feat(goose-acp): enable parallel sessions with isolated agent state (#6392)

Signed-off-by: Adrian Cole <adrian@tetrate.io>

crates/goose/src/agents/schedule_tool.rs

@@ -20,20 +20,13 @@ impl Agent {
         arguments: serde_json::Value,
         _request_id: String,
     ) -> ToolResult<Vec<Content>> {
-        let scheduler = self
-            .scheduler_service
-            .lock()
-            .await
-            .as_ref()
-            .ok_or_else(|| {
-                ErrorData::new(
-                    ErrorCode::INTERNAL_ERROR,
-                    "Scheduler service should be available when schedule tool is called"
-                        .to_string(),
-                    None,
-                )
-            })?
-            .clone();
+        let scheduler = self.config.scheduler_service.clone().ok_or_else(|| {
+            ErrorData::new(
+                ErrorCode::INTERNAL_ERROR,
+                "Scheduler not available".to_string(),
+                None,
+            )
+        })?;
 
         let action = arguments
             .get("action")
@@ -441,7 +434,12 @@ impl Agent {
                 )
             })?;
 
-        let session = match crate::session::SessionManager::get_session(session_id, true).await {
+        let session = match self
+            .config
+            .session_manager
+            .get_session(session_id, true)
+            .await
+        {
             Ok(metadata) => metadata,
             Err(e) => {
                 return Err(ErrorData::new(