The ~0.9GB per-apply cond KV cache had two OOM paths on tight cards:
- swapping the reference image left the previous MODEL output (and its
cache) alive in ComfyUI's execution cache while the new one built —
_build_cond_kv now evicts every other state's cache first (they rebuild
lazily if that model is sampled again);
- the cache is allocated lazily inside the first DiT forward, where
comfy's memory manager can no longer make room — a PREPARE_SAMPLING
wrapper now enforces a free-VRAM floor (cache*1.25 + 768MB) before
sampling, partially unloading model weights instead of OOMing.
Verified: headless A->B->A swap run logs 'evicted 1 stale cond KV
cache(s)' per swap, no OOM, outputs clean.
Co-Authored-By: Claude Fable 5 <noreply@anthropic.com>
