A base model is a broad textbook. Fine-tuning adds a narrow set of reliable notes in the margins. LoRA (Low-Rank Adaptation) makes that practical by training a small adapter instead of changing every model weight.
What you will learn
- Why prompting, RAG, and fine-tuning solve different problems
- How a JSONL training example pairs an instruction with a desired answer
- What an adapter is and why it is much smaller than the base model
- How training loss is a useful signal—but not proof of intelligence
Train a tiny adapter
This is an honest educational simulation of the fine-tuning loop. It runs instantly in the browser so testers do not need a 4B model. The companion Mac run will use the real Qwen3/MLX pipeline later.
1. Build training examples
2. Run the adapter training
The simulated run updates the adapter signal across 60 iterations. Watch the loss fall, then compare the base and adapted answers.
3. Compare the behavior
No adapter has been trained yet.
Checkpoint
Which change is the best fit for fine-tuning?
What does LoRA usually train?