review: Shingler ranks correctness, then duplication and fewest elements; re-reviews only the new commits

[midagedev]

Tunes Shingler's instructions (Kent Beck's simple design, in this project's order). Only .github/review/reviewer.md and validator.md change. No workflow change is needed: review.yml already gives a re-review only the diff since the last reviewed head (mode=incremental).

• Priority: 1) works/tests pass, 2) no duplication and fewest elements (equal weight, MUST_FIX), 3) reveals intent. Must-fix items are listed in that order.
• Unneeded elements (dead code, a one-user abstraction, an extra flag/parameter/file) are kind B MUST_FIX, not ⚠.
• A dedup fix never adds net elements; no new helper/abstraction unless it removes more than it adds.
• Duplication, element and missing-PIN findings all go in the first full review, in one batch.
• Re-review: earlier findings plus the new commits only. No new finding on unchanged, already-reviewed code except a kind A behavior bug.
• Revert PRs and no-merge mirror PRs: correctness (kind A) only.
• Optimization headroom: a hot-path PR (kernel, decode/prefill loop, tier/offload, scheduler) gets an advisory section, at most 3 items, each mapped to an axis of docs/research/opt-axes.md with file:line and expected effect. It is never a must-fix unless the PR regresses an axis, and it adds no elements. The validator keeps only cited, axis-mapped items.
• The validator removes findings outside these scopes (reason not-to-flag).

Why: across #124–#155, most extra must-fix rounds came from new R14 findings on later rounds (#125, #135, #147), and the #139 revert and #140 mirror were blocked on duplication and pins.

Written by the bloomery AI assistant; approved by the maintainer on 2026-10-14.