gameboardPlanIndex
gameboardPlanIndex(
plan):GameboardPlanIndex
Defined in: packages/declarative-hex-worlds/src/gameboard/plan.ts:246
Return memoized indexes for a GameboardPlan, building them lazily the first time and caching per-plan thereafter (PRD B4).
Hot-path callers should prefer this over inlining
new Map(plan.tiles.map(...)) — that rebuild cost shows up under
profiling on every render of large boards.