diagrammo

name	diagrammo
description	Inspect and render Mermaid blocks in Markdown as themed SVG output with the packaged ahm-diagrammo CLI.

Diagrammo

Use the packaged CLI. Do not reimplement parsing, renderer selection, layout, theming, or SVG generation.

1. Confirm the requested Markdown input and output directory. If the input is missing or invalid, stop and report the problem instead of guessing.
2. Inspect before render when appropriate, especially for unfamiliar input or when the user asks what will be generated: npx --yes ahm-diagrammo "$INPUT" --list
3. Render into an explicit output directory: npx --yes ahm-diagrammo "$INPUT" --out "$OUTPUT" --strict
4. Verify the command exited successfully. Inspect $OUTPUT for .svg files, confirm each is non-empty, and report the emitted files.

Preserve the user's Markdown. Surface CLI diagnostics and non-zero exits rather than masking them. --sync-markdown is the sole, explicit opt-in exception: only invoke it when the user asks to check in an editable-source-plus-rendered-SVG Markdown file, never as a default action. Its first generated SVG filename is stable for that managed block's lifetime — do not hand-edit its <!-- diagrammo:sync ... --> markers; renaming a heading or a fence's title=/name= later is safe and never renames the file. The Mermaid source itself lives fully hidden (not merely collapsed) inside a <!-- diagrammo:source ... --> comment, with every literal --> escaped to -->. Editing it directly is safe — write real, unescaped Mermaid (a raw --> is fine); the next --sync-markdown run decodes, re-renders, and re-escapes it. Never hand-type the literal --> token into a fence — the CLI rejects a fence that already contains it, since decoding would then be ambiguous.

Per-diagram directives

Author-controlled options live inside the fence as %%| key: value lines (also settable via fence-info key=value or a diagrammo: frontmatter block). Common keys: theme, title, subtitle, lanes, legend, alt, and laneLabels.

To make a wide swimlane narrower, set %%| laneLabels: false. It hides the right-hand lane-label text and reclaims that gutter — nothing else moves: node placement, edge routing, edge state colors, lane bands, and SVG height are all unchanged. There is no width-wrapping/maxWidth knob; narrowing is achieved only by reclaiming the label gutter, never by wrapping lanes onto extra rows. laneLabels defaults to true (labels shown); a non-boolean value warns and falls back to true.