Package weight, payload capacity and per-kg payout (ISS-045)

Packages carry a real weightKg (unit weight x count with +/-30% jitter),
plane capacity becomes maxPayloadKg instead of 6 slots, load validation
sums cargo weight against the payload, and the payout gains a per-kg part.
Loadout display shows tonnage; OpenAPI swaps CatalogEntry.capacity for
maxPayloadKg and adds PackageState.weightKg.

lib/game/seed.ts

@@ -50,6 +50,8 @@ export interface SeedPackage {
   reward: number;
   cargoType: string;
   cargoCount: number;
+  // Package weight in kg (v0.27.0, ISS-045) — unit weight × count with ±30% jitter.
+  weightKg: number;
   deadlineSimTime: number;
   status: 'open';
   planeId: null;
@@ -80,10 +82,12 @@ export const PACKAGE_COUNT_MAX = 12; // inclusive
 // count after expiries, so the job board never runs dry.
 export const MARKET_TARGET_OPEN_PACKAGES = 10;
 
-// Reward formula (v0.6.0 — deliberately simple; real revenue/cost modeling is a
-// later increment): reward = BASE_REWARD + REWARD_PER_KM * great-circle km.
+// Reward formula (v0.6.0 distance part, deliberately simple; real revenue/cost
+// modeling is a later increment; v0.27.0 weight part): reward = BASE_REWARD +
+// REWARD_PER_KM * great-circle km + REWARD_PER_KG * package weight kg.
 export const BASE_REWARD = 500;
 export const REWARD_PER_KM = 2.5;
+export const REWARD_PER_KG = 0.5;
 
 // Package deadlines: now + a plausible game-time window of 6–72 hours.
 const DEADLINE_MIN_HOURS = 6;
@@ -91,19 +95,33 @@ const DEADLINE_MAX_HOURS = 72;
 
 const CARGO_TYPES = ['Passengers', 'Mail', 'Perishables', 'Electronics', 'Auto parts'] as const;
 
-export function rewardForDistanceKm(km: number): number {
-  return Math.round(BASE_REWARD + REWARD_PER_KM * km);
+// ponytail: balance-tunable unit weights (kg per passenger/pallet). Chosen so every cargo
+// type at MAX count × max jitter (1.3×) still fits the ATR 72-600's payload alone, and
+// typical packages land ~400–2500 kg — a normal flight carries roughly 3–6 by weight.
+export const UNIT_WEIGHT_KG: Record<string, number> = {
+  Passengers: 50, // max 50 × 68 × 1.3 = 4420 < 4800
+  Mail: 60, // max 60 × 50 × 1.3 = 3900
+  Perishables: 70, // max 70 × 50 × 1.3 = 4550
+  Electronics: 40, // max 40 × 50 × 1.3 = 2600
+  'Auto parts': 72, // max 72 × 50 × 1.3 = 4680
+};
+
+export function rewardFor(km: number, weightKg: number): number {
+  return Math.round(BASE_REWARD + REWARD_PER_KM * km + REWARD_PER_KG * weightKg);
 }
 
 // Shared package generator, used by BOTH the first-run seed and the runtime
 // market spawn (v0.7.0) so spawned packages match seeded ones exactly: random
-// distinct airports from the dataset, distance-based reward, cargo flavor,
-// 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 package
-// is fixed: origin, dest, cargoType, cargoCount, [deadline window].
+// distinct airports from the dataset, distance+weight-based reward, cargo flavor,
+// weight = unit weight × count with ±30% jitter (v0.27.0), 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 package is fixed: origin,
+// dest, cargoType, cargoCount, weight jitter, [deadline window].
 // v0.8.0: originIcao/destIcao optionally FORCE an endpoint (spawn coverage rule +
 // the e2e create-package hook); a forced endpoint consumes no RNG draws, so
 // callers that omit both get byte-identical behavior to before.
+// v0.27.0: weightKg optionally FORCES the package weight (e2e hook) — it skips the
+// jitter draw, same pattern as forced endpoints.
 export function generatePackage(input: {
   id: string;
   airports: SeedAirport[];
@@ -112,6 +130,7 @@ export function generatePackage(input: {
   deadlineOffsetMs?: number;
   originIcao?: string;
   destIcao?: string;
+  weightKg?: number;
 }): SeedPackage {
   const { airports, rng, nowMs } = input;
   if (airports.length < 2) throw new Error('package generation needs at least two airports');
@@ -143,6 +162,9 @@ export function generatePackage(input: {
   // Passengers up to the ATR 72's ~68 seats; other cargo in pallets.
   const cargoCount =
     cargoType === 'Passengers' ? 1 + Math.floor(rng() * 68) : 1 + Math.floor(rng() * 50);
+  // Weight (v0.27.0): unit weight × count with ±30% jitter, integer kg — drawn AFTER
+  // cargoCount so the fixed RNG order above holds; a forced weightKg skips the draw.
+  const weightKg = input.weightKg ?? Math.round(UNIT_WEIGHT_KG[cargoType] * cargoCount * (0.7 + 0.6 * rng()));
   const deadlineMs =
     input.deadlineOffsetMs ?? (DEADLINE_MIN_HOURS + rng() * (DEADLINE_MAX_HOURS - DEADLINE_MIN_HOURS)) * 3_600_000;
 
@@ -150,9 +172,10 @@ export function generatePackage(input: {
     id: input.id,
     originIcao: origin.icao,
     destIcao: dest.icao,
-    reward: rewardForDistanceKm(km),
+    reward: rewardFor(km, weightKg),
     cargoType,
     cargoCount,
+    weightKg,
     deadlineSimTime: Math.round(nowMs + deadlineMs),
     status: 'open',
     planeId: null,