Mode Switch Test: DOM Base
1. DOM -> Pixel (pushState)
2. DOM -> Pixel (replaceState)
3. Back / Forward (soft traversal)
4. Rapid same-direction: DOM -> Pixel x3
5. Rapid mixed: DOM->Pixel->DOM->Pixel
6. Hash change (no mode switch, clears pending)
7. Same-mode nav cancels pending hint
8. Forward after back
9. replaceState on nav URL
Log: