Interchange

JSON (lossless)

sysml2kit.interchange reads and writes the Systems Modeling API serialization: a flat list of records like

{"@id": "…", "@type": "PartUsage", "declaredName": "battery",
 "owningRelatedElement": {"@id": "…"}, "definition": {"@id": "…"}}

• model_to_json(model) / write_json(model, path) — deterministic output: elements sorted by qualified name, keys sorted per record, so committed files diff cleanly. Pair with model.assign_stable_ids() for generated models.
• model_from_json(records_or_path) — unknown @type records become OpaqueElement and re-export byte-identically.

json -> model -> json is a fixpoint; the property is tested with hypothesis.

Textual notation (readable, parseable)

sysml2kit.text.write_model(model) emits deterministic .sysml text: ownership order, four-space indent, values as = 52.0 [dBW], requirement statements as doc bodies, satisfy X by Y; / allocate X to Y; statements. Verify and derive have no standalone textual statement in the grammar, so they emit as dependency from A to B; // verify — the JSON keeps the precise kind.

Reading text back goes through a parser backend.