The invisible/SynthID diffusion pass loads the whole SDXL fp16 pipeline
into VRAM via `pipeline.to("cuda")`. On an 8 GB card the weights alone
(~7 GB) leave no room for activations, so the run OOMs and there is no
in-tool way to recover short of falling back to CPU (~9 min/image).
Add an opt-in `--cpu-offload` flag (default off) that calls diffusers'
`enable_model_cpu_offload()` instead: submodules are streamed to the GPU
on demand, dropping peak VRAM to roughly the largest single submodule at
the cost of per-step transfers. CUDA-only; a no-op on cpu/mps. Threaded
through `invisible`, `all`, and `batch` to keep the knob set identical
across the three, mirroring the existing `--device`/`--pipeline` options.
Measured on a GTX 1070 Ti (8 GB): `invisible --pipeline sdxl --cpu-offload`
runs the SynthID scrub on-GPU in ~2.5 min vs ~9 min on CPU, where the
default full-VRAM path OOMs.
Test drives the placement decision with a mock pipeline (no model/GPU),
gated on torch so it runs under the `gpu` extra and skips the core CI
matrix, consistent with the model-running test policy.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Victor Kuznetsov