feat: handle PermissionDenied hook event and drive Permission character state (closes #256)

src-tauri/src/types.rs

@@ -344,6 +344,16 @@ pub struct TaskCreatedEvent {
     pub conversation_id: Option<String>,
 }
 
+#[derive(Debug, Clone, Serialize, Deserialize)]
+pub struct PermissionDeniedEvent {
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub tool_name: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub reason: Option<String>,
+    #[serde(skip_serializing_if = "Option::is_none")]
+    pub conversation_id: Option<String>,
+}
+
 #[derive(Debug, Clone, Serialize, Deserialize)]
 pub struct AgentStartEvent {
     pub tool_use_id: String,
@@ -860,4 +870,44 @@ mod tests {
         assert!(!serialized.contains("parent_tool_use_id"));
         assert!(!serialized.contains("conversation_id"));
     }
+
+    #[test]
+    fn test_permission_denied_event_serialization() {
+        let event = PermissionDeniedEvent {
+            tool_name: Some("Bash".to_string()),
+            reason: Some("Tool not in allow list".to_string()),
+            conversation_id: Some("conv-abc".to_string()),
+        };
+
+        let serialized = serde_json::to_string(&event).unwrap();
+        assert!(serialized.contains("\"tool_name\":\"Bash\""));
+        assert!(serialized.contains("\"reason\":\"Tool not in allow list\""));
+        assert!(serialized.contains("\"conversation_id\":\"conv-abc\""));
+    }
+
+    #[test]
+    fn test_permission_denied_event_omits_none_fields() {
+        let event = PermissionDeniedEvent {
+            tool_name: None,
+            reason: None,
+            conversation_id: None,
+        };
+
+        let serialized = serde_json::to_string(&event).unwrap();
+        assert_eq!(serialized, "{}");
+    }
+
+    #[test]
+    fn test_permission_denied_event_partial_fields() {
+        let event = PermissionDeniedEvent {
+            tool_name: Some("Edit".to_string()),
+            reason: None,
+            conversation_id: None,
+        };
+
+        let serialized = serde_json::to_string(&event).unwrap();
+        assert!(serialized.contains("\"tool_name\":\"Edit\""));
+        assert!(!serialized.contains("reason"));
+        assert!(!serialized.contains("conversation_id"));
+    }
 }