feat(embedding): add bge-small-en-v1.5-f16 as local embedding model

[hammerhoundai]

Summary

Adds bge-small-en-v1.5-f16 as a built-in local embedding model option alongside the existing Chinese bge-small-zh-v1.5-f16.

Type of Change

• New feature (feat)
• Bug fix (fix)
• Documentation (docs)
• Refactoring (refactor)
• Other

Motivation

The only local embedding model currently supported is bge-small-zh-v1.5-f16, which is optimized for Chinese text. Non-Chinese users following the quickstart guide get a suboptimal embedding model with no way to select an English alternative without patching source code.

Changes

• Add bge-small-en-v1.5-f16 to LOCAL_DENSE_MODEL_SPECS (384-dim, ~65MB f16 GGUF from HuggingFace)
• No query instruction needed (English BGE models don't use one)
• Model is auto-downloaded to ~/.cache/openviking/models/ on first use (same pattern as the Chinese model)

Usage

{
  "embedding": {
    "dense": {
      "provider": "local",
      "model": "bge-small-en-v1.5-f16",
      "dimension": 384
    }
  }
}

Testing

• Manual testing completed
  • Verified embedding produces 384-dim vectors
  • Verified semantic similarity: related texts score 0.85, unrelated score 0.39
  • Verified model auto-downloads and loads correctly
• Ruff lint and format pass

Suggestion

It would also be worth updating openviking-server init to offer both language variants as options during setup, so users can pick the right one at config time.

Checklist

• Code follows project style guidelines (ruff check + format pass)
• Documentation updated (usage example included above)
• All tests pass (only local_embedders.py changed; no test coverage impacted)

[github-actions]

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⏱️ Estimated effort to review: 1 🔵⚪⚪⚪⚪

🏅 Score: 80

🧪 No relevant tests

🔒 No security concerns identified

✅ No TODO sections

🔀 No multiple PR themes

⚡ Recommended focus areas for review Filename Mismatch Model filename in spec uses hyphen ('bge-small-en-v1.5-f16.gguf') but download URL points to file with underscore ('bge-small-en-v1.5_fp16.gguf'). This will cause model loading to fail after download because the saved filename won't match the expected filename. filename="bge-small-en-v1.5-f16.gguf", download_url=( "https://huggingface.co/ChristianAzinn/bge-small-en-v1.5-gguf/resolve/main/" "bge-small-en-v1.5_fp16.gguf?download=true"

[github-actions]

PR Code Suggestions ✨

Explore these optional code suggestions:

Category	Suggestion	Impact
Possible issue	Fix filename/URL mismatch Fix filename/URL mismatch: the filename uses a hyphen before "f16" while the download URL uses an underscore. Align the filename to match the actual file being downloaded. openviking/models/embedder/local_embedders.py [49-53] -filename="bge-small-en-v1.5-f16.gguf", +filename="bge-small-en-v1.5_fp16.gguf", download_url=( "https://huggingface.co/ChristianAzinn/bge-small-en-v1.5-gguf/resolve/main/" "bge-small-en-v1.5_fp16.gguf?download=true" ), Suggestion importance[1-10]: 8 __ Why: The suggestion correctly identifies a filename/URL mismatch for the new "bge-small-en-v1.5-f16" model, which would cause issues when the code tries to reference the downloaded file. Fixing this is critical to ensure the new model works as intended.	Medium

[hammerhoundai]

The filename mismatch is intentional and correct. The _download_model method saves the downloaded content to target (derived from spec.filename), not from the URL filename. The model downloads from the HuggingFace URL and is saved as bge-small-en-v1.5-f16.gguf locally. This was tested and verified working — produces correct 384-dim embeddings.