name: preflight description: > Use this skill when the user wants to validate their MD-DDL model before committing or publishing, asks "is this valid?", "run pre-flight checks", "check my domain", or indicates they are ready to commit. Also offer to run this at the end of any modelling session where domain files were created or modified.

Skill: Pre-Flight Check

Runs the five Level-1 mechanical checks defined in the MD-DDL Validation Model against a domain folder and presents the findings to the user.

The checks cover YAML syntax, Mermaid syntax, internal link integrity, entity reference consistency, and domain version. See 1-Foundation.md § Pre-Flight Check Scope for the rationale and exact scope of each check.

Steps

1 — Identify the domain folder

If the domain folder is not clear from context, ask:

Which domain folder should I check? (e.g. domains/customer or the current working directory if you are inside a domain folder)

The folder must contain a domain.md at its root.

2 — Run the script

python .github/scripts/preflight.py "<domain-folder>"

If the pyyaml package is not installed, instruct the user to run:

pip install pyyaml

3 — Present findings

Exit code 0 — pass:

Pre-flight passed. No mechanical issues found.

The model is clear to commit from a mechanical standpoint. Remind the user that Levels 2–5 (structure, convention, quality, domain fitness) are covered by agent-driven review, not this script.

Exit code 1 — findings:

Present findings grouped by check type. For each finding, show the file path, line number, and a plain-language explanation of what needs fixing.

All findings must be resolved before committing — there is no warning/error distinction. Every finding is a pre-flight failure.

Common fixes by check:

Exit code 2 — invocation error:

Report the error and correct the command. Check that the path is a directory containing domain.md.

4 — After fixes

Once the user has resolved findings, re-run the script to confirm a clean pass before they proceed to commit.

Notes

• The internal-links check covers three link forms: markdown [text](path), HTML href='path' or href="path" (used in Mermaid node labels), and same-page anchors #heading. All must resolve.
• {{INCLUDE: path}} directives in agent/skill files are not covered — they live outside domain folders and are a separate concern.
• The script skips files under sources/ and products/ for entity reference checks, because those files use the source: key for system names, not entity names.
• Checks 1–3 (YAML, Mermaid, links) run against every .md file in the domain folder tree.
• Checks 4–5 require domain.md to exist at the domain folder root.
• This script does not check governance completeness, naming conventions, or modelling quality — those are agent-review concerns (Levels 2–5).