diff --git a/packages/vscode/e2e/lint/suite-ancestor/ancestor.test.ts b/packages/vscode/e2e/lint/suite-ancestor/ancestor.test.ts
index f5d91a3d..40b0fd18 100644
--- a/packages/vscode/e2e/lint/suite-ancestor/ancestor.test.ts
+++ b/packages/vscode/e2e/lint/suite-ancestor/ancestor.test.ts
@@ -46,6 +46,38 @@ suite('rslint config above the workspace folder', function () {
       diagnosticRuleIdIncludes(diagnostic, 'no-debugger'),
     );
 
+  // On macOS, Node's directory `fs.watch` runs on one FSEventStream per
+  // process, and libuv destroys and recreates that stream (from
+  // `kFSEventStreamEventIdSinceNow`) whenever a directory watcher starts or
+  // stops. VS Code's non-recursive watchers share one watcher process, so an
+  // edit made while any other directory watcher starts can be lost by all of
+  // them. Startup still churns watchers right after the first diagnostics (Go
+  // registers its own ancestor watchers only once initialized), and macOS CI
+  // lost the first edit there: the diagnostics never changed. Writing the same
+  // content again, as a user saving twice would, re-signals the edit. The
+  // diagnostics must still follow the file within the overall timeout.
+  async function writeConfigUntilDiagnostics(
+    document: vscode.TextDocument,
+    filePath: string,
+    content: string,
+    predicate: (diagnostics: vscode.Diagnostic[]) => boolean,
+  ): Promise<void> {
+    const deadline = Date.now() + 60_000;
+    for (;;) {
+      fs.writeFileSync(filePath, content);
+      try {
+        await waitForDiagnostics(
+          document,
+          predicate,
+          Math.max(0, Math.min(10_000, deadline - Date.now())),
+        );
+        return;
+      } catch (error) {
+        if (Date.now() >= deadline) throw error;
+      }
+    }
+  }
+
   teardown(async () => {
     fs.rmSync(nearerConfigPath(), { force: true });
     fs.writeFileSync(rootConfigPath(), configWithNoDebugger('error'));
@@ -56,14 +88,19 @@ suite('rslint config above the workspace folder', function () {
     const document = await openIndex();
     await waitForDiagnostics(document, hasNoDebugger);
 
-    fs.writeFileSync(rootConfigPath(), configWithNoDebugger('off'));
-    await waitForDiagnostics(
+    await writeConfigUntilDiagnostics(
       document,
+      rootConfigPath(),
+      configWithNoDebugger('off'),
       (diagnostics) => !hasNoDebugger(diagnostics),
     );
 
-    fs.writeFileSync(rootConfigPath(), configWithNoDebugger('error'));
-    await waitForDiagnostics(document, hasNoDebugger);
+    await writeConfigUntilDiagnostics(
+      document,
+      rootConfigPath(),
+      configWithNoDebugger('error'),
+      hasNoDebugger,
+    );
   });
 
   // The live runtime keeps its key; the extension's ancestor watchers send
diff --git a/packages/vscode/package.json b/packages/vscode/package.json
index 1c096ff9..08e2ba3b 100644
--- a/packages/vscode/package.json
+++ b/packages/vscode/package.json
@@ -445,7 +445,7 @@
     "@vscode/test-electron": "^3.1.0",
     "@vscode/vsce": "^3.9.2",
     "birpc": "^4.2.0",
-    "core-js-pure": "^3.50.0",
+    "core-js-pure": "^3.51.0",
     "mocha": "^11.8.0",
     "ovsx": "^1.3.0",
     "picomatch": "^4.0.7",
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 7f5a18a4..5adab70e 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -60,8 +60,8 @@ importers:
         specifier: ^4.2.0
         version: 4.2.0
       core-js-pure:
-        specifier: ^3.50.0
-        version: 3.50.0
+        specifier: ^3.51.0
+        version: 3.51.0
       mocha:
         specifier: ^11.8.0
         version: 11.8.0
@@ -1503,8 +1503,8 @@ packages:
   commander@2.20.3:
     resolution: {integrity: sha512-GpVkmM8vF2vQUkj2LvZmD35JxeJOLCwJ9cUkugyk2nuhbv3+mJvpLYYt+0+USMxE+oj+ey/lJEnhZw75x/OMcQ==}
 
-  core-js-pure@3.50.0:
-    resolution: {integrity: sha512-6GP3Pxz4IKyWjAfa747vIu/jilB5z29JWROLqH/b+pXVcpgh6tM06ZIBwSuglgVqzDYURhOK6oEzTrG0bCHitA==}
+  core-js-pure@3.51.0:
+    resolution: {integrity: sha512-NE4SFDJ+qzQeqHG2vVSNwopzS6zZNPYJ5kinIqs+OofTqGzOmICgT89E/yvS9XY7rwb3eU1utWXTJ9nVFqv74A==}
 
   core-util-is@1.0.3:
     resolution: {integrity: sha512-ZQBvi1DcpJ4GDqanjucZ2Hj3wEO5pZDS89BWbkcrvdxksJorwUDDZamX9ldFkp9aw2lmBDLgkObEA4DWNJ9FYQ==}
@@ -4233,7 +4233,7 @@ snapshots:
 
   commander@2.20.3: {}
 
-  core-js-pure@3.50.0: {}
+  core-js-pure@3.51.0: {}
 
   core-util-is@1.0.3: {}