feat: add retry with exponential backoff for file send/download

- withRetry helper: configurable maxAttempts, baseDelayMs, shouldRetry
- sendFile: upload and message send wrapped with 3 retries, 1s/2s/4s backoff
- downloadMessageFile: wrapped with 3 retries
- Add unit tests (6) for retry behavior and sendFile retry integration

hub/test/unit/feishu-retry.test.ts

@@ -0,0 +1,163 @@
+import { afterEach, beforeEach, describe, expect, it, vi, type Mock } from "vitest";
+import { mkdtemp, rm, writeFile } from "node:fs/promises";
+import { tmpdir } from "node:os";
+import { join } from "node:path";
+import { sendFile, withRetry, type FeishuRuntime } from "../../src/feishu/client.js";
+
+describe("withRetry", () => {
+  beforeEach(() => {
+    vi.useFakeTimers();
+  });
+
+  afterEach(() => {
+    vi.restoreAllMocks();
+    vi.useRealTimers();
+  });
+
+  it("succeeds on first attempt without delaying", async () => {
+    const setTimeoutSpy = vi.spyOn(globalThis, "setTimeout");
+    const fn = vi.fn(async () => "ok");
+
+    await expect(withRetry(fn)).resolves.toBe("ok");
+
+    expect(fn).toHaveBeenCalledTimes(1);
+    expect(setTimeoutSpy).not.toHaveBeenCalled();
+  });
+
+  it("retries on failure then succeeds", async () => {
+    const fn = vi.fn()
+      .mockRejectedValueOnce(new Error("temporary failure"))
+      .mockResolvedValueOnce("ok");
+
+    const result = withRetry(fn);
+    await Promise.resolve();
+
+    expect(fn).toHaveBeenCalledTimes(1);
+
+    await vi.advanceTimersByTimeAsync(1000);
+
+    await expect(result).resolves.toBe("ok");
+    expect(fn).toHaveBeenCalledTimes(2);
+  });
+
+  it("exhausts all attempts and rethrows", async () => {
+    const error = new Error("still failing");
+    const fn = vi.fn(async () => {
+      throw error;
+    });
+
+    const result = withRetry(fn);
+    const assertion = expect(result).rejects.toBe(error);
+    await Promise.resolve();
+
+    await vi.advanceTimersByTimeAsync(1000);
+    await vi.advanceTimersByTimeAsync(2000);
+
+    await assertion;
+    expect(fn).toHaveBeenCalledTimes(3);
+  });
+
+  it("respects shouldRetry predicate", async () => {
+    const error = new Error("validation failure");
+    const setTimeoutSpy = vi.spyOn(globalThis, "setTimeout");
+    const shouldRetry = vi.fn(() => false);
+    const fn = vi.fn(async () => {
+      throw error;
+    });
+
+    await expect(withRetry(fn, { shouldRetry })).rejects.toBe(error);
+
+    expect(fn).toHaveBeenCalledTimes(1);
+    expect(shouldRetry).toHaveBeenCalledWith(error);
+    expect(setTimeoutSpy).not.toHaveBeenCalled();
+  });
+
+  it("uses exponential backoff delays", async () => {
+    const setTimeoutSpy = vi.spyOn(globalThis, "setTimeout");
+    const fn = vi.fn()
+      .mockRejectedValueOnce(new Error("first failure"))
+      .mockRejectedValueOnce(new Error("second failure"))
+      .mockResolvedValueOnce("ok");
+
+    const result = withRetry(fn);
+    await Promise.resolve();
+    await vi.advanceTimersByTimeAsync(1000);
+    await vi.advanceTimersByTimeAsync(2000);
+
+    await expect(result).resolves.toBe("ok");
+    expect(setTimeoutSpy.mock.calls.map(([, delay]) => delay)).toEqual([1000, 2000]);
+  });
+});
+
+describe("sendFile retry", () => {
+  afterEach(() => {
+    vi.useRealTimers();
+  });
+
+  it("retries upload on transient failure", async () => {
+    const dir = await mkdtemp(join(tmpdir(), "hub-feishu-retry-"));
+    try {
+      const file = join(dir, "student.pdf");
+      await writeFile(file, "pdf bytes");
+
+      let failFirstUpload: (error: Error) => void = () => {
+        throw new Error("upload rejection was not initialized");
+      };
+      const firstUpload = new Promise<never>((_resolve, reject) => {
+        failFirstUpload = reject;
+      });
+      const fileCreate = vi.fn()
+        .mockReturnValueOnce(firstUpload)
+        .mockResolvedValueOnce({ data: { file_key: "file-key-1" } });
+      const messageCreate = vi.fn(async () => ({ data: { message_id: "message-1" } }));
+      const rt = mockRuntime({ fileCreate, messageCreate });
+
+      const result = sendFile(rt, "chat-1", file, "student.pdf");
+      await waitForCalls(fileCreate, 1);
+      vi.useFakeTimers();
+      failFirstUpload(new Error("temporary upload failure"));
+      await Promise.resolve();
+      await vi.advanceTimersByTimeAsync(1000);
+
+      await expect(result).resolves.toBe("message-1");
+      expect(fileCreate).toHaveBeenCalledTimes(2);
+      expect(messageCreate).toHaveBeenCalledTimes(1);
+    } finally {
+      vi.useRealTimers();
+      await rm(dir, { recursive: true, force: true });
+    }
+  });
+});
+
+async function waitForCalls(mock: Mock, expectedCalls: number): Promise<void> {
+  for (let attempt = 0; attempt < 50; attempt += 1) {
+    if (mock.mock.calls.length >= expectedCalls) return;
+    await new Promise((resolve) => setTimeout(resolve, 0));
+  }
+  throw new Error(`Timed out waiting for mock to be called ${expectedCalls} time(s)`);
+}
+
+function mockRuntime(options: {
+  readonly fileCreate: (payload: unknown) => Promise<unknown>;
+  readonly messageCreate: (payload: unknown) => Promise<unknown>;
+}): FeishuRuntime {
+  return {
+    client: {
+      im: {
+        v1: {
+          file: { create: options.fileCreate },
+          message: { create: options.messageCreate },
+        },
+      },
+    } as unknown as FeishuRuntime["client"],
+    logger: {
+      info() {},
+      warn() {},
+      error() {},
+      debug() {},
+      fatal() {},
+      child() { return this; },
+      level: "silent",
+    } as unknown as FeishuRuntime["logger"],
+  };
+}