Piebald-AI/tweakcc

What tweakcc does

tweakcc is a command‑line utility that lets you personalise the Claude Code desktop app (Anthropic’s AI‑assistant UI). It works by patching the app’s JavaScript bundle (or the native Bun binary that ships with Claude Code) and then re‑packing it, so the changes take effect the next time you launch Claude Code.

Core capabilities

Area	What you can change
System prompts	Replace the default prompts that Claude receives at start‑up, or pick from a library of community‑maintained prompts.
Themes & colours	Pick colours with an HSL/RGB picker, change the whole UI palette, hide the ASCII border, style user messages, and even customise the spinner animation that shows while Claude is thinking.
Toolsets & commands	Define custom toolsets that become available via a new /toolset command inside Claude Code.
Session handling	Give chats a name (/title, /rename), enable a “session memory” feature (/remember), and control how sub‑agents (Plan, Explore, etc.) pick their model.
Model aliases & limits	Add aliases such as opusplan[1m] (Opus for planning + Sonnet‑1M context) and adjust the context‑limit via CLAUDE_CODE_CONTEXT_LIMIT.
Display tweaks	Choose table styles (Unicode, ASCII, markdown), show token counts, throttle status‑line updates, and hide various UI hints.
Performance	Speed up start‑up by ~50 % with non‑blocking MCP connections and configurable parallel batch sizes.
Safety & permissions	Options to bypass permission checks in sudo, suppress native installer warnings, and disable Ctrl‑Z suspend.

How it works under the hood

1. Discovery – tweakcc locates the Claude Code installation (npm/yarn/pnpm/bun, native binary, Homebrew, Nix, etc.).
2. Extraction – For native Bun binaries it uses node‑lief (Node bindings to the LIEF library) to pull the bundled JavaScript (cli.js) out of the executable.
3. Patch application – Customisations are read from ~/.tweakcc/config.json (or a remote URL) and applied as text replacements, regexes, or full‑script patches.
4. Re‑packing – The modified JavaScript is written back into the binary (or directly overwrites cli.js for npm installs). A backup of the original binary is kept so tweakcc --restore can revert changes.
5. CLI & API – You can run the interactive UI with npx tweakcc, use sub‑commands (unpack, repack, adhoc‑patch) for advanced workflows, or import the library (npm i tweakcc) and call its API from your own Node project.

Typical workflow

# Run the interactive UI, create a theme and a custom prompt
npx tweakcc

# Apply the saved config to Claude Code (non‑interactive, useful in scripts)
npx tweakcc --apply --yes

# Quickly test a one‑off change without editing config
npx tweakcc adhoc-patch --string "old text" "new text"

Who might use it?

• Power users of Claude Code who want a darker‑mode‑friendly colour scheme, custom thinking verbs, or a different spinner.
• Teams that share a standard set of system prompts or toolsets across members.
• Developers building extensions for Claude Code and needing a reproducible way to inject patches.
• Researchers who want to experiment with alternative model‑selection logic (e.g., the opusplan[1m] alias) without modifying Claude’s source.

Limits & caveats

• The tool is tied to specific Claude Code versions; it is verified for 2.1.162 and may need updates for newer releases.
• When Claude Code updates, your patches are removed; you must re‑run tweakcc --apply to restore them.
• Native‑binary patching requires Node 20+ (for the sandboxed script mode) and may involve ad‑hoc code‑signing on Apple Silicon.

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TL;DR: tweakcc is a Node‑based CLI that lets you theme, extend, and tweak the Claude Code AI‑assistant desktop app by patching its JavaScript bundle. It supports both npm‑installed and native Bun binaries, offers an API for programmatic use, and provides a rich set of UI and behaviour customisations for power users and teams.