gamescope keeps the pointer out of its PipeWire node — it lives on a hardware
plane for scanout, and `paint_pipewire()` composites a separate, reduced frame
that never includes it. So punktfunk has always reconstructed it from XFixes
and blended it in host-side.
That blend is what has been blocking the zero-CSC encode path, and the cost is
larger than it sounds: `VulkanVideoEncoder::open` refuses the RGB-direct (EFC)
source for any session with `cursor_blend`, because that front end is
fixed-function and has no blend stage. `cursor_blend_for` sets it
unconditionally for gamescope. Net effect: a gamescope session paid a
full-frame colour-conversion pass per frame, forever, for a pointer.
So put the cursor where it belongs. A second carried gamescope patch adds
`--pipewire-composite-cursor` (off by default — the node has never carried it,
and a consumer that draws its own would get two), painting it with the same
`MouseCursor::paint` call the scanout composite uses. It scales for free:
paint_pipewire has already set `currentOutputWidth/Height` to the capture size,
which is what that function scales against. The repaint test grows the cursor's
state beside the commit ids — a pointer-only move produces no commit, so
without it the composited cursor would freeze on a static screen while the real
one moved, and a cursor that became hidden would never be erased.
Host side, the `+pfhdr` marker becomes a monotonic PATCH LEVEL, so one probe
answers every capability the session must know before it is planned (level 1 =
HDR formats, level 2 = the cursor flag). `cursor_blend_for` and the
`gamescope_cursor` resolver both consult it through one helper, because they
have to agree: the reader without the blend is a wasted X11 connection, the
blend without the reader is a stream with no pointer, and both together with a
gamescope that paints its own would draw two.
⚠ The two indirect spawn modes carry the flag through `PF_HDR_ARGS`, so this
shares a dependency with the HDR flags: a session that ignores
`GAMESCOPE_BIN`/`PATH` and execs the distro's gamescope gets neither. HDR fails
loudly there (negotiation timeout + SDR latch); a missing cursor would be
silent. Noted in packaging/gamescope/README.md as worth a post-spawn
`/proc/<pid>/cmdline` check if it ever bites.
enricobuehler
fd648aa776