Route OSS patch reviews by diff blast radius before spending model calls

The article argues that patches should receive review effort proportional to measurable diff properties rather than reviewer intuition. It proposes a deterministic router that reads git diff --numstat against a pinned base and assigns a review tier without making any model calls. Tiers are driven by signals such as protected paths, build-file changes, the presence of tests, and the total number of changed lines. Each tier carries a checklist of evidence that must exist before a patch counts as reviewed. The router is a standard-library Python script that judges no correctness and answers only which review depth is warranted.