Add realtime transport config (#17097)

Adds realtime.transport config with websocket as the default and webrtc
wired through the effective config.

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

codex-rs/config/src/config_toml.rs

@@ -445,6 +445,15 @@ pub enum RealtimeWsMode {
     Transcription,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, Copy, Default, PartialEq, Eq, JsonSchema)]
+#[serde(rename_all = "snake_case")]
+pub enum RealtimeTransport {
+    #[serde(rename = "webrtc")]
+    WebRtc,
+    #[default]
+    Websocket,
+}
+
 pub use codex_protocol::protocol::RealtimeConversationVersion as RealtimeWsVersion;
 
 #[derive(Serialize, Deserialize, Debug, Clone, Default, PartialEq, Eq, JsonSchema)]
@@ -453,6 +462,7 @@ pub struct RealtimeConfig {
     pub version: RealtimeWsVersion,
     #[serde(rename = "type")]
     pub session_type: RealtimeWsMode,
+    pub transport: RealtimeTransport,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone, Default, PartialEq, Eq, JsonSchema)]
@@ -461,6 +471,7 @@ pub struct RealtimeToml {
     pub version: Option<RealtimeWsVersion>,
     #[serde(rename = "type")]
     pub session_type: Option<RealtimeWsMode>,
+    pub transport: Option<RealtimeTransport>,
 }
 
 #[derive(Serialize, Deserialize, Debug, Clone, Default, PartialEq, Eq, JsonSchema)]

codex-rs/core/config.schema.json

@@ -1497,6 +1497,9 @@
     "RealtimeToml": {
       "additionalProperties": false,
       "properties": {
+        "transport": {
+          "$ref": "#/definitions/RealtimeTransport"
+        },
         "type": {
           "$ref": "#/definitions/RealtimeWsMode"
         },
@@ -1506,6 +1509,13 @@
       },
       "type": "object"
     },
+    "RealtimeTransport": {
+      "enum": [
+        "webrtc",
+        "websocket"
+      ],
+      "type": "string"
+    },
     "RealtimeWsMode": {
       "enum": [
         "conversational",

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

@@ -12,6 +12,7 @@ use codex_config::config_toml::ProjectConfig;
 use codex_config::config_toml::RealtimeAudioConfig;
 use codex_config::config_toml::RealtimeConfig;
 use codex_config::config_toml::RealtimeToml;
+use codex_config::config_toml::RealtimeTransport;
 use codex_config::config_toml::RealtimeWsMode;
 use codex_config::config_toml::RealtimeWsVersion;
 use codex_config::config_toml::ToolsToml;
@@ -6487,6 +6488,7 @@ fn realtime_loads_from_config_toml() -> std::io::Result<()> {
 [realtime]
 version = "v2"
 type = "transcription"
+transport = "webrtc"
 "#,
     )
     .expect("TOML deserialization should succeed");
@@ -6496,6 +6498,7 @@ type = "transcription"
         Some(RealtimeToml {
             version: Some(RealtimeWsVersion::V2),
             session_type: Some(RealtimeWsMode::Transcription),
+            transport: Some(RealtimeTransport::WebRtc),
         })
     );
 
@@ -6511,6 +6514,7 @@ type = "transcription"
         RealtimeConfig {
             version: RealtimeWsVersion::V2,
             session_type: RealtimeWsMode::Transcription,
+            transport: RealtimeTransport::WebRtc,
         }
     );
     Ok(())

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

@@ -2095,6 +2095,7 @@ impl Config {
                 .map_or_else(RealtimeConfig::default, |realtime| RealtimeConfig {
                     version: realtime.version.unwrap_or_default(),
                     session_type: realtime.session_type.unwrap_or_default(),
+                    transport: realtime.transport.unwrap_or_default(),
                 }),
             experimental_realtime_ws_backend_prompt: cfg.experimental_realtime_ws_backend_prompt,
             experimental_realtime_ws_startup_context: cfg.experimental_realtime_ws_startup_context,