feat(core): Introduce Message enum for async communication

crates/app/cli/src/main.rs

@@ -1,4 +1,5 @@
 mod commands;
+mod messages;
 
 use clap::{Parser, ValueEnum};
 use color_eyre::eyre::{Result, eyre};

crates/app/cli/src/messages.rs

@@ -0,0 +1,49 @@
+use serde::{Deserialize, Serialize};
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum Message {
+    UserAction(UserAction),
+    AgentResponse(AgentResponse),
+    System(SystemNotification),
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum UserAction {
+    Input(String),
+    Command(String),
+    Exit,
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum AgentResponse {
+    Token(String),
+    ToolCall { name: String, args: String },
+    Complete,
+    Error(String),
+}
+
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub enum SystemNotification {
+    StateUpdate(String), 
+    Warning(String),
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use tokio::sync::mpsc;
+
+    #[tokio::test]
+    async fn test_message_channel() {
+        let (tx, mut rx) = mpsc::channel(32);
+
+        let msg = Message::UserAction(UserAction::Input("Hello".to_string()));
+        tx.send(msg).await.unwrap();
+
+        let received = rx.recv().await.unwrap();
+        match received {
+            Message::UserAction(UserAction::Input(s)) => assert_eq!(s, "Hello"),
+            _ => panic!("Wrong message type"),
+        }
+    }
+}