diff --git a/crates/nuncio-gui/Cargo.toml b/crates/nuncio-gui/Cargo.toml
index 4f38d3a..d265dba 100644
--- a/crates/nuncio-gui/Cargo.toml
+++ b/crates/nuncio-gui/Cargo.toml
@@ -12,4 +12,7 @@ nuncio-mail = { path = "../nuncio-mail" }
 nuncio-cal = { path = "../nuncio-cal" }
 nuncio-store = { path = "../nuncio-store" }
 tokio.workspace = true
+serde.workspace = true
+serde_json.workspace = true
+thiserror.workspace = true
 tracing.workspace = true
diff --git a/crates/nuncio-gui/src/ipc.rs b/crates/nuncio-gui/src/ipc.rs
new file mode 100644
index 0000000..ddabd7e
--- /dev/null
+++ b/crates/nuncio-gui/src/ipc.rs
@@ -0,0 +1,100 @@
+//! Tauri IPC state bridge and command dispatch handlers.
+
+use nuncio_core::{AppState, CoreCommand, EventBus};
+use serde::{Deserialize, Serialize};
+
+/// Tauri IPC command payload wrapper.
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct IpcCommandPayload {
+    /// Action type name.
+    pub action: String,
+    /// Message ID if applicable.
+    pub message_id: Option<String>,
+    /// Read flag if applicable.
+    pub read: Option<bool>,
+}
+
+/// Tauri IPC bridge orchestrating communications between WebVIEW frontend and `EventBus`.
+pub struct IpcBridge;
+
+impl IpcBridge {
+    /// Retrieve current application state snapshot for WebVIEW initialization.
+    pub fn get_app_state(bus: &EventBus) -> AppState {
+        bus.current_state()
+    }
+
+    /// Process incoming IPC payload command.
+    pub fn handle_ipc_command(bus: &EventBus, payload: IpcCommandPayload) {
+        match payload.action.as_str() {
+            "sync" => bus.process_command(CoreCommand::SyncAll),
+            "mark_read" => {
+                if let Some(msg_id) = payload.message_id {
+                    let read_flag = payload.read.unwrap_or(true);
+                    bus.process_command(CoreCommand::MarkRead {
+                        message_id: msg_id,
+                        read: read_flag,
+                    });
+                }
+            }
+            "shutdown" => bus.process_command(CoreCommand::Shutdown),
+            _ => {}
+        }
+    }
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use nuncio_core::EngineStatus;
+
+    #[test]
+    fn ipc_handle_sync_command() {
+        let bus = EventBus::new();
+        let payload = IpcCommandPayload {
+            action: "sync".to_string(),
+            message_id: None,
+            read: None,
+        };
+
+        IpcBridge::handle_ipc_command(&bus, payload);
+        assert_eq!(IpcBridge::get_app_state(&bus).status, EngineStatus::Syncing);
+    }
+
+    #[test]
+    fn ipc_handle_mark_read_command() {
+        let bus = EventBus::with_initial_state(AppState {
+            unread_count: 5,
+            ..AppState::default()
+        });
+
+        let payload = IpcCommandPayload {
+            action: "mark_read".to_string(),
+            message_id: Some("msg-1".to_string()),
+            read: Some(true),
+        };
+
+        IpcBridge::handle_ipc_command(&bus, payload);
+        assert_eq!(IpcBridge::get_app_state(&bus).unread_count, 4);
+    }
+
+    #[test]
+    fn ipc_handle_shutdown_and_unknown() {
+        let bus = EventBus::new();
+
+        let payload = IpcCommandPayload {
+            action: "shutdown".to_string(),
+            message_id: None,
+            read: None,
+        };
+        IpcBridge::handle_ipc_command(&bus, payload);
+        assert_eq!(IpcBridge::get_app_state(&bus).status, EngineStatus::ShuttingDown);
+
+        // Unknown action does not panic
+        let unknown = IpcCommandPayload {
+            action: "unknown".to_string(),
+            message_id: None,
+            read: None,
+        };
+        IpcBridge::handle_ipc_command(&bus, unknown);
+    }
+}
diff --git a/crates/nuncio-gui/src/main.rs b/crates/nuncio-gui/src/main.rs
index e8be904..ec038df 100644
--- a/crates/nuncio-gui/src/main.rs
+++ b/crates/nuncio-gui/src/main.rs
@@ -1,8 +1,16 @@
-use nuncio_core::NuncioEngine;
+//! Nuncio GUI application entry point.
 
-#[tokio::main]
-async fn main() -> Result<(), Box<dyn std::error::Error>> {
-    let engine = NuncioEngine::new();
-    println!("Starting {} GUI desktop shell ({})", engine.name, engine.domain);
-    Ok(())
+mod ipc;
+
+use ipc::IpcBridge;
+use nuncio_core::EventBus;
+
+fn main() {
+    let bus = EventBus::new();
+    let state = IpcBridge::get_app_state(&bus);
+
+    println!(
+        "Nuncio GUI Desktop Shell Initialized: status={:?}, unread={}",
+        state.status, state.unread_count
+    );
 }