Add experimental exec server URL handling (#15196)

Add a config and attempt to start the server.

codex-rs/exec-server/src/environment.rs

@@ -1,11 +1,76 @@
+use crate::ExecServerClient;
+use crate::ExecServerError;
+use crate::RemoteExecServerConnectArgs;
 use crate::fs;
 use crate::fs::ExecutorFileSystem;
 
-#[derive(Clone, Debug, Default)]
-pub struct Environment;
+#[derive(Clone, Default)]
+pub struct Environment {
+    experimental_exec_server_url: Option<String>,
+    remote_exec_server_client: Option<ExecServerClient>,
+}
+
+impl std::fmt::Debug for Environment {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        f.debug_struct("Environment")
+            .field(
+                "experimental_exec_server_url",
+                &self.experimental_exec_server_url,
+            )
+            .field(
+                "has_remote_exec_server_client",
+                &self.remote_exec_server_client.is_some(),
+            )
+            .finish()
+    }
+}
 
 impl Environment {
+    pub async fn create(
+        experimental_exec_server_url: Option<String>,
+    ) -> Result<Self, ExecServerError> {
+        let remote_exec_server_client =
+            if let Some(websocket_url) = experimental_exec_server_url.as_deref() {
+                Some(
+                    ExecServerClient::connect_websocket(RemoteExecServerConnectArgs::new(
+                        websocket_url.to_string(),
+                        "codex-core".to_string(),
+                    ))
+                    .await?,
+                )
+            } else {
+                None
+            };
+
+        Ok(Self {
+            experimental_exec_server_url,
+            remote_exec_server_client,
+        })
+    }
+
+    pub fn experimental_exec_server_url(&self) -> Option<&str> {
+        self.experimental_exec_server_url.as_deref()
+    }
+
+    pub fn remote_exec_server_client(&self) -> Option<&ExecServerClient> {
+        self.remote_exec_server_client.as_ref()
+    }
+
     pub fn get_filesystem(&self) -> impl ExecutorFileSystem + use<> {
         fs::LocalFileSystem
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::Environment;
+    use pretty_assertions::assert_eq;
+
+    #[tokio::test]
+    async fn create_without_remote_exec_server_url_does_not_connect() {
+        let environment = Environment::create(None).await.expect("create environment");
+
+        assert_eq!(environment.experimental_exec_server_url(), None);
+        assert!(environment.remote_exec_server_client().is_none());
+    }
+}