Canonical handoff (research note) for the U.4c flap fix + the three residuals the
visual gate revealed (#78 terrain-not-gated-inside, camera-collision need, U.5).
Records the full hypothesis journey (H1/H2 both evidence-disproven) so the next
session doesn't re-walk them. ISSUES.md: flap recorded in Recently-closed; #78
annotated (more visible post-fix). CLAUDE.md: U-phase orientation updated with the
flap-fixed status + the canonical handoff pointer + camera-collision-next.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>