DLFM BlockTune โ€” research preview

DLFM ยท BlockTune

Diffusion LFM2.5 ยท 24B-A2B ยท Merged BF16

Block prediction, measured end to end.

Status License Weights Architecture Temperature

Quick start ยท Results ยท Research report ยท ๆ—ฅๆœฌ่ชž


License โ€” LFM Open License v1.0

This model is derived from LiquidAI's LFM2.5-24B-A2B and remains subject to the LFM Open License v1.0, licensed by Liquid AI, Inc. The complete, unmodified upstream license text is included as LICENSE and licenses/LFM-Open-License-v1.0.txt.

The license contains a commercial-use revenue threshold defined as US$10,000,000 annual revenue or more; Section 5 sets out the commercial-use limitation and the qualified non-profit exception. Read the original terms for the operative conditions. Redistribution must retain the license and applicable notices and identify modified files. See NOTICE for this release's modifications and license-notice.txt for retained model/data attribution.

LFM Open License v1.0 is not an Apache-2.0 or MIT license. This derivative does not replace it or grant rights beyond applicable upstream model and data terms.

A research checkpointโ€”with the evidence attached

DLFM ยท BlockTune is an experimental block-diffusion derivative of summerAIO/diffusion-lfm2.5-24b-a2b. It incorporates the final rank-8 attention LoRA from a short adaptation study, then packages the resulting weights as a complete, sharded BF16 checkpoint. No separate LoRA application or base-model download is required once this repository is downloaded.

The release includes the diffusion sampler, batched best-of-N selection, repetition controls, reproducible configuration, and both positive and negative results.

Research previewโ€”not a production-quality coding model. BF16 merging did not meet the predeclared prediction-equivalence tolerance. The fastest decoding setting produces mostly incorrect answers. No tested configuration combined the quality gate with 1,000 returned token/s. Full-checkpoint byte/structure checks are documented separately from model-loading tests; a fresh end-to-end reload of this assembled full checkpoint has not been run.

At a glance

Component Release
Backbone LFM2.5-24B-A2B-derived hybrid convolution / attention MoE
Stored precision BF16 weights; inherited FP32 buffers preserved
Adaptation Rank 8, alpha 16, q/k/v/out projections in all 10 attention layers
Runtime Explicit block-diffusion sampler; causal prefix, bidirectional canvas
Evaluated hardware H100 80GB for adaptation; A100 80GB for decoding
Tested temperature 0.9
Weight format 13 Safetensors shards, approximately 47.94 GB
Recommended status Experimental; no quality-approved throughput preset

Quick start

Use an 80GB-class CUDA GPU for the demonstrated BF16 setup. Download this repository, then run the included inference script from its folder:

hf download summerAIO/diffusion-lfm2.5-24b-a2b-blocktune \
  --local-dir ./dlfm-blocktune

Inside dlfm-blocktune:

uv run --python 3.11 --locked python inference.py \
  --model . \
  --preset balanced \
  --prompt "Write only Python code defining add(a,b) that returns their sum. No explanation."

The balanced preset uses block32 / 16 steps / top-k20 / best-of4 at temperature0.9. It selects candidates using syntax, the function name requested in the prompt, model likelihood and repetitionโ€”not reference answers or hidden tests. Optional code-prefix extraction is enabled by default. This was the best observed speed/accuracy compromise among the completed small-task comparisons, but it did not pass the overall quality gate.

Throughput diagnosticโ€”not a quality recommendation:

uv run --python 3.11 --locked python inference.py \
  --model . --preset throughput --seed 900 \
  --prompt "Explain masked diffusion text generation and autoregressive text generation in detail. Write a coherent essay of at least 1000 words comparing their operation, advantages, and limitations."

This preset uses block1024 / 1 step / top-k50. It prints the output to stdout and the actual output length, elapsed time and throughput to stderr.

Python API

from inference import load_model
from selection_runtime import cfg, generate_selected

sampler, tokenizer = load_model(".")
settings = cfg(block=32, steps=16, best_of=4, top_k=20, repair=True)
text, metrics = generate_selected(
    sampler, tokenizer,
    "Write only Python code defining square(x) that returns x*x. No explanation.",
    settings, seed=2201,
)
print(text)
print(metrics)

The native Transformers model can load the weights, but its ordinary model.generate() is autoregressive. Use inference.py for the block-diffusion path measured in this report. The loader deliberately avoids the upstream custom AutoModel mapping and does not enable the numerically unverified prefix cache.

What the experiments show

1 ยท Adaptation improved a narrow block-prediction metric

On 32 held-out Python-code blocks, with 128 context tokens and a fully masked 64-token target, single-forward token accuracy increased from 6.15% to 8.69% after adaptation. Entire-block exact match stayed at 0/32.

These are pre-merge adapter-path results, not a claim that the assembled BF16 checkpoint reproduces that accuracy. The test set was reused across exploratory stages; near-duplicate contamination and prior training exposure were not ruled out.

2 ยท More candidate tokens do not mean faster useful answers

All rows below use temperature0.9. Task correctness is a small suite of 6 English fact/code tasks ร— 3 seeds; speed is measured separately on a long-form prompt.

Decoding setting Returned token/s, median Task correctness
block1024 / 1 step / top-k50 8,623.29 1/18 ยท 5.6%
Same block/steps + 32-token-window bigram ban, controlled sampler 3,771.05 0/18 ยท 0%
block32 / 16 steps / best-of4 / top-k20 17.89 13/18 ยท 72.2%
Same quality-oriented setting, best-of16 13.24 13/18 ยท 72.2%
Same quality-oriented setting, best-of64 4.52 13/18 ยท 72.2%
Same quality-oriented setting, best-of256 1.33 13/18 ยท 72.2%

Read the speed column carefully. Timings are CUDA-synchronized and count actual tokens emitted before EOS. Output lengths differ. Best-of-N timings include candidate generation, rejection sampling, ranking and post-processing. Discarded candidates are not counted as returned tokens. The controlled sampler has additional CPU work and a slightly different candidate distribution; its slowdown is not an isolated estimate of repetition-control cost.

The 8,623 token/s figure is a throughput result with poor correctnessโ€”not a claim of useful coding output at that speed. High distinct-n-gram rates can simply reflect random, incoherent text.

3 ยท The merge has a known numerical discrepancy

The measured BF16 merge had top-1 agreement of 82.81โ€“96.88% across four probes, below the fixed 98% per-probe acceptance threshold. Maximum absolute logit deviation reached 2.5996. Saved merged weights reload byte-exactly, but that is a different check from agreement with the unmerged LoRA computation.

See merge_validation.json and the full report.

Repetition controls and best-of-N

uv run --python 3.11 --locked python inference.py \
  --model . --preset balanced \
  --block 32 --steps 16 --best-of 4 --top-k 20 \
  --window 128 --ngram 3 --penalty 1.1 \
  --prompt "Write only Python code defining reverse(xs) returning the list in reverse order. No explanation."

This is a custom-control example, not the measured best preset. Stronger penalties and harder bans were not consistently better. Constraints inspect resolved, contiguous left context; with multiple diffusion steps, they do not guarantee a globally repetition-free completed canvas across previously masked gaps.

For the balanced preset, --long continues selected blocks up to max(1024, block) tokens, respecting EOS. --max-new-tokens controls the throughput preset. The sampler is fixed at temperature0.9 to match the experiments.

Release contents

model-00001-of-00013.safetensors ... model-00013-of-00013.safetensors
model.safetensors.index.json     # complete checkpoint index
config.json + tokenizer files
diffusion.safetensors            # learned mask embedding
inference.py                    # full-checkpoint loader and CLI
diffusion_runtime.py             # evaluated reference sampler
selection_runtime.py             # window constraints and best-of-N
REPORT.md                       # consolidated research report
reports/                        # detailed reports and raw measurements
release_manifest.json           # source/output hashes and replaced tensor names
merge_validation.json           # pre/post merge checks
adapter_reference.safetensors   # provenance/reproduction only; already merged
licenses/ + license-notice.txt

Do not apply adapter_reference.safetensors again to these already-merged weights. It is included only to preserve the adaptation provenance.

Provenance and licensing

This release does not grant unrestricted commercial rights or replace upstream model/data terms. The additional dataset card did not specify a license in the metadata inspected during preparation; review the relevant source terms.

ๆ—ฅๆœฌ่ชžใ‚ตใƒžใƒช

ใƒฉใ‚คใ‚ปใƒณใ‚นใฏLiquid AI, Inc.ใฎLFM Open License v1.0ใงใ™ใ€‚ ๅŽŸๆ–‡ๅ…จๆ–‡ใ‚’ LICENSEใซๅŒๆขฑใ—ใ€ๅนดๅ•†ๅŸบๆบ–ใซ้–ขใ™ใ‚‹ๅ•†็”จๅˆฉ็”จๆกไปถใ€ๅ†้…ๅธƒใƒปๅค‰ๆ›ด่กจ็คบๆกไปถใ‚’ ๅŽŸๆ–‡ใฉใŠใ‚Š้ฉ็”จใ—ใพใ™ใ€‚่ฟฝๅŠ ๅญฆ็ฟ’ใ‚„ใƒžใƒผใ‚ธใซใ‚ˆใฃใฆๅˆฅใƒฉใ‚คใ‚ปใƒณใ‚นใธ็ฝฎใๆ›ใˆใฆใ„ใพใ›ใ‚“ใ€‚

ๆœ€็ต‚LoRAใ‚’็ตฑๅˆใ—ใŸใ€ใƒ•ใƒซ้‡ใฟไป˜ใใฎ็ ”็ฉถ็”จใƒใ‚งใƒƒใ‚ฏใƒใ‚คใƒณใƒˆใงใ™ใ€‚ READMEใƒปๆŽจ่ซ–ใ‚ณใƒผใƒ‰ใƒปๅญฆ็ฟ’ใจ้€ŸๅบฆๆŽข็ดขใฎใƒฌใƒใƒผใƒˆใƒป็”Ÿใฎ่ฉ•ไพกใƒ‡ใƒผใ‚ฟใ‚’ๅŒๆขฑใ—ใฆใ„ใพใ™ใ€‚

  • ่ฟฝๅŠ ๅญฆ็ฟ’ใงblockๅ†…tokenๆญฃ่งฃ็އใฏ6.15%โ†’8.69%ใซๆ”นๅ–„ใ€‚ใŸใ ใ—ใ“ใฎๆ•ฐๅ€คใฏใƒžใƒผใ‚ธๅ‰ใฎ่ฉ•ไพกใงใ™ใ€‚
  • ้€Ÿๅบฆๅ„ชๅ…ˆ่จญๅฎšใฏ8,623 token/sใงใ™ใŒใ€่ชฒ้กŒๆญฃ่งฃ็އใฏ1/18ใ€‚้ซ˜ๅ“่ณชใช็”Ÿๆˆ้€Ÿๅบฆใ‚’ๆ„ๅ‘ณใ—ใพใ›ใ‚“ใ€‚
  • ๅ“่ณชๅฏ„ใ‚Šใฎๆšซๅฎš่จญๅฎšใฏblock32ใƒป16stepใƒปtop-k20ใƒปbest-of4ใ€‚13/18ๆญฃ่งฃใ€่ฟ”ๅด้€Ÿๅบฆ17.89 token/sใงใ—ใŸใ€‚
  • 16ใ€œ256ๅ€™่ฃœใธๅข—ใ‚„ใ—ใฆใ‚‚ๅŒใ˜่จญๅฎšใฎๆญฃ่งฃ็އใฏไผธใณใพใ›ใ‚“ใงใ—ใŸใ€‚
  • ใƒžใƒผใ‚ธๅ‰ๅพŒใฎๆ•ฐๅ€คๅŒ็ญ‰ๆ€งใฏๆœช้”ใ€‚ๅ“่ณชใจ1000 token/sใฎไธก็ซ‹ใ‚‚ๆœช้”ใงใ™ใ€‚

่ฉณใ—ใใฏ็ทๅˆใƒฌใƒใƒผใƒˆใ€ๅญฆ็ฟ’ใƒฌใƒใƒผใƒˆใ€ A100ๆŽข็ดขใƒฌใƒใƒผใƒˆใ‚’ใ”่ฆงใใ ใ•ใ„ใ€‚

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