Add compile performance budget regression test

tests/perf-budget.test.js

@@ -0,0 +1,61 @@
+import test from "node:test";
+import assert from "node:assert/strict";
+import { performance } from "node:perf_hooks";
+import { compile } from "../src/compile.js";
+
+function createLargeModel(instanceCount = 220) {
+  const instances = [];
+  const nets = [];
+
+  for (let i = 0; i < instanceCount; i += 1) {
+    const idx = i + 1;
+    instances.push({
+      ref: `R${idx}`,
+      part: "resistor",
+      properties: { value: `${(idx % 100) + 1}k` },
+      placement: { x: null, y: null, rotation: 0, locked: false }
+    });
+  }
+
+  for (let i = 0; i < instanceCount - 1; i += 1) {
+    const idx = i + 1;
+    nets.push({
+      name: `SIG_${idx}`,
+      class: "signal",
+      nodes: [
+        { ref: `R${idx}`, pin: "2" },
+        { ref: `R${idx + 1}`, pin: "1" }
+      ]
+    });
+  }
+
+  nets.push({
+    name: "GND",
+    class: "ground",
+    nodes: [
+      { ref: "R1", pin: "1" },
+      { ref: `R${instanceCount}`, pin: "2" }
+    ]
+  });
+
+  return {
+    meta: { title: "Perf chain" },
+    symbols: {},
+    instances,
+    nets,
+    constraints: {},
+    annotations: []
+  };
+}
+
+test("compile remains under baseline perf budget for large synthetic model", () => {
+  const model = createLargeModel();
+  const started = performance.now();
+  const result = compile(model);
+  const elapsedMs = performance.now() - started;
+
+  assert.equal(result.ok, true);
+  assert.equal(typeof result.layout_metrics.crossings, "number");
+  assert.equal(typeof result.layout_metrics.overlap_edges, "number");
+  assert.ok(elapsedMs < 5_000, `compile exceeded baseline budget: ${elapsedMs.toFixed(1)}ms`);
+});