Swift Code Review

Lead with actionable findings ordered by severity. A review is not a narration of the diff.

Evidence workflow

1. Read the change, surrounding contracts, callers, manifest, platform conditions, and relevant tests.
2. Reproduce or statically trace each suspected defect.
3. Check optionals, value/reference semantics, ARC cycles, errors, Codable shape, public ABI/API, actor isolation, Sendable crossings, cancellation, resources, and C/Objective-C boundaries.
4. Confirm tests would fail for plausible defects and use production paths.
5. Report location, trigger, impact, and the smallest credible remedy.

Severity

• Critical: data loss, exploitable security defect, broad outage, or irreversible compatibility break.
• High: common wrong result, race/leak, broken public contract, or migration parity failure.
• Medium: bounded correctness, resilience, performance, or maintainability risk.
• Low: concrete improvement with limited operational impact.