feat: parse plugin_errors from stream-json init event (#270)

Adds plugin_errors field to the System init message type and emits a claude:output error event for each failed plugin, giving users visibility into plugin load failures within Hikari Desktop. Requires Claude Code v2.1.111+.

src-tauri/src/types.rs

@@ -98,6 +98,10 @@ pub enum ClaudeMessage {
         /// Output style hint from Claude Code (v2.1.81+). Informational only.
         #[serde(default)]
         output_style: Option<String>,
+        /// Plugin errors from Claude Code (v2.1.111+). Populated when plugins are demoted
+        /// due to unsatisfied dependencies.
+        #[serde(default)]
+        plugin_errors: Option<serde_json::Value>,
     },
     #[serde(rename = "assistant")]
     Assistant {
@@ -977,6 +981,44 @@ mod tests {
         }
     }
 
+    #[test]
+    fn test_system_init_with_plugin_errors() {
+        let json = r#"{"type":"system","subtype":"init","session_id":"sess-1","plugin_errors":["Plugin 'foo' requires 'bar' which is not installed","Plugin 'baz' failed to load"]}"#;
+        let msg: ClaudeMessage = serde_json::from_str(json).unwrap();
+        if let ClaudeMessage::System { plugin_errors, .. } = msg {
+            let errors = plugin_errors.expect("plugin_errors should be present");
+            let arr = errors.as_array().expect("plugin_errors should be an array");
+            assert_eq!(arr.len(), 2);
+            assert_eq!(arr[0].as_str(), Some("Plugin 'foo' requires 'bar' which is not installed"));
+        } else {
+            panic!("Expected System variant");
+        }
+    }
+
+    #[test]
+    fn test_system_init_without_plugin_errors() {
+        let json = r#"{"type":"system","subtype":"init","session_id":"sess-1"}"#;
+        let msg: ClaudeMessage = serde_json::from_str(json).unwrap();
+        if let ClaudeMessage::System { plugin_errors, .. } = msg {
+            assert!(plugin_errors.is_none());
+        } else {
+            panic!("Expected System variant");
+        }
+    }
+
+    #[test]
+    fn test_system_init_with_empty_plugin_errors() {
+        let json = r#"{"type":"system","subtype":"init","session_id":"sess-1","plugin_errors":[]}"#;
+        let msg: ClaudeMessage = serde_json::from_str(json).unwrap();
+        if let ClaudeMessage::System { plugin_errors, .. } = msg {
+            let errors = plugin_errors.expect("plugin_errors should be present");
+            let arr = errors.as_array().expect("plugin_errors should be an array");
+            assert!(arr.is_empty());
+        } else {
+            panic!("Expected System variant");
+        }
+    }
+
     #[test]
     fn test_result_message_with_fast_mode_state() {
         let json = r#"{"type":"result","subtype":"success","fast_mode_state":"enabled"}"#;

src-tauri/src/wsl_bridge.rs

@@ -1850,6 +1850,7 @@ fn process_json_line(
             subtype,
             session_id,
             cwd,
+            plugin_errors,
             ..
         } => {
             if subtype == "init" {
@@ -1874,6 +1875,31 @@ fn process_json_line(
                         },
                     );
                 }
+
+                // Warn about any plugins that failed to load (v2.1.111+)
+                if let Some(errors) = plugin_errors {
+                    if let Some(arr) = errors.as_array() {
+                        for error in arr {
+                            let msg = if let Some(s) = error.as_str() {
+                                s.to_string()
+                            } else {
+                                error.to_string()
+                            };
+                            let _ = app.emit(
+                                "claude:output",
+                                OutputEvent {
+                                    line_type: "error".to_string(),
+                                    content: format!("Plugin error: {}", msg),
+                                    tool_name: None,
+                                    conversation_id: conversation_id.clone(),
+                                    cost: None,
+                                    parent_tool_use_id: None,
+                                },
+                            );
+                        }
+                    }
+                }
+
                 emit_state_change(app, CharacterState::Idle, None, conversation_id.clone());
             }
         }