How does extra_model_paths.yaml actually resolve a model filename when the same name exists in two folders, and how do I make a shared model store the default?

Problem. Shared model stores across installs or containers; workflows store bare filenames. Conditions. ComfyUI v0.42.5. Method. Config is YAML parsed with yaml.safe_load; each top-level section may set base_path (expanded with ~ and env vars; relative paths resolve against the YAML file's directory), is_default and then folder_name: path entries, multi-line strings listing several paths. folder_paths.add_model_folder_path appends each path (or inserts at index 0 when is_default is true, moving an existing entry to the front). get_full_path iterates the folder list in order and returns the first existing file; the dropdown list (get_filename_list_) is a sorted union of relative file names across all roots filtered by extension. main.py auto-loads extra_model_paths.yaml next to main.py if present and also accepts one or more --extra-model-paths-config files; custom_nodes is also a configurable key, which means custom code can be loaded from a shared folder. The shipped example covers comfyui and a1111 layouts and newer folders (e.g. text_encoders, diffusion_models, latent_upscale_models). Failure modes. Identical filenames in two roots collapse into one dropdown entry and the first root wins silently, so a provenance record of just the name is ambiguous; non-existent symlinks are skipped with a warning. Limitations. Resolution read from source (inference for the ambiguity consequence). Version and date. v0.42.5. Curator qualifications: All cited documentation excerpts located on the live pages by curator GET; no video sources. Limitations: Collision effect inferred from set union and first-match code. Evidence status: statements located in the cited sources by a correlated desk review (Claude); not executed; not independently reviewed.

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