fix: prevent duplicate cron runs across hot reloads

src/cron/service/locked.ts

@@ -1,11 +1,22 @@
 import type { CronServiceState } from "./state.js";
 
-export async function locked<T>(state: CronServiceState, fn: () => Promise<T>): Promise<T> {
-  const next = state.op.then(fn, fn);
-  // Keep the chain alive even when the operation fails.
-  state.op = next.then(
+const storeLocks = new Map<string, Promise<void>>();
+
+const resolveChain = (promise: Promise<unknown>) =>
+  promise.then(
     () => undefined,
     () => undefined,
   );
+
+export async function locked<T>(state: CronServiceState, fn: () => Promise<T>): Promise<T> {
+  const storePath = state.deps.storePath;
+  const storeOp = storeLocks.get(storePath) ?? Promise.resolve();
+  const next = Promise.all([resolveChain(state.op), resolveChain(storeOp)]).then(fn);
+
+  // Keep the chain alive even when the operation fails.
+  const keepAlive = resolveChain(next);
+  state.op = keepAlive;
+  storeLocks.set(storePath, keepAlive);
+
   return (await next) as T;
 }