feat(tui): implement agent turn engine for background processing and enhance input handling

apps/interfaces/daemon/src/state.rs

@@ -100,7 +100,7 @@ pub enum Overlay {
     Effort,
     /// MCP server management panel.
     Mcp,
-    /// TODO list overlay.
+    /// Task list overlay.
     Todo,
     /// Session rewind / history scrubber.
     Rewind,
@@ -311,6 +311,8 @@ pub struct MiscState {
     pub lesson_running: bool,
     /// Text waiting to be written to the system clipboard.
     pub pending_clipboard_copy: Option<String>,
+    /// Inline editor state, if the editor overlay is active.
+    pub editor: Option<EditorState>,
 }
 
 impl MiscState {
@@ -327,6 +329,7 @@ impl MiscState {
             todo_content: String::new(),
             lesson_running: false,
             pending_clipboard_copy: None,
+            editor: None,
         }
     }
 
@@ -362,7 +365,7 @@ pub struct AgentState {
     pub current_tool: String,
 }
 
-/// Minimal workflow-engine placeholder for hive-mind orchestration state.
+/// Workflow engine state tracking agents in hive-mind orchestration.
 #[derive(Debug, Clone, Default)]
 pub struct WorkflowEngine {
     /// List of running workflow agent states.
@@ -378,6 +381,34 @@ impl WorkflowEngine {
     }
 }
 
+/// Simple inline editor state for the TUI.
+#[derive(Debug, Clone)]
+pub struct EditorState {
+    /// Path to the file being edited.
+    pub path: PathBuf,
+    /// Current buffer content.
+    pub content: String,
+    /// Cursor position (byte offset).
+    pub cursor: usize,
+}
+
+impl EditorState {
+    /// Create a new editor state for the given path.
+    pub fn new(path: PathBuf, content: String) -> Self {
+        let cursor = content.len();
+        EditorState {
+            path,
+            content,
+            cursor,
+        }
+    }
+
+    /// Return the full buffer content.
+    pub fn as_string(&self) -> String {
+        self.content.clone()
+    }
+}
+
 // ---------------------------------------------------------------------------
 // AppStateRest — single source-of-truth application state
 // ---------------------------------------------------------------------------