fix(core): make @rstest/core tree-shakeable and fix runCli changed flag

- Convert the worker `setup` side-effect module into an explicit
  `installGracefulExit()` call so `@rstest/core` is safe to mark
  `sideEffects: false`. Tree-shaking consumers can now drop unused
  `loadConfig`/`mergeRstestConfig`/`mergeProjectConfig` together with the
  `@rsbuild/core` -> `@rspack/core` graph they value-import, while worker
  entries still opt in to the SIGTERM profiling handler.
- Drop an explicit `changed: false` before building `runCli()` options
  (mirrors `toCommonOptions`), so `isRelatedRun` no longer treats it as
  changed-mode and `runCli({ changed: false })` runs the full suite.

Author: fi3ework

packages/core/package.json

@@ -18,6 +18,7 @@
     "directory": "packages/core"
   },
   "license": "MIT",
+  "sideEffects": false,
   "type": "module",
   "exports": {
     ".": {

packages/core/src/api/index.ts

@@ -587,6 +587,14 @@ export async function runCli(
   const { _: positionals, ...commonOptions } = argv;
   const filters = positionals ?? [];
 
+  // `isRelatedRun` treats any defined `changed` as changed-mode. An embedder
+  // forwarding parsed argv with boolean defaults (`changed: false`) would then
+  // wrongly run only git-changed tests / reject positional filters, so drop the
+  // explicit `false` here the same way `toCommonOptions` does for `run()`.
+  if (commonOptions.changed === false) {
+    commonOptions.changed = undefined;
+  }
+
   return executeHostSafeRun(async () => {
     // Match the CLI's environment setup so workers (spawned per run) observe
     // `NODE_ENV=test` / `RSTEST=true`. Run it *inside* the guarded section so the

packages/core/src/runtime/worker/globalSetupWorker.ts

@@ -1,8 +1,10 @@
-import './setup';
 import { install } from 'source-map-support';
 import type { FormattedError } from '../../types';
 import { color } from '../../utils/logger';
 import { formatTestError } from '../util';
+import { installGracefulExit } from './setup';
+
+installGracefulExit();
 
 let teardownCallbacks: (() => Promise<void> | void)[] = [];
 // Track environment variable changes

packages/core/src/runtime/worker/index.ts

@@ -1,4 +1,3 @@
-import './setup';
 import { isMainThread } from 'node:worker_threads';
 import {
   isWorkerRequestEnvelope,
@@ -10,6 +9,9 @@ import {
 import { ENV } from '../../utils/env';
 import { channel } from './channels';
 import { runInPool } from './runInPool';
+import { installGracefulExit } from './setup';
+
+installGracefulExit();
 
 const send = (response: WorkerResponse): void => {
   channel.send(wrapWorkerResponse(response));

packages/core/src/runtime/worker/setup.ts

@@ -1,16 +1,22 @@
-const gracefulExit: boolean = process.execArgv.some(
-  (execArg) =>
-    execArg.startsWith('--perf') ||
-    execArg.startsWith('--prof') ||
-    execArg.startsWith('--cpu-prof') ||
-    execArg.startsWith('--heap-prof') ||
-    execArg.startsWith('--diagnostic-dir'),
-);
+// Registered via an explicit call (not a bare `import './setup'`) so the module
+// carries no import-time side effect — this keeps `@rstest/core` safe to mark
+// `sideEffects: false` for tree-shaking consumers while the worker entries still
+// opt in by calling `installGracefulExit()`.
+export function installGracefulExit(): void {
+  const gracefulExit = process.execArgv.some(
+    (execArg) =>
+      execArg.startsWith('--perf') ||
+      execArg.startsWith('--prof') ||
+      execArg.startsWith('--cpu-prof') ||
+      execArg.startsWith('--heap-prof') ||
+      execArg.startsWith('--diagnostic-dir'),
+  );
 
-if (gracefulExit) {
-  // gracefully handle SIGTERM to generate CPU profile
-  // https://github.com/nodejs/node/issues/55094
-  process.on('SIGTERM', () => {
-    process.exit();
-  });
+  if (gracefulExit) {
+    // gracefully handle SIGTERM to generate CPU profile
+    // https://github.com/nodejs/node/issues/55094
+    process.on('SIGTERM', () => {
+      process.exit();
+    });
+  }
 }