ADR-0013: Filename patterns

Status: Proposed

Context

A type schema sets a filename pattern. The only example is "{date}-{slug}". The PRD does not say which other placeholders are allowed, or what happens to the path when someone edits date.

path_invalid requires the path to match the type's folder and filename pattern, so a date change that leaves the old path in place would fail validation. This ADR recommends one rule. The product owner has not confirmed it.

Options

1. Allow any {token}, and leave the path unchanged when date changes.
2. Allow only {date} and {slug}. Changing date rewrites the path in the same save and does not change the slug.
3. Allow {date}, {slug}, and {title}, and keep the original path forever.

Decision

This is a recommended resolution of an ambiguity. The product owner has not confirmed it.

The only placeholders are {date} and {slug}, written exactly that way. Any other {…} in the pattern makes the schema fail to load (schema_invalid, ADR-0015).

{slug} is the document slug from ADR-0012. {date} is the document's date field in YYYY-MM-DD form. If the pattern contains {date} and the date is missing or not in that form, the document fails path_invalid and is not saved.

The path is {folder}/{pattern} with those tokens replaced. Creating a document sets that path.

Editing date on an existing document recomputes the path in the same save. The slug does not change. Links use the slug, so they still resolve. The old path is not kept as a redirect. If another document already uses the new path, the save is rejected with path_invalid, the path stays as it was, and no revision is written.

Replaces

The unspecified placeholder list and the unspecified effect of editing date, in section 2.3 (filename patterns).

Consequences

• F01: paths come from the type folder and this pattern.
• F06: path_invalid covers a bad date, an unknown placeholder's refusal at schema load, and a path collision.
• F09: a date edit saves a new path in that same save.