Fixes#24127
On headless Linux VPS (no DISPLAY or WAYLAND_DISPLAY), some Python
webbrowser backends register TUI programs such as links, lynx, or
www-browser. GenericBrowser.open() spawns these without redirecting
stdin/stdout, allowing them to take over the terminal. This can cause
the process to receive SIGHUP and exit immediately even though uvicorn
bound the port successfully, producing a misleading success message
followed by an empty --status.
Fix: detect headless Linux at startup and skip the auto-open when no
display server is available. On such systems the URL is still printed
so the user can open it manually or via an SSH tunnel. The webbrowser
call is also wrapped in a try/except so any unexpected failure on other
platforms is silently absorbed rather than surfacing as an unhandled
exception in the daemon thread.
e3858772d0