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.test.ts

@@ -9,8 +9,9 @@ import {
   generatePackage,
   HUB_ICAO,
   mulberry32,
+  REWARD_PER_KG,
   REWARD_PER_KM,
-  rewardForDistanceKm,
+  rewardFor,
   STARTING_CASH,
   STARTING_REPUTATION,
   type SeedAirport,
@@ -70,12 +71,26 @@ describe('buildSeed', () => {
     expect(new Set(seed.packages.map((c) => c.id)).size).toBe(seed.packages.length);
   });
 
-  it('scales reward by haversine distance: round(500 + 2.5 * km)', () => {
+  it('applies the reward formula: round(500 + 2.5 * km + 0.5 * weightKg)', () => {
     const seed = seedWith(42);
     for (const c of seed.packages) {
       const o = AIRPORTS.find((a) => a.icao === c.originIcao)!;
       const d = AIRPORTS.find((a) => a.icao === c.destIcao)!;
-      expect(c.reward).toBe(Math.round(BASE_REWARD + REWARD_PER_KM * haversineKm(o.lat, o.lon, d.lat, d.lon)));
+      expect(c.reward).toBe(
+        Math.round(BASE_REWARD + REWARD_PER_KM * haversineKm(o.lat, o.lon, d.lat, d.lon) + REWARD_PER_KG * c.weightKg),
+      );
+    }
+  });
+
+  it('gives every package a positive integer weight that fits the starter plane alone (balance constraint)', () => {
+    const maxPayload = PLANE_TYPES[STARTER_MODEL].maxPayloadKg;
+    for (const seed of [seedWith(42), seedWith(7)]) {
+      for (const c of seed.packages) {
+        expect(Number.isInteger(c.weightKg)).toBe(true);
+        expect(c.weightKg).toBeGreaterThan(0);
+        // max count × max jitter (1.3×) must still fit the ATR alone — see UNIT_WEIGHT_KG.
+        expect(c.weightKg).toBeLessThanOrEqual(maxPayload);
+      }
     }
   });
 
@@ -106,9 +121,9 @@ describe('buildSeed', () => {
     expect(() => buildSeed({ airports: AIRPORTS.slice(0, 1), rng: mulberry32(42), nowMs: NOW })).toThrow();
   });
 
-  it('rewardForDistanceKm applies the documented formula', () => {
-    expect(rewardForDistanceKm(0)).toBe(BASE_REWARD);
-    expect(rewardForDistanceKm(1000)).toBe(Math.round(BASE_REWARD + REWARD_PER_KM * 1000));
+  it('rewardFor applies the documented formula', () => {
+    expect(rewardFor(0, 0)).toBe(BASE_REWARD);
+    expect(rewardFor(1000, 2_000)).toBe(Math.round(BASE_REWARD + REWARD_PER_KM * 1000 + REWARD_PER_KG * 2_000));
   });
 });
 
@@ -127,7 +142,9 @@ describe('generatePackage (shared seed/spawn builder)', () => {
 
     const o = AIRPORTS.find((a) => a.icao === c.originIcao)!;
     const d = AIRPORTS.find((a) => a.icao === c.destIcao)!;
-    expect(c.reward).toBe(Math.round(BASE_REWARD + REWARD_PER_KM * haversineKm(o.lat, o.lon, d.lat, d.lon)));
+    expect(c.reward).toBe(
+      Math.round(BASE_REWARD + REWARD_PER_KM * haversineKm(o.lat, o.lon, d.lat, d.lon) + REWARD_PER_KG * c.weightKg),
+    );
 
     // Same 6–72h game-time deadline window as the seed.
     expect(c.deadlineSimTime).toBeGreaterThan(NOW + 6 * 3_600_000 - 1);
@@ -173,7 +190,9 @@ describe('generatePackage (shared seed/spawn builder)', () => {
 
       const o = AIRPORTS.find((a) => a.icao === c.originIcao)!;
       const d = AIRPORTS.find((a) => a.icao === c.destIcao)!;
-      expect(c.reward).toBe(Math.round(BASE_REWARD + REWARD_PER_KM * haversineKm(o.lat, o.lon, d.lat, d.lon)));
+      expect(c.reward).toBe(
+        Math.round(BASE_REWARD + REWARD_PER_KM * haversineKm(o.lat, o.lon, d.lat, d.lon) + REWARD_PER_KG * c.weightKg),
+      );
     });
 
     it('destIcao forces the destination; origin stays random but distinct', () => {
@@ -189,7 +208,9 @@ describe('generatePackage (shared seed/spawn builder)', () => {
 
       const o = AIRPORTS[0]; // EDDF
       const d = AIRPORTS[1]; // EHAM
-      expect(c.reward).toBe(Math.round(BASE_REWARD + REWARD_PER_KM * haversineKm(o.lat, o.lon, d.lat, d.lon)));
+      expect(c.reward).toBe(
+        Math.round(BASE_REWARD + REWARD_PER_KM * haversineKm(o.lat, o.lon, d.lat, d.lon) + REWARD_PER_KG * c.weightKg),
+      );
     });
 
     it('is deterministic for a fixed RNG with forced endpoints', () => {
@@ -212,4 +233,22 @@ describe('generatePackage (shared seed/spawn builder)', () => {
       expect(a).toEqual(b);
     });
   });
+
+  describe('forced weight (v0.27.0 e2e hook)', () => {
+    it('weightKg forces the package weight and feeds the payout', () => {
+      const c = generatePackage({ id: 'c-w', airports: AIRPORTS, rng: mulberry32(42), nowMs: NOW, weightKg: 1_234 });
+      expect(c.weightKg).toBe(1_234);
+
+      const o = AIRPORTS.find((a) => a.icao === c.originIcao)!;
+      const d = AIRPORTS.find((a) => a.icao === c.destIcao)!;
+      expect(c.reward).toBe(Math.round(BASE_REWARD + REWARD_PER_KM * haversineKm(o.lat, o.lon, d.lat, d.lon) + REWARD_PER_KG * 1_234));
+
+      // Deterministic for a fixed RNG…
+      const again = generatePackage({ id: 'c-w', airports: AIRPORTS, rng: mulberry32(42), nowMs: NOW, weightKg: 1_234 });
+      expect(again).toEqual(c);
+      // …and the forced value consumes no RNG draw — the deadline lands where an unforced call's jitter would.
+      const unforced = generatePackage({ id: 'c-u', airports: AIRPORTS, rng: mulberry32(42), nowMs: NOW });
+      expect(c.deadlineSimTime).not.toBe(unforced.deadlineSimTime);
+    });
+  });
 });