feat: New theme + wire price adjustement

tests/engine.test.js

@@ -138,6 +138,59 @@ test('auto-buy restocks material when funds allow', () => {
   assert.ok(s.material > 50);
 });
 
+test('material is costly at first and cheaper relative to the sale price as production grows', () => {
+  const { fairPrice } = ctx.rules.market;
+  const costShare = (totalProduced) => {
+    const s = fresh();
+    s.totalProduced = totalProduced;
+    const d = derive(s, ctx);
+    return d.batchCost / d.batchSize / fairPrice;
+  };
+  assert.ok(costShare(0) > 0.25, 'expensive at the start');
+  assert.ok(costShare(1e4) < costShare(0));
+  assert.ok(costShare(1e6) < costShare(1e4));
+  assert.ok(costShare(1e9) < 0.1, 'a small share of revenue late in the game');
+});
+
+test('material lots grow with the operation, in doublings', () => {
+  const sizeAt = (total) => {
+    const s = fresh();
+    s.totalProduced = total;
+    return derive(s, ctx).batchSize;
+  };
+  assert.equal(sizeAt(0), ctx.rules.materialMarket.minBatch);
+  assert.ok(sizeAt(1e6) > sizeAt(1e4));
+  assert.equal(Math.log2(sizeAt(1e6) / ctx.rules.materialMarket.minBatch) % 1, 0);
+});
+
+test('the material market is erratic but stays within its bounds', () => {
+  const m = ctx.rules.materialMarket;
+  const s = fresh();
+  let seed = 7;
+  const rng = () => (seed = (seed * 16807) % 2147483647) / 2147483647;
+  const seen = [];
+  for (let i = 0; i < 2000; i++) {
+    advance(s, ctx, m.updateEverySeconds, rng);
+    seen.push(s.materialFactor);
+  }
+  assert.ok(Math.min(...seen) >= m.minFactor && Math.max(...seen) <= m.maxFactor);
+  assert.ok(Math.max(...seen) > 1.6 && Math.min(...seen) < 0.6, 'swings widely');
+  assert.ok(new Set(seen.map((f) => f.toFixed(2))).size > 100, 'does not sit still');
+});
+
+test('auto-buy waits for a fair price unless stock is nearly gone', () => {
+  const s = fresh();
+  s.upgrades = ['auto_buy'];
+  s.funds = 1e6;
+  s.materialFactor = 2.5; // expensive
+  s.material = 40; // low but not desperate (< lot/2, > lot/10)
+  advance(s, ctx, 0.1, () => 0.5);
+  assert.equal(s.material, 40, 'did not buy at a high price');
+  s.material = 5; // desperate
+  advance(s, ctx, 0.1, () => 0.5);
+  assert.ok(s.material > 50, 'buys when nearly out');
+});
+
 test('offline progress is capped, discounted, and ignored when short', () => {
   const s = fresh();
   s.generators.gen1 = 5;