Mutation error

A typed edit was rejected because it does not apply to the narrowed family or its target does not exist (e.g. set_label on a missing node id). Re-narrow the parsed diagram, confirm the target id against the current model, and fall back to editing the preserved source directly when the construct is not structurally modeled (opaque fallback).

See the library API for the typed parse → narrow → mutate → verify surface.

am verify diagram.mmd --json

Return the structured error to the caller when a safe automatic fix is not obvious.

Machine-readable: this page as Markdown.

Back to all errors, or open a blank editor to test a source file.