# Session-aware host — known limitations & follow-ups

Status: 2026-06-14. The host auto-detects the live session (Gaming / KDE / GNOME / wlroots) **per
connect** and routes both video and input at it — managed gamescope at the client's resolution in
Steam Gaming Mode, a KWin/Mutter virtual output at the client's resolution on a Desktop. A watcher
(opt-in: `PUNKTFUNK_SESSION_WATCH=1`) follows a Gaming↔Desktop switch **mid-stream** and rebuilds the
backend in place without a reconnect.

Live-validated on the Bazzite F44 box (`bazzite-deck-nvidia:testing`, RTX 4090): Desktop KDE at
5120×1440 + input; Gaming managed at 5120×1440; warm-session reuse on quick reconnect; Feature B
video-switch both directions.

## Resolved (2026-06-15, `3363576`)

- **#2 — mid-stream-switch input** ✅ `vdisplay::settle_desktop_portal()` pushes the live session env
  into the systemd/D-Bus activation environment and restarts the KWin portal on a switch, so input
  lands without a reconnect. Validated live: `settled desktop portal env … compositor=kwin` →
  `libei: portal granted devices` → `device RESUMED` on a Gaming→Desktop mid-stream switch.
- **#3 — KWin/Mutter virtual output primary** ✅ `apply_session_env` defaults
  `PUNKTFUNK_KWIN_VIRTUAL_PRIMARY` / `PUNKTFUNK_MUTTER_VIRTUAL_PRIMARY` on for the auto desktop path.
  Validated live: `KWin: streamed output set as the sole desktop also_disabled=["HDMI-A-1"]` — panels
  now render on the streamed screen.

## Still parked

### 1. F44 gamescope teardown corrupts the GPU context
Every gamescope teardown on this box (stop the autologin on connect; stop the managed session on
restore) risks leaking the NVIDIA GPU context — surfaces as `CUDA_ERROR_ILLEGAL_STATE` (401) in
`cuCtxCreate` / `vkCreateDevice` `VK_ERROR_INITIALIZATION_FAILED` (-3), then a black screen that
**needs a reboot**. The 5 s debounced restore + the desktop restore-guard cut the teardown *count*
but don't eliminate it. Options, in order of preference:
- **SIGKILL the gamescope on teardown** instead of `systemctl stop` (SIGTERM). Hypothesis: skipping
  gamescope's buggy SIGTERM teardown handler (the part that SIGSEGVs, exit 139) lets the process die
  hard and the driver reclaim its GPU resources cleanly via normal process exit — no half-torn-down
  context. Change `stop_autologin_sessions` + `stop_session` (`vdisplay/gamescope.rs`) to
  `systemctl --user kill --signal=SIGKILL <unit>` (+ a follow-up `stop`/`reset-failed` to clear unit
  state). **Untested** — this is the first thing to try; it would preserve "managed client-res
  gaming AND TV-shows-gaming-when-idle".
- **Keep the managed session warm** (no per-disconnect restore): spawn once, reuse forever, never
  tear down → ~1 teardown per host lifetime. Tradeoff: the TV is blank/idle when no client is
  connected (the autologin is never restored; return to gaming manually).
- Upstream gamescope/driver fix.

(#2 mid-stream-switch input and #3 virtual-output-primary are **resolved** — see the Resolved section above.)

## Lower priority / polish

### 4. Mid-stream-switch input loss window (~6 s)
During the libei portal setup on a switch, buffered input drops (`libei: DROP — no resumed device`,
hundreds of events). Polish: pre-warm the portal, or hold events instead of dropping during the
device-resume window.

### 5. NVENC `InitializeEncoder failed: invalid param` (recovered)
At 5120×1440@240 the first NVENC open fails with `invalid param (8)` and **recovers** via the 2-way
split-encode path (the stream is live). Cosmetic but noisy — investigate the first-attempt failure /
silence the log.

### 6. NVENC HEVC bitrate cap (~800 Mbps on the RTX 4090)
HEVC opens at the GPU's max (~800 Mbps) when a higher rate is requested (e.g. 1600). Not a bug;
consider preferring AV1 when the client requests >~800 Mbps HEVC, and surface the cap in the
speed-test / bitrate UI.

### 7. Restore-guard / keep-warm model interaction
`do_restore_tv_session`, when a desktop is active, still stops the idle managed gamescope (a teardown
— leak risk per #1) and consumes `STOPPED_AUTOLOGIN` (so a later return-to-gaming won't auto-restore
the TV session). Resolve together with the keep-warm decision in #1.

### 8. Feature B is opt-in
The mid-stream watcher is gated behind `PUNKTFUNK_SESSION_WATCH=1` pending broader validation. Promote
to default-on once #2 (mid-stream input) lands and it's exercised on more boxes.