fix: prevent int32 overflow in box_iou

[Nikhi00718]

Summary

Fixes incorrect scalar IoU and IoS calculations for large int32 bounding boxes.

sv.box_iou now promotes box coordinates to float64 before computing areas. This prevents integer overflow and aligns its behavior with sv.box_iou_batch.

Reproduction

For two 60000 ? 60000 int32 boxes offset by 30,000 pixels, the previous scalar implementation could return an IoU greater than 1 and an IoS of 0. The corrected results are:

• IoU: 1 / 3
• IoS: 1 / 2

Changes

• Promote scalar box coordinates to float64 before overlap arithmetic.
• Add regression coverage for both IoU and IoS with large int32 inputs.
• Add an unreleased changelog entry.

Validation

• uv run pytest --cov=supervision ? 3568 passed, 20 skipped
• uv run pre-commit run --all-files ? passed
• python -m uv run pytest tests/detection/utils/test_iou_and_nms.py -q ? 212 passed

AI assistance disclosure

I identified and reproduced the issue, then used OpenAI Codex to assist with the implementation and regression-test work. I personally reviewed the resulting diff and ran the validation commands listed above to verify the fix. Any full-suite or local-environment limitations are documented in the validation section.

[CLAassistant]

All committers have signed the CLA.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 88%. Comparing base (803378d) to head (37b387b).

Additional details and impacted files

@@           Coverage Diff           @@
##           develop   #2485   +/-   ##
=======================================
  Coverage       88%     88%           
=======================================
  Files           85      85           
  Lines        12042   12048    +6     
=======================================
+ Hits         10561   10567    +6     
  Misses        1481    1481           

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[Copilot]

Pull request overview

Prevents int32 overflow in scalar box overlap calculations.

Changes:

• Promotes scalar coordinates to float64.
• Adds IoU and IoS regression tests.
• Documents the fix in the changelog.

Assessment: Code quality 4/5 · Testing 5/5 · Documentation 5/5

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 1 comment.

File	Description
src/supervision/detection/utils/iou_and_nms.py	Adds safe coordinate promotion.
tests/detection/utils/test_iou_and_nms.py	Covers large int32 boxes.
docs/changelog.md	Records the fix.

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