Review round 2 on PR #166: Lstat on the walk root checks only its last component, so search with Wing+Hall (root wiki/<wing>/<hall>) walked a symlinked <wing> whose target had a real <hall> directory. WalkRegular now Lstats every prefix of the root and requires each to be a real directory. New brainfs and search (Wing+Hall) tests; the Wing-only search test is renamed to say what it covers. The doc now records the accepted residual: a directory swapped for a symlink between listing and read is still followed; os.Root keeps the read inside the brain but not inside the walk root. Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>