feat: support goose mode in UI (#1434)

Co-authored-by: Lily Delalande <ldelalande@squareup.com>

crates/goose-server/src/state.rs

@@ -3,13 +3,13 @@ use goose::agents::Agent;
 use serde_json::Value;
 use std::collections::HashMap;
 use std::sync::Arc;
-use tokio::sync::Mutex;
+use tokio::sync::{Mutex, RwLock};
 
 /// Shared application state
 #[allow(dead_code)]
 #[derive(Clone)]
 pub struct AppState {
-    pub agent: Arc<Mutex<Option<Box<dyn Agent>>>>,
+    pub agent: Arc<RwLock<Option<Box<dyn Agent>>>>,
     pub secret_key: String,
     pub config: Arc<Mutex<HashMap<String, Value>>>,
 }
@@ -17,7 +17,7 @@ pub struct AppState {
 impl AppState {
     pub async fn new(secret_key: String) -> Result<Self> {
         Ok(Self {
-            agent: Arc::new(Mutex::new(None)),
+            agent: Arc::new(RwLock::new(None)),
             secret_key,
             config: Arc::new(Mutex::new(HashMap::new())),
         })