A hard fork of Piebald-AI/tweakcc that patches an installed Claude Code in place — both npm cli.js and the JavaScript embedded in a native Bun binary — to apply curated system-prompt overrides and a set of fork-only patches. It is purpose-built to pair with skrabe/lobotomized-claude-code, and it stays current with every Claude Code release through its own prompt-extraction pipeline.
Important
This fork is a superset of upstream and no longer merges from it (2026-06-04). Upstream's tweakcc gates system-prompt overrides off for native installs and doesn't have this fork's override mechanisms (inline-blob, system-reminders) or extended extractor; we add those and apply system prompts to native installs too. Upstream is essentially static — recent releases are version bumps plus prompt-data drops we supersede (our extractor names 383 prompts for CC 2.1.167; Piebald's latest published extract is 2.1.166 with 340) — so there's nothing to gain by merging. We keep the upstream remote only as a fetch-only comparison signal and extract our own prompts.
| This fork | skrabe/tweakcc-fixed |
| Base | Piebald-AI/tweakcc @ bc41a43, then diverged |
| Target CC versions | 2.0.98 through 2.1.167 |
| npm package | tweakcc-fixed (separate from upstream's tweakcc) |
| Pairs with | skrabe/lobotomized-claude-code (Opus 4.8 overrides) |
| Agent guide | AGENTS.md — bug-class diagnostics, patch authoring, the version-bump pipeline |
These mechanisms extend what's reachable for system-prompt customization ("lobotomization") beyond the base's named-prompt overrides. They don't exist upstream.
A directory ~/.tweakcc/system-reminders/ with one .md file per editable dynamic injection. This targets the per-turn / event-driven <system-reminder> wrappers that never appear as named prompts in prompts-X.Y.Z.json and therefore bypass the named-prompt pipeline.
- Empty body → injection suppressed.
- Custom body → pristine content replaced.
{{placeholder}}tokens → whitelisted JS expressions substituted at apply time.
Files are seeded automatically on first --apply. The registry (~30 entries) covers the claudeMd context wrapper, the anti-thinking nudge, MCP per-server overrides, token/budget telemetry, plan-mode reminders, hook/tool-call wrappers, the task-list reminder, the ultrathink booster, the user-sent-new-message wrap, the stop-hook session-goal, and more. UI: tweakcc → System reminders (injection lobotomy).
Auto-generates ~/.tweakcc/system-reminders/mcp-<server-name>.md for each connected MCP server (from ~/.claude.json mcpServers) and patches cli.js so MCP-instruction assembly consults those files at runtime — empty body drops the server's block from the model's context, custom body replaces it, and {{server_instructions}} resolves to the server's pristine instructions.
Extends the inline-blob mechanism to double-quoted JS string literals (previously array/template only), reaching blobs like function xu3(){return"Users may configure 'hooks'..."} that the base couldn't override.
A UI surface for managing ~/.claude/settings.json skillOverrides — per-skill cycle through on / name-only / user-invocable-only / off. Writes settings.json natively (CC honors it immediately; no patch required).
Short-circuits CC's universal reminder wrapper so empty / "(no content)" text produces no <system-reminder> block, killing the drift-inducing <system-reminder>(no content)</system-reminder> appended after empty tool outputs. Cache-control-safe (returns the unwrapped placeholder, not an empty text block, so prompt-cached message blocks aren't rejected).
Patches the claudeMd wrapper so the claudeMd / userEmail / currentDate system-reminder injects only on the first API call per conversation (re-firing after /clear), instead of CC's default of re-prepending it every call.
A Misc-Configurable toggle that defaults Opus to "max" reasoning effort instead of "xhigh". Override at runtime with /effort or CLAUDE_CODE_EFFORT_LEVEL.
Beyond the fork-only features above, this fork carries correctness fixes that originated in open upstream PRs and in BenIsLegit's now-unmaintained tweakcc-fixed, plus fork-only patch work. They are now simply part of this fork (we don't merge upstream, so nothing here is "pending"). Credit:
| Source | Author | Fix |
|---|---|---|
| #601 | @signadou | Handle WASMagic import errors gracefully during native-installation detection |
| #646 | @sla-te | Support React Compiler output / async refactoring introduced in CC 2.1.85–2.1.88 |
| #655 | @LeonFedotov | Fall back to npm source when Bun-bytecode extraction yields non-patchable JS; thread clearBytecode through repack |
| #664 | @mike1858 | Fix two patches that broke cli.js on literal \" sequences in prompt content (#660) |
Fork-only patch work: scoping #664's backslash-doubling to quote contexts only (template literals already get a parity-aware backtick pass); adapting opusplan1m / patchesAppliedIndication / thinkerFormat / verboseProperty / userMessageDisplay matchers across successive CC minified shapes; the past-tense thinking-verb array fix; the migration.test.ts vi.mock fix; and TS7 build + Linux native-binary patching. See AGENTS.md for the full rundown and how to extend the fork.
These come from the tweakcc base and work unchanged in this fork: system-prompt customization, custom themes, thinking-verb and spinner customization, toolsets (/toolset), input-pattern highlighters, opusplan[1m], MCP startup optimization, table-format options, token-count rounding, statusline throttling, AGENTS.md/CLAUDE.md alternate names, session naming (/title, /rename), subagent model selection, and the unpack / repack CLI commands.
For detailed docs on these shared features, see the upstream tweakcc README — with the caveat that upstream is now v4 and has diverged, so its API / adhoc-patch / remote-config sections and native-install behavior describe upstream's build, not this fork.
Use this fork's extraction surface with skrabe/lobotomized-claude-code — overrides tuned for Claude Opus 4.8 against this fork's extraction. Our named-prompt JSON catches prompts Piebald's published extract doesn't (383 named for CC 2.1.167 vs their 340 for 2.1.166, their latest published), and the system-reminder + string-kind reach lets the overrides cover content the base mechanisms can't.
Published to npm as tweakcc-fixed:
npx tweakcc-fixed@latest # interactive UI
npx tweakcc-fixed@latest --apply # apply customizations from ~/.tweakcc/config.json
npm install -g tweakcc-fixed@latest # or install globally (re-run to upgrade)Tip
Use @latest — this fork iterates as new Claude Code versions ship; without it, npx may reuse a cached copy and miss newly-published fixes.
For development, or to run patches that aren't published to npm yet, build and run from source:
git clone https://github.com/skrabe/tweakcc-fixed ~/dev/tweakcc-fixed
cd ~/dev/tweakcc-fixed && pnpm install && pnpm build
node dist/index.mjs --applytweakcc-fixed patches Claude Code's minified cli.js, reading customizations from ~/.tweakcc/config.json. For npm installs cli.js is patched directly; for native installs the JS is extracted from the Bun binary with node-lief, patched, and repacked (with stale Bun bytecode cleared). Updating Claude Code overwrites the patches, but they live in your config, so reapply with --apply. Revert with --restore.
MIT. Fork of Piebald-AI/tweakcc; upstream © Piebald LLC.