBuilder):
+        """Test that async resources are properly cleaned up."""
+        g = builder
+        image = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+
+        # Create multiple async nodes that use resources
+        resource_nodes = []
+        for i in range(5):
+            node = g.node("TestAsyncResourceUser",
+                         value=image.out(0),
+                         resource_id=f"resource_{i}",
+                         duration=0.1)
+            resource_nodes.append(node)
+            g.node("PreviewImage", images=node.out(0))
+
+        result = client.run(g)
+
+        # Verify all nodes executed
+        for node in resource_nodes:
+            assert result.did_run(node)
+
+        # Run again to ensure resources were cleaned up
+        result2 = client.run(g)
+        # Should be cached but not error due to resource conflicts
+        for node in resource_nodes:
+            assert not result2.did_run(node), "Should be cached"
+
+    def test_async_cancellation(self, client: ComfyClient, builder: GraphBuilder):
+        """Test cancellation of async operations."""
+        # This would require implementing cancellation in the client
+        # For now, we'll test that long-running async operations can be interrupted
+        pass  # TODO: Implement when cancellation API is available
+
+    def test_mixed_sync_async_execution(self, client: ComfyClient, builder: GraphBuilder):
+        """Test workflows with both sync and async nodes."""
+        g = builder
+        image1 = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        image2 = g.node("StubImage", content="WHITE", height=512, width=512, batch_size=1)
+        mask = g.node("StubMask", value=0.5, height=512, width=512, batch_size=1)
+
+        # Mix of sync and async operations
+        # Sync: lazy mix images
+        sync_op1 = g.node("TestLazyMixImages", image1=image1.out(0), image2=image2.out(0), mask=mask.out(0))
+        # Async: sleep
+        async_op1 = g.node("TestSleep", value=sync_op1.out(0), seconds=0.2)
+        # Sync: custom validation
+        sync_op2 = g.node("TestCustomValidation1", input1=async_op1.out(0), input2=0.5)
+        # Async: sleep again
+        async_op2 = g.node("TestSleep", value=sync_op2.out(0), seconds=0.2)
+
+        output = g.node("SaveImage", images=async_op2.out(0))
+
+        result = client.run(g)
+
+        # Verify all nodes executed in correct order
+        assert result.did_run(sync_op1)
+        assert result.did_run(async_op1)
+        assert result.did_run(sync_op2)
+        assert result.did_run(async_op2)
+
+        # Image should be a mix of black and white (gray)
+        result_images = result.get_images(output)
+        avg_value = np.array(result_images[0]).mean()
+        assert abs(avg_value - 63.75) < 5, f"Average value {avg_value} should be ~63.75"

tests/inference/test_execution.py

@@ -252,7 +252,7 @@ class TestExecution:
 
     @pytest.mark.parametrize("test_type, test_value", [
         ("StubInt", 5),
-        ("StubFloat", 5.0)
+        ("StubMask", 5.0)
     ])
     def test_validation_error_edge1(self, test_type, test_value, client: ComfyClient, builder: GraphBuilder):
         g = builder
@@ -497,6 +497,69 @@ class TestExecution:
         assert numpy.array(images[0]).min() == 63 and numpy.array(images[0]).max() == 63, "Image should have value 0.25"
         assert not result.did_run(test_node), "The execution should have been cached"
 
+    def test_parallel_sleep_nodes(self, client: ComfyClient, builder: GraphBuilder):
+        g = builder
+        image = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+
+        # Create sleep nodes for each duration
+        sleep_node1 = g.node("TestSleep", value=image.out(0), seconds=2.8)
+        sleep_node2 = g.node("TestSleep", value=image.out(0), seconds=2.9)
+        sleep_node3 = g.node("TestSleep", value=image.out(0), seconds=3.0)
+
+        # Add outputs to verify the execution
+        _output1 = g.node("PreviewImage", images=sleep_node1.out(0))
+        _output2 = g.node("PreviewImage", images=sleep_node2.out(0))
+        _output3 = g.node("PreviewImage", images=sleep_node3.out(0))
+
+        start_time = time.time()
+        result = client.run(g)
+        elapsed_time = time.time() - start_time
+
+        # The test should take around 0.4 seconds (the longest sleep duration)
+        # plus some overhead, but definitely less than the sum of all sleeps (0.9s)
+        # We'll allow for up to 0.8s total to account for overhead
+        assert elapsed_time < 4.0, f"Parallel execution took {elapsed_time}s, expected less than 0.8s"
+
+        # Verify that all nodes executed
+        assert result.did_run(sleep_node1), "Sleep node 1 should have run"
+        assert result.did_run(sleep_node2), "Sleep node 2 should have run"
+        assert result.did_run(sleep_node3), "Sleep node 3 should have run"
+
+    def test_parallel_sleep_expansion(self, client: ComfyClient, builder: GraphBuilder):
+        g = builder
+        # Create input images with different values
+        image1 = g.node("StubImage", content="BLACK", height=512, width=512, batch_size=1)
+        image2 = g.node("StubImage", content="WHITE", height=512, width=512, batch_size=1)
+        image3 = g.node("StubImage", content="WHITE", height=512, width=512, batch_size=1)
+
+        # Create a TestParallelSleep node that expands into multiple TestSleep nodes
+        parallel_sleep = g.node("TestParallelSleep",
+                                image1=image1.out(0),
+                                image2=image2.out(0),
+                                image3=image3.out(0),
+                                sleep1=0.4,
+                                sleep2=0.5,
+                                sleep3=0.6)
+        output = g.node("SaveImage", images=parallel_sleep.out(0))
+
+        start_time = time.time()
+        result = client.run(g)
+        elapsed_time = time.time() - start_time
+
+        # Similar to the previous test, expect parallel execution of the sleep nodes
+        # which should complete in less than the sum of all sleeps
+        assert elapsed_time < 0.8, f"Expansion execution took {elapsed_time}s, expected less than 0.8s"
+
+        # Verify the parallel sleep node executed
+        assert result.did_run(parallel_sleep), "ParallelSleep node should have run"
+
+        # Verify we get an image as output (blend of the three input images)
+        result_images = result.get_images(output)
+        assert len(result_images) == 1, "Should have 1 image"
+        # Average pixel value should be around 170 (255 * 2 // 3)
+        avg_value = numpy.array(result_images[0]).mean()
+        assert avg_value == 170, f"Image average value {avg_value} should be 170"
+
     # This tests that nodes with OUTPUT_IS_LIST function correctly when they receive an ExecutionBlocker
     # as input. We also test that when that list (containing an ExecutionBlocker) is passed to a node,
     # only that one entry in the list is blocked.

tests/inference/testing_nodes/testing-pack/__init__.py

@@ -3,6 +3,7 @@ from .flow_control import FLOW_CONTROL_NODE_CLASS_MAPPINGS, FLOW_CONTROL_NODE_DI
 from .util import UTILITY_NODE_CLASS_MAPPINGS, UTILITY_NODE_DISPLAY_NAME_MAPPINGS
 from .conditions import CONDITION_NODE_CLASS_MAPPINGS, CONDITION_NODE_DISPLAY_NAME_MAPPINGS
 from .stubs import TEST_STUB_NODE_CLASS_MAPPINGS, TEST_STUB_NODE_DISPLAY_NAME_MAPPINGS
+from .async_test_nodes import ASYNC_TEST_NODE_CLASS_MAPPINGS, ASYNC_TEST_NODE_DISPLAY_NAME_MAPPINGS
 
 # NODE_CLASS_MAPPINGS = GENERAL_NODE_CLASS_MAPPINGS.update(COMPONENT_NODE_CLASS_MAPPINGS)
 # NODE_DISPLAY_NAME_MAPPINGS = GENERAL_NODE_DISPLAY_NAME_MAPPINGS.update(COMPONENT_NODE_DISPLAY_NAME_MAPPINGS)
@@ -13,6 +14,7 @@ NODE_CLASS_MAPPINGS.update(FLOW_CONTROL_NODE_CLASS_MAPPINGS)
 NODE_CLASS_MAPPINGS.update(UTILITY_NODE_CLASS_MAPPINGS)
 NODE_CLASS_MAPPINGS.update(CONDITION_NODE_CLASS_MAPPINGS)
 NODE_CLASS_MAPPINGS.update(TEST_STUB_NODE_CLASS_MAPPINGS)
+NODE_CLASS_MAPPINGS.update(ASYNC_TEST_NODE_CLASS_MAPPINGS)
 
 NODE_DISPLAY_NAME_MAPPINGS = {}
 NODE_DISPLAY_NAME_MAPPINGS.update(TEST_NODE_DISPLAY_NAME_MAPPINGS)
@@ -20,4 +22,5 @@ NODE_DISPLAY_NAME_MAPPINGS.update(FLOW_CONTROL_NODE_DISPLAY_NAME_MAPPINGS)
 NODE_DISPLAY_NAME_MAPPINGS.update(UTILITY_NODE_DISPLAY_NAME_MAPPINGS)
 NODE_DISPLAY_NAME_MAPPINGS.update(CONDITION_NODE_DISPLAY_NAME_MAPPINGS)
 NODE_DISPLAY_NAME_MAPPINGS.update(TEST_STUB_NODE_DISPLAY_NAME_MAPPINGS)
+NODE_DISPLAY_NAME_MAPPINGS.update(ASYNC_TEST_NODE_DISPLAY_NAME_MAPPINGS)
 

tests/inference/testing_nodes/testing-pack/async_test_nodes.py

@@ -0,0 +1,343 @@
+import torch
+import asyncio
+from typing import Dict
+from comfy.utils import ProgressBar
+from comfy_execution.graph_utils import GraphBuilder
+from comfy.comfy_types.node_typing import ComfyNodeABC
+from comfy.comfy_types import IO
+
+
+class TestAsyncValidation(ComfyNodeABC):
+    """Test node with async VALIDATE_INPUTS."""
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "value": ("FLOAT", {"default": 5.0}),
+                "threshold": ("FLOAT", {"default": 10.0}),
+            },
+        }
+
+    RETURN_TYPES = ("IMAGE",)
+    FUNCTION = "process"
+    CATEGORY = "_for_testing/async"
+
+    @classmethod
+    async def VALIDATE_INPUTS(cls, value, threshold):
+        # Simulate async validation (e.g., checking remote service)
+        await asyncio.sleep(0.05)
+
+        if value > threshold:
+            return f"Value {value} exceeds threshold {threshold}"
+        return True
+
+    def process(self, value, threshold):
+        # Create image based on value
+        intensity = value / 10.0
+        image = torch.ones([1, 512, 512, 3]) * intensity
+        return (image,)
+
+
+class TestAsyncError(ComfyNodeABC):
+    """Test node that errors during async execution."""
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "value": (IO.ANY, {}),
+                "error_after": ("FLOAT", {"default": 0.1, "min": 0.0, "max": 10.0}),
+            },
+        }
+
+    RETURN_TYPES = (IO.ANY,)
+    FUNCTION = "error_execution"
+    CATEGORY = "_for_testing/async"
+
+    async def error_execution(self, value, error_after):
+        await asyncio.sleep(error_after)
+        raise RuntimeError("Intentional async execution error for testing")
+
+
+class TestAsyncValidationError(ComfyNodeABC):
+    """Test node with async validation that always fails."""
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "value": ("FLOAT", {"default": 5.0}),
+                "max_value": ("FLOAT", {"default": 10.0}),
+            },
+        }
+
+    RETURN_TYPES = ("IMAGE",)
+    FUNCTION = "process"
+    CATEGORY = "_for_testing/async"
+
+    @classmethod
+    async def VALIDATE_INPUTS(cls, value, max_value):
+        await asyncio.sleep(0.05)
+        # Always fail validation for values > max_value
+        if value > max_value:
+            return f"Async validation failed: {value} > {max_value}"
+        return True
+
+    def process(self, value, max_value):
+        # This won't be reached if validation fails
+        image = torch.ones([1, 512, 512, 3]) * (value / max_value)
+        return (image,)
+
+
+class TestAsyncTimeout(ComfyNodeABC):
+    """Test node that simulates timeout scenarios."""
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "value": (IO.ANY, {}),
+                "timeout": ("FLOAT", {"default": 1.0, "min": 0.1, "max": 10.0}),
+                "operation_time": ("FLOAT", {"default": 2.0, "min": 0.1, "max": 10.0}),
+            },
+        }
+
+    RETURN_TYPES = (IO.ANY,)
+    FUNCTION = "timeout_execution"
+    CATEGORY = "_for_testing/async"
+
+    async def timeout_execution(self, value, timeout, operation_time):
+        try:
+            # This will timeout if operation_time > timeout
+            await asyncio.wait_for(asyncio.sleep(operation_time), timeout=timeout)
+            return (value,)
+        except asyncio.TimeoutError:
+            raise RuntimeError(f"Operation timed out after {timeout} seconds")
+
+
+class TestSyncError(ComfyNodeABC):
+    """Test node that errors synchronously (for mixed sync/async testing)."""
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "value": (IO.ANY, {}),
+            },
+        }
+
+    RETURN_TYPES = (IO.ANY,)
+    FUNCTION = "sync_error"
+    CATEGORY = "_for_testing/async"
+
+    def sync_error(self, value):
+        raise RuntimeError("Intentional sync execution error for testing")
+
+
+class TestAsyncLazyCheck(ComfyNodeABC):
+    """Test node with async check_lazy_status."""
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "input1": (IO.ANY, {"lazy": True}),
+                "input2": (IO.ANY, {"lazy": True}),
+                "condition": ("BOOLEAN", {"default": True}),
+            },
+        }
+
+    RETURN_TYPES = ("IMAGE",)
+    FUNCTION = "process"
+    CATEGORY = "_for_testing/async"
+
+    async def check_lazy_status(self, condition, input1, input2):
+        # Simulate async checking (e.g., querying remote service)
+        await asyncio.sleep(0.05)
+
+        needed = []
+        if condition and input1 is None:
+            needed.append("input1")
+        if not condition and input2 is None:
+            needed.append("input2")
+        return needed
+
+    def process(self, input1, input2, condition):
+        # Return a simple image
+        return (torch.ones([1, 512, 512, 3]),)
+
+
+class TestDynamicAsyncGeneration(ComfyNodeABC):
+    """Test node that dynamically generates async nodes."""
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "image1": ("IMAGE",),
+                "image2": ("IMAGE",),
+                "num_async_nodes": ("INT", {"default": 3, "min": 1, "max": 10}),
+                "sleep_duration": ("FLOAT", {"default": 0.2, "min": 0.1, "max": 1.0}),
+            },
+        }
+
+    RETURN_TYPES = ("IMAGE",)
+    FUNCTION = "generate_async_workflow"
+    CATEGORY = "_for_testing/async"
+
+    def generate_async_workflow(self, image1, image2, num_async_nodes, sleep_duration):
+        g = GraphBuilder()
+
+        # Create multiple async sleep nodes
+        sleep_nodes = []
+        for i in range(num_async_nodes):
+            image = image1 if i % 2 == 0 else image2
+            sleep_node = g.node("TestSleep", value=image, seconds=sleep_duration)
+            sleep_nodes.append(sleep_node)
+
+        # Average all results
+        if len(sleep_nodes) == 1:
+            final_node = sleep_nodes[0]
+        else:
+            avg_inputs = {"input1": sleep_nodes[0].out(0)}
+            for i, node in enumerate(sleep_nodes[1:], 2):
+                avg_inputs[f"input{i}"] = node.out(0)
+            final_node = g.node("TestVariadicAverage", **avg_inputs)
+
+        return {
+            "result": (final_node.out(0),),
+            "expand": g.finalize(),
+        }
+
+
+class TestAsyncResourceUser(ComfyNodeABC):
+    """Test node that uses resources during async execution."""
+
+    # Class-level resource tracking for testing
+    _active_resources: Dict[str, bool] = {}
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "value": (IO.ANY, {}),
+                "resource_id": ("STRING", {"default": "resource_0"}),
+                "duration": ("FLOAT", {"default": 0.1, "min": 0.0, "max": 1.0}),
+            },
+        }
+
+    RETURN_TYPES = (IO.ANY,)
+    FUNCTION = "use_resource"
+    CATEGORY = "_for_testing/async"
+
+    async def use_resource(self, value, resource_id, duration):
+        # Check if resource is already in use
+        if self._active_resources.get(resource_id, False):
+            raise RuntimeError(f"Resource {resource_id} is already in use!")
+
+        # Mark resource as in use
+        self._active_resources[resource_id] = True
+
+        try:
+            # Simulate resource usage
+            await asyncio.sleep(duration)
+            return (value,)
+        finally:
+            # Always clean up resource
+            self._active_resources[resource_id] = False
+
+
+class TestAsyncBatchProcessing(ComfyNodeABC):
+    """Test async processing of batched inputs."""
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "images": ("IMAGE",),
+                "process_time_per_item": ("FLOAT", {"default": 0.1, "min": 0.01, "max": 1.0}),
+            },
+            "hidden": {
+                "unique_id": "UNIQUE_ID",
+            },
+        }
+
+    RETURN_TYPES = ("IMAGE",)
+    FUNCTION = "process_batch"
+    CATEGORY = "_for_testing/async"
+
+    async def process_batch(self, images, process_time_per_item, unique_id):
+        batch_size = images.shape[0]
+        pbar = ProgressBar(batch_size, node_id=unique_id)
+
+        # Process each image in the batch
+        processed = []
+        for i in range(batch_size):
+            # Simulate async processing
+            await asyncio.sleep(process_time_per_item)
+
+            # Simple processing: invert the image
+            processed_image = 1.0 - images[i:i+1]
+            processed.append(processed_image)
+
+            pbar.update(1)
+
+        # Stack processed images
+        result = torch.cat(processed, dim=0)
+        return (result,)
+
+
+class TestAsyncConcurrentLimit(ComfyNodeABC):
+    """Test concurrent execution limits for async nodes."""
+
+    _semaphore = asyncio.Semaphore(2)  # Only allow 2 concurrent executions
+
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "value": (IO.ANY, {}),
+                "duration": ("FLOAT", {"default": 0.5, "min": 0.1, "max": 2.0}),
+                "node_id": ("INT", {"default": 0}),
+            },
+        }
+
+    RETURN_TYPES = (IO.ANY,)
+    FUNCTION = "limited_execution"
+    CATEGORY = "_for_testing/async"
+
+    async def limited_execution(self, value, duration, node_id):
+        async with self._semaphore:
+            # Node {node_id} acquired semaphore
+            await asyncio.sleep(duration)
+            # Node {node_id} releasing semaphore
+            return (value,)
+
+
+# Add node mappings
+ASYNC_TEST_NODE_CLASS_MAPPINGS = {
+    "TestAsyncValidation": TestAsyncValidation,
+    "TestAsyncError": TestAsyncError,
+    "TestAsyncValidationError": TestAsyncValidationError,
+    "TestAsyncTimeout": TestAsyncTimeout,
+    "TestSyncError": TestSyncError,
+    "TestAsyncLazyCheck": TestAsyncLazyCheck,
+    "TestDynamicAsyncGeneration": TestDynamicAsyncGeneration,
+    "TestAsyncResourceUser": TestAsyncResourceUser,
+    "TestAsyncBatchProcessing": TestAsyncBatchProcessing,
+    "TestAsyncConcurrentLimit": TestAsyncConcurrentLimit,
+}
+
+ASYNC_TEST_NODE_DISPLAY_NAME_MAPPINGS = {
+    "TestAsyncValidation": "Test Async Validation",
+    "TestAsyncError": "Test Async Error",
+    "TestAsyncValidationError": "Test Async Validation Error",
+    "TestAsyncTimeout": "Test Async Timeout",
+    "TestSyncError": "Test Sync Error",
+    "TestAsyncLazyCheck": "Test Async Lazy Check",
+    "TestDynamicAsyncGeneration": "Test Dynamic Async Generation",
+    "TestAsyncResourceUser": "Test Async Resource User",
+    "TestAsyncBatchProcessing": "Test Async Batch Processing",
+    "TestAsyncConcurrentLimit": "Test Async Concurrent Limit",
+}

tests/inference/testing_nodes/testing-pack/specific_tests.py

@@ -1,6 +1,11 @@
 import torch
+import time
+import asyncio
+from comfy.utils import ProgressBar
 from .tools import VariantSupport
 from comfy_execution.graph_utils import GraphBuilder
+from comfy.comfy_types.node_typing import ComfyNodeABC
+from comfy.comfy_types import IO
 
 class TestLazyMixImages:
     @classmethod
@@ -333,6 +338,131 @@ class TestMixedExpansionReturns:
                 "expand": g.finalize(),
             }
 
+class TestSamplingInExpansion:
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "model": ("MODEL",),
+                "clip": ("CLIP",),
+                "vae": ("VAE",),
+                "seed": ("INT", {"default": 0, "min": 0, "max": 0xffffffffffffffff}),
+                "steps": ("INT", {"default": 20, "min": 1, "max": 100}),
+                "cfg": ("FLOAT", {"default": 7.0, "min": 0.0, "max": 30.0}),
+                "prompt": ("STRING", {"multiline": True, "default": "a beautiful landscape with mountains and trees"}),
+                "negative_prompt": ("STRING", {"multiline": True, "default": "blurry, bad quality, worst quality"}),
+            },
+        }
+
+    RETURN_TYPES = ("IMAGE",)
+    FUNCTION = "sampling_in_expansion"
+
+    CATEGORY = "Testing/Nodes"
+
+    def sampling_in_expansion(self, model, clip, vae, seed, steps, cfg, prompt, negative_prompt):
+        g = GraphBuilder()
+
+        # Create a basic image generation workflow using the input model, clip and vae
+        # 1. Setup text prompts using the provided CLIP model
+        positive_prompt = g.node("CLIPTextEncode",
+                               text=prompt,
+                               clip=clip)
+        negative_prompt = g.node("CLIPTextEncode",
+                                text=negative_prompt,
+                                clip=clip)
+
+        # 2. Create empty latent with specified size
+        empty_latent = g.node("EmptyLatentImage", width=512, height=512, batch_size=1)
+
+        # 3. Setup sampler and generate image latent
+        sampler = g.node("KSampler",
+                        model=model,
+                        positive=positive_prompt.out(0),
+                        negative=negative_prompt.out(0),
+                        latent_image=empty_latent.out(0),
+                        seed=seed,
+                        steps=steps,
+                        cfg=cfg,
+                        sampler_name="euler_ancestral",
+                        scheduler="normal")
+
+        # 4. Decode latent to image using VAE
+        output = g.node("VAEDecode", samples=sampler.out(0), vae=vae)
+
+        return {
+            "result": (output.out(0),),
+            "expand": g.finalize(),
+        }
+
+class TestSleep(ComfyNodeABC):
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "value": (IO.ANY, {}),
+                "seconds": ("FLOAT", {"default": 1.0, "min": 0.0, "max": 9999.0, "step": 0.01, "tooltip": "The amount of seconds to sleep."}),
+            },
+            "hidden": {
+                "unique_id": "UNIQUE_ID",
+            },
+        }
+    RETURN_TYPES = (IO.ANY,)
+    FUNCTION = "sleep"
+
+    CATEGORY = "_for_testing"
+
+    async def sleep(self, value, seconds, unique_id):
+        pbar = ProgressBar(seconds, node_id=unique_id)
+        start = time.time()
+        expiration = start + seconds
+        now = start
+        while now < expiration:
+            now = time.time()
+            pbar.update_absolute(now - start)
+            await asyncio.sleep(0.01)
+        return (value,)
+
+class TestParallelSleep(ComfyNodeABC):
+    @classmethod
+    def INPUT_TYPES(cls):
+        return {
+            "required": {
+                "image1": ("IMAGE", ),
+                "image2": ("IMAGE", ),
+                "image3": ("IMAGE", ),
+                "sleep1": ("FLOAT", {"default": 0.5, "min": 0.0, "max": 10.0, "step": 0.01}),
+                "sleep2": ("FLOAT", {"default": 0.5, "min": 0.0, "max": 10.0, "step": 0.01}),
+                "sleep3": ("FLOAT", {"default": 0.5, "min": 0.0, "max": 10.0, "step": 0.01}),
+            },
+            "hidden": {
+                "unique_id": "UNIQUE_ID",
+            },
+        }
+    RETURN_TYPES = ("IMAGE",)
+    FUNCTION = "parallel_sleep"
+    CATEGORY = "_for_testing"
+    OUTPUT_NODE = True
+
+    def parallel_sleep(self, image1, image2, image3, sleep1, sleep2, sleep3, unique_id):
+        # Create a graph dynamically with three TestSleep nodes
+        g = GraphBuilder()
+
+        # Create sleep nodes for each duration and image
+        sleep_node1 = g.node("TestSleep", value=image1, seconds=sleep1)
+        sleep_node2 = g.node("TestSleep", value=image2, seconds=sleep2)
+        sleep_node3 = g.node("TestSleep", value=image3, seconds=sleep3)
+
+        # Blend the results using TestVariadicAverage
+        blend = g.node("TestVariadicAverage",
+                       input1=sleep_node1.out(0),
+                       input2=sleep_node2.out(0),
+                       input3=sleep_node3.out(0))
+
+        return {
+            "result": (blend.out(0),),
+            "expand": g.finalize(),
+        }
+
 TEST_NODE_CLASS_MAPPINGS = {
     "TestLazyMixImages": TestLazyMixImages,
     "TestVariadicAverage": TestVariadicAverage,
@@ -345,6 +475,9 @@ TEST_NODE_CLASS_MAPPINGS = {
     "TestCustomValidation5": TestCustomValidation5,
     "TestDynamicDependencyCycle": TestDynamicDependencyCycle,
     "TestMixedExpansionReturns": TestMixedExpansionReturns,
+    "TestSamplingInExpansion": TestSamplingInExpansion,
+    "TestSleep": TestSleep,
+    "TestParallelSleep": TestParallelSleep,
 }
 
 TEST_NODE_DISPLAY_NAME_MAPPINGS = {
@@ -359,4 +492,7 @@ TEST_NODE_DISPLAY_NAME_MAPPINGS = {
     "TestCustomValidation5": "Custom Validation 5",
     "TestDynamicDependencyCycle": "Dynamic Dependency Cycle",
     "TestMixedExpansionReturns": "Mixed Expansion Returns",
+    "TestSamplingInExpansion": "Sampling In Expansion",
+    "TestSleep": "Test Sleep",
+    "TestParallelSleep": "Test Parallel Sleep",
 }