Register named exec environments for app-server threads

Add execEnvironment register/list requests, thread start selection, and thread metadata plumbing so app-server threads can bind to a named exec-server environment.

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

codex-rs/app-server-protocol/src/protocol/common.rs

@@ -241,6 +241,14 @@ client_request_definitions! {
         inspect_params: true,
         response: v2::ThreadStartResponse,
     },
+    ExecServerEnvironmentRegister => "execEnvironment/register" {
+        params: v2::ExecServerEnvironmentRegisterParams,
+        response: v2::ExecServerEnvironmentRegisterResponse,
+    },
+    ExecServerEnvironmentList => "execEnvironment/list" {
+        params: v2::ExecServerEnvironmentListParams,
+        response: v2::ExecServerEnvironmentListResponse,
+    },
     ThreadResume => "thread/resume" {
         params: v2::ThreadResumeParams,
         inspect_params: true,
@@ -1395,6 +1403,7 @@ mod tests {
                 thread: v2::Thread {
                     id: "67e55044-10b1-426f-9247-bb680e5fe0c8".to_string(),
                     forked_from_id: None,
+                    exec_environment_name: None,
                     preview: "first prompt".to_string(),
                     ephemeral: true,
                     model_provider: "openai".to_string(),
@@ -1433,6 +1442,7 @@ mod tests {
                     "thread": {
                         "id": "67e55044-10b1-426f-9247-bb680e5fe0c8",
                         "forkedFromId": null,
+                        "execEnvironmentName": null,
                         "preview": "first prompt",
                         "ephemeral": true,
                         "modelProvider": "openai",

codex-rs/app-server-protocol/src/protocol/v2.rs

@@ -2683,6 +2683,9 @@ pub struct ThreadStartParams {
     #[experimental("thread/start.mockExperimentalField")]
     #[ts(optional = nullable)]
     pub mock_experimental_field: Option<String>,
+    /// Optional named exec-server environment to use for this thread.
+    #[ts(optional = nullable)]
+    pub exec_environment_name: Option<String>,
     /// If true, opt into emitting raw Responses API items on the event stream.
     /// This is for internal use only (e.g. Codex Cloud).
     #[experimental("thread/start.experimentalRawEvents")]
@@ -2695,6 +2698,56 @@ pub struct ThreadStartParams {
     pub persist_extended_history: bool,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ExecServerEnvironment {
+    /// Unique name used to reference this exec-server environment.
+    pub name: String,
+    /// Exec-server URL used when binding a thread to this environment.
+    pub exec_server_url: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ExecServerEnvironmentRegisterParams {
+    /// Human-readable name for selecting this environment in thread start.
+    pub name: String,
+    /// Exec-server URL to register under this environment name.
+    pub exec_server_url: String,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ExecServerEnvironmentRegisterResponse {
+    /// The environment entry that was registered.
+    pub environment: ExecServerEnvironment,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, Default, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ExecServerEnvironmentListParams {
+    /// Opaque pagination cursor returned by a previous call.
+    #[ts(optional = nullable)]
+    pub cursor: Option<String>,
+    /// Optional page size; defaults to a reasonable server-side value.
+    #[ts(optional = nullable)]
+    pub limit: Option<u32>,
+}
+
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
+#[serde(rename_all = "camelCase")]
+#[ts(export_to = "v2/")]
+pub struct ExecServerEnvironmentListResponse {
+    pub data: Vec<ExecServerEnvironment>,
+    /// Opaque cursor to pass to the next call to continue after the last item.
+    /// If None, there are no more items to return.
+    pub next_cursor: Option<String>,
+}
+
 #[derive(Serialize, Deserialize, Debug, Default, Clone, PartialEq, JsonSchema, TS)]
 #[serde(rename_all = "camelCase")]
 #[ts(export_to = "v2/")]
@@ -3718,6 +3771,8 @@ pub struct Thread {
     pub id: String,
     /// Source thread id when this thread was created by forking another thread.
     pub forked_from_id: Option<String>,
+    /// Optional named exec-server environment selected for this thread.
+    pub exec_environment_name: Option<String>,
     /// Usually the first user message in the thread, if available.
     pub preview: String,
     /// Whether the thread is ephemeral and should not be materialized on disk.
@@ -8576,6 +8631,7 @@ mod tests {
             "thread": {
                 "id": "thread-id",
                 "forkedFromId": null,
+                "execEnvironmentName": null,
                 "preview": "",
                 "ephemeral": false,
                 "modelProvider": "openai",