Agent-Skills.md

Agent Skills: diagram

This skill should be used when the user asks to "render a diagram", "draw a diagram", "create a diagram from text", "convert PlantUML to SVG", "render Mermaid", "render PlantUML", "render GraphViz", "render D2", "render DBML", "render BPMN", "convert .puml to png", "convert .mmd to svg", "make a flowchart", "make a sequence diagram", "make an ERD", "draw a UML diagram", "diagram as code", "Kroki", "C4 diagram", or otherwise needs to convert textual diagram source (PlantUML, Mermaid, GraphViz/dot, D2, DBML, BPMN, Excalidraw, Erd, Ditaa, Nomnoml, Pikchr, Structurizr, SvgBob, TikZ, Vega/Vega-Lite, WaveDrom, WireViz, BlockDiag family) into SVG, PNG, PDF, or JPEG. Backed by the Kroki HTTP service — no local diagram toolchain required.

UncategorizedID: thilinatlm/claude-plugins/diagram

Repository

thilinatlm/claude-plugins
ThilinaTLMLicense: MIT
31

Install this agent skill to your local

pnpm dlx add-skill https://github.com/ThilinaTLM/agent-skills/tree/HEAD/diagram

Skill Files

Browse the full folder contents for diagram.

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diagram/SKILL.md

Skill Metadata

Name
diagram
Description
This skill should be used when the user asks to "render a diagram", "draw a diagram", "create a diagram from text", "convert PlantUML to SVG", "render Mermaid", "render PlantUML", "render GraphViz", "render D2", "render DBML", "render BPMN", "convert .puml to png", "convert .mmd to svg", "make a flowchart", "make a sequence diagram", "make an ERD", "draw a UML diagram", "diagram as code", "Kroki", "C4 diagram", or otherwise needs to convert textual diagram source (PlantUML, Mermaid, GraphViz/dot, D2, DBML, BPMN, Excalidraw, Erd, Ditaa, Nomnoml, Pikchr, Structurizr, SvgBob, TikZ, Vega/Vega-Lite, WaveDrom, WireViz, BlockDiag family) into SVG, PNG, PDF, or JPEG. Backed by the Kroki HTTP service — no local diagram toolchain required.

diagram

CLI for rendering text-based diagrams (PlantUML, Mermaid, GraphViz, D2, DBML, BPMN, C4, Erd, Ditaa, Nomnoml, Pikchr, Structurizr, SvgBob, TikZ, Vega, Vega-Lite, WaveDrom, WireViz, BlockDiag / SeqDiag / ActDiag / NwDiag / PacketDiag / RackDiag, Excalidraw, Bytefield, Symbolator, UMlet) to SVG / PNG / PDF / JPEG / TXT / Base64 via the Kroki HTTP API. JSON output.

CLI

  • Path: ./diagram-cli/diagram (relative to this SKILL.md). On Windows use diagram.cmd or diagram.ps1.
  • Requires uv (install). First call provisions the Python environment automatically.
  • Subcommands: render (primary), types (capability discovery).
  • Run diagram render --help for current flags.

Endpoint resolution

The CLI picks the Kroki endpoint in this order:

  1. --endpoint <url> flag
  2. KROKI_URL environment variable
  3. .kroki-url file (one URL, no quotes) walked up from the current working directory — useful for pinning a project to a self-hosted Kroki without touching shell config
  4. https://kroki.io (default, free public instance)

Add .kroki-url to .gitignore if it points to an internal hostname.

Subcommands

diagram render

Renders one diagram and writes the output to a file. Always pass --output <path> — the JSON envelope is the only thing on stdout; the rendered bytes go to the file. After a successful call, use the Read tool on the produced file path to confirm the output looks right.

| Flag | Description | | -------------------- | ---------------------------------------------------------------------------------------------------------- | | --input <path> | Read diagram source from a file. Extension drives type auto-detect (see table below). | | --source "<text>" | Inline diagram source (alternative to --input). | | stdin | Used when neither --input nor --source is given and stdin is piped. | | --type <name> | Diagram type (e.g. plantuml, mermaid, graphviz, d2). Required if not derivable from the extension. | | --format <name> | Output format. Default svg. Support varies by type — see diagram types. | | --output <path> | Required. Output file. Parent directories are created. | | --endpoint <url> | Override Kroki endpoint (also KROKI_URL, .kroki-url). | | --timeout <secs> | HTTP timeout. Default 30. |

Examples:

# Auto-detect type from extension (.mmd → mermaid), default SVG
./diagram-cli/diagram render --input docs/flow.mmd --output docs/flow.svg

# PlantUML to PNG with explicit type/format
./diagram-cli/diagram render --input arch.puml --type plantuml --format png --output assets/arch.png

# Inline GraphViz
./diagram-cli/diagram render \
  --type graphviz \
  --source 'digraph G { Hello -> World }' \
  --output /tmp/hello.svg

# Stdin
cat diagram.d2 | ./diagram-cli/diagram render --type d2 --output diagram.svg

# Self-hosted Kroki
KROKI_URL=http://kroki.internal:8000 ./diagram-cli/diagram render \
  --input flow.puml --output flow.svg

Success output:

{"ok":true,"file":"/abs/path/flow.svg","type":"plantuml","format":"svg","bytes":12345,"endpoint":"https://kroki.io","sourceOrigin":"file"}

diagram types

Lists supported diagram types and their formats. No network call — the table is baked into the CLI. Use this to discover what --type / --format combinations are valid before calling render.

./diagram-cli/diagram types            # all types
./diagram-cli/diagram types mermaid    # one type

Supported diagram types (summary)

| Type | File extensions | Output formats | | ------------- | ------------------------------ | --------------------------- | | plantuml | .puml, .plantuml, .iuml | svg, png, pdf, txt, base64 | | mermaid | .mmd, .mermaid | svg, png | | graphviz | .dot, .gv | svg, png, jpeg, pdf | | d2 | .d2 | svg | | dbml | .dbml | svg | | bpmn | .bpmn | svg | | c4plantuml | .c4, .c4puml | svg, png, pdf, txt, base64 | | erd | .erd | svg, png, jpeg, pdf | | ditaa | .ditaa | svg, png | | excalidraw | .excalidraw | svg | | nomnoml | .nomnoml | svg | | pikchr | .pikchr | svg | | structurizr | .structurizr, .dsl | svg, png, pdf, txt, base64 | | svgbob | .svgbob | svg | | tikz | .tikz | svg, png, jpeg, pdf | | vega | .vega | svg, png, pdf | | vegalite | .vl, .vegalite | svg, png, pdf | | wavedrom | .wavedrom | svg | | wireviz | .wireviz | svg, png | | bytefield | .bytefield | svg | | symbolator | — | svg | | umlet | — | svg, png, jpeg | | blockdiag family (blockdiag, seqdiag, actdiag, nwdiag, packetdiag, rackdiag) | matching .*diag extension | svg, png, pdf |

Run diagram types for the machine-readable, always-current list.

Workflow guidance

  • Default to SVG. It scales, embeds cleanly in HTML/Markdown, and every diagram type supports it. Switch to PNG only when the consumer can't render SVG (image-only chat, certain markdown renderers).
  • Prefer writing the diagram source to a file with an unambiguous extension (.puml, .mmd, .dot, etc.). The CLI then auto-detects --type and you keep the source under version control alongside the rendered output.
  • When RENDER_FAILED comes back, the hint field contains Kroki's syntax-error message — surface it verbatim to the user and to your reasoning. Most of the time it includes a line number.
  • For very large diagrams, raise --timeout. The default 30 s is generous for Kroki's free instance but a self-hosted one rendering complex PlantUML or TikZ may need more.

Error codes

| Code | Meaning | | -------------------- | -------------------------------------------------------------------------------- | | PREREQ_MISSING | uv is not installed. | | INPUT_CONFLICT | More than one of --input / --source / stdin was provided. | | INPUT_MISSING | No diagram source was provided. | | INPUT_NOT_FOUND | --input path does not exist, is not a file, or could not be decoded as UTF-8. | | OUTPUT_MISSING | --output was not provided. | | TYPE_MISSING | Type was not given and could not be inferred from the input file extension. | | TYPE_UNKNOWN | Type name is not in the supported list — run diagram types. | | FORMAT_UNSUPPORTED | The (type, format) combination is not supported by Kroki for that type. | | RENDER_FAILED | Kroki returned 4xx. Usually a syntax error in the source; details in hint. | | KROKI_UNAVAILABLE | Network failure, timeout, or Kroki returned 5xx. | | IO_ERROR | Could not write the --output file. | | INTERNAL_ERROR | Unexpected CLI failure — file a bug if you see this. |