---
license: apache-2.0
base_model: Qwen/Qwen3-Embedding-0.6B
base_model_relation: adapter
pipeline_tag: text-classification
tags:
  - text-classification
  - embeddings
  - lora
  - prototype-network
  - example
---

# example-repro — jev-topic-head training, reproduced from the public spec

A self-contained reimplementation of the training described in
`../jev-topic-head/README.md` (the scaffold), written **without the original code**:
Qwen3-Embedding-0.6B + LoRA(r16) + prototype head (56 anchors + learned scale),
on 279/85/105-item synthetic data matching the real split structure.

**This validates the pipeline, not the numbers.** The real labels live in the private
`Kodep/jev-topic-data` (school-email text, not pushed yet). When they land, point
`config.yaml: data.dir` at them and rerun; everything else stays.

## Try it (no training needed)
The repo ships the seed-0 weights — everything we created, nothing we didn't:
```
weights/seed0/lora/adapter_model.safetensors   ~39 MB   10.1M LoRA params (fixes the encoder)
weights/seed0/lora/adapter_config.json                    how to stack the adapter (r, targets, base)
weights/seed0/head/head.pt                     ~230 KB  56 prototype vectors + scale (the head)
```
The **base model is intentionally not here** — `Qwen/Qwen3-Embedding-0.6B` is public;
`from_pretrained` fetches it from huggingface.co on first load. Ship the delta, not the pantry.

```bash
hf download Kodep/jev-topic-head-example --local-dir .
pip install torch transformers peft        # plus internet for the one-time base download
python predict.py --weights weights/seed0 "Soccer practice moved to the north field"
# {"topic": "soccer", "confidence": 0.96, "top3": [...]}
```
Reminder: these weights trained on synthetic data — a working demo, not the real classifier.

## Files
| file | what |
|---|---|
| `config.yaml` | every hyperparameter from the spec checklist |
| `make_toy_data.py` | synthetic 56-topic dataset (same shapes/skew/14-unseen-topics/hard-pairs) |
| `train_head.py` | the training loop: seed protos from descriptions, LoRA, 2 AdamW groups, warmup→decay, 1/√count sampler, early stop on val macro-F1 |
| `evaluate.py` | per-item dump + top-1/macro-F1/confidence buckets (eval/ schema) |
| `predict.py` | inference with the shipped seed-0 weights (no training stack needed) |

## Run (on Sunny, 4090)
```bash
cd ~/jev-example
.venv/bin/python make_toy_data.py
.venv/bin/python train_head.py --config config.yaml --seed 0   # downloads base model once
.venv/bin/python evaluate.py --config config.yaml --run runs/seed0
```

## Spec fidelity notes
- Implemented from the checklist: r16/α32/dropout 0.05 on q/k/v/o + gate/up/down;
  protos seeded from description embeddings; scale init 20; CE + label smoothing 0.05;
  lora 3e-4 wd .01 / head 2e-3 no wd; warmup 10% → linear decay to 5%; batch 16;
  ≤12 epochs; early stop on val macro-F1 (patience 3); sampler 1/√count × hard-pair 2.
- Inferences the spec left open, marked in code: **last-token pooling** (official
  Qwen3-Embedding recipe), **bf16 = bf16 base weights + fp32 head**.
- Show/hide rules (`rules_table.json`) are not modeled — they're a fixed downstream
  table, not part of the head.

## Results (synthetic data, 4090, 2026-10-04)
- Trainable: **10,092,544 LoRA + 57,345 head params** (1.67% of 605.9M) — matches the
  spec's shape: head = 56×1024 + 1 exactly.
- Early stop at epoch 4 (patience 3); best val macro-F1 0.949 (seed 0).
- Test vs labels, identical across seeds 0/1/2: **top-1 0.971, macro-F1 0.956**;
  78/105 items ≥0.9 confidence; **zero errors above 0.9 confidence** — the same
  "errors live in the low-confidence bucket" pattern the real report claims.
- These numbers validate plumbing only: synthetic labels are clean, the real ones are
  Jev's noisy silver answers (real span: macro-F1 0.49–0.59).

## Status
Code path fully exercised end-to-end (3 seeds + evals, artifacts in `results/`).
Awaiting the real `Kodep/jev-topic-data` push → set `config.yaml: data.dir` to it and
rerun unchanged to attempt the actual 92/105 · 0.572 · 90.5% numbers.