A late merge is named however its modules read since the cut; a walk builds the commits it carries (hq ADR 0276 review)

internal/inventory/plans.go

@@ -94,6 +94,21 @@ func (p Plan) CommitOf(repository string) string {
 	return ""
 }
 
+// CommitOn is the commit of a repository's branch the walk carries; empty when it carries none of it. A
+// commit kept without its branch matches any branch.
+func (p Plan) CommitOn(repository, branch string) string {
+	for _, c := range p.Commits {
+		if strings.EqualFold(c.Repository, repository) && (branch == "" || c.Branch == "" || c.Branch == branch) {
+			return c.Commit
+		}
+	}
+	if len(p.Commits) == 0 && strings.EqualFold(p.Repository, repository) &&
+		(branch == "" || p.Branch == "" || p.Branch == branch) {
+		return p.Commit
+	}
+	return ""
+}
+
 // Carried is every repository's commit the walk carries: Commits, or its one repository and commit.
 func (p Plan) Carried() []PlanCommit {
 	if len(p.Commits) > 0 {