#The other seven engines

Mermaid ships inside Pamphlet. The other seven are each their own package — install the one you need. Everyone else downloads nothing: all seven together weigh about 340MB, and d2 alone is 91.4MB.

Each has its own page — follow the first column: what it is, what it draws, how the fence looks, and what the traps are.

Using a fence without its engine reports DIAG-301 and fails the whole build (no placeholder box), with the command from the third column in the hint. pamphlet doctor lists all seven at once.

#Why not just bundle them all

Installing @nekoleapuki/pamphlet-cli gives you the compiler only, with no engine attached.

That is not laziness, it is arithmetic: all the engines together weigh about 340MB. Measured (npm install of six engines plus du -sh node_modules): 270 packages, 189MB, plus Playwright and Chromium at about 150MB.

For a Markdown tool that is an adoption killer. Optional dependencies put the weight exactly on the people who use that engine — a text-only user installs none of them.

#Maths is block-level only

```math
E = mc^2
```

$E=mc^2$ inline is not supported.

$ is everywhere in technical writing — $ npm install, $HOME, $99. Supporting it would require conflict detection and escaping rules, and a false positive turns ordinary prose into a formula.

Even a single symbol has to be a block fence; or use raw HTML <sub> / <sup> (raw HTML passes through).

Incidentally the maths engine will be MathJax v3 rather than KaTeX: KaTeX emits HTML+CSS rather than SVG by default (https://katex.org/), which does not suit a "pre-render to inline SVG" pipeline.

#PlantUML needs Java

Of the seven it is the only one requiring Java ≥ 11. That cost is accepted knowingly — it is the only engine that would add advanced UML and real C4 modelling.

So Java is a documented optional prerequisite, not a hidden requirement. pamphlet doctor will check java -version and give a clear diagnostic when it is missing, rather than letting a raw spawn failure surface.

#Libraries, never CLI packages

Measurement showed that of those 189MB, about 38MB is raster-output dependencies — and Pamphlet only needs SVG:

• vega-cli drags in canvas at 19MB (a native module needing local compilation, the kind that most often fails to install in CI)
• wavedrom-cli drags in @jimp / gifwrap / @resvg, about 19MB

Using the vega + vega-lite libraries (view.toSVG()) and the wavedrom library itself removes all 38MB.

#Bringing your own engine

Describe an external command in the engines frontmatter field — source in on stdin, SVG out on stdout:

engines:
  my-engine:
    langs: [mylang]
    command: [my-renderer, --svg, -]

No JavaScript from you means no third-party code at build time. See Adding a custom diagram engine.

Sources: ADR-0048, ADR-0008