[quality] normalizeSweep in src/utils/config.ts: empty sweep mapping and non-Error lookback rethrow branches are untested

[hivecommons-hive]

Finding

src/utils/config.ts normalizeSweep has two branch arms with no unit coverage:

• line 594, if (raw.lookback !== undefined) false arm — a sweep: {} mapping with no lookback. Every existing parse test in __tests__/cronJobTest/sweep.test.ts supplies a lookback (valid or invalid), so the pass-through to stripUndefined({ lookback: undefined }) is never exercised.
• line 603, e instanceof Error ? e.message : e non-Error arm — parseDuration only ever throws Error, so the fallback is reachable only by faking the thrown value.

Unit evidence: npm ci && npx vitest run --coverage on main @ c48bd6d → config.ts | 100 stmts | 99.03 branch | 100 funcs | 100 lines | uncovered 594,603.
End-to-end evidence: the prow / prow check dogfoods the built action but emits no coverage data (see #209), so there is no e2e coverage source to compare against; this finding is unit-only. Priority is therefore capped at medium.

Disjoint from the open hold-gated PRs: #217 (auth), #219 (tide queue), #221 (approve events), #223 (labelSync/approve/lgtm/mergeQueue), #225 (meow/trigger/tide), #227 (requireMatchingLabel) — none touch config.ts or a config test file.

Recommendation

Add __tests__/utils/configSweep.test.ts with two cases:

• parseProwConfig('x', 'sweep: {}\n') → { sweep: {} }
• vi.mock('../../src/utils/duration', { spy: true }), make parseDuration throw a string once, assert parseProwConfig rethrows x: <string>

Brings config.ts to 100% branch coverage.

Priority

• Impact: low
• Effort: low

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Filed by quality agent (hold-gated mode)

🐝 Hive Agent: quality | Instance: hosted-available-lke648397-260827-5q9t | SHA: c48bd6d

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

[github-actions]

Please add a kind label with /kind failing-test or /kind cleanup.