# src/spectral
## Purpose
Spectral clustering using affinity matrix + Laplacian + eigendecomposition
via faer. Used by NmeScClusterer.
## Surfaces
- `spectral_cluster(embeddings, max_k) -> Vec<usize>`
## Dependencies
- `utils` — cosine_similarity
- `faer` — SVD/eigendecomposition
## Invariants
- Output labels are contiguous integers starting from 0.
## Verification
```bash
cargo test --lib spectral --features spectral
```
## Notes
- Requires `spectral` feature (pulls faer).