feat: v0.8.0 — player-actions API: accept/dispatch/buy/sell/refuel endpoints (tick-first, full-snapshot responses), spawn coverage rule, test create-contract hook

lib/game/seed.ts

@@ -98,19 +98,40 @@ export function rewardForDistanceKm(km: number): number {
 // deadline now + 6–72h game time (or now + deadlineOffsetMs when given — used by
 // the e2e test hook to force a near-term expiry). The RNG call order per contract
 // is fixed: origin, dest, cargoType, cargoCount, [deadline window].
+// v0.8.0: originIcao/destIcao optionally FORCE an endpoint (spawn coverage rule +
+// the e2e create-contract hook); a forced endpoint consumes no RNG draws, so
+// callers that omit both get byte-identical behavior to before.
 export function generateContract(input: {
   id: string;
   airports: SeedAirport[];
   rng: Rng;
   nowMs: number;
   deadlineOffsetMs?: number;
+  originIcao?: string;
+  destIcao?: string;
 }): SeedContract {
   const { airports, rng, nowMs } = input;
   if (airports.length < 2) throw new Error('contract generation needs at least two airports');
 
-  const oi = Math.floor(rng() * airports.length);
-  let di = Math.floor(rng() * airports.length);
-  if (di === oi) di = (di + 1) % airports.length;
+  let oi: number;
+  if (input.originIcao !== undefined) {
+    oi = airports.findIndex((a) => a.icao === input.originIcao);
+    if (oi < 0) throw new Error(`unknown origin airport ${input.originIcao}`);
+  } else {
+    oi = Math.floor(rng() * airports.length);
+  }
+  let di: number;
+  if (input.destIcao !== undefined) {
+    di = airports.findIndex((a) => a.icao === input.destIcao);
+    if (di < 0) throw new Error(`unknown destination airport ${input.destIcao}`);
+    // A RANDOM origin may have landed on the forced destination — shift it (no
+    // extra RNG draw), mirroring the unforced collision handling below.
+    if (oi === di && input.originIcao === undefined) oi = (oi + 1) % airports.length;
+  } else {
+    di = Math.floor(rng() * airports.length);
+    if (di === oi) di = (di + 1) % airports.length;
+  }
+  if (oi === di) throw new Error('origin and destination must differ'); // both forced identical
   const origin = airports[oi];
   const dest = airports[di];