Two new tests: - browser back button works after navigation: URL returns to original, content renders (not blank), no raw SX visible - back button preserves layout: heading stays in top area, no side-by-side All 7 navigation tests pass including forward nav, back button, layout, content update, header survival, and raw SX checks. Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>