feat: add Cron Triggers support to module framework

- modules may declare crons: [{ schedule, name, handler }]
- handler signature (event, { db, sql, env }) matches init context
- scheduled() export in src/index.js dispatches to matching handlers with fan-out and per-handler error isolation
- registry validates cron entries and collects into registry.crons
- wrangler.toml [triggers] crons must still be populated manually by module author

tests/modules/cron-dispatcher.test.js

@@ -0,0 +1,126 @@
+import { beforeEach, describe, expect, it, vi } from "vitest";
+import { dispatchScheduled } from "../../src/modules/cron-dispatcher.js";
+import { makeFakeKv } from "../fakes/fake-kv-namespace.js";
+
+// ---------------------------------------------------------------------------
+// Helpers
+// ---------------------------------------------------------------------------
+
+function makeFakeRegistry(entries) {
+  return { crons: entries };
+}
+
+function makeModule(name) {
+  return { name };
+}
+
+function makeCronEntry(moduleName, schedule, name, handler) {
+  return { module: makeModule(moduleName), schedule, name, handler };
+}
+
+function makeFakeCtx() {
+  const promises = [];
+  return {
+    ctx: { waitUntil: (p) => promises.push(p) },
+    flush: () => Promise.all(promises),
+  };
+}
+
+function makeFakeEnv() {
+  return { KV: makeFakeKv(), DB: null, MODULES: "test" };
+}
+
+// ---------------------------------------------------------------------------
+// Tests
+// ---------------------------------------------------------------------------
+
+describe("dispatchScheduled", () => {
+  it("calls handler for matching schedule", async () => {
+    const called = [];
+    const handler = vi.fn(async () => called.push("ran"));
+    const reg = makeFakeRegistry([makeCronEntry("mod", "0 1 * * *", "nightly", handler)]);
+    const { ctx, flush } = makeFakeCtx();
+
+    dispatchScheduled({ cron: "0 1 * * *" }, makeFakeEnv(), ctx, reg);
+    await flush();
+
+    expect(handler).toHaveBeenCalledOnce();
+    expect(called).toEqual(["ran"]);
+  });
+
+  it("does NOT call handler when schedule does not match", async () => {
+    const handler = vi.fn();
+    const reg = makeFakeRegistry([makeCronEntry("mod", "0 2 * * *", "other", handler)]);
+    const { ctx, flush } = makeFakeCtx();
+
+    dispatchScheduled({ cron: "0 1 * * *" }, makeFakeEnv(), ctx, reg);
+    await flush();
+
+    expect(handler).not.toHaveBeenCalled();
+  });
+
+  it("fan-out: two modules sharing same schedule both fire", async () => {
+    const callLog = [];
+    const handlerA = async () => callLog.push("a");
+    const handlerB = async () => callLog.push("b");
+    const reg = makeFakeRegistry([
+      makeCronEntry("mod-a", "*/5 * * * *", "tick-a", handlerA),
+      makeCronEntry("mod-b", "*/5 * * * *", "tick-b", handlerB),
+    ]);
+    const { ctx, flush } = makeFakeCtx();
+
+    dispatchScheduled({ cron: "*/5 * * * *" }, makeFakeEnv(), ctx, reg);
+    await flush();
+
+    expect(callLog.sort()).toEqual(["a", "b"]);
+  });
+
+  it("error isolation: one handler throwing does not prevent others", async () => {
+    const callLog = [];
+    const failing = async () => {
+      throw new Error("boom");
+    };
+    const surviving = async () => callLog.push("survived");
+    const reg = makeFakeRegistry([
+      makeCronEntry("mod-a", "0 0 * * *", "fail", failing),
+      makeCronEntry("mod-b", "0 0 * * *", "ok", surviving),
+    ]);
+    const { ctx, flush } = makeFakeCtx();
+    const consoleSpy = vi.spyOn(console, "error").mockImplementation(() => {});
+
+    dispatchScheduled({ cron: "0 0 * * *" }, makeFakeEnv(), ctx, reg);
+    await flush();
+
+    expect(callLog).toEqual(["survived"]);
+    expect(consoleSpy).toHaveBeenCalledOnce();
+    expect(consoleSpy.mock.calls[0][0]).toMatch(/cron.*fail.*mod-a/);
+    consoleSpy.mockRestore();
+  });
+
+  it("passes event and { db, sql, env } to handler", async () => {
+    let received;
+    const handler = async (event, handlerCtx) => {
+      received = { event, handlerCtx };
+    };
+    const env = makeFakeEnv();
+    const reg = makeFakeRegistry([makeCronEntry("mod", "0 3 * * *", "ctx-check", handler)]);
+    const { ctx, flush } = makeFakeCtx();
+    const fakeEvent = { cron: "0 3 * * *", scheduledTime: 123 };
+
+    dispatchScheduled(fakeEvent, env, ctx, reg);
+    await flush();
+
+    expect(received.event).toBe(fakeEvent);
+    expect(typeof received.handlerCtx.db).toBe("object");
+    expect(typeof received.handlerCtx.sql).toBe("object");
+    expect(received.handlerCtx.env).toBe(env);
+  });
+
+  it("no-op when registry has no cron entries", async () => {
+    const reg = makeFakeRegistry([]);
+    const { ctx, flush } = makeFakeCtx();
+    // Should not throw.
+    expect(() => dispatchScheduled({ cron: "0 1 * * *" }, makeFakeEnv(), ctx, reg)).not.toThrow();
+    await flush();
+  });
+});