half-fixed

Most codebases have siblings: provider adapters, database drivers, cache stores, payment gateways, platform ports. Each one does the same job its own way. When a bug turns up in one of them, someone fixes that one and moves on. The siblings often have the same code and the same bug, and nobody notices until a user hits it.

half-fixed reads your git history and finds those gaps. It's a fast, offline scanner and two Agent Skills: one checks which findings are real bugs and fixes them with tests, and the other writes the pull request the way the project's maintainers expect.

Quick start

Claude Code. Type these inside a Claude Code session, not a shell:

/plugin marketplace add heyzainali/half-fixed
/plugin install half-fixed@half-fixed

Codex

codex plugin marketplace add heyzainali/half-fixed
codex plugin add half-fixed@half-fixed

Any other agent that supports SKILL.md can use the Agent Skills CLI:

npx skills add heyzainali/half-fixed   # or: bunx skills add heyzainali/half-fixed

Then ask your agent to "Find half-fixed bugs in this repo".

• Only want the scanner? Run npx half-fixed scan in any git repository. It needs Node 18 or newer and nothing else. For a repository you don't control, start it from outside and pass the path, npx half-fixed scan /path/to/repo, because npx trusts the node_modules and .npmrc of the directory it starts in.
• Rather your agent did the install? Paste the prompt below into it.

Install the half-fixed skills from https://github.com/heyzainali/half-fixed.

Work out which agent you are, then use the matching method. If a command fails or you can't run it, tell me the exact command to run myself.

- Claude Code: run `claude plugin marketplace add heyzainali/half-fixed`, then `claude plugin install half-fixed@half-fixed`. If the `claude` CLI isn't available, tell me to type `/plugin marketplace add heyzainali/half-fixed` and then `/plugin install half-fixed@half-fixed` in this session.
- Codex: run `codex plugin marketplace add heyzainali/half-fixed`, then `codex plugin add half-fixed@half-fixed`.
- Any other agent that supports SKILL.md: run `npx skills add heyzainali/half-fixed`. If that doesn't work, clone the repository to a temporary directory and copy both folders in its `plugins/half-fixed/skills/` directory into your skills directory.

Prefer a project install unless I asked for a global one. When you're done, tell me what you installed, where, and whether I need to restart you.

Bugs it has found

Each one started as a single finding, like hf-5505660 in the demo above. Found a half-fixed bug with it? Open a pull request that adds it to this table, and leave a ⭐ so others can find the tool.

How it works

1. Find siblings. Files whose paths differ in exactly one directory form a group, like src/Providers/*/Maps/ToolMap.php. So do files in one directory that share a name suffix, like src/Cache/*Store.php. Tests, vendored code, and build output are skipped.
2. Replay history. For every commit that changed only some members of a group, half-fixed takes the code the commit replaced, plus just enough surrounding lines to pin it down. A fix that wraps old code instead of deleting it still counts.
3. Check the rest. If another member still has that code, ignoring whitespace, and doesn't already have the new lines, it's reported as missing the change.
4. Rank. Fix commits rank above features and refactors. Commits about lint, types, or formatting don't count as fixes. A change that relies on names only the fixed file has, like a renamed local variable, ranks lower, because no sibling could take it as-is.

The only program