DL-249
A leader sequence is authored as space-separated segments in the EXISTING KeymapEntry.chord string ("G B"), no new field — collision-free because the Space key is already normalized to the token "Space" (dispatch.ts:45), so no event-derived chord contains a space and sequence rows are inert in the DEFAULT_KEYMAP.filter (dispatch.ts:112-114); the leader-prefix set is DERIVED from the table via leaderPrefixes, never hard-coded; authoring rules (T1 invariant test): exactly two modifier-less segments, and a leader prefix never doubles as a complete single chord. A parallel sequence?: string[] field was rejected (forks every consumer for zero gain).
Status: Active (Matt, 2026-08-23)