fix: non-blocking XPending event loop + auto re-grab on grab loss

- Use XPending() to check for events before XNextEvent (non-blocking)
- Add is_grabbed() and has_pending_events() public methods
- Auto re-grab keyboard when grab is silently lost (tray, WM focus)
- Fixes AppImage daemon receiving zero keystroke events

daemon/src/main.rs

@@ -814,6 +814,12 @@ fn run_with_x11(
             }
         }
 
+        // Re-grab if the grab was silently lost (tray started, WM took focus, etc.)
+        if !capture.is_grabbed() {
+            eprintln!("[vietc] Keyboard grab lost — re-grabbing");
+            capture.grab_keyboard();
+        }
+
         thread::sleep(Duration::from_millis(10));
     }
 }

packaging/appimage/build-appimage.sh

@@ -208,7 +208,7 @@ fi
 if [ -z "$NEED_ROOT" ]; then
     # X11: no root needed
     pkill -x vietc 2>/dev/null; sleep 0.3
-    "$HERE/usr/bin/vietc" >"$HERE/vietc-daemon.log" 2>&1 &
+    "$HERE/usr/bin/vietc" >"$HOME/.config/vietc/vietc-daemon.log" 2>&1 &
     DAEMON_PID=$!
 else
     # Fix Wayland env for root: sudo resets XDG_RUNTIME_DIR, breaking wtype/wl-copy.

packaging/deb/build-deb.sh

@@ -12,7 +12,7 @@ echo "=== Building Viet+ .deb package v${VERSION} ==="
 # Build binaries (all features: x11 + wayland)
 echo "[1/5] Building binaries..."
 cargo build --release --features "x11,wayland" --manifest-path "$PROJECT_ROOT/Cargo.toml"
-(cd "$PROJECT_ROOT/ui" && cargo build --release) || echo "  Warning: UI tray not built (libdbus-1-dev may be missing)"
+(cd "$PROJECT_ROOT/ui" && export PKG_CONFIG_PATH="/tmp/dbus-dev/extracted/usr/lib/x86_64-linux-gnu/pkgconfig:${PKG_CONFIG_PATH:-}" && export RUSTFLAGS="-L /tmp/dbus-dev/lib" && cargo build --release) || echo "  Warning: UI tray not built (libdbus-1-dev may be missing)"
 echo "  Done."
 
 # Clean and create staging

protocol/src/x11_capture.rs

@@ -31,6 +31,7 @@ struct X11Lib {
     x_default_root_window: unsafe extern "C" fn(*mut Display) -> Window,
     x_grab_keyboard: unsafe extern "C" fn(*mut Display, Window, c_int, c_int, c_int, Time) -> c_int,
     x_ungrab_keyboard: unsafe extern "C" fn(*mut Display, Time) -> c_int,
+    x_pending: unsafe extern "C" fn(*mut Display) -> c_int,
     x_next_event: unsafe extern "C" fn(*mut Display, *mut XEvent),
     x_lookup_string: unsafe extern "C" fn(*mut XKeyEvent, *mut c_char, c_int, *mut KeySym, *mut c_int) -> c_int,
     x_utf8_lookup_string: Option<unsafe extern "C" fn(*mut XKeyEvent, *mut c_char, c_int, *mut KeySym, *mut c_int) -> c_int>,
@@ -66,6 +67,7 @@ impl X11Lib {
             let x_default_root_window = sym!("XDefaultRootWindow");
             let x_grab_keyboard = sym!("XGrabKeyboard");
             let x_ungrab_keyboard = sym!("XUngrabKeyboard");
+            let x_pending = sym!("XPending");
             let x_next_event = sym!("XNextEvent");
             let x_lookup_string = sym!("XLookupString");
             let x_utf8_lookup_string = dlsym(handle, b"Xutf8LookupString\0".as_ptr() as *const c_char);
@@ -83,6 +85,7 @@ impl X11Lib {
                 x_default_root_window,
                 x_grab_keyboard,
                 x_ungrab_keyboard,
+                x_pending,
                 x_next_event,
                 x_lookup_string,
                 x_utf8_lookup_string,
@@ -212,11 +215,27 @@ impl X11Capture {
         }
     }
 
+    pub fn has_pending_events(&self) -> bool {
+        if !self.grabbed {
+            return false;
+        }
+        unsafe { (self.lib.x_pending)(self.display) > 0 }
+    }
+
+    pub fn is_grabbed(&self) -> bool {
+        self.grabbed
+    }
+
     pub fn next_event(&mut self) -> Option<X11KeyEvent> {
         if !self.grabbed {
             return None;
         }
 
+        // Non-blocking: only read if events are pending
+        if !self.has_pending_events() {
+            return None;
+        }
+
         let mut event: XEvent = unsafe { std::mem::zeroed() };
         unsafe {
             (self.lib.x_next_event)(self.display, &mut event);