Limits and troubleshooting#

Optional backend missing

Install/build the selected Annoy or Voyager capability; do not silently reinterpret the request as exact KNN.

Unexpected imputed values

Verify feature scaling, metric, missing-value representation, neighbor count, weighting and initial strategy before tuning index search effort.

Current review caveats

The maintenance review records a broad Annoy fallback behavior that needs a clearer ownership decision and an unused module-scope pandas import. It also notes that local mirror tests for _base.py currently exercise sklearn behavior more than local ownership. Treat release claims for the experimental path separately from the stable standard imputers.