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

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.

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.