feat: v0.16.0 — ISS-005 weight-proportional fuel burn + refuel just enough for the loaded package

Part A: r(F) = k(We + rho*F) L/km, k calibrated so a full tank burns exactly
the old constant; closed forms in lib/sim/movement.ts (fuelAtWeighted,
requiredFuelFor, burnRateConstant, FUEL_DENSITY_KG_PER_L). Catalog gains
emptyWeightKg (ATR72 OEW 9300 kg), exposed in the snapshot. All three burn
call sites (engine landing, state live fuel, fly validation) moved to the
weighted model; old constant-rate fuelAt removed.

Part B: POST /api/planes/{planeId}/refuel takes an optional body
{mode:'full'|'forFlight', packageId} — no body keeps today's fill-to-full
behavior exactly (fuel lands bit-exact on maxFuel); forFlight adds just
enough for the loaded package's destination leg (409 not-loaded/expired/
doesn't-fit, 400 bad body). UI: per-cargo-row 'Refuel' button
(refuel-for-{pkg.id}), market button renamed 'Refuel to full'.

OpenAPI: RefuelRequest schema + optional requestBody + 400 on refuel, fly's
409 description updated, CatalogEntry.emptyWeightKg. Tests: new weighted-burn
suite, forFlight action/route cases (incl. ~7670 km UNNT<->LPPD doesn't-fit),
openapi guards; landing-fuel assertions in engine.test.ts + e2e/actions.spec.ts
use the closed form; the e2e 'return leg unfuelable' scenario reworked — a full
tank now covers the EDDF<->LEZL round trip, so the 409 moves to the second
outbound. New e2e: row Refuel deducts exactly L*price / raises fuel by exactly
L via the endpoint's own response snapshot.

lib/game/actions.test.ts

@@ -6,6 +6,8 @@ import { afterAll, beforeAll, describe, expect, it, vi } from 'vitest';
 import { openGameDb, type GameDb } from '@/lib/db/client';
 import * as schema from '@/lib/db/schema';
 import { loadAirportsGeoJson } from '@/lib/airports';
+import { haversineKm } from '@/lib/geo';
+import { requiredFuelFor } from '@/lib/sim/movement';
 import { FUEL_PRICE_PER_L, PLANE_TYPES, SELL_FRACTION } from './catalog';
 import { HUB_ICAO } from './seed';
 import {
@@ -412,4 +414,86 @@ describe('refuelPlane', () => {
     const inst = await freshDb('refuel-unknown.db');
     await expectActionError(refuelPlane(inst, 'ghost'), 404);
   });
+
+  // --- forFlight mode (v0.16.0) ---
+
+  it('forFlight adds exactly the liters needed for the package leg and deducts L × price', async () => {
+    const inst = await freshDb('refuel-forflight-ok.db');
+    await insertOpenPackage(inst, 'p-ff', { destIcao: 'LEMD' }); // EDDF → LEMD
+    await loadPackage(inst, 'p-ff', 'plane-starter');
+
+    const fc = await loadAirportsGeoJson();
+    const from = fc.features.find((f) => f.properties.icao === HUB_ICAO)!.properties;
+    const to = fc.features.find((f) => f.properties.icao === 'LEMD')!.properties;
+    const km = haversineKm(from.lat, from.lon, to.lat, to.lon);
+    const type = PLANE_TYPES.atr72;
+    const required = requiredFuelFor(type.burnPerKm, type.emptyWeightKg, type.maxFuel, km);
+
+    // Partial tank below the requirement so L > 0.
+    const startFuel = Math.round(required / 2);
+    await inst.db.update(schema.planes).set({ fuel: startFuel }).where(eq(schema.planes.id, 'plane-starter'));
+    const cashBefore = (await inst.db.select().from(schema.account))[0].cash;
+
+    const { cost } = await refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-ff' });
+
+    expect(cost).toBe(Math.round((required - startFuel) * FUEL_PRICE_PER_L * 100) / 100);
+    const plane = (await inst.db.select().from(schema.planes))[0];
+    expect(plane.fuel).toBeCloseTo(required, 6); // topped up to exactly the leg requirement
+    const account = (await inst.db.select().from(schema.account))[0];
+    expect(account.cash).toBeCloseTo(cashBefore - cost, 6);
+  });
+
+  it('forFlight is a free no-op when the tank already covers the leg', async () => {
+    const inst = await freshDb('refuel-forflight-enough.db'); // seeded starter is full at EDDF
+    await insertOpenPackage(inst, 'p-ff2', { destIcao: 'LEMD' });
+    await loadPackage(inst, 'p-ff2', 'plane-starter');
+    const cashBefore = (await inst.db.select().from(schema.account))[0].cash;
+
+    const { cost } = await refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-ff2' });
+
+    expect(cost).toBe(0);
+    const plane = (await inst.db.select().from(schema.planes))[0];
+    expect(plane.fuel).toBe(PLANE_TYPES.atr72.maxFuel); // untouched
+    expect((await inst.db.select().from(schema.account))[0].cash).toBe(cashBefore);
+  });
+
+  it('forFlight rejects a package that is not loaded on this plane with 409', async () => {
+    const inst = await freshDb('refuel-ff-open.db'); // open — never loaded
+    await insertOpenPackage(inst, 'p-x');
+    await expectActionError(refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-x' }), 409);
+
+    const inst2 = await freshDb('refuel-ff-other.db'); // loaded on ANOTHER plane
+    await insertOpenPackage(inst2, 'p-y', { status: 'loaded', planeId: 'plane-someone-else' });
+    await expectActionError(refuelPlane(inst2, 'plane-starter', { mode: 'forFlight', packageId: 'p-y' }), 409);
+  });
+
+  it('forFlight rejects an expired package with 409', async () => {
+    const inst = await freshDb('refuel-ff-expired.db');
+    await insertOpenPackage(inst, 'p-z', { status: 'expired', planeId: 'plane-starter' });
+    await expectActionError(refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-z' }), 409);
+  });
+
+  it('forFlight rejects an unknown package id with 404', async () => {
+    const inst = await freshDb('refuel-ff-unknown.db');
+    await expectActionError(refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'nope' }), 404);
+  });
+
+  it('forFlight rejects a missing packageId with 400', async () => {
+    const inst = await freshDb('refuel-ff-nopkg.db');
+    await expectActionError(refuelPlane(inst, 'plane-starter', { mode: 'forFlight' }), 400);
+  });
+
+  it('forFlight rejects a leg that does not fit even a full tank with 409', async () => {
+    const inst = await freshDb('refuel-ff-nofit.db');
+    // UNNT (Narsarsuaq, Greenland) ↔ LPPD are ~7670 km apart — far beyond the ATR's range.
+    await insertOpenPackage(inst, 'p-far', { destIcao: 'LPPD' });
+    await loadPackage(inst, 'p-far', 'plane-starter');
+    await inst.db.update(schema.planes).set({ locationIcao: 'UNNT' }).where(eq(schema.planes.id, 'plane-starter'));
+
+    await expectActionError(
+      refuelPlane(inst, 'plane-starter', { mode: 'forFlight', packageId: 'p-far' }),
+      409,
+      /does not fit/i,
+    );
+  });
 });