v1.0.8 — UVR phantom-output root cause + remix stems arg The "model produced no output files" failure that bit every downstream consumer of /v1/audio/restore/uvr-* turned out to be a 3-layer config bug, not a model issue: 1. audio-separator snapshots output_dir at load_model() time; mutating sep.output_dir after load only updates the outer wrapper. Inner model_instance still writes to cwd (/app/, root-owned) → EACCES → library silently catches → audiolla sees "claimed but never written" files and drops them all. 2. output_single_stem filter matched the wrong stem-name namespace (model's own primary_stem_name vs engines.json's primary_stem). 3. Near-silent stem dropper masked layers 1 and 2 on synthetic fixtures. Fix: drop output_single_stem= from the Separator() call (audiolla picks the right stem post-hoc); propagate output_dir to sep.model_instance.output_dir alongside sep.output_dir before each separate() call. Plus a heavy-reverb test fixture + strict UVR output assertions (>= 10 s real WAV, no graceful no-output skip). Also: remix handler now passes stems to separate() (was failing with TypeError, masked pre-v1.0.7 by FastAPI's plain-text 500). 482/482 CUDA integration tests passing.