[quality] getArgumentLabels and anyLabelMatches have no production caller — only their unit tests keep them covered #366

Finding

Two exported helpers in src/utils/ have no production caller. The only code that invokes them is their own unit test, so they count toward the 100 % unit line coverage on main @ 3fc21f2 while nothing the action ships ever runs them:

Evidence:

• grep -rn "getArgumentLabels\|anyLabelMatches" src/ → only the two definitions.
• git log -S"getArgumentLabels(" -- src → 78b07b0 deletes the import and call in prefixed.ts and keeps the export; git log -S"anyLabelMatches" -- src __tests__ → a single commit, f5d7bc3, introducing export and test together.
• npm run test:coverage:e2e on a scratch branch = origin/main (3fc21f2) + the heads of all 44 open hold-gated bundle PRs (chore(coverage): emit lcovonly and json-summary reporters from vitest.config.mjs #230…test(bundle): drive the OWNERS filters-ignored arm (owners.ts parseOwners) through dist/index.js #365, 48 files / 430 tests pass): 96.4 % statements; both functions have 0 hits (labeling.ts 52–59, labelMatch.ts 47 remain uncovered). Every other residual line in that run is a defensive throw on a malformed payload, a test-only reset*Cache() export, or already claimed by one of those PRs.
• Both still ship: grep -n "getArgumentLabels\|anyLabelMatches" dist/index.js → dist/index.js:41388, dist/index.js:43239 (ncc does not tree-shake them).

Why it matters for the test suite rather than just tidiness: the unit report cannot distinguish "covered because it runs in the bundle" from "covered because a test calls it", so these two keep a green line over code that would silently rot — getArgumentLabels still throws the pre-#137 yaml malformed, expected '<arg>' top level key message that no user can reach.

Recommendation

One PR, one deliverable (deleting both exports and their test blocks is a single mechanical change; npm run pack to drop them from dist/):

• remove getArgumentLabels from src/utils/labeling.ts and its describe block in __tests__/utils/labeling.test.ts
• remove anyLabelMatches from src/utils/labelMatch.ts and its tests in __tests__/utils/labelMatch.test.ts (or wire it into matchesAnyLabel-style call sites if a consumer was intended in feat!: do-not-merge/* label family; /hold applies do-not-merge/hold; configurable merge gate #154)
• npm run build && npm run pack so the dist/ drift gate passes

This touches production source, so it is not a PR this lane opens; it is filed for a maintainer. Related, but deliberately not in this issue because it is a design choice rather than dead code: repoHasOwners/defaultBranch (src/utils/owners.ts:282-284, 348-359) are reachable only when a pull_request payload lacks base.ref (approve.ts:504, tide.ts:543), so they too have 0 e2e hits.

Priority

• Impact: low
• Effort: low

🐝 Hive Agent: quality | Instance: hosted-available-lke648397-260827-5q9t | SHA: 3fc21f2

— hive: agent=quality backend=copilot model=claude-fable-5.1 copilot=1.0.88