What problem does it solve? Contributors to the gmt library need a consistent, rules-driven process for adding new date/time methods to packages/gmt/src without duplicating existing helpers, breaking string-first I/O contracts, or mixing plain and zoned Temporal logic. ## Core Features & Use Cases - Reuse-first implementation flow: Searches all gmt namespaces (calendar, duration, instant, plain, precision, regex, span, unix, utc, zoned) for existing helpers before writing new Temporal code. - Convention enforcement: Applies naming patterns (ForDate/ForZoned suffixes, startOf*/endOf*, isBetween*, get*), module boundary rules, and typed fallback returns ("" for strings, null for numbers/objects, false for booleans, [] for arrays, 0n for bigint). - Testing and release checklist: Mandates unit tests with DST/timezone boundary matrices via battleTestTimeZones, plus index.ts exports, package.json subpaths, and README API Surface updates. - Use Case: A contributor wants to add a getQuarterForZoned method. The skill guides them to check existing quarter helpers, place the logic in zoned/, return ISO strings, add Chatham/Santiago/Apia transition test rows, and update exports and docs. ## Quick Start Ask the assistant to implement a new gmt method such as getQuarterForZoned in packages/gmt/src following the contributor implementation rules.
