spec-render — render a spec's diagrams for review

User-invokable only. This skill has side effects (writes SVGs and an index). Claude does not invoke it autonomously.

Invocation

/spec-render <slug> — where <slug> corresponds to docs/specs/<slug>.md.

Prerequisites

• java on PATH (JDK 8+) + the pinned plantuml.jar at .claude/bin/plantuml.jar (fetched at install time; SHA-verified). The render script invokes java -jar .claude/bin/plantuml.jar -tsvg ... and exits 2 with a named remedy if either dep is missing.
• The spec at docs/specs/<slug>.md exists and passes spec_diagram_presence_guard + plantuml_syntax_guard — otherwise rendering will surface the same errors.

Steps

1. Validate the slug: docs/specs/<slug>.md must exist.
2. Run the render script:

   node .claude/skills/spec-render/render.mjs <slug>
   

   The script:
   • Reads docs/specs/<slug>.md.
   • Extracts every plantuml fenced block in source order.
   • For each block: classifies it by marker (c4_context / c4_container / c4_component / sequence / class / dependency_graph / state / other), writes docs/specs/_rendered/<slug>/<NN>_<kind>.puml, then renders to <NN>_<kind>.svg.
   • Writes docs/specs/_rendered/<slug>/index.md with section titles and image links in order.
3. Report the output path and a short per-kind count to the user.
4. If any block fails to render, surface the offending index + first line + stderr tail, and exit non-zero. Do not silently skip broken blocks.

Output

• docs/specs/_rendered/<slug>/<NN>_<kind>.svg — one per diagram block.
• docs/specs/_rendered/<slug>/<NN>_<kind>.puml — source kept next to the SVG for easier diffs.
• docs/specs/_rendered/<slug>/index.md — markdown index with embedded images.

Notes

• The render directory is a build output. Add docs/specs/_rendered/ to .gitignore if you don't want the SVGs in the repo; the PlantUML sources in the spec are the source of truth.
• For offline review without Java + the pinned jar, use the plantuml MCP server from .mcp.json — it talks to a PlantUML renderer over HTTP. This skill prefers the local java -jar path because it's faster, keeps renders self-contained, and uses the SHA-pinned jar (so the version a consumer renders against matches what this baseline was tested with).