Prefer websockets when providers support them (#13592)

Remove all flags and model settings.

---------

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/src/codex.rs

@@ -53,7 +53,6 @@ use crate::terminal;
 use crate::truncate::TruncationPolicy;
 use crate::turn_metadata::TurnMetadataState;
 use crate::util::error_or_panic;
-use crate::ws_version_from_features;
 use async_channel::Receiver;
 use async_channel::Sender;
 use chrono::Local;
@@ -1807,7 +1806,6 @@ impl Session {
                 session_configuration.provider.clone(),
                 session_configuration.session_source.clone(),
                 config.model_verbosity,
-                ws_version_from_features(config.as_ref()),
                 config.features.enabled(Feature::EnableRequestCompression),
                 config.features.enabled(Feature::RuntimeMetrics),
                 Self::build_model_client_beta_features_header(config.as_ref()),
@@ -6239,10 +6237,7 @@ async fn run_sampling_request(
             // transient reconnect messages. In debug builds, keep full visibility for diagnosis.
             let report_error = retries > 1
                 || cfg!(debug_assertions)
-                || !sess
-                    .services
-                    .model_client
-                    .responses_websocket_enabled(&turn_context.model_info);
+                || !sess.services.model_client.responses_websocket_enabled();
             if report_error {
                 // Surface retry information to any UI/front‑end so the
                 // user understands what is happening instead of staring