docs(self-hosted): note worker-file deploy limitation (#5429) + extract currentDir

Extract currentDir in WorkerTaskService for readability, and add pointers to issue #5429
(standalone server build must externalize the worker-file packages) next to both runtime
sidecar-file loaders (background-tasks worker, scheduler bree pollWorker).

Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>

Author: adrians5j

packages/api-scheduler-server/src/BreeSchedulerService.ts

@@ -9,6 +9,9 @@ import {
 } from "@webiny/api-scheduler/shared/abstractions.js";
 import type { Logger } from "@webiny/api-core/features/logger/abstractions.js";
 
+// bree loads this worker file at runtime, resolved relative to this module's own dist. Works in
+// `webiny watch`; shipping a standalone server build requires externalizing this package so the
+// worker travels in node_modules — tracked in https://github.com/webiny/webiny-js/issues/5429.
 const jobsDir = join(dirname(fileURLToPath(import.meta.url)), "jobs");
 const workerPath = join(jobsDir, "pollWorker.js");
 

packages/background-tasks-server/src/service/WorkerTaskService.ts

@@ -46,12 +46,12 @@ class WorkerServiceImpl implements TaskService.Interface {
         // ("/static/assets/workerEntry.<hash>.js") that `new Worker()` can't load as a filesystem
         // path. `path.join` off `import.meta.url` (which resolves to this file inside dist) is left
         // untouched by the bundler and points at the real, node-resolvable dist worker.
-        const workerPath = path.join(
-            path.dirname(fileURLToPath(import.meta.url)),
-            "..",
-            "worker",
-            "workerEntry.js"
-        );
+        //
+        // NOTE: this works in `webiny watch` (dist resolves via the monorepo). Shipping a standalone
+        // server build requires this package to be externalized so the worker file travels in
+        // node_modules — tracked in https://github.com/webiny/webiny-js/issues/5429.
+        const currentDir = path.dirname(fileURLToPath(import.meta.url));
+        const workerPath = path.join(currentDir, "..", "worker", "workerEntry.js");
         const worker = new Worker(workerPath);
 
         const handle: WorkerHandle = {