place_at padded a mix up to the scene length with apad and let atrim end the
stream. That handoff is a race. A bare apad loses it by generating silence for
ever: ffmpeg never reaches EOF and spins at 100% CPU with the output
half-written -- 4 hangs in 10 runs, and two orphans left on a dev host by
test_compose_dialogue had burned 14h and 10h of CPU unnoticed. apad=whole_dur
stops the hang and loses the same race the other way, emitting a track one clip
short (3s for 4s) in 3 of 14 runs with no error anywhere. Neither -threads 1
nor -filter_threads 1 helps.

A silent base input of exactly the target length, mixed under the placements
with amix=duration=first, has no handoff to lose: 0 bad in 20 runs, one output
size. The other apad sites feed no mix, but take whole_dur too since the length
is known there as well.

Also pass config/subfolder to the single-file component loader, the way the
GGUF branch already does and for the same reason: left to itself
from_single_file infers a base repo from the checkpoint's own metadata, so
Krea-2-RealDream reached for krea/Krea-2-Raw and died on a repo nobody named.
Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_014T3rZnLhydX9QqUcfBbqLu