repairing-workflows

Repair loop for ComfyUI prompts. Consumes the two error channels documented in ../comfyui-execution/reference/error-payloads.md:

• Channel 1 node_errors from POST /prompt validation
• Channel 2 execution_error frames from /ws

Produces a structured repair plan and a partial_execution_targets list that minimises re-execution.

When this Skill applies

Invoke when any of the following is true:

• submit_prompt.py stdout contains a non-empty node_errors
• subscribe_ws.py stdout has an {"type":"execution_error"} frame
• A capability Skill's compile.py output failed to submit successfully
• A downstream evaluator flagged a run as failed due to an engine error

Do not invoke for evaluator "criteria not met" failures — those route to the planner, not the repair loop.

Pipeline

1. scripts/classify_error.py — reads a unified error envelope on stdin, emits an error class ∈ {link, parameter, default, missing_resource} plus per-class hints.
2. Repair authoring (caller): apply the class-appropriate patch to the prompt JSON. Patches are deterministic JSON edits, not LLM-authored graph rewrites.
3. scripts/plan_partial_rerun.py — reads {prompt, failed_node_id, output_nodes} on stdin and emits {partial_execution_targets} covering only the failing subgraph and its descendants up to output nodes.
4. Re-submit via comfyui-execution's submit_prompt.py with the targets.

Error classes

See reference/error-classes.md.

Class	Trigger	Repair
link	bad_linked_input, return_type_mismatch, invalid_prompt	Fix link tuple or add converter node
parameter	exception_during_validation, custom_validation_failed, runtime TypeError/ValueError with named input	Patch parameter value
default	required_input_missing	Supply default from object_info
missing_resource	value_not_in_list on a filename field (ckpt_name, lora_name, vae_name, embeddings)	Route to setup wizard / list substitution

Copilot's debug_agent.py analyze_error_type() covers three of these. missing_resource is v1-specific and required by the acceptance test.

Repair strategies

See reference/repair-strategies.md for the patch recipes.

Scripts

• scripts/classify_error.py — pure function, stdlib only. Input envelope:

  {"channel": "node_errors" | "execution_error", "payload": { ... }}
  

  Output:

  {"class": "link|parameter|default|missing_resource",
   "node_id": "...", "hint": "...", "input_name": "..."}
  

• scripts/plan_partial_rerun.py — computes descendants of the failing node in the prompt graph up to any node in output_nodes, returns their IDs as partial_execution_targets.

Explicit error handling

Both scripts must never raise an unhandled exception to the caller. On bad input they emit {"error": "...", "code": "..."} with a non-zero exit code.

References

• ../comfyui-execution/reference/error-payloads.md
• knowledge/workflows/ComfyUI_workflow.md §3 (partial_execution_targets), §4.4
• knowledge/plans/v1/plan_v1.md §6 Group C