fix: harden webhook reliability, fix bugs, add test suite

- Statuspage webhook always returns 200 to prevent subscriber removal
- Fix parseKvKey returning string chatId instead of number
- Queue consumer retries on Telegram 5xx instead of acking (prevents message loss)
- Fix observability top-level enabled flag (false → true)
- Add defensive null checks for webhook payload body
- Cache Bot instance per isolate to avoid middleware rebuild per request
- Add vitest + @cloudflare/vitest-pool-workers with 31 tests
- Document DLQ and KV sharding as declined features

test/queue-consumer.test.js

@@ -0,0 +1,79 @@
+import { describe, it, expect, vi, beforeEach } from "vitest";
+import { handleQueue } from "../src/queue-consumer.js";
+
+/**
+ * Create a mock queue message with ack/retry tracking
+ */
+function mockMessage(body) {
+  return {
+    body,
+    ack: vi.fn(),
+    retry: vi.fn(),
+  };
+}
+
+describe("handleQueue", () => {
+  let env;
+
+  beforeEach(() => {
+    env = {
+      BOT_TOKEN: "test-token",
+      claude_status: {
+        delete: vi.fn(),
+      },
+    };
+    vi.restoreAllMocks();
+  });
+
+  it("acks on successful send", async () => {
+    vi.stubGlobal("fetch", vi.fn().mockResolvedValue({ ok: true, status: 200 }));
+    const msg = mockMessage({ chatId: 123, html: "<b>test</b>" });
+    await handleQueue({ messages: [msg] }, env);
+    expect(msg.ack).toHaveBeenCalled();
+    expect(msg.retry).not.toHaveBeenCalled();
+  });
+
+  it("removes subscriber and acks on 403", async () => {
+    vi.stubGlobal("fetch", vi.fn().mockResolvedValue({ ok: false, status: 403 }));
+    const msg = mockMessage({ chatId: 123, threadId: null, html: "<b>test</b>" });
+    await handleQueue({ messages: [msg] }, env);
+    expect(msg.ack).toHaveBeenCalled();
+    expect(env.claude_status.delete).toHaveBeenCalled();
+  });
+
+  it("retries on 429 rate limit", async () => {
+    vi.stubGlobal(
+      "fetch",
+      vi.fn().mockResolvedValue({
+        ok: false,
+        status: 429,
+        headers: new Headers({ "Retry-After": "5" }),
+      })
+    );
+    const msg = mockMessage({ chatId: 123, html: "<b>test</b>" });
+    await handleQueue({ messages: [msg] }, env);
+    expect(msg.retry).toHaveBeenCalled();
+    expect(msg.ack).not.toHaveBeenCalled();
+  });
+
+  it("retries on 5xx server error", async () => {
+    vi.stubGlobal("fetch", vi.fn().mockResolvedValue({ ok: false, status: 502 }));
+    const msg = mockMessage({ chatId: 123, html: "<b>test</b>" });
+    await handleQueue({ messages: [msg] }, env);
+    expect(msg.retry).toHaveBeenCalled();
+    expect(msg.ack).not.toHaveBeenCalled();
+  });
+
+  it("retries on network error", async () => {
+    vi.stubGlobal("fetch", vi.fn().mockRejectedValue(new Error("network fail")));
+    const msg = mockMessage({ chatId: 123, html: "<b>test</b>" });
+    await handleQueue({ messages: [msg] }, env);
+    expect(msg.retry).toHaveBeenCalled();
+  });
+
+  it("skips malformed messages", async () => {
+    const msg = mockMessage({ chatId: null, html: null });
+    await handleQueue({ messages: [msg] }, env);
+    expect(msg.ack).toHaveBeenCalled();
+  });
+});