regression-guardlisted

# /regression-guard — emit a REGRESSION-GUARD test stub for a refactor commit Thin wrapper around the `regression-guard` binary (installed at `~/.local/bin/regression-guard`; built by `install.sh`). Binary owns: `git show` of the commit, diff pattern auto-detection, test skeleton rendering. Agent fills in the test body. ## Steps 1. **Invoke the binary** with the refactor commit hash: ```sh regression-guard <commit-hash> \ [--pattern <override>] \ [--test-name <fn-name>] \ [--module-path <crate::path::to::mod>] \ [--git-dir <repo-path>] ``` Stdout is a Rust source snippet (test fn + REGRESSION-GUARD docstring referencing the commit + the detected pattern). 2. **Paste the snippet into the test module** of the file the refactor touched (typically `src/<file>.rs`'s `#[cfg(test)] mod tests` block). 3. **Fill in the test body** with the actual exercise of the pathological input the refactor defends against. Examples per pattern are listed in the snippet's TODO comment. 4. **Run the test**: `cargo test <test_name>` — it MUST pass on the post-refactor code (that's the point — it locks in the new behaviour). If it fails, the test isn't asserting the right thing; revisit. 5. **Commit** the test in the same PR / commit-chain as the refactor, or in a `[REGRESSION-GUARD]`-prefixed follow-up commit referencing the refactor hash. ## Net visible tool calls per r