| --- |
| license: apache-2.0 |
| library_name: sentence-transformers |
| pipeline_tag: sentence-similarity |
| tags: |
| - sentence-transformers |
| - feature-extraction |
| - fitness |
| - retrieval |
| base_model: BAAI/bge-small-en-v1.5 |
| --- |
| |
| # CoachTwin Embedder |
|
|
| The sentence embedding model powering workout retrieval in the |
| [CoachTwin](https://huggingface.co/spaces/OrDora/coachtwin) app. It is |
| `BAAI/bge-small-en-v1.5`, chosen by evaluating three encoders on the |
| [CoachTwin Workouts](https://huggingface.co/datasets/OrDora/coachtwin-workouts) |
| dataset (10,393 workouts). |
|
|
| ## Why this model |
|
|
| Leave-one-out retrieval. *Strict* relevance requires a match on |
| both `goal` and `body_focus`; *loose* requires `body_focus`. |
|
|
| | model | params | dim | strict P@3 | loose P@3 | MRR@10 | corpus encode | |
| |---|---|---|---|---|---|---| |
| | **bge-small-en-v1.5** | 33M | 384 | 0.6687 | 0.8273 | 0.8020 | 10.4s | |
| | all-mpnet-base-v2 | 110M | 768 | 0.5047 | 0.7453 | 0.6866 | 31.2s | |
| | all-MiniLM-L6-v2 | 22M | 384 | 0.4733 | 0.6667 | 0.6686 | 7.0s | |
|
|
| Random-retrieval baseline: strict P@3 **0.0220**, loose 0.1200, MRR@10 0.0685. |
| A precision number without its baseline is not interpretable. |
|
|
| **Selected: `BAAI/bge-small-en-v1.5`** - strict P@3 0.669, about **30x random**. |
|
|
| The middle row is the interesting one: `all-mpnet-base-v2` is 3.3x the parameters, |
| 3x slower, and *scores worse*. The bigger encoder is not the better one here. |
|
|
| ## Usage |
|
|
| from sentence_transformers import SentenceTransformer |
| model = SentenceTransformer("OrDora/coachtwin-embedder") |
| emb = model.encode([text], normalize_embeddings=True) |
| |
| Documents and queries use different templates, both recorded in |
| `embedding_info.json`. This is a BGE model, so queries - not documents - take the |
| prefix `Represent this sentence for searching relevant passages: ` |
| (`needs_query_prefix: true`). |
|
|
| ## Serialization note |
|
|
| Saved in the **sentence-transformers 3.x** module format. A repo saved by 5.x fails |
| on 3.x with `No module named 'sentence_transformers.base'`, and a client with a |
| try/except fallback then silently swaps in a different encoder - no error, wrong |
| neighbours, because several candidates share 384 dimensions. |
|
|
| ## Limitations |
|
|
| Base checkpoint, **not fine-tuned**. Evaluated only on synthetic |
| English workout descriptions. Not fitness or medical advice. |
