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chartjs2img

Claude Code plugin ​

The chartjs2img plugin bundles three skills that let Claude Code install the CLI, author configs from a description, and render to PNG / JPEG / WebP. The Chart.js JSON shape and a plugin catalog are inlined into the author skill itself — no separate "load the reference" step required.

Prerequisites ​

  • Claude Code installed and working.
  • git on PATH (the marketplace is a git clone).

That's it. The plugin's /chartjs2img-install skill handles the CLI binary + auto-downloads Chromium.

1. Add the marketplace ​

The chartjs2img plugin is distributed via ideamans/claude-public-plugins (an aggregate marketplace for Ideamans' open-source plugins).

In Claude Code:

/plugin marketplace add ideamans/claude-public-plugins

The first add clones the marketplace; subsequent sessions reuse the cache. Claude Code will confirm with something like:

Added marketplace ideamans-plugins from github.com/ideamans/claude-public-plugins

2. Install the plugin ​

/plugin install chartjs2img@ideamans-plugins

This registers three slash commands:

  • /chartjs2img-install — install / update the CLI
  • /chartjs2img-author — compose a config from a description (JSON constraints and plugin catalog inlined)
  • /chartjs2img-render — render a config to PNG / JPEG / WebP

3. Install the CLI binary ​

/chartjs2img-install

The skill:

  1. Detects your OS + arch (linux / darwin / windows × amd64 / arm64).
  2. Fetches the matching release asset from github.com/ideamans/chartjs2img/releases.
  3. Verifies the SHA-256 checksum.
  4. Drops the binary in ~/.local/bin (or another writable PATH directory).
  5. Runs chartjs2img --version to confirm.

If no writable PATH directory exists, the skill stages the binary in /tmp and prints the exact sudo mv command to complete the install.

Verify:

chartjs2img --version

Should print chartjs2img v0.2.2 (or whatever tag is latest).

4. Author a chart ​

/chartjs2img-author monthly sales bar chart for Jan-Jun, data 12 19 3 5 2 15

The skill picks the chart type (bar), fills in a realistic skeleton, validates with chartjs2img render, and iterates on any Chart.js error messages until the render is clean.

It hands back the PNG path plus the JSON config so you can save, edit, or feed into your own pipeline.

If the agent needs deeper plugin-option detail than the skill inlines, it can pipe chartjs2img llm (or a single section of it) into the conversation — see the CLI reference.

5. Render an existing config ​

If you already have a .json file:

/chartjs2img-render sales.json

The skill redirects chartjs2img render's stderr and inspects it for [chart ERROR] / [chart WARN] messages. A clean render ends with a one-line summary (path + size); a messaged render ends with concrete fix suggestions (misspelled chart type, missing dataset shape, etc.).

Updating ​

When a new chartjs2img version ships:

/plugin marketplace update
/plugin update chartjs2img@ideamans-plugins
/chartjs2img-install      # upgrades the CLI binary in place

The plugin manifest's version is pinned to chartjs2img's own version, so a CLI bump implies a plugin bump.

Troubleshooting ​

/chartjs2img-* : unknown command — the plugin isn't installed. Run /plugin list to confirm; if missing, repeat step 2.

chartjs2img: command not found — binary not on PATH. Run /chartjs2img-install again, or check whether your shell picked up ~/.local/bin (start a new shell or exec $SHELL).

Rendering fails with a Chromium error — on first render, chartjs2img downloads Chrome for Testing. If that fails (firewall, corporate proxy, linux-arm64), fall back to manual install + set CHROMIUM_PATH. See Install.

Rendered image is blank — check the skill's output for X-Chart-Messages. A typo in chart.type or missing datasets is the usual culprit. The render still succeeded technically (exit 0), but Chart.js gave up on drawing.

See also ​

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