Expose current environment selections for a running turn (#47970)

## Why

`active_turn_environment_selections()` returns the selections captured at turn start, so it does not reflect later environment settings updates.

## What changed

Add `CodexThread::current_turn_environment_selections(expected_turn_id)` to read the running turn's current selections, including environments that are still starting or have failed. Return `None` when the requested turn is no longer active or has been cancelled.

## Testing

Add a regression test covering selection updates, mismatched turn IDs, and completed turns, while verifying that the initial selection snapshot remains unchanged.

GitOrigin-RevId: bb526a686d549209142150ffde99ad1444add205

codex-rs/core/src/codex_thread.rs

@@ -546,6 +546,20 @@ impl CodexThread {
         Some(task.turn_context.initial_environments.all_selections())
     }
 
+    /// Returns the named running turn's current selections, including environments that are
+    /// still starting or have failed. Returns `None` if that turn is no longer running.
+    pub async fn current_turn_environment_selections(
+        &self,
+        expected_turn_id: &str,
+    ) -> Option<Vec<TurnEnvironmentSelection>> {
+        let active = self.session.active_turn.lock().await;
+        let task = active.as_ref()?.task.as_ref()?;
+        if task.turn_context.sub_id != expected_turn_id || task.cancellation_token.is_cancelled() {
+            return None;
+        }
+        Some(self.session.services.turn_environments.selections())
+    }
+
     /// Captures a regular turn only after its input is recorded. The caller must flush the rollout.
     pub async fn interrupted_turn(
         &self,

codex-rs/core/tests/suite/step_settings/environment_selection.rs

@@ -10,6 +10,64 @@ use core_test_support::submit_thread_settings;
 use core_test_support::test_codex::environment_config_for_selection;
 use pretty_assertions::assert_eq;
 
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn current_turn_environment_selections_follow_active_updates() -> Result<()> {
+    skip_if_no_network!(Ok(()));
+
+    let server = start_mock_server().await;
+    mount_sse_sequence(
+        &server,
+        vec![paused_response("first", "pause"), sse_completed("second")],
+    )
+    .await;
+    let test = step_settings_test().build_with_auto_env(&server).await?;
+    let thread = &test.codex;
+    let turn_id = start_paused_turn(thread).await?.turn_id;
+    let initial = thread
+        .active_turn_environment_selections()
+        .await
+        .expect("running turn");
+    assert_eq!(initial.len(), 1);
+    assert_eq!(
+        thread.current_turn_environment_selections(&turn_id).await,
+        Some(initial.clone())
+    );
+    assert_eq!(
+        thread
+            .current_turn_environment_selections("other-turn")
+            .await,
+        None
+    );
+
+    for environments in [vec![], initial.clone()] {
+        apply_turn_settings(
+            thread,
+            &turn_id,
+            TurnSettingsUpdate {
+                environments: Some(environments.clone()),
+                ..Default::default()
+            },
+        )
+        .await?;
+        assert_eq!(
+            thread.current_turn_environment_selections(&turn_id).await,
+            Some(environments)
+        );
+        assert_eq!(
+            thread.active_turn_environment_selections().await,
+            Some(initial.clone())
+        );
+    }
+
+    answer_paused_turn(thread, &turn_id).await?;
+    wait_for_event(thread, |event| matches!(event, EventMsg::TurnComplete(_))).await;
+    assert_eq!(
+        thread.current_turn_environment_selections(&turn_id).await,
+        None
+    );
+    Ok(())
+}
+
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn model_update_preserves_active_environment_and_next_turn_uses_new_selection() -> Result<()>
 {