Bazzite/SteamOS boxes flip between Steam Gaming Mode (gamescope) and a
KDE/GNOME desktop. The host statically read PUNKTFUNK_COMPOSITOR /
XDG_CURRENT_DESKTOP once, so switching to Desktop Mode failed the stream, and
the gamescope managed-session path stopped+relaunched the autologin per connect
— leaking GPU context on F44 (reconnect → black screen).
Replace the static read with a runtime probe of the live session and route each
connect to the right backend, churn-free:
- vdisplay::detect_active_session() probes /proc for the running compositor of
our uid (gamescope|kwin_wayland|gnome-shell|sway, desktop outranks a leftover
gamescope) + scans the runtime dir for the live wayland-* socket. Returns an
ActiveKind + the SessionEnv (WAYLAND_DISPLAY/XDG_RUNTIME_DIR/DBUS/
XDG_CURRENT_DESKTOP) that targets it.
- apply_session_env() writes that into the process env per connect (host serves
one session at a time), so every backend (capture + input) opens against the
live session; apply_input_env() points input at the matching backend and
selects gamescope ATTACH (no managed restart) unless PUNKTFUNK_GAMESCOPE_MANAGED.
- resolve_compositor() (native path) auto-detects + applies; explicit
PUNKTFUNK_COMPOSITOR still wins (legacy/CI/forcing). detect() is now
active-aware for the GameStream/mgmt callers too.
- Bazzite host.env drops the static gamescope force; documents auto-detection
+ the optional overrides.
Result: Desktop Mode → KWin/Mutter virtual output at the client's mode
(churn-free, the reliable path); Gaming Mode → attach to the running gamescope
(no SIGSEGV/GPU leak on reconnect). Compiles + clippy-clean; 78 host tests pass.
Live validation on the Bazzite box pending (box offline).
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
enricobuehler
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