chore(#597): replace count-based ratchet guards with AST lint + named-set allowlists (#603)

The windows-test-parity ratchet greps test source for fs.rmSync-without-
maxRetries (and six other Windows-portability anti-patterns), failing when an
integer offender COUNT exceeds a frozen baseline (rmSync: 95). A count ratchet
is a Goodhart metric: fixing one offender and adding another keeps the count
constant, so a new defect slips through green. Replace it — and every other
count ratchet in the repo — with a layered, masking-proof design.

Behavioral seam test
- tests/helpers-cleanup.test.cjs proves helpers.cleanup() carries the Windows
  EBUSY retry budget. cleanup() delegates retries to Node's fs.rmSync via
  maxRetries (it owns no loop), so the test asserts the option contract
  (recursive/force/maxRetries>0/retryDelay>0) + real-FS removal + the cwd-guard,
  rather than a loop that does not exist. The EBUSY risk is now tested ONCE at
  the helper, not approximated textually at every call site.

Write-time ESLint rule (AST-accurate, replaces the grep)
- eslint-rules/no-raw-rmsync-in-tests.cjs (error in tests/**/*.test.cjs) bans
  raw fs.rmSync, steering to cleanup(). Catches member, computed (fs['rmSync']),
  destructured and aliased forms; escape hatch is inline
  `// eslint-disable-next-line local/no-raw-rmsync-in-tests -- <reason>` only.
- Migrated 336 raw fs.rmSync teardown calls across ~116 test files to cleanup().
  ~18 genuinely load-bearing sites (mid-test SUT/fault-injection removals,
  error-swallowing or name-colliding local teardown helpers) keep the raw call
  with an inline eslint-disable + reason.

Shared anti-ratchet primitive
- scripts/lib/allowlist-ratchet.cjs:
  - assertWithinAllowlist: fails on NOVEL ids (new offender introduced) AND on
    STALE ids (a known offender was fixed but not pruned) — identity, not count,
    and a ratchet DOWN toward zero.
  - assertTightCeiling: a size/length budget whose ceiling must stay within a
    grace band of the high-water mark, so budgets may only tighten, never creep.

Ratchets converted onto the primitive
- windows-test-parity-guard.test.cjs: rmSync rule deleted (now ESLint-enforced);
  the remaining six patterns moved from integer baselines to named-set
  allowlists with ratchet-down.
- scripts/lint-test-file-count.{cjs,allowlist.json}: per-module integer counts →
  named filename sets (closes the swap-a-file-keep-the-count blind spot); a
  module dropping under cap now FAILS to force pruning its allowlist entry.
- enh-2790 skill-count `<= 63` → named skill allowlist (ratchets toward ~58).

Size budgets hardened (tighten-only)
- agent-size / workflow-size / feat-3039 help-tiered: ceilings lowered to the
  current high-water mark and an assertTightCeiling anti-creep check added per
  tier. Fixed external-contract limits (description ≤100 chars, agent ≤100 KB)
  are intentionally left as-is — they are not grandfathered creeping budgets.

No user-facing behavior change (tests + tooling only); no USER_FACING_PREFIXES
touched, so no changeset fragment is required.

Co-authored-by: Claude Opus 4.8 <noreply@anthropic.com>

tests/affected-tests-lib.test.cjs

@@ -18,6 +18,8 @@ const {
   resolveRelativeDependency,
 } = require('../scripts/affected-tests-lib.cjs');
 
+const { cleanup } = require('./helpers.cjs');
+
 // ---------------------------------------------------------------------------
 // Helpers
 // ---------------------------------------------------------------------------
@@ -188,7 +190,7 @@ test('transitive: changing a deep dependency selects the test that depends on it
     'get-shit-done/bin/lib/depA.cjs': `'use strict';\nconst depB = require('./depB.cjs');\nmodule.exports = { a: depB };\n`,
     'tests/t.test.cjs': `'use strict';\nconst depA = require('../get-shit-done/bin/lib/depA.cjs');\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   const reverseIndex = buildTransitiveReverseIndex(dir, ['tests/t.test.cjs']);
   const selected = pickAffectedTests(
@@ -213,7 +215,7 @@ test('adversarial(a): cycle depA<->depB — changing depA selects test, no hang'
     'get-shit-done/bin/lib/depB.cjs': `'use strict';\nconst depA = require('./depA.cjs');\nmodule.exports = {};\n`,
     'tests/cycle.test.cjs': `'use strict';\nconst depA = require('../get-shit-done/bin/lib/depA.cjs');\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   // Must complete without hanging
   const reverseIndex = buildTransitiveReverseIndex(dir, ['tests/cycle.test.cjs']);
@@ -234,7 +236,7 @@ test('adversarial(b): missing require (gone file) — null resolve, no crash', (
     // Requires a file that does not exist
     'tests/missing.test.cjs': `'use strict';\nconst x = require('../get-shit-done/bin/lib/gone.cjs');\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   // Should not throw
   let reverseIndex;
@@ -258,7 +260,7 @@ test('adversarial(c): .json dependency — changing data.json selects the test',
     'get-shit-done/bin/lib/data.json': `{"key":"value"}`,
     'tests/json.test.cjs': `'use strict';\nconst data = require('../get-shit-done/bin/lib/data.json');\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   const reverseIndex = buildTransitiveReverseIndex(dir, ['tests/json.test.cjs']);
   const selected = pickAffectedTests(
@@ -279,7 +281,7 @@ test('adversarial(d): re-export chain — changing depB selects the test that re
     'get-shit-done/bin/lib/reexporter.cjs': `'use strict';\nmodule.exports = require('./depB.cjs');\n`,
     'tests/reexport.test.cjs': `'use strict';\nconst x = require('../get-shit-done/bin/lib/reexporter.cjs');\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   const reverseIndex = buildTransitiveReverseIndex(dir, ['tests/reexport.test.cjs']);
   const selected = pickAffectedTests(
@@ -313,7 +315,7 @@ test('adversarial(f): WIDEN — changing a src file with no test dependents wide
     'get-shit-done/bin/lib/orphan.cjs': `'use strict';\nmodule.exports = {};\n`,
     'tests/unrelated.test.cjs': `'use strict';\n// requires nothing\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   const reverseIndex = buildTransitiveReverseIndex(dir, ['tests/unrelated.test.cjs']);
 
@@ -345,7 +347,7 @@ test('adversarial(g): dynamic require in changed file with no static dependents
     'get-shit-done/bin/lib/dynamic.cjs': `'use strict';\nconst x = 'foo';\nconst m = require(\`./\${x}\`);\nmodule.exports = {};\n`,
     'tests/unrelated.test.cjs': `'use strict';\n// does not require dynamic.cjs\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   const reverseIndex = buildTransitiveReverseIndex(dir, ['tests/unrelated.test.cjs']);
 
@@ -367,7 +369,7 @@ test('resolveRelativeDependency resolves .ts, .json extensions', (t) => {
     'src/helper.ts': `export const x = 1;\n`,
     'src/data.json': `{"k":1}`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   const fromAbs = path.join(dir, 'tests/consumer.cjs');
 
@@ -444,7 +446,7 @@ test('regression(mixed-diff): widen plan covers integration suite; concrete matc
     'tests/server.integration.test.cjs': `'use strict';\nconst s = require('../bin/lib/server.cjs');\n`,
     'tests/unrelated.test.cjs': `'use strict';\n// requires nothing\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   // Act: build graph over both test files
   const allTests = [
@@ -532,7 +534,7 @@ test('regression(delete-only-source): deleting a source file triggers widen, nev
     'get-shit-done/bin/lib/other.cjs': `'use strict';\nmodule.exports = {};\n`,
     'tests/unrelated.test.cjs': `'use strict';\n// requires nothing from gone.cjs\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   // Act
   const allTests = ['tests/unrelated.test.cjs'];
@@ -592,7 +594,7 @@ test('regression(rename-stale-old-path): deleted old path triggers widen, protec
     'tests/newname.test.cjs': `'use strict';\nconst x = require('../get-shit-done/bin/lib/newname.cjs');\n`,
     'tests/unrelated.test.cjs': `'use strict';\n// no dependency on oldname or newname\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   // Act
   const allTests = ['tests/newname.test.cjs', 'tests/unrelated.test.cjs'];
@@ -646,7 +648,7 @@ test('regression(delete-only-test): deleting a test file does not trigger widen
   const dir = makeFixture({
     'tests/surviving.test.cjs': `'use strict';\n// a plain surviving unit test\n`,
   });
-  t.after(() => fs.rmSync(dir, { recursive: true, force: true }));
+  t.after(() => cleanup(dir));
 
   // Act
   // allTests comes from the fixture's tests/ directory — gone.test.cjs is absent.