The stalled loader thread is a lost wakeup in Xenia's POSIX threading, fixed on the canary branch as a60fe7d11 and written up here. A thread created suspended publishes state_ and suspend_count_ in two separate lock scopes, and Resume() waits only for state_ before testing suspend_count_ == 0 - so a resumer in the gap drops the resume and the thread waits forever. The Linux XThread::Resume discards that false, which is why the guest saw success. On the first clean boot after the fix the loader thread is the CALLER on 20 kernel-call lines and issues 4 ResolvePath reads. Every failed boot before it had exactly zero of both. Stated plainly as not shown: that boots now reach the menu RELIABLY. One post-fix boot, and it is confounded by the harness. Which is the second half. skip_intro.sh's title test has now been wrong twice in opposite directions: originally one absolute pixel (625,618) - a 1280x720 coordinate against the 1279x675 game surface, so it read the copyright line and timed out with the title on screen - and then my replacement, screen_id.py, which is too loose and called the SQUARE ENIX publisher logo "title" 151s into a boot, spending the script's single press there. is_title.py now counts the green (A) glyph over the whole frame: geometry-independent and specific, measured at 0 pixels on the logo and 1520 on a real title.