Fix board outline closure for edge cuts

src/gerber/convert-soup-to-gerber-commands/index.ts

@@ -644,9 +644,24 @@ export const convertSoupToGerberCommands = (
           aperture_number: 10,
         })
         if (outline && outline.length > 2) {
-          gerberBuild.add("move_operation", outline[0])
+          const firstPoint = outline[0]
+          gerberBuild.add("move_operation", {
+            x: firstPoint.x,
+            y: mfy(firstPoint.y),
+          })
           for (let i = 1; i < outline.length; i++) {
-            gerberBuild.add("plot_operation", outline[i])
+            gerberBuild.add("plot_operation", {
+              x: outline[i].x,
+              y: mfy(outline[i].y),
+            })
+          }
+
+          const lastPoint = outline[outline.length - 1]
+          if (lastPoint.x !== firstPoint.x || lastPoint.y !== firstPoint.y) {
+            gerberBuild.add("plot_operation", {
+              x: firstPoint.x,
+              y: mfy(firstPoint.y),
+            })
           }
         } else {
           gerberBuild

tests/gerber/generate-board-outline-closure.test.tsx

@@ -0,0 +1,54 @@
+import { Circuit } from "@tscircuit/core"
+import { expect, test } from "bun:test"
+import { convertSoupToGerberCommands } from "src/gerber/convert-soup-to-gerber-commands"
+import { stringifyGerberCommandLayers } from "src/gerber/stringify-gerber"
+
+// Regression test: outlines should be closed in the Edge_Cuts layer
+// even if the provided outline path does not repeat the starting point.
+test("board outline paths are closed and flipped when required", async () => {
+  const circuit = new Circuit()
+  circuit.add(
+    <board
+      width={10}
+      height={10}
+      outline={[
+        { x: 0, y: 0 },
+        { x: 10, y: 0 },
+        { x: 10, y: 5 },
+        { x: 0, y: 5 },
+      ]}
+    />, // outline intentionally does not repeat the starting point
+  )
+
+  const soup = circuit.getCircuitJson()
+  const edgeCuts = convertSoupToGerberCommands(soup as any, {
+    flip_y_axis: true,
+  }).Edge_Cuts
+
+  const outlineCommands = edgeCuts.filter(
+    (cmd) => cmd.command_code === "D02" || cmd.command_code === "D01",
+  )
+
+  expect(
+    outlineCommands.map(({ command_code, x, y }) => ({
+      command_code,
+      x,
+      y: Object.is(y, -0) ? 0 : y,
+    })),
+  ).toEqual([
+    { command_code: "D02", x: 0, y: 0 },
+    { command_code: "D01", x: 10, y: 0 },
+    { command_code: "D01", x: 10, y: -5 },
+    { command_code: "D01", x: 0, y: -5 },
+    { command_code: "D01", x: 0, y: 0 },
+  ])
+
+  const gerberOutput = stringifyGerberCommandLayers(
+    convertSoupToGerberCommands(soup as any, { flip_y_axis: true }),
+  )
+
+  await expect(gerberOutput).toMatchGerberSnapshot(
+    import.meta.path,
+    "outline-closure",
+  )
+})