Development record

The build loop's landMerged proves a lane landed only by ancestry; after a squash or rebase merge it refuses and hands the worktree and branch cleanup to a person, though abcd land now proves the same case through the forge (landing.MergedAt: a merged, same-repository pull request at the gated head into the default branch). The two landings disagree about one fact, and the loop's refusal costs a person a manual cleanup on every squash-merged lane. Found by the round 3 reviewers of the abcd land change, 2026-10-15.