Constant KTSTR_PROJECT_COMMIT_ENV 

pub const KTSTR_PROJECT_COMMIT_ENV: &str = "KTSTR_PROJECT_COMMIT";

Name of the environment variable cargo-ktstr’s perf-delta sets to the PROJECT tree’s short commit hash (with a -dirty suffix when the tree is dirty) that the child’s sidecars must record as their project_commit. Unlike KTSTR_KERNEL_COMMIT_ENV this is a single value, not a dir=commit map — a child has exactly one project tree.

perf-delta computes the A/B commit labels ONCE in the orchestrator (short_hash) and both the pool FILTER and the two run children read the same value: the filter partitions on it, and each child records it verbatim (the sidecar writer’s detect_project_commit returns this value when the env is set), so the recorded project_commit and the filter can never diverge on the -dirty suffix. It also lets the baseline run, whose tree is a plain gix checkout with no .git, skip a gix::discover that would otherwise resolve to the wrong repo (or none).

Override only: an absent or empty env falls back to the in-process gix::discover + dirty-walk, which is correct for a normal (non perf-delta) test run.