optimize: terminal spawn lifecycle to eliminate output race condition

Move PTY spawn from context layer to view layer so event subscription
happens before spawn, preventing loss of initial terminal output.

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

src-tauri/src/commands/terminal.rs

@@ -69,11 +69,14 @@ pub(crate) fn prepare_credential_env(
 pub async fn terminal_spawn(
     working_dir: String,
     initial_command: Option<String>,
+    terminal_id: Option<String>,
     manager: State<'_, TerminalManager>,
     app_handle: tauri::AppHandle,
     window: tauri::WebviewWindow,
 ) -> Result<String, TerminalError> {
-    let terminal_id = uuid::Uuid::new_v4().to_string();
+    let terminal_id = terminal_id
+        .filter(|id| !id.is_empty() && id.len() <= 256)
+        .unwrap_or_else(|| uuid::Uuid::new_v4().to_string());
 
     let app_data_dir = app_handle
         .path()

src-tauri/src/terminal/manager.rs

@@ -162,6 +162,17 @@ impl TerminalManager {
         opts: SpawnOptions,
         emitter: EventEmitter,
     ) -> Result<String, TerminalError> {
+        // Reject duplicate IDs to prevent orphaning an existing PTY process.
+        {
+            let terminals = self.terminals.lock().unwrap();
+            if terminals.contains_key(&opts.terminal_id) {
+                return Err(TerminalError::SpawnFailed(format!(
+                    "terminal id '{}' already exists",
+                    opts.terminal_id
+                )));
+            }
+        }
+
         let pty_system = native_pty_system();
 
         let pair = pty_system

src-tauri/src/web/handlers/terminal.rs

@@ -18,6 +18,7 @@ use crate::terminal::types::TerminalInfo;
 pub struct TerminalSpawnParams {
     pub working_dir: String,
     pub initial_command: Option<String>,
+    pub terminal_id: Option<String>,
 }
 
 #[derive(Deserialize)]
@@ -50,7 +51,10 @@ pub async fn terminal_spawn(
     Json(params): Json<TerminalSpawnParams>,
 ) -> Result<Json<String>, AppCommandError> {
     let manager = &state.terminal_manager;
-    let terminal_id = uuid::Uuid::new_v4().to_string();
+    let terminal_id = params
+        .terminal_id
+        .filter(|id| !id.is_empty() && id.len() <= 256)
+        .unwrap_or_else(|| uuid::Uuid::new_v4().to_string());
 
     let extra_env = prepare_credential_env(&state.data_dir);