test(cli): prove sync restores only what antigravity setup wrote

cli/tests/e2e/antigravity-foreign-files.e2e.test.ts

@@ -0,0 +1,96 @@
+import { existsSync } from "node:fs";
+import { mkdir, readFile, writeFile } from "node:fs/promises";
+import { join, resolve } from "node:path";
+import { describe, expect, it } from "vitest";
+import { createTestEnv, runCli } from "./helpers.js";
+
+const FRAMEWORK_REAL_PATH = resolve(process.cwd(), "tests/fixtures/framework-real");
+const OWN_SKILL = "aidd-vcs-01-commit/SKILL.md";
+const FOREIGN_SKILL = "# mine\n";
+const OWN_HOOKED_SKILL = "aidd-context-05-learn/SKILL.md";
+const FOREIGN_HOOK = { SessionStart: [{ type: "command", command: "echo lint" }] };
+
+describe("E2E: antigravity under a .agents/ it does not own", () => {
+  it("clean removes the skills it wrote and leaves a user skill beside them", async () => {
+    const test = await createTestEnv("clean-antigravity-foreign");
+    try {
+      const skills = join(test.projectDir, ".agents", "skills");
+      const foreign = join(skills, "mine", "SKILL.md");
+      await mkdir(join(skills, "mine"), { recursive: true });
+      await writeFile(foreign, FOREIGN_SKILL);
+
+      const setup = await runCli(
+        [
+          "setup",
+          "--source",
+          "local",
+          "--path",
+          FRAMEWORK_REAL_PATH,
+          "--ai",
+          "antigravity",
+          "--plugins",
+          "aidd-vcs",
+          "--yes",
+        ],
+        test.projectDir,
+        test.fakeHome
+      );
+      expect(setup.exitCode).toBe(0);
+      expect(existsSync(join(skills, OWN_SKILL))).toBe(true);
+
+      const clean = await runCli(["clean", "--force"], test.projectDir, test.fakeHome);
+
+      expect(clean.exitCode).toBe(0);
+      expect(existsSync(join(skills, OWN_SKILL))).toBe(false);
+      expect(await readFile(foreign, "utf-8")).toBe(FOREIGN_SKILL);
+    } finally {
+      await test.cleanup();
+    }
+  });
+
+  it("sync --force restores a drifted skill it wrote and leaves a user skill and a user named hook as they were", async () => {
+    const test = await createTestEnv("sync-antigravity-foreign");
+    try {
+      const skills = join(test.projectDir, ".agents", "skills");
+      const hooksFile = join(test.projectDir, ".agents", "hooks.json");
+      const foreign = join(skills, "mine", "SKILL.md");
+      const own = join(skills, OWN_HOOKED_SKILL);
+
+      const setup = await runCli(
+        [
+          "setup",
+          "--source",
+          "local",
+          "--path",
+          FRAMEWORK_REAL_PATH,
+          "--ai",
+          "antigravity",
+          "--plugins",
+          "aidd-context",
+          "--yes",
+        ],
+        test.projectDir,
+        test.fakeHome
+      );
+      expect(setup.exitCode).toBe(0);
+      const installed = await readFile(own, "utf-8");
+      const hooks = JSON.parse(await readFile(hooksFile, "utf-8"));
+      expect(Object.keys(hooks)).toEqual(["aidd-context"]);
+      await writeFile(hooksFile, JSON.stringify({ ...hooks, lint: FOREIGN_HOOK }, null, 2));
+      await mkdir(join(skills, "mine"), { recursive: true });
+      await writeFile(foreign, FOREIGN_SKILL);
+      await writeFile(own, `${installed}drift\n`);
+
+      const sync = await runCli(["sync", "--force"], test.projectDir, test.fakeHome);
+
+      expect(sync.exitCode).toBe(0);
+      expect(await readFile(own, "utf-8")).toBe(installed);
+      expect(await readFile(foreign, "utf-8")).toBe(FOREIGN_SKILL);
+      // Restore unmerges then remerges its own key, so key order may move; content may not.
+      const restored = JSON.parse(await readFile(hooksFile, "utf-8"));
+      expect(restored).toEqual({ ...hooks, lint: FOREIGN_HOOK });
+    } finally {
+      await test.cleanup();
+    }
+  });
+});