Users can now right-click nodes and assign meta hints
(primary_model, primary_sampler, positive_prompt,
negative_prompt) to override the metadata processor's
heuristic inference.
- Store extra_data from the API request so workflow node
properties (including lm_marker_role) are accessible
during metadata processing.
- _get_user_marks scans extra_data.extra_pnginfo.workflow
for meta_* marks, falling back to prompt.original_prompt.
- extract_generation_params checks user marks before
heuristic inference for sampler, model, and prompts.
- Warn on duplicate marks or invalid marked nodes.
