Remove WebSocket wire format (#10179)

I'd like WireApi to go away (when chat is removed) and WebSockets is
still responses API just over a different transport.

codex-rs/core/config.schema.json

@@ -443,6 +443,11 @@
           "minimum": 0.0,
           "type": "integer"
         },
+        "supports_websockets": {
+          "default": false,
+          "description": "Whether this provider supports the Responses API WebSocket transport.",
+          "type": "boolean"
+        },
         "wire_api": {
           "allOf": [
             {
@@ -1081,13 +1086,6 @@
           ],
           "type": "string"
         },
-        {
-          "description": "Experimental: Responses API over WebSocket transport.",
-          "enum": [
-            "responses_websocket"
-          ],
-          "type": "string"
-        },
         {
           "description": "Regular Chat Completions compatible with `/v1/chat/completions`.",
           "enum": [

codex-rs/core/src/client.rs

@@ -260,12 +260,18 @@ impl ModelClientSession {
     /// For Chat providers, the underlying stream is optionally aggregated
     /// based on the `show_raw_agent_reasoning` flag in the config.
     pub async fn stream(&mut self, prompt: &Prompt) -> Result<ResponseStream> {
-        let wire_api = self
-            .transport_manager
-            .effective_wire_api(self.state.provider.wire_api);
+        let wire_api = self.state.provider.wire_api;
         match wire_api {
-            WireApi::Responses => self.stream_responses_api(prompt).await,
-            WireApi::ResponsesWebsocket => self.stream_responses_websocket(prompt).await,
+            WireApi::Responses => {
+                let websocket_enabled = self.responses_websocket_enabled()
+                    && !self.transport_manager.disable_websockets();
+
+                if websocket_enabled {
+                    self.stream_responses_websocket(prompt).await
+                } else {
+                    self.stream_responses_api(prompt).await
+                }
+            }
             WireApi::Chat => {
                 let api_stream = self.stream_chat_completions(prompt).await?;
 
@@ -285,9 +291,10 @@ impl ModelClientSession {
     }
 
     pub(crate) fn try_switch_fallback_transport(&mut self) -> bool {
+        let websocket_enabled = self.responses_websocket_enabled();
         let activated = self
             .transport_manager
-            .activate_http_fallback(self.state.provider.wire_api);
+            .activate_http_fallback(websocket_enabled);
         if activated {
             warn!("falling back to HTTP");
             self.state.otel_manager.counter(
@@ -302,6 +309,15 @@ impl ModelClientSession {
         activated
     }
 
+    fn responses_websocket_enabled(&self) -> bool {
+        self.state.provider.supports_websockets
+            && self
+                .state
+                .config
+                .features
+                .enabled(Feature::ResponsesWebsockets)
+    }
+
     fn build_responses_request(&self, prompt: &Prompt) -> Result<ApiPrompt> {
         let instructions = prompt.base_instructions.text.clone();
         let tools_json: Vec<Value> = create_tools_json_for_responses_api(&prompt.tools)?;

codex-rs/core/src/config/mod.rs

@@ -1372,12 +1372,6 @@ impl Config {
             || cfg.sandbox_mode.is_some();
 
         let mut model_providers = built_in_model_providers();
-        if features.enabled(Feature::ResponsesWebsockets)
-            && let Some(provider) = model_providers.get_mut("openai")
-            && provider.is_openai()
-        {
-            provider.wire_api = crate::model_provider_info::WireApi::ResponsesWebsocket;
-        }
         // Merge user-defined providers into the built-in list.
         for (key, provider) in cfg.model_providers.into_iter() {
             model_providers.entry(key).or_insert(provider);
@@ -2555,7 +2549,7 @@ profile = "project"
     }
 
     #[test]
-    fn responses_websockets_feature_updates_openai_provider() -> std::io::Result<()> {
+    fn responses_websockets_feature_does_not_change_wire_api() -> std::io::Result<()> {
         let codex_home = TempDir::new()?;
         let mut entries = BTreeMap::new();
         entries.insert("responses_websockets".to_string(), true);
@@ -2572,7 +2566,7 @@ profile = "project"
 
         assert_eq!(
             config.model_provider.wire_api,
-            crate::model_provider_info::WireApi::ResponsesWebsocket
+            crate::model_provider_info::WireApi::Responses
         );
 
         Ok(())
@@ -3692,6 +3686,7 @@ model_verbosity = "high"
             stream_max_retries: Some(10),
             stream_idle_timeout_ms: Some(300_000),
             requires_openai_auth: false,
+            supports_websockets: false,
         };
         let model_provider_map = {
             let mut model_provider_map = built_in_model_providers();

codex-rs/core/src/model_provider_info.rs

@@ -43,10 +43,6 @@ pub enum WireApi {
     /// The Responses API exposed by OpenAI at `/v1/responses`.
     Responses,
 
-    /// Experimental: Responses API over WebSocket transport.
-    #[serde(rename = "responses_websocket")]
-    ResponsesWebsocket,
-
     /// Regular Chat Completions compatible with `/v1/chat/completions`.
     #[default]
     Chat,
@@ -105,6 +101,10 @@ pub struct ModelProviderInfo {
     /// and API key (if needed) comes from the "env_key" environment variable.
     #[serde(default)]
     pub requires_openai_auth: bool,
+
+    /// Whether this provider supports the Responses API WebSocket transport.
+    #[serde(default)]
+    pub supports_websockets: bool,
 }
 
 impl ModelProviderInfo {
@@ -162,7 +162,6 @@ impl ModelProviderInfo {
             query_params: self.query_params.clone(),
             wire: match self.wire_api {
                 WireApi::Responses => ApiWireApi::Responses,
-                WireApi::ResponsesWebsocket => ApiWireApi::Responses,
                 WireApi::Chat => ApiWireApi::Chat,
             },
             headers,
@@ -254,6 +253,7 @@ impl ModelProviderInfo {
             stream_max_retries: None,
             stream_idle_timeout_ms: None,
             requires_openai_auth: true,
+            supports_websockets: true,
         }
     }
 
@@ -332,6 +332,7 @@ pub fn create_oss_provider_with_base_url(base_url: &str, wire_api: WireApi) -> M
         stream_max_retries: None,
         stream_idle_timeout_ms: None,
         requires_openai_auth: false,
+        supports_websockets: false,
     }
 }
 
@@ -360,6 +361,7 @@ base_url = "http://localhost:11434/v1"
             stream_max_retries: None,
             stream_idle_timeout_ms: None,
             requires_openai_auth: false,
+            supports_websockets: false,
         };
 
         let provider: ModelProviderInfo = toml::from_str(azure_provider_toml).unwrap();
@@ -390,6 +392,7 @@ query_params = { api-version = "2025-04-01-preview" }
             stream_max_retries: None,
             stream_idle_timeout_ms: None,
             requires_openai_auth: false,
+            supports_websockets: false,
         };
 
         let provider: ModelProviderInfo = toml::from_str(azure_provider_toml).unwrap();
@@ -423,6 +426,7 @@ env_http_headers = { "X-Example-Env-Header" = "EXAMPLE_ENV_VAR" }
             stream_max_retries: None,
             stream_idle_timeout_ms: None,
             requires_openai_auth: false,
+            supports_websockets: false,
         };
 
         let provider: ModelProviderInfo = toml::from_str(azure_provider_toml).unwrap();
@@ -454,6 +458,7 @@ env_http_headers = { "X-Example-Env-Header" = "EXAMPLE_ENV_VAR" }
                 stream_max_retries: None,
                 stream_idle_timeout_ms: None,
                 requires_openai_auth: false,
+                supports_websockets: false,
             };
             let api = provider.to_api_provider(None).expect("api provider");
             assert!(
@@ -476,6 +481,7 @@ env_http_headers = { "X-Example-Env-Header" = "EXAMPLE_ENV_VAR" }
             stream_max_retries: None,
             stream_idle_timeout_ms: None,
             requires_openai_auth: false,
+            supports_websockets: false,
         };
         let named_api = named_provider.to_api_provider(None).expect("api provider");
         assert!(named_api.is_azure_responses_endpoint());
@@ -500,6 +506,7 @@ env_http_headers = { "X-Example-Env-Header" = "EXAMPLE_ENV_VAR" }
                 stream_max_retries: None,
                 stream_idle_timeout_ms: None,
                 requires_openai_auth: false,
+                supports_websockets: false,
             };
             let api = provider.to_api_provider(None).expect("api provider");
             assert!(

codex-rs/core/src/models_manager/manager.rs

@@ -432,6 +432,7 @@ mod tests {
             stream_max_retries: Some(0),
             stream_idle_timeout_ms: Some(5_000),
             requires_openai_auth: false,
+            supports_websockets: false,
         }
     }
 

codex-rs/core/src/transport_manager.rs

@@ -2,11 +2,9 @@ use std::sync::Arc;
 use std::sync::atomic::AtomicBool;
 use std::sync::atomic::Ordering;
 
-use crate::model_provider_info::WireApi;
-
 #[derive(Clone, Debug, Default)]
 pub struct TransportManager {
-    fallback_to_http: Arc<AtomicBool>,
+    disable_websockets: Arc<AtomicBool>,
 }
 
 impl TransportManager {
@@ -14,18 +12,11 @@ impl TransportManager {
         Self::default()
     }
 
-    pub fn effective_wire_api(&self, provider_wire_api: WireApi) -> WireApi {
-        if self.fallback_to_http.load(Ordering::Relaxed)
-            && provider_wire_api == WireApi::ResponsesWebsocket
-        {
-            WireApi::Responses
-        } else {
-            provider_wire_api
-        }
+    pub fn disable_websockets(&self) -> bool {
+        self.disable_websockets.load(Ordering::Relaxed)
     }
 
-    pub fn activate_http_fallback(&self, provider_wire_api: WireApi) -> bool {
-        provider_wire_api == WireApi::ResponsesWebsocket
-            && !self.fallback_to_http.swap(true, Ordering::Relaxed)
+    pub fn activate_http_fallback(&self, websocket_enabled: bool) -> bool {
+        websocket_enabled && !self.disable_websockets.swap(true, Ordering::Relaxed)
     }
 }

codex-rs/core/tests/chat_completions_payload.rs

@@ -60,6 +60,7 @@ async fn run_request(input: Vec<ResponseItem>) -> Value {
         stream_max_retries: Some(0),
         stream_idle_timeout_ms: Some(5_000),
         requires_openai_auth: false,
+        supports_websockets: false,
     };
 
     let codex_home = match TempDir::new() {

codex-rs/core/tests/chat_completions_sse.rs

@@ -59,6 +59,7 @@ async fn run_stream_with_bytes(sse_body: &[u8]) -> Vec<ResponseEvent> {
         stream_max_retries: Some(0),
         stream_idle_timeout_ms: Some(5_000),
         requires_openai_auth: false,
+        supports_websockets: false,
     };
 
     let codex_home = match TempDir::new() {

codex-rs/core/tests/common/test_codex.rs

@@ -8,7 +8,6 @@ use codex_core::CodexAuth;
 use codex_core::CodexThread;
 use codex_core::ModelProviderInfo;
 use codex_core::ThreadManager;
-use codex_core::WireApi;
 use codex_core::built_in_model_providers;
 use codex_core::config::Config;
 use codex_core::features::Feature;
@@ -127,7 +126,7 @@ impl TestCodexBuilder {
         let base_url_clone = base_url.clone();
         self.config_mutators.push(Box::new(move |config| {
             config.model_provider.base_url = Some(base_url_clone);
-            config.model_provider.wire_api = WireApi::ResponsesWebsocket;
+            config.features.enable(Feature::ResponsesWebsockets);
         }));
         self.build_with_home_and_base_url(base_url, home, None)
             .await

codex-rs/core/tests/responses_headers.rs

@@ -57,6 +57,7 @@ async fn responses_stream_includes_subagent_header_on_review() {
         stream_max_retries: Some(0),
         stream_idle_timeout_ms: Some(5_000),
         requires_openai_auth: false,
+        supports_websockets: false,
     };
 
     let codex_home = TempDir::new().expect("failed to create TempDir");
@@ -154,6 +155,7 @@ async fn responses_stream_includes_subagent_header_on_other() {
         stream_max_retries: Some(0),
         stream_idle_timeout_ms: Some(5_000),
         requires_openai_auth: false,
+        supports_websockets: false,
     };
 
     let codex_home = TempDir::new().expect("failed to create TempDir");
@@ -307,6 +309,7 @@ async fn responses_respects_model_info_overrides_from_config() {
         stream_max_retries: Some(0),
         stream_idle_timeout_ms: Some(5_000),
         requires_openai_auth: false,
+        supports_websockets: false,
     };
 
     let codex_home = TempDir::new().expect("failed to create TempDir");

codex-rs/core/tests/suite/client.rs

@@ -1151,6 +1151,7 @@ async fn azure_responses_request_includes_store_and_reasoning_ids() {
         stream_max_retries: Some(0),
         stream_idle_timeout_ms: Some(5_000),
         requires_openai_auth: false,
+        supports_websockets: false,
     };
 
     let codex_home = TempDir::new().unwrap();
@@ -1671,6 +1672,7 @@ async fn azure_overrides_assign_properties_used_for_responses_url() {
         stream_max_retries: None,
         stream_idle_timeout_ms: None,
         requires_openai_auth: false,
+        supports_websockets: false,
     };
 
     // Init session
@@ -1751,6 +1753,7 @@ async fn env_var_overrides_loaded_auth() {
         stream_max_retries: None,
         stream_idle_timeout_ms: None,
         requires_openai_auth: false,
+        supports_websockets: false,
     };
 
     // Init session

codex-rs/core/tests/suite/client_websockets.rs

@@ -10,6 +10,7 @@ use codex_core::ResponseEvent;
 use codex_core::ResponseItem;
 use codex_core::TransportManager;
 use codex_core::WireApi;
+use codex_core::features::Feature;
 use codex_core::models_manager::manager::ModelsManager;
 use codex_core::protocol::SessionSource;
 use codex_otel::OtelManager;
@@ -188,7 +189,7 @@ fn websocket_provider(server: &WebSocketTestServer) -> ModelProviderInfo {
         env_key: None,
         env_key_instructions: None,
         experimental_bearer_token: None,
-        wire_api: WireApi::ResponsesWebsocket,
+        wire_api: WireApi::Responses,
         query_params: None,
         http_headers: None,
         env_http_headers: None,
@@ -196,6 +197,7 @@ fn websocket_provider(server: &WebSocketTestServer) -> ModelProviderInfo {
         stream_max_retries: Some(0),
         stream_idle_timeout_ms: Some(5_000),
         requires_openai_auth: false,
+        supports_websockets: true,
     }
 }
 
@@ -204,6 +206,7 @@ async fn websocket_harness(server: &WebSocketTestServer) -> WebsocketTestHarness
     let codex_home = TempDir::new().unwrap();
     let mut config = load_default_config_for_test(&codex_home).await;
     config.model = Some(MODEL.to_string());
+    config.features.enable(Feature::ResponsesWebsockets);
     let config = Arc::new(config);
     let model_info = ModelsManager::construct_model_info_offline(MODEL, &config);
     let conversation_id = ThreadId::new();

codex-rs/core/tests/suite/stream_error_allows_next_turn.rs

@@ -73,6 +73,7 @@ async fn continue_after_stream_error() {
         stream_max_retries: Some(1),
         stream_idle_timeout_ms: Some(2_000),
         requires_openai_auth: false,
+        supports_websockets: false,
     };
 
     let TestCodex { codex, .. } = test_codex()

codex-rs/core/tests/suite/stream_no_completed.rs

@@ -81,6 +81,7 @@ async fn retries_on_early_close() {
         stream_max_retries: Some(1),
         stream_idle_timeout_ms: Some(2000),
         requires_openai_auth: false,
+        supports_websockets: false,
     };
 
     let TestCodex { codex, .. } = test_codex()

codex-rs/core/tests/suite/websocket_fallback.rs

@@ -1,5 +1,5 @@
 use anyhow::Result;
-use codex_core::WireApi;
+use codex_core::features::Feature;
 use core_test_support::responses;
 use core_test_support::responses::ev_completed;
 use core_test_support::responses::ev_response_created;
@@ -26,7 +26,8 @@ async fn websocket_fallback_switches_to_http_after_retries_exhausted() -> Result
         let base_url = format!("{}/v1", server.uri());
         move |config| {
             config.model_provider.base_url = Some(base_url);
-            config.model_provider.wire_api = WireApi::ResponsesWebsocket;
+            config.model_provider.wire_api = codex_core::WireApi::Responses;
+            config.features.enable(Feature::ResponsesWebsockets);
             config.model_provider.stream_max_retries = Some(0);
             config.model_provider.request_max_retries = Some(0);
         }
@@ -70,7 +71,8 @@ async fn websocket_fallback_is_sticky_across_turns() -> Result<()> {
         let base_url = format!("{}/v1", server.uri());
         move |config| {
             config.model_provider.base_url = Some(base_url);
-            config.model_provider.wire_api = WireApi::ResponsesWebsocket;
+            config.model_provider.wire_api = codex_core::WireApi::Responses;
+            config.features.enable(Feature::ResponsesWebsockets);
             config.model_provider.stream_max_retries = Some(0);
             config.model_provider.request_max_retries = Some(0);
         }