Function plan_commit 

pub fn plan_commit(
    tree: &Tree,
    cwd_host_root: &Path,
) -> Result<CommitPlan, CommitPlanError>

Compute the CommitPlan for tree, anchoring relative paths against cwd_host_root.

The function consults the filesystem only to test whether a haz.yml already exists under each project root; it never writes anything (that’s apply_commit’s job).

Errors

Returns CommitPlanError::SanitisationFailed when a project root’s basename cannot be sanitised to a valid ProjectName.