March 2026 Monthly Summary for Swift Foundation (swiftlang/swift-foundation) Key achievements focused on correcting JSON encoding/decoding behavior for CodingKeyRepresentable dictionaries, improving correctness, stability, and test coverage while preserving existing key transformation for nested properties. Key ACHIEVEMENTS: - Fixed JSON Encoding/Decoding strategy application for CodingKeyRepresentable dictionary keys (issue #1526). Only nested Encodable/Decodable properties are affected; non-nested keys bypass the key encoding/decoding strategy. - Extended encoder/decoder markers to cover all CodingKeyRepresentable keys, replacing the previous String-only marker to avoid unnecessary AnyHashable boxing. - Added regression tests verifying that key strategies bypass non-nested keys while nested properties continue to apply key transformation. - Commit reference: 0506e469fe003a012f8acf05a2885f6e5ea4efed in swiftlang/swift-foundation. Overall impact: - Correctness: Ensures JSON encoding/decoding respects CodingKeyRepresentable dictionary semantics, reducing data transformation errors. - Stability: Prevents unintended key transformations on non-nested dictionary properties, lowering bug surface for downstream users. - Quality: Strengthened test coverage around CodingKeyRepresentable dictionaries and marker protocol behavior. Technologies/Skills Demonstrated: - Swift language, JSON encoding/decoding workflows, and CodingKeyRepresentable patterns - Protocol/marker-based design to scope key strategies - Test-driven development with regression tests for dictionary key behavior - Codebase hygiene: targeted fixes with minimal surface area impact Business value: - Safer and more predictable JSON round-trips for developers relying on CodingKeyRepresentable dictionaries - Reduced risk of subtle data changes due to key strategy application in critical data paths