fix(nodes): let Load Image Metadata value outputs drive dropdown widgets

model_name, sampler_name and scheduler were declared as COMBO outputs, so the
documented wiring failed at queue time with "Return type mismatch between linked
nodes". ComfyUI only accepts a COMBO output into a node that declares its
dropdown as COMBO/IO.Combo, while Load Checkpoint, KSampler and the LoRA Manager
loaders expose their options as a plain list; comfy_execution.validation rejects
any non-string input type there, and a STRING output is rejected the same way.

Declare the three sockets untyped ("*"), the type ComfyUI's own Primitive node
uses to feed widget inputs. Verified with execution.validate_inputs that they now
link into both classic list dropdowns and IO.Combo inputs.

Also corrects the wiring guide, which claimed COMBO was the supported type.

docs/load-image-metadata.md

@@ -24,11 +24,16 @@ this change and refresh the page. This Python node needs no Vue widget build.
    model/LoRA names, local resolution status and warnings. The original `report`
    output remains notes followed by formatted JSON; it is not a pure JSON string.
 
-`model_name`, `sampler_name`, and `scheduler` use COMBO outputs for converted
+`model_name`, `sampler_name`, and `scheduler` are declared as untyped (`*`)
-dropdown inputs in current ComfyUI. `model_name` contains the matching local
+outputs so they can feed the dropdown widget inputs on both
-checkpoint or diffusion-model filename. The report identifies the resolved type;
+**Load Checkpoint**/**KSampler** and the LoRA Manager loaders. Typing them
-connect it to the appropriate loader. Lookup searches both categories regardless
+`COMBO` does not work: ComfyUI only accepts a `COMBO` output into a node that
-of how the original metadata labels the model.
+declares its dropdown as `COMBO`/`IO.Combo`, while classic dropdowns expose a
+plain option list, and the server rejects the link with "Return type mismatch
+between linked nodes". `model_name` contains the matching local checkpoint or
+diffusion-model filename. The report identifies the resolved type; connect it to
+the appropriate loader. Lookup searches both categories regardless of how the
+original metadata labels the model.
 
 For a diffusion-model workflow, connect `model_name` to **Unet Loader
 (LoraManager)** and select the correct text encoder(s), VAE, latent node and

py/nodes/load_image_metadata.py

@@ -118,9 +118,16 @@ class LoadImageMetadataLM:
         "Connect lora_stack to Lora Loader. Convert loader/sampler widgets to inputs for the other outputs. "
         "Extraction failures use starter defaults and are shown as ERROR messages in readable_report."
     )
+    # model_name, sampler_name and scheduler select a value from a loader or
+    # sampler dropdown. They must stay untyped (Any, "*"): ComfyUI rejects a
+    # "COMBO" (and a "STRING") output linked into the classic list-style combo
+    # inputs used by Load Checkpoint, KSampler, and the LoRA Manager loaders
+    # (comfy_execution/validation.py refuses a non-string input type), which
+    # surfaced as "Return type mismatch between linked nodes" at queue time.
+    # "*" is the same type ComfyUI's own Primitive node uses to feed widgets.
     RETURN_TYPES = (
-        "IMAGE", "MASK", "STRING", "STRING", "COMBO", "LORA_STACK", "STRING",
+        "IMAGE", "MASK", "STRING", "STRING", "*", "LORA_STACK", "STRING",
-        "INT", "INT", "FLOAT", "COMBO", "COMBO", "INT", "INT", "FLOAT", "STRING", "STRING", "STRING",
+        "INT", "INT", "FLOAT", "*", "*", "INT", "INT", "FLOAT", "STRING", "STRING", "STRING",
     )
     RETURN_NAMES = (
         "image", "mask", "positive", "negative", "model_name", "lora_stack", "lora_stack_text",

tests/nodes/test_load_image_metadata.py

@@ -61,6 +61,22 @@ def test_full_node_contract_with_real_png_metadata(runtime):
     assert LoadImageMetadataLM.INPUT_TYPES()["required"]["image"][1]["image_upload"]
 
 
+def test_value_selector_outputs_stay_untyped():
+    """These sockets must not be typed COMBO/STRING.
+
+    Load Checkpoint, KSampler and the LoRA Manager loaders declare their name
+    dropdowns as plain option lists ("classic" combos). ComfyUI's
+    comfy_execution.validation rejects any non-string input type for those, so a
+    COMBO (or STRING) output linked into them fails at queue time with
+    "Return type mismatch between linked nodes". Only an untyped ("*") output
+    works, which is also what ComfyUI's own Primitive node uses for widgets.
+    """
+    types = LoadImageMetadataLM.RETURN_TYPES
+    names = LoadImageMetadataLM.RETURN_NAMES
+    for output in ("model_name", "sampler_name", "scheduler"):
+        assert types[names.index(output)] == "*", output
+
+
 @pytest.mark.parametrize("extension", ["webp", "jpg"])
 def test_exif_parameters_from_real_image(runtime, extension):
     image_path, *_ = runtime