diff --git a/frontend/e2e/files-plugin.spec.js b/frontend/e2e/files-plugin.spec.js
index adcdac4..629f4f9 100644
--- a/frontend/e2e/files-plugin.spec.js
+++ b/frontend/e2e/files-plugin.spec.js
@@ -114,6 +114,24 @@ test.describe('G: Files Plugin', () => {
     await expect(page.locator('[data-file-name="bad"]')).toHaveCount(0);
   });
 
+  test('files explorer shows inline rename conflict errors', async ({ page }) => {
+    await page.locator('.wt-label').filter({ hasText: 'Project' }).click();
+    await openFilesTool(page);
+    await expect(page.locator('.files-breadcrumb')).toContainText('Project', { timeout: 10000 });
+
+    await page.locator('[data-file-name="project-only.txt"]').click();
+    await page.locator('[data-files-action="rename"]').click();
+    await page.locator('[data-files-rename-input]').fill('Notes');
+    await page.locator('[data-files-rename-confirm]').click();
+
+    await expect(page.locator('[data-files-rename-error]')).toBeVisible();
+    await expect(page.locator('[data-files-rename-error]')).toContainText('already exists');
+    await expect(page.locator('[data-files-rename-input]')).toBeVisible();
+    await expect(page.locator('[data-files-rename-input]')).toHaveValue('Notes');
+    await expect(page.locator('[data-file-name="project-only.txt"]')).toBeVisible();
+    await expect(page.locator('[data-file-name="Notes"]')).toBeVisible();
+  });
+
   test('files explorer shows inline create validation errors', async ({ page }) => {
     await page.locator('.wt-label').filter({ hasText: 'Project' }).click();
     await openFilesTool(page);
diff --git a/frontend/src/lib/test/wails-mock.js b/frontend/src/lib/test/wails-mock.js
index 50d4cbd..75e03d9 100644
--- a/frontend/src/lib/test/wails-mock.js
+++ b/frontend/src/lib/test/wails-mock.js
@@ -749,6 +749,10 @@
       function parent(path) { path = clean(path); var i = path.lastIndexOf('/'); return i < 0 ? '' : path.slice(0, i); }
       function ext(name) { var i = String(name || '').lastIndexOf('.'); return i > 0 ? name.slice(i + 1).toLowerCase() : ''; }
       function base(path) { path = clean(path); var i = path.lastIndexOf('/'); return i < 0 ? path : path.slice(i + 1); }
+      function isConflictError(err) {
+        var message = (err && err.message) ? err.message : String(err || '');
+        return /conflict|already exists|exists/i.test(message);
+      }
       function formatDate(value) {
         if (!value) return '';
         var date = new Date(value);
@@ -1064,7 +1068,10 @@
             if (newName === '.' || newName === '..' || newName[0] === ' ' || newName[newName.length - 1] === ' ' || newName[newName.length - 1] === '.') { setRenameError('Invalid name'); return; }
             var to = parent(renaming.relativePath);
             to = to ? to + '/' + newName : newName;
-            api.files.move(renaming.relativePath, to, { overwrite: false }).then(function () { cancelRename(); load(); }).catch(function (err) { setRenameError('Error: ' + ((err && err.message) ? err.message : String(err))); });
+            api.files.move(renaming.relativePath, to, { overwrite: false }).then(function () { cancelRename(); load(); }).catch(function (err) {
+              if (isConflictError(err)) { setRenameError('A file with that name already exists'); return; }
+              setRenameError('Error: ' + ((err && err.message) ? err.message : String(err)));
+            });
           }
           function confirmModal(message, options) {
             options = options || {};