ascii-rendering

name	ascii-rendering
description	This skill should be used when the user asks to "draw a diagram", "show a status box", "render ASCII art", "make a callout", "wrap text in a box", "plot these numbers", or any request involving boxed messages, two-box-and-arrow diagrams, scatter plots, or tables rendered as ASCII. Uses JBang to invoke the JaiClaw ASCII renderer; do not hand-draw borders character-by-character.
version	0.1.0

ASCII Rendering

This skill lets you render structured ASCII art instead of hand-drawing borders character-by-character. Two scripts under scripts/, both JBang-shebanged so they self-resolve their Maven dependency on first run.

When to use

Use this skill whenever the user asks for:

• A boxed status message, callout, or warning
• A simple diagram (two or three boxes joined by lines)
• A scatter plot of numbers
• A table grid
• "Draw me X in ASCII"

Do not use it when the user wants rich HTML, interactive UI, or images — those need a different tool.

What's here

• scripts/RenderBox.java — quick wrapper for "put this text in a box"
• scripts/RenderScene.java — full scene renderer (rectangles, lines, labels, text blocks, dots, circles, ellipses, tables, scatter plots)
• examples/*.json — three reference scenes you can adapt

How to invoke

Quick boxed message — RenderBox.java

jbang ${CLAUDE_PLUGIN_ROOT}/skills/ascii-rendering/scripts/RenderBox.java --content "Build green — all tests pass." \
                              --title=STATUS --border=double

Output (stdout):

╔════════════════════════════════════════════════════════════╗
║[ STATUS ]                                                  ║
║Build green — all tests pass.                               ║
╚════════════════════════════════════════════════════════════╝

Flags:

Flag	Default	Notes
--content TEXT or --file PATH or stdin	—	Source text
--width N	60	Max inner width (clamped to [4, 500])
--border single|double|bold|rounded	single	Border style
--title TEXT	—	Top-edge banner [ TEXT ]

Structured scene — RenderScene.java

Write the scene JSON to a temp file, then:

jbang ${CLAUDE_PLUGIN_ROOT}/skills/ascii-rendering/scripts/RenderScene.java --file /tmp/scene.json

Or pipe via stdin:

echo '{"width":40,"height":5,"elements":[{"type":"rectangle"}]}' | \
    jbang ${CLAUDE_PLUGIN_ROOT}/skills/ascii-rendering/scripts/RenderScene.java

Scene JSON shape

{
  "width":  40,                  // canvas width in characters
  "height": 5,                   // canvas height in characters
  "trim":   true,                // optional; default true
  "elements": [
    {"type": "rectangle"},
    {"type": "label",
     "params": {"text": "Hello", "x": 15, "y": 2}}
  ]
}

Element catalogue

Coordinates: origin (0, 0) at top-left; x grows right, y grows down. Position keys are optional — omitting them centres or fills automatically.

type	Required params	Optional params
rectangle	—	x, y, width, height
line	x1, y1, x2, y2	pen (single char, default ●)
label	text	x, y, width (single line; truncated with …)
text	text	x, y, width, height (multi-line; word-wraps)
dot	—	x, y
circle	—	x, y, radius
ellipse	—	x, y, width, height
table	rows, columns (both > 0)	x, y, width, height
plot	points (list of [x, y]), width, height (> 0)	x, y
glyph	x, y, and either name (registry lookup: ok, fail, warn, , , , , , , ) OR + optional

Look at ${CLAUDE_PLUGIN_ROOT}/skills/ascii-rendering/examples/boxed-hello.json, call-graph.json, and scatter-plot.json in the same directory for full reference scenes. See GLYPHS.md (next to this file) for the full glyph vocabulary, the GlyphContribution SPI for registering your own glyphs, and the AnsiPalette post-processor that colorizes the rendered output for terminals.

Errors

Bad input prints to stderr with a precise location, then exits non-zero:

• [element 3]: 'columns' and 'rows' must be positive.
• [element 2]: Unknown element type 'marshmallow'.
• Missing or non-positive 'width'.

When you see one, fix the indicated element and retry the script. Don't try to hand-render the result; the script is the authoritative renderer.

Prerequisites

The host must have JBang installed (brew install jbang / curl -Ls https://sh.jbang.dev | bash). JBang manages Java automatically; no separate Java install needed.

First invocation pulls the jaiclaw-ascii-render jar + Jackson + SLF4J from Maven (~3 MB total) and caches them under ~/.jbang/cache/. Subsequent calls start in well under a second.