feat: Flatpak tray, X11 dlopen window query, desktop menu entry

- Add system tray (vietc-tray) to Flatpak build; command changed to
  vietc-tray which spawns the daemon
- Desktop menu entry: Viet+ appears in app launcher for search/install/uninstall
- Tray fixes: find_sibling_binary tries {name}-daemon fallback for Flatpak;
  is_daemon_running checks both vietc and vietc-daemon process names
- Native X11 _NET_ACTIVE_WINDOW via dlopen(libX11.so.6) — third fallback in
  get_active_window_id() that works inside Flatpak sandbox (no xdotool/xprop)
- Update README with install/uninstall commands
- Update CHANGELOG

CHANGELOG.md

@@ -14,9 +14,16 @@
 - **Engine dead code removed** — unused methods `is_empty`, `is_tone_or_mark_key`, `process_string`, `last_base_char`, `apply_cluster_mark`, `apply_mark` in `BambooEngine`; `RuleEffect` enum and `special_rules` field in `InputMethodRules`.
 - **Production logging** — per-key `eprintln!` removed from evdev loop and uinput paste path. Only startup/error/window-change messages remain (`log_info` to both stderr and file).
 
-### Flatpak Build
+### Flatpak Build & System Tray
+- **System tray** (`vietc-tray` using ksni/DBus StatusNotifier) is now built and included in the Flatpak bundle. The tray launches the daemon and shows Vietnamese/English mode.
+- **Desktop menu entry** — the app now appears when searching **"Viet+"** in the application menu. Search, launch, or uninstall from there.
+- **Flatpak command** changed from `vietc-daemon` to `vietc-tray` (the tray spawns the daemon).
+- **Tray fixes for Flatpak** — `find_sibling_binary()` now tries `{name}-daemon` fallback; `is_daemon_running()` checks both `vietc` and `vietc-daemon` process names.
 - **Fixed `mkdir -p`** — `build-flatpak.sh` now creates `/app/share/applications` before installing the desktop file.
-- **Bundle**: `VietPlus-0.1.5.flatpak` (47 MB, runtime `org.gnome.Platform//50`). Warning-free build with default Rust profile (no `#![allow()]` needed).
+
+### Active Window Detection (Flatpak fix)
+- **Native X11 `_NET_ACTIVE_WINDOW` query** via `dlopen("libX11.so.6")` — added as third fallback in `get_active_window_id()`. Works inside the Flatpak sandbox where `xdotool`/`xprop` are unavailable. No subprocess, no external dependencies.
+- **Bundle**: `VietPlus-0.1.5.flatpak` (66 MB with tray, runtime `org.gnome.Platform//50`). Warning-free build.
 
 ---
 

README.md

@@ -270,10 +270,17 @@ Flexible typing: type the full syllable, then add marks/tone keys at the end. Ex
 
 ### Flatpak (recommended)
 
+System tray icon + daemon. Find **"Viet+"** in your app menu to launch, or run from terminal.
+
 ```bash
-# Download from the release page, then:
+# Install
 flatpak install --user --bundle VietPlus-x86_64.flatpak
+
+# Launch via app menu, or:
 flatpak run io.github.vietc.VietPlus
+
+# Uninstall
+flatpak uninstall --user io.github.vietc.VietPlus
 ```
 
 Includes daemon + CLI + system tray + uinput daemon. Sandboxed — no system libraries are touched.
@@ -294,7 +301,7 @@ flatpak install --user flathub org.gnome.Sdk//50
 flatpak install --user flathub org.freedesktop.Sdk.Extension.rust-stable//25.08
 ```
 
-The Flatpak build now produces a warning-free bundle (~47 MB compressed). No external runtime dependencies are needed — everything is sandboxed.
+The Flatpak bundle includes the system tray and desktop menu entry. Find **"Viet+"** in your app launcher to start it, or search for it to uninstall. Warning-free build — no `#![allow()]` needed.
 
 See `packaging/flatpak/FLATPAK_BUILD.md` for detailed build instructions.
 

daemon/src/app_state.rs

@@ -3,6 +3,114 @@ use std::collections::HashMap;
 use std::fs;
 use std::process::Command;
 
+/// Query _NET_ACTIVE_WINDOW directly via X11 client library (dlopen).
+/// Works inside the Flatpak sandbox where xdotool/xprop are unavailable
+/// but libX11.so.6 is present in the GNOME runtime.  No external process
+/// or subclassing needed — open display, query property, return hex ID.
+fn get_active_window_x11_dlopen() -> Option<String> {
+    unsafe {
+        let lib = libc::dlopen(
+            b"libX11.so.6\0".as_ptr() as *const libc::c_char,
+            libc::RTLD_LAZY,
+        );
+        if lib.is_null() {
+            return None;
+        }
+
+        type FnOpenDisplay =
+            unsafe extern "C" fn(*const libc::c_char) -> *mut libc::c_void;
+        type FnDefaultRoot =
+            unsafe extern "C" fn(*mut libc::c_void) -> u64;
+        type FnInternAtom = unsafe extern "C" fn(
+            *mut libc::c_void, *const libc::c_char, libc::c_int,
+        ) -> u64;
+        type FnGetProperty = unsafe extern "C" fn(
+            *mut libc::c_void, u64, u64, u64, u64, u64, libc::c_int,
+            *mut u64, *mut libc::c_int, *mut u64, *mut u64,
+            *mut *mut u8,
+        ) -> libc::c_int;
+        type FnFree = unsafe extern "C" fn(*mut libc::c_void) -> libc::c_int;
+        type FnCloseDisplay =
+            unsafe extern "C" fn(*mut libc::c_void) -> libc::c_int;
+
+        macro_rules! dlsym_fn {
+            ($lib:expr, $name:literal) => {
+                std::mem::transmute::<*mut libc::c_void, _>(libc::dlsym(
+                    $lib,
+                    concat!($name, "\0").as_ptr() as *const libc::c_char,
+                ))
+            };
+        }
+
+        let xopen: FnOpenDisplay = dlsym_fn!(lib, "XOpenDisplay");
+        let xroot: FnDefaultRoot = dlsym_fn!(lib, "XDefaultRootWindow");
+        let xatom: FnInternAtom = dlsym_fn!(lib, "XInternAtom");
+        let xgetprop: FnGetProperty = dlsym_fn!(lib, "XGetProperty");
+        let xfree: FnFree = dlsym_fn!(lib, "XFree");
+        let xclosedpy: FnCloseDisplay = dlsym_fn!(lib, "XCloseDisplay");
+
+        let dpy = xopen(std::ptr::null());
+        if dpy.is_null() {
+            libc::dlclose(lib);
+            return None;
+        }
+
+        let root = xroot(dpy);
+        let net_active = xatom(
+            dpy,
+            b"_NET_ACTIVE_WINDOW\0".as_ptr() as *const libc::c_char,
+            0,
+        );
+
+        // XA_WINDOW = 33 (the standard X11 atom for Window type)
+        let xa_window: u64 = 33;
+        let mut actual_type: u64 = 0;
+        let mut actual_format: libc::c_int = 0;
+        let mut nitems: u64 = 0;
+        let mut bytes_after: u64 = 0;
+        let mut data: *mut u8 = std::ptr::null_mut();
+
+        let status = xgetprop(
+            dpy,
+            root,
+            net_active,
+            xa_window,
+            0,    // offset
+            1,    // length
+            0,    // delete
+            &mut actual_type,
+            &mut actual_format,
+            &mut nitems,
+            &mut bytes_after,
+            &mut data,
+        );
+
+        let result = if status != 0
+            && !data.is_null()
+            && nitems > 0
+            && actual_format == 32
+        {
+            // Format=32 elements are returned as unsigned long arrays
+            let id = *(data as *const u64);
+            if id != 0 {
+                Some(format!("0x{:x}", id))
+            } else {
+                None
+            }
+        } else {
+            None
+        };
+
+        if !data.is_null() {
+            xfree(data as *mut libc::c_void);
+        }
+        xclosedpy(dpy);
+        libc::dlclose(lib);
+
+        result
+    }
+}
+
 /// Get the active window's X11 ID (unique per window — even within the same
 /// application).  Returns a unique window-identifier string.
 pub fn get_active_window_id() -> Option<String> {
@@ -36,6 +144,11 @@ pub fn get_active_window_id() -> Option<String> {
         }
     }
 
+    // Final fallback: direct X11 client library query (works in Flatpak sandbox)
+    if let Some(id) = get_active_window_x11_dlopen() {
+        return Some(id);
+    }
+
     None
 }
 

packaging/flatpak/build-flatpak.sh

@@ -24,10 +24,10 @@ BUILD='export PATH=/usr/lib/sdk/rust-stable/bin:$PATH
 export CARGO_HOME=/app/cargo
 cd /app/src/vietc'
 
-# Build daemon + CLI + uinputd
+# Build daemon + CLI + uinputd + tray
 echo ""
-echo "=== Compiling daemon, CLI, uinputd... ==="
-flatpak build --share=network build-dir sh -c "$BUILD && cargo build --release -p vietc-daemon -p vietc-cli -p vietc-uinputd"
+echo "=== Compiling daemon, CLI, uinputd, tray... ==="
+flatpak build --share=network build-dir sh -c "$BUILD && cargo build --release -p vietc-daemon -p vietc-cli -p vietc-uinputd && cargo build --release --manifest-path ui/Cargo.toml"
 
 # Install files
 echo ""
@@ -37,6 +37,7 @@ set -e
 install -Dm755 /app/src/vietc/target/release/vietc /app/bin/vietc-daemon
 install -Dm755 /app/src/vietc/target/release/vietc-cli /app/bin/vietc-cli
 install -Dm755 /app/src/vietc/target/release/vietc-uinputd /app/bin/vietc-uinputd
+install -Dm755 /app/src/vietc/ui/target/release/vietc-tray /app/bin/vietc-tray
 
 install -Dm644 /app/src/vietc/packaging/icons/vietc.svg /app/share/icons/hicolor/scalable/apps/io.github.vietc.VietPlus.svg
 install -Dm644 /app/src/vietc/packaging/icons/vietc-vn.svg /app/share/icons/hicolor/scalable/apps/io.github.vietc.VietPlus.vietc-vn.svg
@@ -47,7 +48,7 @@ install -Dm644 /app/src/vietc/packaging/icons/vietc-vn.svg /app/share/icons/hico
 [Desktop Entry]
 Name=Viet+
 Comment=Vietnamese Input Method
-Exec=/app/bin/vietc-daemon
+Exec=/app/bin/vietc-tray
 Icon=io.github.vietc.VietPlus
 Terminal=false
 Type=Application
@@ -85,7 +86,7 @@ flatpak build-finish build-dir \
   --talk-name=org.freedesktop.Notifications \
   --talk-name=org.a11y.Bus \
   --talk-name=org.freedesktop.portal.Clipboard \
-  --command=vietc-daemon
+  --command=vietc-tray
 
 # Export
 echo ""
@@ -104,3 +105,4 @@ echo "Size: $(du -h "$SCRIPT_DIR/VietPlus-${VERSION}.flatpak" | cut -f1)"
 echo ""
 echo "Install: flatpak install --user --bundle VietPlus-${VERSION}.flatpak"
 echo "Run:     flatpak run io.github.vietc.VietPlus"
+echo "Search:  'Viet+' in app menu"

ui/src/main.rs

@@ -12,20 +12,31 @@ fn exe_dir() -> PathBuf {
 }
 
 fn find_sibling_binary(name: &str) -> String {
-    let sibling = exe_dir().join(name);
+    let dir = exe_dir();
+    // Try exact name (e.g. "vietc" outside Flatpak)
+    let sibling = dir.join(name);
     if sibling.exists() {
         return sibling.to_string_lossy().into_owned();
     }
+    // Try name-daemon (e.g. "vietc-daemon" inside Flatpak)
+    let daemon = dir.join(format!("{}-daemon", name));
+    if daemon.exists() {
+        return daemon.to_string_lossy().into_owned();
+    }
     name.to_string()
 }
 
 fn is_daemon_running() -> bool {
+    // Check both "vietc" (outside Flatpak) and "vietc-daemon" (inside Flatpak)
+    let check = |name: &str| -> bool {
         std::process::Command::new("pgrep")
             .arg("-x")
-        .arg("vietc")
+            .arg(name)
             .status()
             .map(|s| s.success())
             .unwrap_or(false)
+    };
+    check("vietc") || check("vietc-daemon")
 }
 
 fn needs_root() -> bool {