A compositor pin silently vetoed dedicated game sessions — and a mid-bring-up mode switch was killing GNOME outright #121

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enricobuehler merged 1 commits from worktree-dedicated-session-pin-and-recovery into main 2026-08-08 15:38:40 +00:00

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Author	SHA1	Message	Date
enricobuehler	f23e0df64c	fix(host): a compositor pin silently vetoed dedicated game sessions ... `PUNKTFUNK_COMPOSITOR` is documented as "which backend to drive", but it also quietly discarded `game_session=dedicated`: `resolve_compositor` gated the dedicated route on `!overridden` and logged nothing either way. A host whose pin was a forgotten validation leftover therefore went on displaying "dedicated" in the console while every launch landed in the desktop instead — for 30 days on the box that surfaced this, the only evidence being the ABSENCE of a log line. The pin still wins, since it is the operator's explicit hand-set knob, but it now says so and names itself. Two further holes the same triage turned up: - The pin put its backend into `available()` unconditionally AND skipped `apply_session_env`'s `XDG_CURRENT_DESKTOP` scrub, so `pick_compositor` could never return `None` — the one place `try_recover_session()` is called from. A pinned host whose gnome-shell had segfaulted therefore spent every connect on 8 doomed `RemoteDesktop.CreateSession: ServiceUnknown` retries while the operator's configured `PUNKTFUNK_RECOVER_SESSION_CMD` sat unreachable behind that arm. Liveness is now read on both paths, and a pin aimed at a dead session takes the recovery exit with an error naming the pin. `needs_live_session()` exempts gamescope, which stands its own session up — pinning it on a headless box stays supported. - A mode switch accepted before the pipeline existed was served the long way round: build at the now-stale mode, then immediately rebuild at the new one in the stream loop. That burns a display create, capture attach and encoder open on every such connect, and because the rebuild is deliberately create-before-drop it stands up two Mutter `RecordVirtual` monitors ~400 ms apart — which segfaults mutter 50.4 inside `meta_monitor_manager_rebuild` and takes down the whole desktop session, along with the game just launched into it (so the GAME looks like what crashed). Bring-up now adopts the newest queued mode and builds once, carrying over the H2/H3 correction ack that the replaced rebuild would have sent. Verified on a real Linux host (192.168.1.21, x86_64): `cargo clippy --workspace --all-targets --locked -- -D warnings`, `cargo fmt --all --check` and the punktfunk-host + pf-vdisplay test suites all clean. The gate was proved non-vacuous against a planted `compile_error!`.	2026-08-08 17:37:02 +02:00