add a slash command to grant sandbox read access to inaccessible directories (#11512)

There is an edge case where a directory is not readable by the sandbox.
In practice, we've seen very little of it, but it can happen so this
slash command unlocks users when it does.

Future idea is to make this a tool that the agent knows about so it can
be more integrated.

codex-rs/tui/src/app.rs

@@ -1826,6 +1826,63 @@ impl App {
                     let _ = preset;
                 }
             }
+            AppEvent::BeginWindowsSandboxGrantReadRoot { path } => {
+                #[cfg(target_os = "windows")]
+                {
+                    self.chat_widget
+                        .add_to_history(history_cell::new_info_event(
+                            format!("Granting sandbox read access to {path} ..."),
+                            None,
+                        ));
+
+                    let policy = self.config.sandbox_policy.get().clone();
+                    let policy_cwd = self.config.cwd.clone();
+                    let command_cwd = self.config.cwd.clone();
+                    let env_map: std::collections::HashMap<String, String> =
+                        std::env::vars().collect();
+                    let codex_home = self.config.codex_home.clone();
+                    let tx = self.app_event_tx.clone();
+
+                    tokio::task::spawn_blocking(move || {
+                        let requested_path = PathBuf::from(path);
+                        let event = match codex_core::windows_sandbox_read_grants::grant_read_root_non_elevated(
+                            &policy,
+                            policy_cwd.as_path(),
+                            command_cwd.as_path(),
+                            &env_map,
+                            codex_home.as_path(),
+                            requested_path.as_path(),
+                        ) {
+                            Ok(canonical_path) => AppEvent::WindowsSandboxGrantReadRootCompleted {
+                                path: canonical_path,
+                                error: None,
+                            },
+                            Err(err) => AppEvent::WindowsSandboxGrantReadRootCompleted {
+                                path: requested_path,
+                                error: Some(err.to_string()),
+                            },
+                        };
+                        tx.send(event);
+                    });
+                }
+                #[cfg(not(target_os = "windows"))]
+                {
+                    let _ = path;
+                }
+            }
+            AppEvent::WindowsSandboxGrantReadRootCompleted { path, error } => match error {
+                Some(err) => {
+                    self.chat_widget
+                        .add_to_history(history_cell::new_error_event(format!("Error: {err}")));
+                }
+                None => {
+                    self.chat_widget
+                        .add_to_history(history_cell::new_info_event(
+                            format!("Sandbox read access granted for {}", path.display()),
+                            None,
+                        ));
+                }
+            },
             AppEvent::EnableWindowsSandboxForAgentMode { preset, mode } => {
                 #[cfg(target_os = "windows")]
                 {