fix(cua-driver/linux): report dead input backend on KDE/GNOME Wayland instead of silent no-op (#1982)

libs/cua-driver/rust/crates/platform-linux/src/health_report.rs

@@ -281,6 +281,29 @@ async fn check_wayland_backend() -> CheckEntry {
             format!("All wlroots manager globals advertised ({msg})."),
         );
     }
+    // Input-injection backend check (#1982). A non-wlroots compositor
+    // (KWin/Plasma, Mutter/GNOME) advertises no zwlr_virtual_pointer; on those
+    // the ONLY working input path is libei via xdg-desktop-portal. If this
+    // binary was built without `portal-libei` (the published tarball is — see
+    // #1967), input injection has no backend and silently no-ops: the agent
+    // cursor renders but clicks/keys are never delivered, while list_windows
+    // and capture still work. Report that explicitly instead of the misleading
+    // "input may fall back" partial-pass below.
+    if !snap.virtual_pointer && !crate::wayland::PORTAL_LIBEI_ENABLED {
+        return CheckEntry::fail(
+            NAME_WAYLAND_BACKEND,
+            format!(
+                "Input injection has no backend on this compositor ({msg}): it \
+                 advertises no zwlr_virtual_pointer and this build was compiled \
+                 without libei/portal support, so clicks and key presses will not \
+                 be delivered (the agent cursor still renders). list_windows and \
+                 screen capture are unaffected."
+            ),
+            "Use the portal-enabled Linux build (compiled with --features \
+             portal-libei) for input on KDE Plasma / GNOME, or a wlroots \
+             compositor (sway, labwc, hyprland) where zwlr_virtual_pointer exists.",
+        );
+    }
     // Partial-pass: list_windows + capture both work, but virtual-pointer
     // input is missing. Require `wl_shm` here too — `check_screen_capture_capability`
     // gates on both `screencopy && wl_shm`, so excluding `wl_shm` from the

libs/cua-driver/rust/crates/platform-linux/src/wayland/mod.rs

@@ -26,6 +26,16 @@ pub mod portal_screencast;
 #[cfg(feature = "portal-libei")]
 pub mod libei;
 
+/// Whether this binary was compiled with the `portal-libei` feature — the
+/// xdg-desktop-portal RemoteDesktop + libei input path. It is the ONLY input
+/// backend that works on non-wlroots compositors (KWin/Plasma, Mutter/GNOME),
+/// which do not implement `zwlr_virtual_pointer_v1`. The published
+/// curl-pipe-bash tarball is built WITHOUT it (#1967 — debian:11 CD container
+/// lacks a new-enough PipeWire/libei), so on those compositors input injection
+/// has no backend and silently no-ops. Consulted by the doctor and the input
+/// dispatch so that failure is reported instead of hidden. See #1982.
+pub const PORTAL_LIBEI_ENABLED: bool = cfg!(feature = "portal-libei");
+
 use std::collections::HashMap;
 
 use wayland_client::{
@@ -786,10 +796,22 @@ pub fn open_vptr_session(activate_window_id: Option<u32>) -> anyhow::Result<Vptr
         .seat
         .clone()
         .ok_or_else(|| anyhow::anyhow!("compositor exposed no wl_seat for virtual-pointer input"))?;
-    let mgr = state
-        .vptr_manager
-        .clone()
-        .ok_or_else(|| anyhow::anyhow!("compositor does not expose zwlr_virtual_pointer_manager_v1"))?;
+    let mgr = state.vptr_manager.clone().ok_or_else(|| {
+        if PORTAL_LIBEI_ENABLED {
+            anyhow::anyhow!("compositor does not expose zwlr_virtual_pointer_manager_v1")
+        } else {
+            // KWin/Plasma and Mutter/GNOME don't implement zwlr_virtual_pointer,
+            // and this build has no libei/portal fallback — so input has no
+            // backend at all rather than silently no-op'ing. See #1982.
+            anyhow::anyhow!(
+                "no input backend for this compositor: it exposes no \
+                 zwlr_virtual_pointer_manager_v1 and this build was compiled \
+                 without libei/portal support (#1982). Use the portal-enabled \
+                 Linux build for input on KDE Plasma / GNOME, or a wlroots \
+                 compositor (sway, labwc, hyprland)."
+            )
+        }
+    })?;
 
     if let Some(id) = activate_window_id {
         let handle = state