fix(files): harden drag-and-drop uploads

Co-authored-by: Serhii Dziupin <serkraser@gmail.com>

Co-authored-by: Alan Chen <2144783+alanzchen@users.noreply.github.com>

packages/ui/src/lib/fileContentInvalidation.test.ts

@@ -0,0 +1,38 @@
+import { describe, expect, test } from 'bun:test';
+
+import {
+  notifyFileContentInvalidated,
+  subscribeToFileContentInvalidation,
+} from './fileContentInvalidation';
+
+describe('fileContentInvalidation', () => {
+  test('publishes normalized paths within the captured runtime', () => {
+    const received: Array<{ runtimeKey: string; paths: readonly string[] }> = [];
+    const unsubscribe = subscribeToFileContentInvalidation((invalidation) => {
+      received.push(invalidation);
+    });
+
+    notifyFileContentInvalidated({
+      runtimeKey: ' runtime-a ',
+      paths: [' /repo/a.txt ', '/repo/a.txt', '', '/repo/b.txt'],
+    });
+    unsubscribe();
+
+    expect(received).toEqual([{
+      runtimeKey: 'runtime-a',
+      paths: ['/repo/a.txt', '/repo/b.txt'],
+    }]);
+  });
+
+  test('stops publishing after unsubscribe', () => {
+    let calls = 0;
+    const unsubscribe = subscribeToFileContentInvalidation(() => {
+      calls += 1;
+    });
+    unsubscribe();
+
+    notifyFileContentInvalidated({ runtimeKey: 'runtime-a', paths: ['/repo/a.txt'] });
+
+    expect(calls).toBe(0);
+  });
+});

packages/ui/src/lib/fileContentInvalidation.ts

@@ -0,0 +1,25 @@
+type FileContentInvalidation = {
+  runtimeKey: string;
+  paths: readonly string[];
+};
+
+type FileContentInvalidationListener = (invalidation: FileContentInvalidation) => void;
+
+const listeners = new Set<FileContentInvalidationListener>();
+
+export const notifyFileContentInvalidated = (invalidation: FileContentInvalidation): void => {
+  const runtimeKey = invalidation.runtimeKey.trim();
+  const paths = Array.from(new Set(invalidation.paths.map((path) => path.trim()).filter(Boolean)));
+  if (!runtimeKey || paths.length === 0) return;
+
+  for (const listener of listeners) {
+    listener({ runtimeKey, paths });
+  }
+};
+
+export const subscribeToFileContentInvalidation = (
+  listener: FileContentInvalidationListener,
+): (() => void) => {
+  listeners.add(listener);
+  return () => listeners.delete(listener);
+};