Each file and diagram is bracketed deterministically, in input order:
==> path/to/file.md
--> line 10: sequenceDiagram
<-- line 20: sequenceDiagram
<== path/to/file.md
Renderer diagnostics for a failing diagram are written to stderr between that diagram's markers. The two backends emit differently shaped errors:
- mmdc reports parse failures as a
Parse error on line N:block, which nixie condenses to the error line, the offending source, a caret pointer, and the expectation message. - merman-cli prints its error text directly (for example
Mermaid error: …); nixie passes it through verbatim.
When --renderer merman is forced and merman-cli cannot be found, nixie
prints one error before any diagram is processed:
No Mermaid renderer available. Install merman-cli (cargo install
merman-cli) or a Node environment with @mermaid-js/mermaid-cli.
In auto mode on a machine with neither backend, each diagram instead
reports the historical node-environment guidance, preserving the behaviour
of earlier releases.