Git records no diff entry for a directory itself, so adding
.changes/foo/bar.md only surfaced the nested path, which the single-level
trigger regex skipped. The entry validation and the renderer were both
bypassed, letting a nested directory reach main and break every later
fragment render with 'unexpected directory'.
Trigger the top-level tree validation on any .changes change outside
.changes/released/ (which keeps its own immutability and release-seal
checks), and assert .changes itself is still a tree so replacing it with a
blob or symlink cannot empty the child listing unnoticed.
Re-rendering stays keyed on fragment changes so a README-only edit does
not fail on an empty fragment set.
RuiGong01