Linux distribution strategy: one portable binary vs. desktop + feature coverage (umbrella)

Problem

cua-driver's Linux release aims to be a single curl-pipe-bash binary that works across X11/Wayland and XFCE/GNOME/KDE. Two compatibility axes pull against each other:

1. Runtime desktop adaptation — solvable in one binary. Detect the session and pick the path (x11rb/libxcb on X11, zwlr_virtual_pointer on wlroots Wayland, libei via xdg-desktop-portal on KWin/Mutter). The per-desktop CI runners (gnome/kde/xfce/sway) exist to verify this, not to build variants.

2. Build/ABI compatibility — the hard part. What the binary links against:

• glibc floor — build on the oldest supported distro so it runs everywhere newer (resolved: #1919, was #1925).
• libxcb — hard-linking it makes it a runtime requirement; this is what #1978 / #1991 touched and likely why #1991's CI went red. Decide: hard-link vs dlopen.
• libpipewire + libei (portal-libei) — need newer versions than the debian:11 CD container has; can't bump the container's glibc without breaking axis-1 broad-distro support (#1967 gated this OFF).

The core conflict

You cannot build one binary with both a low glibc floor and libei/PipeWire input. So today the published binary ships without portal-libei → KDE/GNOME Wayland input silently fails (#1982).

Work required (checklist)

• Decide the strategy: two build variants (…-portable low-glibc/no-portal + …-portal newer-glibc/full) with install.sh glibc-sniff, vs. an alternative (static musl? vendored libs? dlopen-everything?)
• CD: produce the second (portal-libei) variant; install.sh selects by host glibc
• libxcb: hard-link vs dlopen decision (unblocks #1991 / #1978 without making libxcb a hard runtime dep)
• Make KDE/GNOME Wayland input actually work in a shipped artifact (closes #1982)
• Guard the CD/publish path against silent failures (#1969)
• Document the support matrix (distro × desktop × feature)

Related

#1982 (KDE/GNOME input — blocked on this), #1978 / #1991 (libxcb), #1967 (portal-libei gate), #1919 / #1925 (glibc floor), #1922 (native-Wayland deps), #1969 (CD race).