feat: overlay manifests for the two reference courses

Co-Authored-By: Claude Opus 5.5 <noreply@anthropic.com>

packages/course-format/test/reference.test.ts

@@ -0,0 +1,32 @@
+import { describe, expect, test } from "bun:test";
+import { existsSync } from "node:fs";
+import { resolve } from "node:path";
+import { createCourseRepository, extractHints } from "../src/index";
+
+const overlays = resolve(import.meta.dir, "../../../overlays");
+const snakeRoot = "/home/user/functional-programming-course";
+const systemicRoot = "/home/user/systemic-design-course";
+
+describe("reference courses", () => {
+  test.skipIf(!existsSync(snakeRoot))("pure-snake loads cleanly", async () => {
+    const repo = await createCourseRepository([overlays]);
+    const c = repo.get("pure-snake")!;
+    expect(c.diagnostics.filter((d) => d.level === "error")).toEqual([]);
+    expect(c.status).toBe("ok");
+    expect(c.manifest!.modules).toHaveLength(13);
+    expect(c.lessonIndex.has("m03-ex-move")).toBe(true);
+    const hints = c.lessonIndex.get("m03-ex-move")!.lesson.hints!;
+    const md = await Bun.file(repo.resolvePath("pure-snake", hints.file)!).text();
+    expect(extractHints(md, hints.match)).toHaveLength(3);
+    expect(await repo.readLessonMarkdown("pure-snake", "m03-ex-move")).toStartWith("### Exercise 3.1");
+  });
+
+  test.skipIf(!existsSync(systemicRoot))("systemic-design loads cleanly", async () => {
+    const repo = await createCourseRepository([overlays]);
+    const c = repo.get("systemic-design")!;
+    expect(c.diagnostics.filter((d) => d.level === "error")).toEqual([]);
+    expect(c.status).toBe("ok");
+    expect(c.manifest!.modules).toHaveLength(11);
+    expect(c.manifest!.gating).toBe("sequential");
+  });
+});