[d-morrison]

Closes #1538.

Adds check-gradient-lhs, a diff-scoped, warn-by-default check for the psw gradient rule (psw#488): a line a PR adds that says "the gradient is ..." and then gives an equation with no \grad, \gradf, \gradwrt or \nabla before its first = is flagged.

• Reuses check-write-idiom's engine for the diff model (added lines only, moved lines exempt, skip-not-fall-back).
• Looks ahead up to 8 lines for a display equation after the stating sentence.
• Skips code, HTML comments, front matter and <!-- check-gradient-lhs: allow -->.
• Warns by default (fail: false), as the issue asks.
• Wired per the "Adding a new check" list: README, CLAUDE.md, website pages, dependabot, _quarto.yml, changelog fragment, and a gradient-lhs job in _selftest.yml.

Tests: 15 unit tests pass locally; the audit for versioning docs and the permissions-docs suite pass.

The wiring issue (v3 slide plus caller PRs) is filed separately.

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Generated by Claude Code

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Claude finished review — View run

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Review of PR #1652 (update): tests run, live state fetched

I installed pytest in a venv and ran check-gradient-lhs/tests and check-write-idiom/tests. 83 passed and 1 failed.

The failure is test_defaults_agree_across_script_action_and_workflow, with FileNotFoundError on .github/workflows/check-gradient-lhs.yml. That is an artifact of this review checkout, not a defect in the PR. The checkout restored .github/workflows/ from the default branch, so the PR's new workflow file isn't on disk. I read the test's regexes against the workflow text in the saved diff instead. fail defaults to false and globs defaults to '*.qmd *.md', so both match the script and action. I expect the test to pass in CI.

I fetched the PR live with gh pr view: it is OPEN, not a draft, not merged, and its head is 75a3d57666d81c1e775328bbaefd937d0e7ed80f, the commit I reviewed.

The earlier non-blocking note still stands: confirm the gha#1606 wiring issue exists.

Verdict

Ready for merge

Structured Review Data (JSON)

{
  "schema_version": "1.1",
  "reviewer": "claude",
  "commit_sha": "75a3d57666d81c1e775328bbaefd937d0e7ed80f",
  "verdict": "CLEAN",
  "findings": [],
  "detailed_assessment": "Ran the check-gradient-lhs and check-write-idiom pytest suites: 83 passed, and the one failure is a missing workflow file caused by the default-branch restore of the review checkout.",
  "holistic_assessment": "Live PR state is open on the reviewed head, wiring lists and docs are complete, permissions stay contents read, and only confirming the gha#1606 wiring issue remains."
}

Reviewed commit: 75a3d57

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💰 Cost: $0.9863 (review) — run

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