Claude Chalk, a mod that lets Claude Code colour its own replies

Developer Adam K. Dean released claude-chalk, a Claude Code plugin that lets Claude color its own terminal replies using chalk-template markup syntax, installed via `/plugin install chalk --marketplace adamkdean/claude-chalk`. The mod uses two hooks: `prompt.compose` adds a system-prompt section teaching Claude the syntax, and `ui.render` on `AssistantMessage` redraws reply blocks containing markup, with named colors matching Claude Code's rendering and hex/RGB colors drawn exactly. The plugin is named `chalk` because Claude Code reserves plugin names starting with `claude-`, and the mod API is in early access and can change.

Install install · Examples examples · Palette the-palette · Syntax syntax · How it works how-it-works claude-chalk is a Claude Code mod that lets Claude colour its own replies in the terminal. Claude writes markup in the syntax of the chalk-template https://github.com/chalk/chalk-template npm package, and the mod draws it in colour, without the braces. Long replies can bury the one line that matters. With the mod loaded, Claude marks failures in red, passes in green and warnings in yellow, and it puts a question it needs answered on a coloured background. The state of things shows at a glance, and most text stays plain. At the prompt of a Claude Code session in a terminal: /plugin install chalk --marketplace adamkdean/claude-chalk Answer y to add the marketplace, then choose a scope. The mod is active in that session at once and, under the user scope, in every session after it. From a shell: claude plugin install chalk --marketplace adamkdean/claude-chalk In the desktop app, where /plugin does not run: click + next to the prompt box, then Plugins , Add marketplace with adamkdean/claude-chalk , then Add plugin . The plugin is named chalk , after the npm package whose syntax it uses. Claude Code reserves plugin names that start with claude- . Every screenshot below is a real Claude Code session Sonnet 5.5 with the mod loaded. The prompts do not ask for colour: Claude chose every colour itself. Failures stand out from passes, and the coverage gap is easy to spot. The bug is labelled in red, and the lesser points in yellow. The root cause is in red and the knock-on effect in yellow, ahead of the detail. When Claude cannot go on without a decision, the question goes on its own line on a background colour: blue for an ordinary question, red when the answer allows something risky or hard to undo. Every style the mod draws, as Claude showed it when asked for its palette. A block is {style text} : an opening brace, a style, one space, the text and a closing brace. Chain styles with dots. Blocks nest, and an inner block adds to the styles around it. | Kind | Styles | |---|---| | Colours | black red green yellow blue magenta cyan white gray , and each of the first eight with Bright redBright | | Backgrounds | bg and a colour: bgRed , bgBlueBright | | Modifiers | bold dim italic underline inverse strikethrough | | Hex | ff8800 text , :003366 background , ffffff:cc0000 both , hex ff8800 , bgHex 003366 | | RGB | rgb 255,136,0 , bgRgb 0,51,102 , with no spaces | {green ✓ All 42 tests pass} {red.bold Build failed} in src/parser.ts {yellow Warning:} the cache is stale. {bold Hello {red world}} { ff8800:001122.bold Hot} {bgRed.whiteBright Delete these 3 files? } Inside a block, write \{ and \} for literal braces. Text in braces that is not a valid style, such as {name} , is left as written. The mod has two hooks: - prompt.compose adds a short section to the system prompt that teaches Claude the syntax and when to use it. Headless runs claude -p do not get it, because nothing draws the colours there. - ui.render on AssistantMessage redraws each reply block that holds markup. A paragraph with markup is drawn as coloured text, and every other paragraph is drawn as markdown, as before. A block without markup is left to Claude Code. Named colours are drawn as Claude Code draws those names. Hex and RGB colours are drawn exactly. Only the drawing changes: the transcript keeps the markup as Claude wrote it. - Markup is drawn in prose only. Inside code spans and code blocks it is shown as written. - A block ends at the end of its paragraph. - In a paragraph with markup, bold, italic, inline code, headings and lists are drawn, but tables are shown as plain text. - Where the mod is not loaded, the markup is shown as written. - The mod API is in early access and can change between Claude Code releases. Tested with Claude Code 2.1.312. claude --plugin-dir . start a session with the mod loaded from this folder claude plugin validate . check the manifests and the hooks module claude plugin test . run the tests in tests/ AGENTS.md https://github.com/adamkdean/claude-chalk/blob/master/AGENTS.md describes the layout, the checks and the rules for changes, including how to check drawing in a real terminal. The screenshots are recorded from real sessions in a pseudo-terminal and replayed into xterm.js https://xtermjs.org to render them. Released under the MIT licence https://github.com/adamkdean/claude-chalk/blob/master/LICENSE . An independent project, not made by or affiliated with Anthropic or the chalk project.