diffuseR 0.2.2

• Every precision recommend() can return is now reachable. bf16 was advertised for flux1 at 24 GB and flux2/zimage at 16-24 GB while no loader accepted it; the flux-family loaders take precision = "bf16", which resolves the unquantized transformer out of the hfhub cache rather than an artifact directory (bf16 is the source the quantizers read, not something built). recommend() explains the tier instead of returning a bare string. On a 16 GB card, flux2 at bf16 renders 1024x1024 in 6.4 s against 9.1 s at fp8 - the highest-quality tier is also the fastest, since nothing dequantizes per layer; it costs the 7.8 GB source staying on disk.

• download_ltx2() gains precision = c("nf4", "fp8") and defaults to nf4, which is what recommend("ltx") returns for any card with 14 GB or more. It previously built only fp8, so the recommended tier had to be built by hand with ltx23_quantize_nf4(). Asking for fp8 without float8 write support now warns and builds nf4 instead of failing inside the quantizer.

• Quantized artifacts stay locally built. Prebuilt weights are not hosted for any model: only flux2 and zimage could be redistributed (Apache-2.0 and ungated), while LTX-2.3 is under the LTX-2 Community License and FLUX.1-schnell is gated, so hosting would cover half the catalog and leave two models on a different workflow.

• Model residency: resident_load(), resident_activate(), resident_deactivate(), resident_generate(), resident_status() and resident_unload() keep a pipeline’s weights page-locked on the host and treat the GPU copy as disposable, so handing a small card between models is a DMA transfer rather than a full reload. Same contract as whisper and chatterbox, with no gpu.ctl dependency. This sits above the per-generation phase offloading in the txt2img_* functions: those swap one component at a time within a render, residency decides who owns the card between renders. For a phase-offloading pipeline (the default) activation is the ownership claim and the transfers stay per-phase; only a pipeline loaded with phase_offload = FALSE is copied to the card wholesale, and that path is checked against free VRAM first. resident_status() reports components_on_gpu alongside state, because the two legitimately disagree: a render returns every component to pinned host memory as its phase ends, so an active handle can hold nothing.

  Verified on an RTX 5060 Ti (16 GB) against local artifacts: flux2 (11.22 GB pinned, 9.1 s render), flux1 (15.73 GB, 40.1 s), zimage (13.45 GB, 19.5 s) and ltx (18.41 GB across 5 components). All three image models reproduce bit-for-bit across a deactivate/activate cycle. FLUX.1 and LTX both have pinned sets larger than the card, so they exercise the refusal path rather than bulk onload.

Addressing the CRAN review of the 0.2.0 submission:

• Every exported .Rd with a \usage block now documents its return value: 50 @return tags added, chiefly to the nn_module generators for the FLUX, FLUX.2, Z-Image, LTX-2.3 and Gemma3 ports.
• Examples: 14 of the 23 \dontrun{} blocks now run during check, and were rewritten to be self-contained instead of referencing undefined objects. The 9 that remain need model weights on disk and are itemised in cran-comments.md.
• ddim_scheduler_create() was uncallable at its documented defaults: beta_schedule was never passed through match.arg(), so switch() errored on the length-3 default, and the device default was a length-2 vector that torch_tensor() rejects. ddim_scheduler_step() had the same missing match.arg() on prediction_type. Every internal caller passed these explicitly, so the broken defaults went unnoticed. device now defaults to torch_device("cpu").
• DESCRIPTION: software names single-quoted (‘Python’, ‘Stable Diffusion’, ‘Hugging Face’ with its URL) and the trailing whitespace that had been folding into double spaces since the first commit removed.
• save_video()’s mp4 example is no longer live: the encoder inherits the session’s stdin, which R CMD check --as-cran uses to feed the example script to R, so it consumed part of the script.

diffuseR 0.2.0.1

• The FLUX-family image loaders (flux_load_pipeline, flux2_load_pipeline, zimage_load_pipeline) now page-lock the phase-swapped transformer, VAE decoder, and text encoder(s) at load, so the per-generation CPU<->GPU moves run at DMA rate (offload becomes a pointer swap). A new pin argument, NULL by default, resolves via options(diffuseR.pin_staging) then the host-RAM-aware recommend() decision. Resident-fp8 transformers (flux2/zimage) stage their fp8 weight fields too.
• flux_load_pipeline() GPU-encodes T5-XXL (bfloat16) on 14 GB+ cards, where its encode phase fits; smaller cards keep the float32 CPU encode. text_device defaults to NULL (resolved from the VRAM tier). An explicit text_device = "cpu" still encodes in place.
• Internal: the pinned-staging helpers lost their ltx23 prefix (staging.R); recommend() and the loaders share one .pin_decision.

diffuseR 0.2.0

Serving

• serve(): a zero-dependency HTTP server (base R sockets, one persistent process, model loaded once) answering OpenAI-style requests - /v1/images/generations for flux2/zimage/flux1, /v1/videos/generations for ltx, GET /health. Never downloads weights; an example systemd unit ships as system.file("diffuser.service", package = "diffuseR"). Port 7812 in the cornball serve range. Hardened for persistence: optional bearer-token auth, hard pixel/frame limits (400 on oversize, including a steps cap, frame-rate bounds, and a joint pixels-x-frames video budget), a bounded LRU of per-prompt connector embeds (~9 MB each, never the raw Gemma stacks), and a clean process exit on CUDA OOM so a supervisor restarts with sane GPU state.

• Every model download is consent-gated: interactive prompt with the size stated, and non-interactive sessions require options(diffuseR.consent = TRUE). Generation functions never download implicitly. ## Native safetensors pipelines

• SD 2.1, SDXL, FLUX.1-schnell, FLUX.2 Klein, Z-Image-Turbo, and LTX-2.3 all run fully natively from diffusers-layout safetensors — no TorchScript step, so everything works on Blackwell (RTX 50xx). download_sd21()/download_sdxl() fetch diffusers weights; sd_pipeline_from_safetensors()/sdxl_pipeline_from_safetensors() build the pipelines; txt2img_sd21()/txt2img_sdxl() take diffusers_dir=.

• Checkpoint loaders build module skeletons (uninitialized weights at the target dtype) instead of initializing fp32 and casting: the LTX-2.3 NF4 pipeline load drops from ~108 GB host RAM to ~21 GB. Loaders hard-error on any parameter the checkpoint does not fill.

• reshard_safetensors() splits oversize weights into sub-2 GB shards readable by stock CRAN safetensors; quantizer shards default to 1.9e9 bytes for the same reason. Requesting fp8/bf16 without a capable safetensors warns and falls back to nf4; legacy oversize shards raise an actionable message.

• Fixed a long-standing native SD 2.1 UNet tiling bug: the timestep embedding used the wrong sin/cos ordering (flip_sin_to_cos/downscale_freq_shift), which compounded through the spatial path into tiled output. Now matches the TorchScript reference at cosine 0.99999.

Machine-aware configuration

• recommend(model): one VRAM-, host-RAM-, and capability-aware recommendation for every model — precision tier, per-component device map, phase offload, pixel budget, attention chunking, and pin (page-lock the phase-swapped host copies; pinned pages are unswappable, so pinning is recommended only when available RAM covers the model’s pinned set twice over). fp8/bf16 tiers are gated on the installed safetensors’ read capabilities; when a card fits a tier the reader can’t load, the fork suggestion is surfaced in $note, never as an error.
• The SD tiers are labeled fp16 at every VRAM level: the SD models ship no quantized weights, so placement varies, not precision.
• New “Performance Levers” vignette documenting the three axes (precision ladder, device placement, memory residency) and a hardware-requirements table in the README.

LTX-2.3 video performance

Warm 768x512x49 renders went from ~90 s to ~44 s across this cycle:

• NF4 dequantization via a precomputed [256, 2] byte lookup table (one embedding gather in the compute dtype) instead of an int64 shift/stack/gather chain — ~6x less per-step memory traffic.
• The CUDA allocator gc gates now actually take effect (ltx23_tune_gc() used to set its options one call after torch had read them) and are pushed into the live allocator.
• Pinned staging for phase offload, on by default: page-locked host copies make onload a DMA transfer (25.1 GB/s measured; 11 GB re-onloads in 0.5 s) and offload a pointer swap. Page-locked memory is allocated via torch_empty_strided(pin_memory = TRUE), avoiding a deprecated overload that printed two warnings per tensor. Opt out with options(diffuseR.pin_staging = FALSE).
• Video decode runs untiled when the estimated activation cost fits the card: in-render decode 12.3 s -> ~1.8 s.
• Attention uses R torch fused scaled-dot-product attention when available; the chunked implementation remains the fallback.

Chained video generation

• txt2vid_ltx2() gains condition_latents= (an already-encoded conditioning prefix, bypassing the VAE), connector_embeds= (precomputed text-connector outputs — the prompt is constant across a chained track, and skipping the per-call connectors phase cuts the denoise peak by ~2.5 GiB), resident= (keep components on the compute device across back-to-back calls, with an idempotent onload), and trim_frames=. Results carry latent_shape; ltx23_tail_latents() slices a result’s trailing latent frames into condition_latents form.

Gemma3 text encoder

• gemma3_quantize_nf4() + load_gemma3_nf4(): the 12B encoder quantizes to a ~8 GB NF4 artifact that loads in ~12 s and encodes in ~7 s on CUDA (vs ~30 s + ~24 s for fp32 CPU) at 8 GB host RAM instead of 45. load_gemma3_text_encoder() dispatches to the artifact automatically and gains pin=: a CPU-resident encoder is page-locked once and encode_with_gemma3() swaps it to the GPU per encode (~0.3 s on, free off).
• gemma3_encode_batch(): sub-batched, disk-cached, resumable prompt encoding for episode-scale workloads.

Fixes

• Qwen3 encoder attention masks build in the query dtype, fixing the “invalid dtype for bias” error on every FLUX.2 prompt encode through fused SDPA.
• txt2vid_ltx2(decode_audio = FALSE, filename = ) no longer hands the raw audio latents to the WAV writer via partial matching.
• Generators accept a three-level verbose (“silent”, “progress”, “steps”); “progress” gives a one-line summary plus a progress bar or periodic ticks in captured logs.