Directory picker returns 403 via 127.0.0.1 but works via localhost

[tree201]

Environment

• macOS
• Running DeepSeek Harness Web UI locally from source

Reproduction

1. Start the Web UI with pnpm dsh web.
2. Open http://127.0.0.1:3080.
3. Click Select workspace and choose a directory.

Actual behavior

The directory picker fails before the native dialog opens:

Unable to open folder
transport failure for /api/host.pickDirectory: HTTP 403

Screenshot: the Web UI shows the Chinese message 无法打开文件夹 (Unable to open folder) with the same host.pickDirectory HTTP 403 transport failure.

Expected behavior

The native directory picker should open for a loopback address.

Comparison

Opening the same local server through http://localhost:3080 works normally: the directory picker opens and a workspace can be selected.

Both 127.0.0.1 and localhost appear to be accepted loopback hosts, so this may be a host/origin trust-fence discrepancy. It would also help to document localhost:3080 as the recommended URL if this difference is intentional.

[xw901103]

it is a known problem for now.

[tree201]

like this