Field report: "on Bazzite when using gaming mode it is mirroring the main display
instead of giving the client its own." It is our own template that does it.
`packaging/bazzite/host.env` set `PUNKTFUNK_GAMESCOPE_ATTACH=1`, and every install
path — rpm, deb, Arch, nix — ships that file as `/usr/share/punktfunk/host.env.bazzite`
with the docs telling people to copy it verbatim. So the recommended Bazzite setup
turned the attach override ON for everyone.
That override is rung 2 of `pick_gamescope_mode`, ABOVE `dedicated_launch` at rung 3.
The rung comment calls the operator overrides a debug/CI escape hatch, which is right —
but we were shipping one as a distro default, so on a Bazzite box the managed takeover
and the dedicated game session were both unreachable. A game launched from a client's
library could not get a session of its own either, which is the case the dedicated
route exists for. With a physical display connected, attach then takes the
`physical_display_connected()` arm and streams the box's own head at the box's own
mode: the mirror the reporter saw.
The template now forces nothing and lets the per-connect detection answer, which on a
box with `gamescope-session-plus` is MANAGED. Attach stays available, documented as the
opt-in it is, with the mirror and the dedicated-session cost stated. Because managed
depends on the `punktfunk` group to stop the display manager, the template now says so
where someone choosing a model will read it, rather than only in the distro guide.
Also fixes the off-switch. Both overrides were read with `var_os(..).is_some()`, so
`PUNKTFUNK_GAMESCOPE_ATTACH=0` meant ATTACH ON — the opposite of what the line says,
and of every other knob on this host. They now use the shared `env_on` grammar, so
`0|false|off|no` disable and a bare `=1` keeps working. Anyone who "turned attach off"
in an older host.env had it on the whole time.
Note an upgrade never rewrites an existing `~/.config/punktfunk/host.env`, so boxes set
up from an older template keep the pin until the line is deleted by hand; the Bazzite
and HDR pages now say that.
Verified: `scripts/xcheck.sh linux` check + clippy `-D warnings` clean, pf-vdisplay
206/0 under rust:1.96, `cargo fmt --all --check` clean. Gate proved non-vacuous against
a planted `compile_error!` in routing.rs.
enricobuehler