Right pane tabs Jobs/Planes market + 5 new plane types with tech-spec panels + sell-plane cargo guard (ISS-047 part A)

lib/sim/movement.test.ts

@@ -5,6 +5,7 @@ import {
   burnRateConstant,
   FUEL_DENSITY_KG_PER_L,
   fuelAtWeighted,
+  maxRangeKm,
   positionAt,
   progressAt,
   requiredFuelFor,
@@ -164,3 +165,24 @@ describe('weighted burn model (v0.16.0)', () => {
     expect(fuelAtWeighted(TANK, BURN, WE, TANK, KM, progressAt(DEP, KM, SPEED, clock))).toBeGreaterThan(0);
   });
 });
+
+describe('maxRangeKm (v0.28.0)', () => {
+  it('ATR 72-600 full tank ≈ 4439 km (±5%)', () => {
+    const r = maxRangeKm(BURN, WE, TANK);
+    expect(r).toBeGreaterThan(4439 * 0.95);
+    expect(r).toBeLessThan(4439 * 1.05);
+  });
+
+  it('increases with tank size and decreases with burn rate', () => {
+    expect(maxRangeKm(BURN, WE, TANK * 2)).toBeGreaterThan(maxRangeKm(BURN, WE, TANK));
+    expect(maxRangeKm(3, WE, TANK)).toBeLessThan(maxRangeKm(BURN, WE, TANK));
+  });
+
+  it('zero fuel → zero range', () => {
+    expect(maxRangeKm(BURN, WE, 0)).toBe(0);
+  });
+
+  it('rejects a non-positive empty weight', () => {
+    expect(() => maxRangeKm(BURN, 0, TANK)).toThrow();
+  });
+});

lib/sim/movement.ts

@@ -118,3 +118,13 @@ export function requiredFuelFor(
   const rho = FUEL_DENSITY_KG_PER_L;
   return (emptyWeightKg / rho) * (Math.exp(k * rho * distanceKm) - 1);
 }
+
+// Max range from a FULL tank under the weighted model — solve requiredFuelFor(d) = maxFuel for d:
+//   (We/ρ)(e^{kρd} − 1) = F  →  d = ln(1 + ρF/We) · (We + ρF)/(ρ·burnPerKm).
+// Returns raw km (call sites round); zero fuel gives exactly 0. Pure — display-only, the sim
+// itself does not model range exhaustion (see fuelAtWeighted).
+export function maxRangeKm(burnPerKm: number, emptyWeightKg: number, maxFuel: number): number {
+  if (!(emptyWeightKg > 0)) throw new Error('emptyWeightKg must be > 0');
+  const rho = FUEL_DENSITY_KG_PER_L;
+  return Math.log(1 + (rho * maxFuel) / emptyWeightKg) * ((emptyWeightKg + rho * maxFuel) / (rho * burnPerKm));
+}