Compose window uses absolute /compose URL path instead of relative path

[tonyg]

Site

(self hosted)

Version

2025.06.12.43d0d1e

Instance

(self hosted)

Browser

Firefox 139.0.1 aarch64 on MacOs

Bug description

With phanpy unpacked into ~/public_html, I access it via https://MACHINE/~USERNAME/phanpy/. Opening the compose panel and then clicking the "pop out" icon to transform it into a standalone window produces a new window on https://MACHINE/compose/, where it should open on https://MACHINE/~USERNAME/phanpy/compose/.

To reproduce

1. Unpack static distribution of phanpy into some non-root URL path of your host. Log in etc.
2. Open the compose panel
3. Click the pop-out icon
4. New window opens on https://MACHINE/compose/

Expected behavior

New window on https://MACHINE/~USERNAME/phanpy/compose/

Other

No response