markdown-post-frontmatter-validation

Validating YAML frontmatter in Markdown posts enforces required fields like title, date, slug, and tags to catch missing metadata. This prevents static site indexing, routing, and rendering regressions before builds ship.

Markdown frontmatter dates lacking a timezone cause build failures because ISO-8601 date-with-timezone discipline is enforced. Rejecting ambiguous dates prevents temporal sorting and rendering regressions across environments.

Enforce slug-to-path consistency by validating that the declared slug matches the file path under content/posts/**/*.md. Flagging mismatches immediately prevents broken routing and indexing regressions.

A controlled vocabulary for Markdown frontmatter tags restricts tags to a predefined schema. It is enforced by validating tags against repository rules, ensuring metadata uniformity and preventing invalid taxonomy entries.

You cannot use underscore-prefixed keys in Markdown post frontmatter. Reserved-field protection blocks underscore-prefixed author fields to prevent schema conflicts and ensure clean metadata parsing during generation.

The best way to re-validate Markdown posts when the frontmatter schema changes is to trigger validation against the new schema implementation. This surfaces metadata violations before the next static site build runs.