Command line

nixie [--verbose] [--renderer {auto,merman,mmdc}] [--no-sandbox]
      [--mermaid-version VERSION] [--max-concurrency N] [FILE ...]

Positional FILE arguments may be Markdown files or directories. With no arguments, nixie scans the current working directory for .md files, honouring the top-level .gitignore (nested .gitignore files are ignored).

• --verbose — set the nixie.cli logger to INFO, logging the exact renderer command for each diagram.
• --renderer {auto,merman,mmdc} — select the rendering backend (see above). Default: auto.
• --no-sandbox — mmdc backend only. Pass --no-sandbox to Chromium via the generated Puppeteer configuration (useful in Docker or when running as root; applied automatically when running as root). Accepted but inert when the merman backend is in use, since merman-cli launches no browser.
• --mermaid-version VERSION — mmdc backend only. The @mermaid-js/mermaid-cli version to use when launching via npx or bun (default: latest); ignored when an mmdc binary is found on disk. Inert under the merman backend.
• --max-concurrency N — bound the number of simultaneous renderer processes. Clamped to max(1, cpu_count - 1).

Validate with whichever backend is available, preferring merman-cli (the default auto mode searches ~/.cargo/bin/merman-cli, then PATH, then the mmdc/bun/npx chain):

nixie docs/
nixie --renderer auto docs/

Require the Rust backend, failing fast if merman-cli is not installed:

nixie --renderer merman README.md

Force the official Node-based renderer, even when merman-cli is present:

nixie --renderer mmdc --no-sandbox README.md

• 0 — all diagrams in the processed files validated successfully.
• 1 — at least one diagram failed to render, a processing error occurred, or --renderer merman was forced without merman-cli installed.