fix(telegram): add sendChatAction 401 backoff guard (land #27415, thanks @widingmarcus-cyber)

Co-authored-by: Marcus Widing <widing.marcus@gmail.com>

src/telegram/sendchataction-401-backoff.test.ts

@@ -0,0 +1,145 @@
+import { describe, expect, it, vi } from "vitest";
+import { createTelegramSendChatActionHandler } from "./sendchataction-401-backoff.js";
+
+// Mock the backoff sleep to avoid real delays in tests
+vi.mock("../infra/backoff.js", async (importOriginal) => {
+  const actual = await importOriginal<typeof import("../infra/backoff.js")>();
+  return {
+    ...actual,
+    sleepWithAbort: vi.fn().mockResolvedValue(undefined),
+  };
+});
+
+describe("createTelegramSendChatActionHandler", () => {
+  const make401Error = () => new Error("401 Unauthorized");
+  const make500Error = () => new Error("500 Internal Server Error");
+
+  it("calls sendChatActionFn on success", async () => {
+    const fn = vi.fn().mockResolvedValue(true);
+    const logger = vi.fn();
+    const handler = createTelegramSendChatActionHandler({
+      sendChatActionFn: fn,
+      logger,
+    });
+
+    await handler.sendChatAction(123, "typing");
+    expect(fn).toHaveBeenCalledWith(123, "typing", undefined);
+    expect(handler.isSuspended()).toBe(false);
+  });
+
+  it("applies exponential backoff on consecutive 401 errors", async () => {
+    const fn = vi.fn().mockRejectedValue(make401Error());
+    const logger = vi.fn();
+    const handler = createTelegramSendChatActionHandler({
+      sendChatActionFn: fn,
+      logger,
+      maxConsecutive401: 5,
+    });
+
+    // First call fails with 401
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("401");
+    expect(handler.isSuspended()).toBe(false);
+
+    // Second call should mention backoff in logs
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("401");
+    expect(logger).toHaveBeenCalledWith(expect.stringContaining("backoff"));
+  });
+
+  it("suspends after maxConsecutive401 failures", async () => {
+    const fn = vi.fn().mockRejectedValue(make401Error());
+    const logger = vi.fn();
+    const handler = createTelegramSendChatActionHandler({
+      sendChatActionFn: fn,
+      logger,
+      maxConsecutive401: 3,
+    });
+
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("401");
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("401");
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("401");
+
+    expect(handler.isSuspended()).toBe(true);
+    expect(logger).toHaveBeenCalledWith(expect.stringContaining("CRITICAL"));
+
+    // Subsequent calls are silently skipped
+    await handler.sendChatAction(123, "typing");
+    expect(fn).toHaveBeenCalledTimes(3); // not called again
+  });
+
+  it("resets failure counter on success", async () => {
+    let callCount = 0;
+    const fn = vi.fn().mockImplementation(() => {
+      callCount++;
+      if (callCount <= 2) {
+        throw make401Error();
+      }
+      return Promise.resolve(true);
+    });
+    const logger = vi.fn();
+    const handler = createTelegramSendChatActionHandler({
+      sendChatActionFn: fn,
+      logger,
+      maxConsecutive401: 5,
+    });
+
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("401");
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("401");
+    // Third call succeeds
+    await handler.sendChatAction(123, "typing");
+
+    expect(handler.isSuspended()).toBe(false);
+    expect(logger).toHaveBeenCalledWith(expect.stringContaining("recovered"));
+  });
+
+  it("does not count non-401 errors toward suspension", async () => {
+    const fn = vi.fn().mockRejectedValue(make500Error());
+    const logger = vi.fn();
+    const handler = createTelegramSendChatActionHandler({
+      sendChatActionFn: fn,
+      logger,
+      maxConsecutive401: 2,
+    });
+
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("500");
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("500");
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("500");
+
+    expect(handler.isSuspended()).toBe(false);
+  });
+
+  it("reset() clears suspension", async () => {
+    const fn = vi.fn().mockRejectedValue(make401Error());
+    const logger = vi.fn();
+    const handler = createTelegramSendChatActionHandler({
+      sendChatActionFn: fn,
+      logger,
+      maxConsecutive401: 1,
+    });
+
+    await expect(handler.sendChatAction(123, "typing")).rejects.toThrow("401");
+    expect(handler.isSuspended()).toBe(true);
+
+    handler.reset();
+    expect(handler.isSuspended()).toBe(false);
+  });
+
+  it("is shared across multiple chatIds (global handler)", async () => {
+    const fn = vi.fn().mockRejectedValue(make401Error());
+    const logger = vi.fn();
+    const handler = createTelegramSendChatActionHandler({
+      sendChatActionFn: fn,
+      logger,
+      maxConsecutive401: 3,
+    });
+
+    // Different chatIds all contribute to the same failure counter
+    await expect(handler.sendChatAction(111, "typing")).rejects.toThrow("401");
+    await expect(handler.sendChatAction(222, "typing")).rejects.toThrow("401");
+    await expect(handler.sendChatAction(333, "typing")).rejects.toThrow("401");
+
+    expect(handler.isSuspended()).toBe(true);
+    // Suspended for all chats
+    await handler.sendChatAction(444, "typing");
+    expect(fn).toHaveBeenCalledTimes(3);
+  });
+});