Function invalidating_paths 

pub fn invalidating_paths(
    root: &Path,
    head: &str,
    record_sha: &str,
    gate: &GateCoverage,
) -> Option<Vec<String>>

2026-09-26: The changed paths that invalidate gate between two commits; empty when the commits are equal.

None means git failed or one commit is not in this clone; callers treat it as not covered.

The question is whether the trees differ on paths the gate cares about, so this runs git diff --name-only and does not require record_sha to be an ancestor of head: a record measured on a branch still covers the squash-merged commit when those paths agree.

The diff has no pathspec; super::coverage::invalidates filters it in Rust, so the per-gate policy stays in coverage.rs.