feat: add get_execution_environment() API for managed deployments

Adds a simple API that lets custom nodes detect whether they are
running in a local, cloud, or remote environment.  Managed deployments
set the COMFY_EXECUTION_ENVIRONMENT env var; the default is "local".

This enables node authors to implement graceful degradation - for
example, skipping model downloads when models are pre-provisioned, or
disabling features that require local hardware.

comfy/utils.py

@@ -1453,3 +1453,22 @@ def normalize_image_embeddings(embeds, embeds_info, scale_factor):
             start_idx = info["index"]
             end_idx = start_idx + info["size"]
             embeds[:, start_idx:end_idx, :] /= scale_factor
+
+
+_VALID_ENVIRONMENTS = {"local", "cloud", "remote"}
+
+def get_execution_environment():
+    """Return the current execution environment.
+
+    Reads the COMFY_EXECUTION_ENVIRONMENT environment variable. Managed
+    deployments (e.g. Comfy Cloud) set this variable so that custom nodes
+    can adapt their behaviour at runtime — for example, skipping model
+    downloads when models are pre-provisioned.
+
+    Returns:
+        str: One of "local" (default), "cloud", or "remote".
+    """
+    value = os.environ.get("COMFY_EXECUTION_ENVIRONMENT", "local").lower().strip()
+    if value not in _VALID_ENVIRONMENTS:
+        return "local"
+    return value