feat(core): bump default watch aggregateTimeout to 100ms; drop fixture overrides

rstest used to default rspack's `watchOptions.aggregateTimeout` to 5ms
(see Watching.ts comment). That was safe under the chokidar watcher
where the aggregate is just a watchpack-level event-merging window,
but is too aggressive under the rspack native watcher on macOS: the
runtime stats the changed file ~5ms after the FSEvent arrives, well
inside the vnode-cache settling window, and reads stale content. The
resulting "No test files need re-run" is the failure mode addressed by
this PR.

Set the default to 100ms in the rstest plugin so every watch project
inherits a sane value without each fixture wiring its own override.
Drop the per-fixture `tools.rspack.watchOptions.aggregateTimeout: 10`
that was added long ago (chokidar era). Individual cases that need a
different value can still set it via `tools.rspack.watchOptions` and
the user value wins through rsbuild's regular merge order.

Author: stormslowly

e2e/filter/fixtures-related-dynamic/rstest.config.mts

@@ -1,11 +1,3 @@
 import { defineConfig } from '@rstest/core';
 
-export default defineConfig({
-  tools: {
-    rspack: {
-      watchOptions: {
-        aggregateTimeout: 100,
-      },
-    },
-  },
-});
+export default defineConfig({});

e2e/watch/fixtures-dynamic/rstest.config.mts

@@ -1,11 +1,3 @@
 import { defineConfig } from '@rstest/core';
 
-export default defineConfig({
-  tools: {
-    rspack: {
-      watchOptions: {
-        aggregateTimeout: 100,
-      },
-    },
-  },
-});
+export default defineConfig({});

e2e/watch/fixtures-setup/rstest.config.mts

@@ -4,11 +4,4 @@ export default defineConfig({
   passWithNoTests: true,
   setupFiles: ['./rstest.setup.ts'],
   exclude: ['**/node_modules/**', '**/dist/**'],
-  tools: {
-    rspack: {
-      watchOptions: {
-        aggregateTimeout: 100,
-      },
-    },
-  },
 });

e2e/watch/fixtures-shortcuts/rstest.config.mts

@@ -6,11 +6,4 @@ process.stdin.setRawMode = () => process.stdin;
 export default defineConfig({
   reporters: ['default'],
   disableConsoleIntercept: true,
-  tools: {
-    rspack: {
-      watchOptions: {
-        aggregateTimeout: 100,
-      },
-    },
-  },
 });

e2e/watch/fixtures/rstest.config.mts

@@ -1,11 +1,3 @@
 import { defineConfig } from '@rstest/core';
 
-export default defineConfig({
-  tools: {
-    rspack: {
-      watchOptions: {
-        aggregateTimeout: 100,
-      },
-    },
-  },
-});
+export default defineConfig({});

packages/core/src/core/plugins/entry.ts

@@ -56,8 +56,14 @@ export const pluginEntryWatch: (params: {
         };
 
         config.watchOptions ??= {};
-        // FIXME: Temporarily default to 5 to debounce rerun in watch mode.
-        config.watchOptions.aggregateTimeout = 5;
+        // Default aggregate window for watch-mode rerun debouncing. On macOS
+        // with the rspack native watcher this also needs to be long enough
+        // for the FSEvent → vnode cache invalidation cycle to complete
+        // before rspack stats the changed file (otherwise the rebuild reads
+        // stale content and rstest reports "No test files need re-run").
+        // 100 ms is the minimum value that survives macos-14 GHA runners.
+        // User configs can override via `tools.rspack.watchOptions`.
+        config.watchOptions.aggregateTimeout = 100;
         // TODO: rspack should support `(string | RegExp)[]` type
         // https://github.com/web-infra-dev/rspack/issues/10596
         config.watchOptions.ignored = castArray(

packages/core/tests/core/__snapshots__/rsbuild.test.ts.snap

@@ -2256,7 +2256,7 @@ exports[`prepareRsbuild > should generate rspack config correctly in watch mode
   },
   "target": "node",
   "watchOptions": {
-    "aggregateTimeout": 5,
+    "aggregateTimeout": 100,
     "ignored": [
       "**/.git",
       "**/node_modules",