Create Validation Rules

Generate a draft VALIDATION.md file for a skill by analyzing its SKILL.md.

WARNING — READ THIS FIRST

This skill generates a DRAFT, not a finished product. The generated VALIDATION.md will likely contain errors, especially in volume formulas. You MUST:

1. Review every check — does it match what the skill actually builds?
2. Verify all volume formulas by hand — volume calculations for complex geometry (shells with posts, lips, ridges) are easy to get wrong. Calculate the expected volume for one set of dimensions and compare with the formula.
3. Test with --validate — run the skill with known-good parameters and --validate to see if the checks pass on correct geometry.
4. Adjust tolerances — the defaults (0.5mm for bbox, 5% for volume) may be too tight or too loose for your skill.
5. Check conditional rules — if your skill has variants, verify each when block covers the right checks.

Common errors in generated VALIDATION.md:

• Volume formulas that forget to add/subtract features (posts, holes, lips, ridges)
• Wrong body labels (FreeCAD may rename bodies)
• Missing conditional branches for skill variants
• Tolerances that are too tight for the geometry complexity

How to use

/create-validation skill-name

Where skill-name is the name of an existing skill (e.g., enclosure, gear).

What to do

1. Read the specified skill's SKILL.md using execute_code:

   import os
   skills_dirs = [
       os.path.expanduser("~/.config/FreeCAD/FreeCADAI/skills"),
   ]
   # Also check built-in skills
   builtin = os.path.join(os.path.dirname(os.path.dirname(os.path.abspath(__file__))), "skills") if '__file__' in dir() else ""
   

   Or use get_document_state context to find the skill path.

2. Analyze the SKILL.md to extract:

   • Parameters: from the "Parameters to extract" section. Note types and defaults.
   • Bodies: from create_body instructions. Note their labels.
   • Geometry steps: pad dimensions, pocket depths, post positions, etc.
   • Variants: different lid types, optional features, conditional construction steps.

3. Generate VALIDATION.md with this structure:

# Validation Rules

## Parameters
(one line per parameter: name: type = default)

## Checks

### Body count
- total_bodies: N

### BodyLabel
- exists: true
- bbox: X_expr, Y_expr, Z_expr (tolerance 0.5)
- volume: formula (tolerance 5%)
- solid_count: 1
- valid_solid: true

#### when variant_param == "value"
- (variant-specific checks)

4. Write the file to the skill directory as VALIDATION.md.

5. IMPORTANT: After writing, display this message to the user:

Draft VALIDATION.md created. This is a starting point, NOT a finished file.

You must verify:

• All volume formulas — calculate expected values by hand for at least one set of dimensions
• Body labels match what FreeCAD actually creates (use get_document_state after running the skill)
• Conditional when blocks cover all variants
• Tolerances are appropriate (0.5mm bbox, 5% volume are defaults)

Test it: Run /skill-name args --validate to check against actual geometry.

Fix it: Edit the VALIDATION.md directly if checks fail on correct geometry.

Rules for generating volume formulas

• Rectangular shell (box with hollow interior): L*W*H - (L-2*T)*(W-2*T)*(H-T)
  • This gives 4 walls + floor, open top
• Cylindrical posts added to interior: + N * pi * R**2 * post_height
  • N = number of posts, R = post radius
• Cylindrical holes subtracted: - N * pi * R**2 * depth
• Solid slab (lid): L * W * T
• Lid with lip: lip volume + slab volume
• Use pi constant, not 3.14159 (the expression evaluator supports pi)
• Use ** for power, not ^ (the evaluator uses Python's ast module)

Available check types

Parameter type reference