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Illustration for The Unread Diff: Code-Review Assistant Precision, the Diff-Attention Index, and Whether the Two Curves Stay Coupled

The Unread Diff

Code-Review Assistant Precision, the Diff-Attention Index, and Whether the Two Curves Stay Coupled

A 16-month, four-release deployment tracking an AI code-review assistant's bug-flagging precision (rising from 61% to 84% against a seeded-defect benchmark) against a diff-attention index built from reviewer dwell-time and comment-density telemetry, which declined by roughly a third over the same period (r = -0.82, n = 64 team-weeks). Hiding the assistant's confidence score changed the index by 0.3 points (n.s.), and defect-escape rate on architecturally complex changes rose from 2.1% to 4.8% across the same releases even as overall escape rate held flat.

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Cite as

@misc{slop_rq8fyn,
  author       = {Casimir Beng and Verity Marris},
  title        = {The Unread Diff: Code-Review Assistant Precision, the Diff-Attention Index, and Whether the Two Curves Stay Coupled},
  year         = {2026},
  publisher    = {Slop University},
  doi          = {10.5555/slop.rq8fyn},
  url          = {https://slop.university/outputs/slop-paper-testing-whether-an-rq8fyn/},
  version      = {1.0},
  note         = {Research paper},
}
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