feat(tui): clarify Windows auto mode requirements (#5568)

## Summary
- Coerce Windows `workspace-write` configs back to read-only, surface
the forced downgrade in the approvals popup,
  and funnel users toward WSL or Full Access.
- Add WSL installation instructions to the Auto preset on Windows while
keeping the preset available for other
  platforms.
- Skip the trust-on-first-run prompt on native Windows so new folders
remain read-only without additional
  confirmation.
- Expose a structured sandbox policy resolution from config to flag
Windows downgrades and adjust tests (core,
exec, TUI) to reflect the new behavior; provide a Windows-only approvals
snapshot.

  ## Testing
  - cargo fmt
- cargo test -p codex-core
config::tests::add_dir_override_extends_workspace_writable_roots
- cargo test -p codex-exec
suite::resume::exec_resume_preserves_cli_configuration_overrides
- cargo test -p codex-tui
chatwidget::tests::approvals_selection_popup_snapshot
- cargo test -p codex-tui
approvals_popup_includes_wsl_note_for_auto_mode
  - cargo test -p codex-tui windows_skips_trust_prompt
  - just fix -p codex-core
  - just fix -p codex-tui

codex-rs/tui/src/lib.rs

@@ -507,14 +507,16 @@ async fn load_config_or_exit(
 /// or if the current cwd project is already trusted. If not, we need to
 /// show the trust screen.
 fn should_show_trust_screen(config: &Config) -> bool {
-    if config.did_user_set_custom_approval_policy_or_sandbox_mode {
-        // if the user has overridden either approval policy or sandbox mode,
-        // skip the trust flow
-        false
-    } else {
-        // otherwise, skip iff the active project is trusted
-        !config.active_project.is_trusted()
+    if cfg!(target_os = "windows") {
+        // Native Windows cannot enforce sandboxed write access without WSL; skip the trust prompt entirely.
+        return false;
     }
+    if config.did_user_set_custom_approval_policy_or_sandbox_mode {
+        // Respect explicit approval/sandbox overrides made by the user.
+        return false;
+    }
+    // otherwise, skip iff the active project is trusted
+    !config.active_project.is_trusted()
 }
 
 fn should_show_onboarding(
@@ -543,3 +545,38 @@ fn should_show_login_screen(login_status: LoginStatus, config: &Config) -> bool
 
     login_status == LoginStatus::NotAuthenticated
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use codex_core::config::ConfigOverrides;
+    use codex_core::config::ConfigToml;
+    use codex_core::config::ProjectConfig;
+    use tempfile::TempDir;
+
+    #[test]
+    fn windows_skips_trust_prompt() -> std::io::Result<()> {
+        let temp_dir = TempDir::new()?;
+        let mut config = Config::load_from_base_config_with_overrides(
+            ConfigToml::default(),
+            ConfigOverrides::default(),
+            temp_dir.path().to_path_buf(),
+        )?;
+        config.did_user_set_custom_approval_policy_or_sandbox_mode = false;
+        config.active_project = ProjectConfig { trust_level: None };
+
+        let should_show = should_show_trust_screen(&config);
+        if cfg!(target_os = "windows") {
+            assert!(
+                !should_show,
+                "Windows trust prompt should always be skipped on native Windows"
+            );
+        } else {
+            assert!(
+                should_show,
+                "Non-Windows should still show trust prompt when project is untrusted"
+            );
+        }
+        Ok(())
+    }
+}