feat: add UserInfo request to JSON-RPC server (#3428)

This adds a simple endpoint that provides the email address encoded in
`$CODEX_HOME/auth.json`.

As noted, for now, we do not hit the server to verify this is the user's
true email address.

codex-rs/Cargo.lock

@@ -769,6 +769,7 @@ version = "0.0.0"
 dependencies = [
  "anyhow",
  "assert_cmd",
+ "base64",
  "codex-arg0",
  "codex-common",
  "codex-core",

codex-rs/mcp-server/Cargo.toml

@@ -40,6 +40,7 @@ uuid = { version = "1", features = ["serde", "v4"] }
 
 [dev-dependencies]
 assert_cmd = "2"
+base64 = "0.22"
 mcp_test_support = { path = "tests/common" }
 os_info = "3.12.0"
 pretty_assertions = "1.4.1"

codex-rs/mcp-server/src/codex_message_processor.rs

@@ -11,6 +11,8 @@ use codex_core::NewConversation;
 use codex_core::RolloutRecorder;
 use codex_core::SessionMeta;
 use codex_core::auth::CLIENT_ID;
+use codex_core::auth::get_auth_file;
+use codex_core::auth::try_read_auth_json;
 use codex_core::config::Config;
 use codex_core::config::ConfigOverrides;
 use codex_core::config::ConfigToml;
@@ -67,6 +69,7 @@ use codex_protocol::mcp_protocol::SendUserMessageResponse;
 use codex_protocol::mcp_protocol::SendUserTurnParams;
 use codex_protocol::mcp_protocol::SendUserTurnResponse;
 use codex_protocol::mcp_protocol::ServerNotification;
+use codex_protocol::mcp_protocol::UserInfoResponse;
 use codex_protocol::mcp_protocol::UserSavedConfig;
 use codex_protocol::models::ContentItem;
 use codex_protocol::models::ResponseItem;
@@ -187,6 +190,9 @@ impl CodexMessageProcessor {
             ClientRequest::GetUserAgent { request_id } => {
                 self.get_user_agent(request_id).await;
             }
+            ClientRequest::UserInfo { request_id } => {
+                self.get_user_info(request_id).await;
+            }
             ClientRequest::ExecOneOffCommand { request_id, params } => {
                 self.exec_one_off_command(request_id, params).await;
             }
@@ -439,6 +445,18 @@ impl CodexMessageProcessor {
         self.outgoing.send_response(request_id, response).await;
     }
 
+    async fn get_user_info(&self, request_id: RequestId) {
+        // Read alleged user email from auth.json (best-effort; not verified).
+        let auth_path = get_auth_file(&self.config.codex_home);
+        let alleged_user_email = match try_read_auth_json(&auth_path) {
+            Ok(auth) => auth.tokens.and_then(|t| t.id_token.email),
+            Err(_) => None,
+        };
+
+        let response = UserInfoResponse { alleged_user_email };
+        self.outgoing.send_response(request_id, response).await;
+    }
+
     async fn exec_one_off_command(&self, request_id: RequestId, params: ExecOneOffCommandParams) {
         tracing::debug!("ExecOneOffCommand params: {params:?}");
 

codex-rs/mcp-server/tests/common/mcp_process.rs

@@ -295,6 +295,11 @@ impl McpProcess {
         self.send_request("getUserAgent", None).await
     }
 
+    /// Send a `userInfo` JSON-RPC request.
+    pub async fn send_user_info_request(&mut self) -> anyhow::Result<i64> {
+        self.send_request("userInfo", None).await
+    }
+
     /// Send a `listConversations` JSON-RPC request.
     pub async fn send_list_conversations_request(
         &mut self,

codex-rs/mcp-server/tests/suite/mod.rs

@@ -10,3 +10,4 @@ mod list_resume;
 mod login;
 mod send_message;
 mod user_agent;
+mod user_info;

codex-rs/mcp-server/tests/suite/user_info.rs

@@ -0,0 +1,78 @@
+use std::time::Duration;
+
+use anyhow::Context;
+use base64::Engine;
+use base64::engine::general_purpose::URL_SAFE_NO_PAD;
+use codex_core::auth::AuthDotJson;
+use codex_core::auth::get_auth_file;
+use codex_core::auth::write_auth_json;
+use codex_core::token_data::IdTokenInfo;
+use codex_core::token_data::TokenData;
+use codex_protocol::mcp_protocol::UserInfoResponse;
+use mcp_test_support::McpProcess;
+use mcp_test_support::to_response;
+use mcp_types::JSONRPCResponse;
+use mcp_types::RequestId;
+use pretty_assertions::assert_eq;
+use serde_json::json;
+use tempfile::TempDir;
+use tokio::time::timeout;
+
+const DEFAULT_READ_TIMEOUT: Duration = Duration::from_secs(10);
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn user_info_returns_email_from_auth_json() {
+    let codex_home = TempDir::new().expect("create tempdir");
+
+    let auth_path = get_auth_file(codex_home.path());
+    let mut id_token = IdTokenInfo::default();
+    id_token.email = Some("user@example.com".to_string());
+    id_token.raw_jwt = encode_id_token_with_email("user@example.com").expect("encode id token");
+
+    let auth = AuthDotJson {
+        openai_api_key: None,
+        tokens: Some(TokenData {
+            id_token,
+            access_token: "access".to_string(),
+            refresh_token: "refresh".to_string(),
+            account_id: None,
+        }),
+        last_refresh: None,
+    };
+    write_auth_json(&auth_path, &auth).expect("write auth.json");
+
+    let mut mcp = McpProcess::new(codex_home.path())
+        .await
+        .expect("spawn mcp process");
+    timeout(DEFAULT_READ_TIMEOUT, mcp.initialize())
+        .await
+        .expect("initialize timeout")
+        .expect("initialize request");
+
+    let request_id = mcp.send_user_info_request().await.expect("send userInfo");
+    let response: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(request_id)),
+    )
+    .await
+    .expect("userInfo timeout")
+    .expect("userInfo response");
+
+    let received: UserInfoResponse = to_response(response).expect("deserialize userInfo response");
+    let expected = UserInfoResponse {
+        alleged_user_email: Some("user@example.com".to_string()),
+    };
+
+    assert_eq!(received, expected);
+}
+
+fn encode_id_token_with_email(email: &str) -> anyhow::Result<String> {
+    let header_b64 = URL_SAFE_NO_PAD.encode(
+        serde_json::to_vec(&json!({ "alg": "none", "typ": "JWT" }))
+            .context("serialize jwt header")?,
+    );
+    let payload =
+        serde_json::to_vec(&json!({ "email": email })).context("serialize jwt payload")?;
+    let payload_b64 = URL_SAFE_NO_PAD.encode(payload);
+    Ok(format!("{header_b64}.{payload_b64}.signature"))
+}

codex-rs/protocol-ts/src/lib.rs

@@ -39,6 +39,7 @@ pub fn generate_ts(out_dir: &Path, prettier: Option<&Path>) -> Result<()> {
     codex_protocol::mcp_protocol::ExecCommandApprovalResponse::export_all_to(out_dir)?;
     codex_protocol::mcp_protocol::GetUserSavedConfigResponse::export_all_to(out_dir)?;
     codex_protocol::mcp_protocol::GetUserAgentResponse::export_all_to(out_dir)?;
+    codex_protocol::mcp_protocol::UserInfoResponse::export_all_to(out_dir)?;
 
     // All notification types reachable from this enum will be generated by
     // induction, so they do not need to be listed individually.

codex-rs/protocol/src/mcp_protocol.rs

@@ -152,6 +152,10 @@ pub enum ClientRequest {
         #[serde(rename = "id")]
         request_id: RequestId,
     },
+    UserInfo {
+        #[serde(rename = "id")]
+        request_id: RequestId,
+    },
     /// Execute a command (argv vector) under the server's sandbox.
     ExecOneOffCommand {
         #[serde(rename = "id")]
@@ -374,6 +378,16 @@ pub struct GetUserAgentResponse {
     pub user_agent: String,
 }
 
+#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, TS)]
+#[serde(rename_all = "camelCase")]
+pub struct UserInfoResponse {
+    /// Note: `alleged_user_email` is not currently verified. We read it from
+    /// the local auth.json, which the user could theoretically modify. In the
+    /// future, we may add logic to verify the email against the server before
+    /// returning it.
+    pub alleged_user_email: Option<String>,
+}
+
 #[derive(Serialize, Deserialize, Debug, Clone, PartialEq, TS)]
 #[serde(rename_all = "camelCase")]
 pub struct GetUserSavedConfigResponse {