Fix reranked scores not matching reranked document order in HFCrossEncoderReranker

[adityaanikam]

Fixes #693.

HFCrossEncoderReranker.rank() sorted docs_with_scores by score to build reranked_docs, but then took scores from the original unsorted scores list instead of from the same sorted sequence. So reranked_docs[i] and scores[i] didn't correspond to the same document once the reranking actually changed the order. arank() delegates to rank(), so this fixes both.

Added a regression test that asserts the returned scores are sorted descending, matching the returned docs. Confirmed it fails with the old code (scores come back in the original order, not sorted) and passes with the fix, using a real cross-encoder model against the exact reproduction from the issue.

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Note

Low Risk
Small, localized bugfix in reranker output pairing with a regression test; no auth, data, or API contract changes beyond correcting score alignment.

Overview
Fixes misaligned scores in HFCrossEncoderReranker.rank() when reranking changes document order (#693).

After sorting (doc, score) pairs by score, the method now builds both reranked_docs and the returned scores from that same sorted slice. Previously it sliced the sorted docs but still returned scores from the original prediction order, so index i in docs and scores could refer to different hits.

Adds an integration regression test that checks returned scores are in descending order when return_score is true (the failure mode from the old code).

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[vishal-bala]

Thanks for the fix! Just one very minor optimization and I think we're good to go

[cursor]

Cursor Bugbot has reviewed your changes using high effort and found 1 potential issue.

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[vishal-bala]

Hi, this looks good! You just need to rebase onto origin/main to pull in some CD/CD-related fixes we made recently.

[adityaanikam]

Hi, this looks good! You just need to rebase onto origin/main to pull in some CD/CD-related fixes we made recently.

done