Builds a timezone, daylight saving time (DST), and leap year / leap second test matrix from wherever a codebase reads or formats dates and times. Finds time-handling code (grep for datetime / Date / Instant / time.time / timezone), sorts each spot into storage, business-logic, display, cron, or billing, picks the edge cases that matter (DST spring-forward / fall-back, ambiguous local time, leap day Feb 29, ISO 8601 / RFC 3339 round-trip, zone-database updates), and emits per-spot test stubs wired to the language's fake-clock (mock-time) library. Use when a codebase needs timezone, DST, and leap-year test coverage derived from its own date/time usage.