We Taught a 230M Language Model to Keep Learning on Android

Small language models can now run directly on phones. But most of them stop learning the moment they ship. For personal AI, that feels like a strange stopping point. Some of the most useful signals arrive only after the model acts: Did the user dismiss the notification? Did they open it later? Did they rewrite the suggestion? Did they ask for it again? These interactions contain useful information about the user, but they are delayed, private, and ambiguous. They are not clean labels, and they are not reliable scalar rewards. To explore this problem, we built Online-SDFT , an open-source prototype that continually fine-tunes a small language model from delayed interactions while keeping the learning loop on the device. The prototype uses: LiquidAI/LFM2.5-230M A rank-4 LoRA adapter ONNX Runtime Training A bounded on-device replay buffer An Android notification-routing testbed Once the model has been provisioned, inference, interaction storage, replay, and adapter updates all happen locally. Why standard fine-tuning is awkward here Suppose the model receives a notification and chooses one of three actions: Show it now Save it for later Archive it Supervised fine-tuning would require a correct action for every notification. But the phone never observes what the ideal action was. Reinforcement learning replaces the correct answer with a reward, but that reward is also difficult to define. Opening a notification does not necessarily mean it arrived at the right time. Ignoring it does not necessarily mean it was unimportant. The user may simply have been busy. There is another complication: the model only observes the result of the action it actually took. If it archives a notification, it cannot know what would have happened had it shown the notification immediately. What the phone receives is not a label or reward. It receives hindsight . Using the same model as student and teacher The core idea is simple: let the model reconsider its decision after seeing what happened