feat: vendor permission system source

pi-permission-system/test/async-cache.test.ts

@@ -0,0 +1,48 @@
+import { describe, expect, it, vi } from "vitest";
+
+import { memoizeAsyncWithRetry } from "#src/async-cache";
+
+describe("memoizeAsyncWithRetry", () => {
+  it("invokes the factory once and shares the resolved value across calls", async () => {
+    const factory = vi.fn<() => Promise<number>>().mockResolvedValue(42);
+    const memoized = memoizeAsyncWithRetry(factory);
+
+    const results = await Promise.all([memoized(), memoized(), memoized()]);
+
+    expect(results).toEqual([42, 42, 42]);
+    expect(factory).toHaveBeenCalledTimes(1);
+  });
+
+  it("caches the same promise instance on success", async () => {
+    const factory = vi.fn<() => Promise<string>>().mockResolvedValue("parser");
+    const memoized = memoizeAsyncWithRetry(factory);
+
+    await memoized();
+    await memoized();
+
+    expect(factory).toHaveBeenCalledTimes(1);
+  });
+
+  it("surfaces the rejection to the caller each time the factory fails", async () => {
+    const error = new Error("init failed");
+    const factory = vi.fn<() => Promise<number>>().mockRejectedValue(error);
+    const memoized = memoizeAsyncWithRetry(factory);
+
+    await expect(memoized()).rejects.toThrow("init failed");
+    await expect(memoized()).rejects.toThrow("init failed");
+  });
+
+  it("drops a rejected result so the next call re-invokes the factory", async () => {
+    const factory = vi
+      .fn<() => Promise<number>>()
+      .mockRejectedValueOnce(new Error("transient"))
+      .mockResolvedValue(7);
+    const memoized = memoizeAsyncWithRetry(factory);
+
+    await expect(memoized()).rejects.toThrow("transient");
+    const recovered = await memoized();
+
+    expect(recovered).toBe(7);
+    expect(factory).toHaveBeenCalledTimes(2);
+  });
+});