feat: merge same-net trace lines by enabling rail alignment in default operations

lib/solvers/TraceCleanupSolver/TraceCleanupSolver.ts

@@ -37,6 +37,7 @@ const DEFAULT_OPERATIONS: readonly TraceCleanupOperation[] = [
   "untangling_traces",
   "minimizing_turns",
   "balancing_l_shapes",
+  "aligning_same_net_rails",
 ]
 
 /**

tests/solvers/TraceCleanupSolver/mergeSameNetTraces.test.ts

@@ -0,0 +1,99 @@
+import { expect, test } from "bun:test"
+import type { InputProblem } from "lib/types/InputProblem"
+import {
+  align,
+  createTrace,
+  verticalProblem,
+  getVerticalPin,
+} from "./fixtures/alignSameNetRails"
+
+test("merges same-net trace lines at same Y coordinate", () => {
+  const inputProblem: InputProblem = {
+    ...verticalProblem,
+    chips: [
+      {
+        chipId: "U1",
+        center: { x: 0, y: 0 },
+        width: 2,
+        height: 6,
+        pins: [
+          { pinId: "U1.1", x: -1, y: 2, _facingDirection: "x-" },
+          { pinId: "U1.2", x: -1, y: 0, _facingDirection: "x-" },
+          { pinId: "U1.3", x: -1, y: -2, _facingDirection: "x-" },
+        ],
+      },
+    ],
+  }
+
+  const traces = [
+    createTrace(
+      "trace_a",
+      [
+        { x: -1, y: 2 },
+        { x: -2, y: 2 },
+        { x: -2, y: 0 },
+        { x: -1, y: 0 },
+      ],
+      [getVerticalPin("U1.1"), getVerticalPin("U1.2")],
+    ),
+    createTrace(
+      "trace_b",
+      [
+        { x: -1, y: 0 },
+        { x: -2.5, y: 0 },
+        { x: -2.5, y: -2 },
+        { x: -1, y: -2 },
+      ],
+      [getVerticalPin("U1.2"), getVerticalPin("U1.3")],
+    ),
+  ]
+
+  const result = align(traces, { inputProblem })
+
+  expect(result.alignedRailGroupCount).toBeGreaterThan(0)
+
+  const traceA = result.traces.find((t) => t.mspPairId === "trace_a")!
+  const traceB = result.traces.find((t) => t.mspPairId === "trace_b")!
+
+  const traceARailX = traceA.tracePath.find((p, i) => i > 0 && i < traceA.tracePath.length - 1 && p.x !== -1)?.x
+  const traceBRailX = traceB.tracePath.find((p, i) => i > 0 && i < traceB.tracePath.length - 1 && p.x !== -1)?.x
+
+  expect(traceARailX).toBe(traceBRailX)
+})
+
+test("merges same-net trace lines at same X coordinate (vertical rails)", () => {
+  const traces = [
+    createTrace(
+      "upper",
+      [
+        { x: -1, y: 2 },
+        { x: -2, y: 2 },
+        { x: -2, y: 0 },
+        { x: -1, y: 0 },
+      ],
+      [getVerticalPin("U1.1"), getVerticalPin("U1.2")],
+    ),
+    createTrace(
+      "lower",
+      [
+        { x: -1, y: 0 },
+        { x: -3, y: 0 },
+        { x: -3, y: -2 },
+        { x: -1, y: -2 },
+      ],
+      [getVerticalPin("U1.2"), getVerticalPin("U1.3")],
+    ),
+  ]
+
+  const result = align(traces)
+
+  expect(result.alignedRailGroupCount).toBeGreaterThan(0)
+
+  const upper = result.traces.find((t) => t.mspPairId === "upper")!
+  const lower = result.traces.find((t) => t.mspPairId === "lower")!
+
+  const upperRailX = upper.tracePath.find((p, i) => i > 0 && i < upper.tracePath.length - 1 && p.x !== -1)?.x
+  const lowerRailX = lower.tracePath.find((p, i) => i > 0 && i < lower.tracePath.length - 1 && p.x !== -1)?.x
+
+  expect(upperRailX).toBe(lowerRailX)
+})