Skill Preflight

A deterministic, self-validating skill: it runs a real check with python3 and returns an honest machine-readable outcome. ok:true proves the target SKILL.md passed every check below — nothing more, nothing less.

This is the executable-validation pattern: encode the process, run it with a real tool, and gate the result on a postcondition instead of trusting a vibe.

Trigger

• /skill-preflight <path-to-SKILL.md | skill-folder>
• Natural language: "check my skill before publishing", "why is my skill missing requirements", "validate this SKILL.md".

Execution

Run the bundled checker against the target skill:

python3 scripts/preflight.py <path-to-SKILL.md | skill-folder>

It emits JSON { ok, reason, checks[] } and exits 0 on pass, 1 on fail, 2 on usage/IO error.

Checks (the validation gate)

1. frontmatter-present — a --- … --- YAML block exists.
2. has-name / has-description / has-version — required keys are present and non-empty.
3. version-semver — version matches N.N.N.
4. requires.bins-declared — metadata.openclaw.requires.bins is declared (an empty list is fine; absent is not).
5. bin: — every declared binary actually resolves on PATH (shutil.which). This is the real-execution gate: a skill that declares a tool it can't find will show as "missing requirements" at load time.

Honest outcome contract

• ok:true → the SKILL.md passed all checks above. It does not guarantee the skill's behaviour is correct, only that its manifest is loadable and its declared tools are present.
• ok:false → reason names the failing checks; checks[] gives per-check detail. Fix those before clawhub publish.

Examples

$ python3 scripts/preflight.py ./my-skill/SKILL.md
{ "ok": true, "reason": "all checks passed", "checks": [ ... ] }

$ python3 scripts/preflight.py ./broken/SKILL.md
{ "ok": false, "reason": "failed: version-semver, bin:jq", "checks": [ ... ] }

Notes

• Pure Python standard library — no pip install, no network.
• Parses frontmatter without PyYAML so it runs anywhere python3 exists.