fix: handle missing resume session id gracefully (#5329)

Exit when a requested resume session is missing after restoring the
terminal and print a helpful message instructing users how to resume
existing sessions.

Partially addresses #5247.

codex-rs/tui/src/lib.rs

@@ -437,7 +437,20 @@ async fn run_ratatui_app(
             Some(path) => resume_picker::ResumeSelection::Resume(path),
             None => {
                 error!("Error finding conversation path: {id_str}");
-                resume_picker::ResumeSelection::StartFresh
+                restore();
+                session_log::log_session_end();
+                let _ = tui.terminal.clear();
+                if let Err(err) = writeln!(
+                    std::io::stdout(),
+                    "No saved session found with ID {id_str}. Run `codex resume` without an ID to choose from existing sessions."
+                ) {
+                    error!("Failed to write resume error message: {err}");
+                }
+                return Ok(AppExitInfo {
+                    token_usage: codex_core::protocol::TokenUsage::default(),
+                    conversation_id: None,
+                    update_action: None,
+                });
             }
         }
     } else if cli.resume_last {