[vincentkoc]

FreeBSD runtime URL-scheme registration currently returns UnsupportedPlatform. Enable the existing XDG implementation for register, unregister, and is_registered, including its dependency and error gates. FreeBSD selects the current executable; Linux retains its AppImage handling.

Validation on exact signed refreshed head 4244c2e34da55dc56fb155b52bcea48ef514168f, which merges frozen upstream 8882934230c903e03d56021669bc146be7a117b7:

• Linux and FreeBSD: locked all-targets tests/build passed; xdg_registration was explicitly executed with --ignored --exact and passed on each platform.
• The actual plugin and installed xdg-mime/update-desktop-database run with isolated HOME/XDG directories. The case checks repeated registration, multiple schemes, executable quoting, and preserving another handler's defaults. Parent/child summaries describe one named case, not two independent tests.
• This proves registration state, not GUI launch or an existing desktop session. CLI intake and existing-instance delivery remain separate in fix(deep-link): handle configured CLI URLs on FreeBSD #3582 and fix(single-instance): enable the D-Bus backend on FreeBSD #3580.

Rust and Cargo 1.98.1; Linux x86_64 and native FreeBSD 15.1 amd64. Locked resolution is unchanged before/after each job (Cargo.lock SHA-256 c72f7a8948c4a9d65d3bb0c527391587b05f93cca3f285a9aa078b975f0d326d). Original report manifests, command results, and source inventories were independently verified. These are component tests, not a GUI/session or release qualification.

XDG command-error/association handling is a separate patch in #3585. Related: openclaw/openclaw#45233.

[FabianLars]

Excuse my lack of knowledge but is FreeBSD enough to consider other BSD versions to work as well and add them here the same?
Or should we wait for someone who can actually test on these systems.