Fix MTHDS bundles

Automatically fix issues in MTHDS method bundles.

Process

Prerequisite: See CLI Prerequisites

Step 1: Validate and Identify Errors

Always use -L pointing to the bundle's own directory to avoid namespace collisions:

mthds-agent pipelex validate <file>.mthds -L <bundle-directory>/

Parse the JSON output:

• If success: true — nothing to fix, report clean status
• If error_type: "ValidateBundleError" — iterate through validation_errors array and fix each (Step 2)
• If model/config error — see Error Handling Reference (cannot be fixed by editing the .mthds file)

Step 2: Fix .mthds Validation Errors

Use the error_type field from each validation error to determine the fix:

Error Type	Fix Strategy
missing_input_variable	Add the missing variable(s) to the parent pipe's inputs line
extraneous_input_variable	Remove the unused variable(s) from the pipe's inputs line
input_stuff_spec_mismatch	Correct the concept type in inputs to match what the sub-pipe expects
inadequate_output_concept	Change the output field to the correct concept type
inadequate_output_multiplicity	Add or remove [] from the output concept
circular_dependency_error	Restructure the method to break the cycle
llm_output_cannot_be_image	Use PipeImgGen instead of PipeLLM for image generation
img_gen_input_not_text_compatible	Ensure PipeImgGen input is text-based (use ImgGenPrompt)
invalid_pipe_code_syntax	Rename the pipe to valid snake_case
unknown_concept	Add the concept definition to the bundle, or fix the typo
batch_item_name_collision	Rename input_item_name (or batch_as) to a distinct singular form of the list name. Also update the branch pipe's inputs to use the new item name.

For error type descriptions, see Error Handling — Validation Error Types.

Step 3: Fix TOML Formatting Issues

These aren't always reported by validation but cause problems:

Multi-line inputs — must be on a single line:

# WRONG
inputs = {
    a = "A",
    b = "B"
}

# CORRECT
inputs = { a = "A", b = "B" }

Pipe ordering — controllers before sub-pipes:

# CORRECT: main pipe first, then sub-pipes in execution order
[pipe.main_workflow]
type = "PipeSequence"
steps = [
    { pipe = "step_one", result = "intermediate" },
    { pipe = "step_two", result = "final" }
]

[pipe.step_one]
...

[pipe.step_two]
...

Missing required fields — add with sensible defaults:

• description on every pipe and concept
• type on every pipe
• output on every pipe

Step 4: Re-validate

After applying fixes, re-validate:

mthds-agent pipelex validate <file>.mthds -L <bundle-directory>/

Continue the fix-validate loop until success: true is returned. Some fixes reveal new issues — for example, fixing a missing_input_variable may expose an input_stuff_spec_mismatch on the newly added input.

If the fix-validate loop gets stuck or errors are unclear, re-run with --log-level debug for additional context:

mthds-agent --log-level debug pipelex validate <file>.mthds -L <bundle-directory>/

Step 5: Report Results

• List all changes made (which pipes were modified and how)
• Show the final validation result
• Flag any remaining warnings or suggestions

Reference

• CLI Prerequisites — read at skill start to check CLI availability
• Error Handling — read when CLI returns an error to determine recovery
• MTHDS Agent Guide — read for CLI command syntax or output format details
• MTHDS Language Reference — read when writing or modifying .mthds TOML syntax
• Native Content Types — read when fixing type mismatches involving native concepts, to verify available attributes