[anth-volk]

Fixes #4053

Top pull request of a stack of five, on #4061. Only the bottom pull request of a stack runs full CI; CI complete fails here by design.

Update, 2026-10-27: metric tier

Anthony decided today to register api.quality.file-length in the metric tier instead of mechanical: the rule fails when a file's line count crosses a threshold, which is what docs/engineering/skills/rules-registry.md calls the metric tier. The second commit:

• sets tier = "metric";
• gives [rule.proof] the metric fields in place of bad_fixture and good_fixture: below_fixture (good_tree.toml, every file exactly at its limit), above_fixture (bad_tree.toml, every file one line over), threshold = 800 and the same test. threshold holds one number, so it names the 800-line source-file limit; the same fixtures also cover the 1,500-line limit for test code. The fixtures and the proof test are unchanged;
• regenerates docs/generated/rules.md (the rule moves from the mechanical row to the metric row) and updates the changelog fragment.

Against origin/file-length-cloud-run-deploy-tests, python -m scripts.rules guard passes, so the metric proof fields validate. The file-length guard and test_repository_has_no_violations fail there only because master has the 805-line policyengine_api/services/report_output_service.py, which #4066 splits. With #4066 merged in, every quality guard and all 142 rules-tool tests pass.

What this changes

#4056, #4059 and #4061 split the five files that were over their limit, so rules/baselines/file-length.txt lists nothing. This pull request makes api.quality.file-length enforced without it:

• rules/registry.toml: status goes from ratcheted to enforced; the [rule.baseline] table (count = 0) and the comment recording the ratcheted start are removed. The rule never had a [rule.downgrade] record: the rules tool requires one only when a rule moves to advisory or doc-only, so there is none to remove. The Alembic revision exception stays.
• rules/baselines/file-length.txt: deleted.
• docs/engineering/skills/file-length.md: the baseline section now says the rule is enforced and has no baseline.
• docs/generated/rules.md and the Rules block in AGENTS.md: regenerated. The rule moves from the ratcheted list to the enforced rules.
• changelog.d/file-length-enforce.changed.md.

The file-length guard needs no change: with no [rule.baseline] it tolerates no file, so any tracked Python file over its limit fails it. Its tests already cover a registry without a baseline (test_unlisted_oversized_file_fails).

Testing

• python scripts/run_quality_guards.py: all guards pass, including file-length. With an 801-line module staged temporarily, file-length failed and named it: policyengine_api/file_length_probe.py has 801 lines, over the 800-line limit for source files.
• python -m scripts.rules guard --base-ref file-length-cloud-run-deploy-tests: pass (moving from ratcheted to enforced needs no downgrade reason); python -m scripts.rules render: no changes after regenerating; python -m unittest discover -s scripts/rules/tests -t .: 142 pass, including the 10 file-length tests.
• ruff format --check ., ruff check .: pass.
• uv lock --check: pass.
• pytest tests/unit/test_ci_complete_gate.py tests/unit/test_locked_test_environments.py tests/unit/test_alembic_skill.py: 28 passed. No Python code changes here; the make test paths passed (3,445) on Split the Cloud Run deployment script tests under the file-length limit #4061.
• # noqa comments: 94 before and after; type: ignore/pyright: ignore: 9 before and after.

Environment variables

None. No workflow, image or deployment file changed.

🤖 Generated with Claude Code

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 87.83%. Comparing base (2bce077) to head (4963752).
⚠️ Report is 4 commits behind head on master.

Additional details and impacted files

@@             Coverage Diff             @@
##           master    #4062       +/-   ##
===========================================
+ Coverage   50.75%   87.83%   +37.08%     
===========================================
  Files         254      270       +16     
  Lines       14634    16057     +1423     
  Branches     2339     2626      +287     
===========================================
+ Hits         7427    14104     +6677     
+ Misses       6580     1284     -5296     
- Partials      627      669       +42     

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