Store the working order and flags. One transaction, all or nothing.

The admin page's full working state.

order is the rail order the admin sees; hidden and regen carry the flags. Anything absent from regen is treated as unflagged, so a save is a complete replacement of the state for every slug it mentions rather than a partial patch. A slug the hidden map never mentions keeps a null override, so its YAML hideFromRail stands.

Every collection is capped and the note is length-limited. A payload that breaks a bound never reaches the service: flask-openapi3 rejects it at the boundary with a 422, which the route documents.