Embed model merge metadata in .safetensors file

modules/extras.py

 import os
 import re
 import shutil
+import json
 
 
 import torch
@@ -71,7 +72,7 @@ def to_half(tensor, enable):
     return tensor
 
 
-def run_modelmerger(id_task, primary_model_name, secondary_model_name, tertiary_model_name, interp_method, multiplier, save_as_half, custom_name, checkpoint_format, config_source, bake_in_vae, discard_weights):
+def run_modelmerger(id_task, primary_model_name, secondary_model_name, tertiary_model_name, interp_method, multiplier, save_as_half, custom_name, checkpoint_format, config_source, bake_in_vae, discard_weights, save_metadata):
     shared.state.begin()
     shared.state.job = 'model-merge'
 
@@ -241,13 +242,52 @@ def run_modelmerger(id_task, primary_model_name, secondary_model_name, tertiary_
     shared.state.textinfo = "Saving"
     print(f"Saving to {output_modelname}...")
 
+    metadata = {"format": "pt", "models": {}, "merge_recipe": None}
+
+    if save_metadata:
+        merge_recipe = {
+            "primary_model_hash": primary_model_info.sha256,
+            "secondary_model_hash": secondary_model_info.sha256 if secondary_model_info else None,
+            "tertiary_model_hash": tertiary_model_info.sha256 if tertiary_model_info else None,
+            "interp_method": interp_method,
+            "multiplier": multiplier,
+            "save_as_half": save_as_half,
+            "custom_name": custom_name,
+            "config_source": config_source,
+            "bake_in_vae": bake_in_vae,
+            "discard_weights": discard_weights,
+            "is_inpainting": result_is_inpainting_model,
+            "is_instruct_pix2pix": result_is_instruct_pix2pix_model
+        }
+        metadata["merge_recipe"] = json.dumps(merge_recipe)
+
+        def add_model_metadata(checkpoint_info):
+            metadata["models"][checkpoint_info.sha256] = {
+                "name": checkpoint_info.name,
+                "legacy_hash": checkpoint_info.hash,
+                "merge_recipe": checkpoint_info.metadata.get("merge_recipe", None)
+            }
+
+            metadata["models"].update(checkpoint_info.metadata.get("models", {}))
+
+        add_model_metadata(primary_model_info)
+        if secondary_model_info:
+            add_model_metadata(secondary_model_info)
+        if tertiary_model_info:
+            add_model_metadata(tertiary_model_info)
+
+        metadata["models"] = json.dumps(metadata["models"])
+
     _, extension = os.path.splitext(output_modelname)
     if extension.lower() == ".safetensors":
-        safetensors.torch.save_file(theta_0, output_modelname, metadata={"format": "pt"})
+        safetensors.torch.save_file(theta_0, output_modelname, metadata=metadata)
     else:
         torch.save(theta_0, output_modelname)
 
     sd_models.list_models()
+    created_model = next((ckpt for ckpt in sd_models.checkpoints_list.values() if ckpt.name == filename), None)
+    if created_model:
+        created_model.calculate_shorthash()
 
     create_config(output_modelname, config_source, primary_model_info, secondary_model_info, tertiary_model_info)
 

modules/sd_models.py

@@ -52,6 +52,15 @@ class CheckpointInfo:
 
         self.ids = [self.hash, self.model_name, self.title, name, f'{name} [{self.hash}]'] + ([self.shorthash, self.sha256, f'{self.name} [{self.shorthash}]'] if self.shorthash else [])
 
+        self.metadata = {}
+
+        _, ext = os.path.splitext(self.filename)
+        if ext.lower() == ".safetensors":
+            try:
+                self.metadata = read_metadata_from_safetensors(filename)
+            except Exception as e:
+                errors.display(e, f"reading checkpoint metadata: {filename}")
+
     def register(self):
         checkpoints_list[self.title] = self
         for id in self.ids:

modules/ui.py

@@ -1019,8 +1019,9 @@ def create_ui():
                 interp_method.change(fn=update_interp_description, inputs=[interp_method], outputs=[interp_description])
 
                 with FormRow():
-                    checkpoint_format = gr.Radio(choices=["ckpt", "safetensors"], value="ckpt", label="Checkpoint format", elem_id="modelmerger_checkpoint_format")
+                    checkpoint_format = gr.Radio(choices=["ckpt", "safetensors"], value="safetensors", label="Checkpoint format", elem_id="modelmerger_checkpoint_format")
                     save_as_half = gr.Checkbox(value=False, label="Save as float16", elem_id="modelmerger_save_as_half")
+                    save_metadata = gr.Checkbox(value=True, label="Save metadata (.safetensors only)", elem_id="modelmerger_save_metadata")
 
                 with FormRow():
                     with gr.Column():
@@ -1658,6 +1659,7 @@ def create_ui():
                 config_source,
                 bake_in_vae,
                 discard_weights,
+                save_metadata,
             ],
             outputs=[
                 primary_model_name,