Online-SDFT reports 70.28% routing accuracy and updates a LoRA adapter on the phone

I-Ju Lin and Zhang-Wei Hong published Online-SDFT, a method that keeps fine-tuning a small language model on a phone from the user’s own stream of decisions. On a synthetic notification-routing benchmark with Liquid AI’s LFM2.5-230M, the authors report 70.28% of decisions matching a hidden user preference against 52.78% for the strongest baseline they tested, and cumulative regret of 44.76 against 105.26, over 720 decisions in three paired streams. They state that this comparison ran on Apple MPS rather than on a phone, and that the confidence intervals are nominal across only three streams.

Self-distillation here means the model teaches itself. The model picks an action first, the phone later observes what happened, and the same model is then run again with that outcome added to its input. Its better-informed answer becomes the training target for the version that saw only the original context, so no second teacher model, no human label and no reward score is needed. The authors keep the 230M base frozen and train a LoRA adapter of 172,032 parameters across 48 tensors in six attention layers, with the teacher pass running with the adapter switched off so student updates cannot move the teacher.

Feeding one interaction at a time into so small an adapter makes it noisy and prone to forgetting, so the authors keep a 64-row buffer of recent lessons and sample each batch from it. Their ablation puts that buffer ahead of the exploration schedule as the load-bearing part, with accuracy dropping from 70.28% to 39.58% and regret climbing from 44.76 to 134.90 once replay is removed, while dropping exploration instead leaves accuracy at 69.44% and regret at 62.00.

The repository carries an Android proof of concept in which LFM2.5-230M decides and ONNX Runtime Training performs the adapter update on the device, with replay and checkpoints in app-private storage that survive a restart. Exporting the model still happens on a Linux host, and the deployment guide asks for Android 12 or newer on ARM64 with 12 GB of RAM at minimum, 16 GB preferred, and 8 GB of free storage, because the training graph is FP32.

The authors call that graph a correctness implementation rather than a claim of practical background training on low-memory phones, and state that they did not measure Android latency, peak memory, battery use or thermal behaviour, and that the benchmark uses synthetic streams rather than real users. The code, the Android app and a Colab notebook are on GitHub under the MIT license. No paper or preprint accompanies the release.