Module edit 

Document Editor Surface

Typed mutators for Document and Card with invariant enforcement.

Invariants

Every successful mutator call leaves the document in a state that:

• Contains no reserved key in any card’s frontmatter (BODY, CARDS, QUILL, CARD).
• Has every composable card.tag() passing sentinel::is_valid_tag_name.
• Can be safely serialized via Document::to_plate_json.

Mutators never modify warnings. Warnings are parse-time observations and remain stable for the lifetime of the document.

Surface

Frontmatter and body mutators live on Card: doc.main_mut().set_field(…), doc.main_mut().replace_body(…), doc.cards_mut()[i].set_field(…). Document keeps only document-level operations (quill-ref, push/insert/remove/move card).

Enums

EditError

Errors returned by document and card mutators.

Constants

RESERVED_NAMES

Reserved field names that may not appear in any Card’s frontmatter. These are the sentinel keys whose presence in user-visible fields would corrupt the plate wire format or the parser’s structural invariants.

Functions

is_reserved_name

Returns true if name is one of the four reserved sentinel names.

is_valid_field_name

Returns true if name is a valid frontmatter / card field name.