diff --git a/codex-rs/app-server/src/message_processor.rs b/codex-rs/app-server/src/message_processor.rs
index ca122920bd..64e3c0ee3c 100644
--- a/codex-rs/app-server/src/message_processor.rs
+++ b/codex-rs/app-server/src/message_processor.rs
@@ -287,7 +287,7 @@ impl MessageProcessor {
                 Some(analytics_events_client.clone()),
                 Arc::clone(&thread_store),
                 codex_core::local_agent_graph_store_from_state_db(state_db.as_ref()),
-                installation_id,
+                installation_id.clone(),
                 Some(app_server_attestation_provider(
                     outgoing.clone(),
                     thread_state_manager.clone(),
@@ -318,6 +318,7 @@ impl MessageProcessor {
             outgoing.clone(),
             Arc::clone(&config),
             config_manager.clone(),
+            installation_id.clone(),
         );
         let apps_processor = AppsRequestProcessor::new(
             auth_manager.clone(),
diff --git a/codex-rs/app-server/src/request_processors/account_processor.rs b/codex-rs/app-server/src/request_processors/account_processor.rs
index f4acc5a8e4..3f5413aca9 100644
--- a/codex-rs/app-server/src/request_processors/account_processor.rs
+++ b/codex-rs/app-server/src/request_processors/account_processor.rs
@@ -71,6 +71,7 @@ pub(crate) struct AccountRequestProcessor {
     config: Arc<Config>,
     config_manager: ConfigManager,
     active_login: Arc<Mutex<Option<ActiveLogin>>>,
+    installation_id: String,
 }
 
 impl AccountRequestProcessor {
@@ -80,6 +81,7 @@ impl AccountRequestProcessor {
         outgoing: Arc<OutgoingMessageSender>,
         config: Arc<Config>,
         config_manager: ConfigManager,
+        installation_id: String,
     ) -> Self {
         Self {
             auth_manager,
@@ -88,6 +90,7 @@ impl AccountRequestProcessor {
             config,
             config_manager,
             active_login: Arc::new(Mutex::new(None)),
+            installation_id,
         }
     }
 
@@ -378,6 +381,9 @@ impl AccountRequestProcessor {
             open_browser: false,
             codex_streamlined_login,
             login_success_page,
+            device_auth_metadata: Some(codex_login::DeviceAuthMetadata {
+                installation_id: self.installation_id.clone(),
+            }),
             ..LoginServerOptions::new(
                 config.codex_home.to_path_buf(),
                 oauth_client_id(),
@@ -394,6 +400,7 @@ impl AccountRequestProcessor {
                 && !issuer.trim().is_empty()
             {
                 opts.issuer = issuer;
+                opts.device_auth_metadata = None;
             }
             if let LoginSuccessPage::Hosted { url, .. } = &mut opts.login_success_page
                 && let Ok(open_app_url) = std::env::var(LOGIN_OPEN_APP_URL_OVERRIDE_ENV_VAR)
diff --git a/codex-rs/app-server/tests/suite/v2/account.rs b/codex-rs/app-server/tests/suite/v2/account.rs
index ccf46321e6..3220f126c7 100644
--- a/codex-rs/app-server/tests/suite/v2/account.rs
+++ b/codex-rs/app-server/tests/suite/v2/account.rs
@@ -17,6 +17,7 @@ use codex_app_server_protocol::CancelLoginAccountResponse;
 use codex_app_server_protocol::CancelLoginAccountStatus;
 use codex_app_server_protocol::ChatgptAuthTokensRefreshReason;
 use codex_app_server_protocol::ChatgptAuthTokensRefreshResponse;
+use codex_app_server_protocol::ClientInfo;
 use codex_app_server_protocol::GetAccountParams;
 use codex_app_server_protocol::GetAccountResponse;
 use codex_app_server_protocol::GetAuthStatusParams;
@@ -1172,7 +1173,17 @@ async fn login_account_chatgpt_device_code_succeeds_and_notifies() -> Result<()>
         ])
         .build()
         .await?;
-    timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
+    let client_name = "device-auth-app-server-test";
+    let client_version = "1.2.3";
+    timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.initialize_with_client_info(ClientInfo {
+            name: client_name.to_string(),
+            title: None,
+            version: client_version.to_string(),
+        }),
+    )
+    .await??;
 
     let request_id = mcp.send_login_account_chatgpt_device_code_request().await?;
     let resp: JSONRPCResponse = timeout(
@@ -1220,6 +1231,29 @@ async fn login_account_chatgpt_device_code_succeeds_and_notifies() -> Result<()>
         codex_home.path().join("auth.json").exists(),
         "auth.json should be created when device code login succeeds"
     );
+    let requests = mock_server.received_requests().await.unwrap();
+    let device_requests: Vec<_> = requests
+        .iter()
+        .filter(|request| request.url.path().starts_with("/api/accounts/deviceauth/"))
+        .collect();
+    assert_eq!(device_requests.len(), 2);
+    for request in device_requests {
+        assert_eq!(
+            request
+                .headers
+                .get("originator")
+                .and_then(|value| value.to_str().ok()),
+            Some(client_name)
+        );
+        assert!(
+            request
+                .headers
+                .get("user-agent")
+                .and_then(|value| value.to_str().ok())
+                .is_some_and(|value| value.contains(&format!("({client_name}; {client_version})")))
+        );
+        assert!(request.headers.get("x-codex-installation-id").is_none());
+    }
     Ok(())
 }
 
diff --git a/codex-rs/cli/src/login.rs b/codex-rs/cli/src/login.rs
index 98d56bec12..e0952b6e43 100644
--- a/codex-rs/cli/src/login.rs
+++ b/codex-rs/cli/src/login.rs
@@ -13,6 +13,7 @@ use codex_login::AuthKeyringBackendKind;
 use codex_login::AuthRouteConfig;
 use codex_login::CLIENT_ID;
 use codex_login::CodexAuth;
+use codex_login::DeviceAuthMetadata;
 use codex_login::ServerOptions;
 use codex_login::login_with_access_token;
 use codex_login::login_with_api_key;
@@ -316,6 +317,14 @@ pub async fn run_login_with_device_code(
         std::process::exit(1);
     }
     let auth_route_config = config.auth_route_config();
+    let installation_id = match codex_core::resolve_installation_id(&config.codex_home).await {
+        Ok(installation_id) => installation_id,
+        Err(err) => {
+            eprintln!("Error resolving installation ID: {err}");
+            std::process::exit(1);
+        }
+    };
+    let uses_default_issuer = issuer_base_url.is_none();
     clear_existing_auth_before_login(
         &config.codex_home,
         config.cli_auth_credentials_store_mode,
@@ -335,6 +344,9 @@ pub async fn run_login_with_device_code(
     if let Some(iss) = issuer_base_url {
         opts.issuer = iss;
     }
+    if uses_default_issuer {
+        opts.device_auth_metadata = Some(DeviceAuthMetadata { installation_id });
+    }
     match run_device_code_login(opts).await {
         Ok(()) => {
             eprintln!("{LOGIN_SUCCESS_MESSAGE}");
@@ -364,6 +376,14 @@ pub async fn run_login_with_device_code_fallback_to_browser(
         std::process::exit(1);
     }
     let auth_route_config = config.auth_route_config();
+    let installation_id = match codex_core::resolve_installation_id(&config.codex_home).await {
+        Ok(installation_id) => installation_id,
+        Err(err) => {
+            eprintln!("Error resolving installation ID: {err}");
+            std::process::exit(1);
+        }
+    };
+    let uses_default_issuer = issuer_base_url.is_none();
     clear_existing_auth_before_login(
         &config.codex_home,
         config.cli_auth_credentials_store_mode,
@@ -384,6 +404,9 @@ pub async fn run_login_with_device_code_fallback_to_browser(
     if let Some(iss) = issuer_base_url {
         opts.issuer = iss;
     }
+    if uses_default_issuer {
+        opts.device_auth_metadata = Some(DeviceAuthMetadata { installation_id });
+    }
     opts.open_browser = false;
 
     match run_device_code_login(opts.clone()).await {
diff --git a/codex-rs/cli/tests/login.rs b/codex-rs/cli/tests/login.rs
index 4f37f41418..4cf5aca68a 100644
--- a/codex-rs/cli/tests/login.rs
+++ b/codex-rs/cli/tests/login.rs
@@ -169,6 +169,26 @@ async fn device_login_revokes_existing_auth_before_requesting_new_tokens() -> Re
             "client_id": CLIENT_ID,
         })
     );
+    let expected_originator =
+        std::env::var(codex_login::default_client::CODEX_INTERNAL_ORIGINATOR_OVERRIDE_ENV_VAR)
+            .unwrap_or_else(|_| codex_login::default_client::DEFAULT_ORIGINATOR.to_string());
+    for request in &requests[1..=2] {
+        assert_eq!(
+            request
+                .headers
+                .get("originator")
+                .and_then(|value| value.to_str().ok()),
+            Some(expected_originator.as_str())
+        );
+        assert!(
+            request
+                .headers
+                .get("user-agent")
+                .and_then(|value| value.to_str().ok())
+                .is_some_and(|value| value.starts_with(&format!("{expected_originator}/")))
+        );
+        assert!(request.headers.get("x-codex-installation-id").is_none());
+    }
 
     let auth = read_auth_json(codex_home.path())?;
     assert_eq!(auth["tokens"]["refresh_token"], "new-refresh");
diff --git a/codex-rs/login/src/device_code_auth.rs b/codex-rs/login/src/device_code_auth.rs
index 70e6dff225..21dc3f6ad9 100644
--- a/codex-rs/login/src/device_code_auth.rs
+++ b/codex-rs/login/src/device_code_auth.rs
@@ -6,7 +6,7 @@ use serde::de::{self};
 use std::time::Duration;
 use std::time::Instant;
 
-use crate::default_client::build_raw_auth_reqwest_client;
+use crate::default_client::build_default_auth_reqwest_client;
 use crate::pkce::PkceCodes;
 use crate::server::ServerOptions;
 use std::io;
@@ -14,6 +14,7 @@ use std::io;
 const ANSI_BLUE: &str = "\x1b[94m";
 const ANSI_GRAY: &str = "\x1b[90m";
 const ANSI_RESET: &str = "\x1b[0m";
+const X_CODEX_INSTALLATION_ID_HEADER: &str = "x-codex-installation-id";
 
 #[derive(Debug, Clone)]
 pub struct DeviceCode {
@@ -63,19 +64,21 @@ async fn request_user_code(
     client: &reqwest::Client,
     auth_base_url: &str,
     client_id: &str,
+    installation_id: Option<&str>,
 ) -> std::io::Result<UserCodeResp> {
     let url = format!("{auth_base_url}/deviceauth/usercode");
     let body = serde_json::to_string(&UserCodeReq {
         client_id: client_id.to_string(),
     })
     .map_err(std::io::Error::other)?;
-    let resp = client
+    let mut request = client
         .post(url)
         .header("Content-Type", "application/json")
-        .body(body)
-        .send()
-        .await
-        .map_err(std::io::Error::other)?;
+        .body(body);
+    if let Some(installation_id) = installation_id {
+        request = request.header(X_CODEX_INSTALLATION_ID_HEADER, installation_id);
+    }
+    let resp = request.send().await.map_err(std::io::Error::other)?;
 
     if !resp.status().is_success() {
         let status = resp.status();
@@ -102,6 +105,7 @@ async fn poll_for_token(
     device_auth_id: &str,
     user_code: &str,
     interval: u64,
+    installation_id: Option<&str>,
 ) -> std::io::Result<CodeSuccessResp> {
     let url = format!("{auth_base_url}/deviceauth/token");
     let max_wait = Duration::from_secs(15 * 60);
@@ -113,13 +117,14 @@ async fn poll_for_token(
             user_code: user_code.to_string(),
         })
         .map_err(std::io::Error::other)?;
-        let resp = client
+        let mut request = client
             .post(&url)
             .header("Content-Type", "application/json")
-            .body(body)
-            .send()
-            .await
-            .map_err(std::io::Error::other)?;
+            .body(body);
+        if let Some(installation_id) = installation_id {
+            request = request.header(X_CODEX_INSTALLATION_ID_HEADER, installation_id);
+        }
+        let resp = request.send().await.map_err(std::io::Error::other)?;
 
         let status = resp.status();
 
@@ -160,9 +165,13 @@ pub async fn request_device_code(opts: &ServerOptions) -> std::io::Result<Device
     let base_url = opts.issuer.trim_end_matches('/');
     // The route selected for the issuer is reused for all device-auth endpoint paths; the endpoint
     // paths are not resolved separately.
-    let client = build_raw_auth_reqwest_client(base_url, opts.auth_route_config.as_ref())?;
+    let client = build_default_auth_reqwest_client(base_url, opts.auth_route_config.as_ref())?;
     let api_base_url = format!("{base_url}/api/accounts");
-    let uc = request_user_code(&client, &api_base_url, &opts.client_id).await?;
+    let installation_id = opts
+        .device_auth_metadata
+        .as_ref()
+        .map(|metadata| metadata.installation_id.as_str());
+    let uc = request_user_code(&client, &api_base_url, &opts.client_id, installation_id).await?;
 
     Ok(DeviceCode {
         verification_url: format!("{base_url}/codex/device"),
@@ -177,8 +186,12 @@ pub async fn complete_device_code_login(
     device_code: DeviceCode,
 ) -> std::io::Result<()> {
     let base_url = opts.issuer.trim_end_matches('/');
-    let client = build_raw_auth_reqwest_client(base_url, opts.auth_route_config.as_ref())?;
+    let client = build_default_auth_reqwest_client(base_url, opts.auth_route_config.as_ref())?;
     let api_base_url = format!("{base_url}/api/accounts");
+    let installation_id = opts
+        .device_auth_metadata
+        .as_ref()
+        .map(|metadata| metadata.installation_id.as_str());
 
     let code_resp = poll_for_token(
         &client,
@@ -186,6 +199,7 @@ pub async fn complete_device_code_login(
         &device_code.device_auth_id,
         &device_code.user_code,
         device_code.interval,
+        installation_id,
     )
     .await?;
 
diff --git a/codex-rs/login/src/lib.rs b/codex-rs/login/src/lib.rs
index 9b3f82f382..5b5ce1d110 100644
--- a/codex-rs/login/src/lib.rs
+++ b/codex-rs/login/src/lib.rs
@@ -14,6 +14,7 @@ pub use device_code_auth::DeviceCode;
 pub use device_code_auth::complete_device_code_login;
 pub use device_code_auth::request_device_code;
 pub use device_code_auth::run_device_code_login;
+pub use server::DeviceAuthMetadata;
 pub use server::LoginServer;
 pub use server::ServerOptions;
 pub use server::ShutdownHandle;
diff --git a/codex-rs/login/src/server.rs b/codex-rs/login/src/server.rs
index 01671bf0b1..e99e6472d7 100644
--- a/codex-rs/login/src/server.rs
+++ b/codex-rs/login/src/server.rs
@@ -78,6 +78,13 @@ pub struct ServerOptions {
     pub cli_auth_credentials_store_mode: AuthCredentialsStoreMode,
     pub auth_keyring_backend_kind: AuthKeyringBackendKind,
     pub auth_route_config: Option<AuthRouteConfig>,
+    pub device_auth_metadata: Option<DeviceAuthMetadata>,
+}
+
+/// Metadata attached only to device authorization requests sent to a trusted issuer.
+#[derive(Debug, Clone)]
+pub struct DeviceAuthMetadata {
+    pub installation_id: String,
 }
 
 impl ServerOptions {
@@ -103,6 +110,7 @@ impl ServerOptions {
             cli_auth_credentials_store_mode,
             auth_keyring_backend_kind,
             auth_route_config,
+            device_auth_metadata: None,
         }
     }
 }
diff --git a/codex-rs/login/tests/suite/device_code_login.rs b/codex-rs/login/tests/suite/device_code_login.rs
index 83cae8af5f..cf870405b7 100644
--- a/codex-rs/login/tests/suite/device_code_login.rs
+++ b/codex-rs/login/tests/suite/device_code_login.rs
@@ -5,6 +5,7 @@ use base64::Engine;
 use base64::engine::general_purpose::URL_SAFE_NO_PAD;
 use codex_config::types::AuthCredentialsStoreMode;
 use codex_login::AuthKeyringBackendKind;
+use codex_login::DeviceAuthMetadata;
 use codex_login::ServerOptions;
 use codex_login::auth::load_auth_dot_json;
 use codex_login::run_device_code_login;
@@ -144,7 +145,11 @@ async fn device_code_login_integration_succeeds() -> anyhow::Result<()> {
     mock_oauth_token_single(&mock_server, jwt.clone()).await;
 
     let issuer = mock_server.uri();
-    let opts = server_opts(&codex_home, issuer, AuthCredentialsStoreMode::File);
+    let installation_id = "123e4567-e89b-42d3-a456-426614174099";
+    let mut opts = server_opts(&codex_home, issuer, AuthCredentialsStoreMode::File);
+    opts.device_auth_metadata = Some(DeviceAuthMetadata {
+        installation_id: installation_id.to_string(),
+    });
 
     run_device_code_login(opts)
         .await
@@ -163,6 +168,38 @@ async fn device_code_login_integration_succeeds() -> anyhow::Result<()> {
     assert_eq!(tokens.refresh_token, "refresh-token-123");
     assert_eq!(tokens.id_token.raw_jwt, jwt);
     assert_eq!(tokens.account_id.as_deref(), Some(WORKSPACE_ID_ALLOWED));
+
+    let requests = mock_server.received_requests().await.unwrap();
+    let device_requests: Vec<&Request> = requests
+        .iter()
+        .filter(|request| request.url.path().starts_with("/api/accounts/deviceauth/"))
+        .collect();
+    assert_eq!(device_requests.len(), 3);
+    let expected_originator = codex_login::default_client::originator().value;
+    let expected_user_agent = codex_login::default_client::get_codex_user_agent();
+    for request in device_requests {
+        assert_eq!(
+            request
+                .headers
+                .get("originator")
+                .and_then(|value| value.to_str().ok()),
+            Some(expected_originator.as_str())
+        );
+        assert_eq!(
+            request
+                .headers
+                .get("user-agent")
+                .and_then(|value| value.to_str().ok()),
+            Some(expected_user_agent.as_str())
+        );
+        assert_eq!(
+            request
+                .headers
+                .get("x-codex-installation-id")
+                .and_then(|value| value.to_str().ok()),
+            Some(installation_id)
+        );
+    }
     Ok(())
 }
 
diff --git a/codex-rs/login/tests/suite/login_server_e2e.rs b/codex-rs/login/tests/suite/login_server_e2e.rs
index dbcd396ef1..36fcece285 100644
--- a/codex-rs/login/tests/suite/login_server_e2e.rs
+++ b/codex-rs/login/tests/suite/login_server_e2e.rs
@@ -125,6 +125,7 @@ async fn end_to_end_login_flow_persists_auth_json() -> Result<()> {
         codex_home: server_home,
         cli_auth_credentials_store_mode: AuthCredentialsStoreMode::File,
         auth_route_config: None,
+        device_auth_metadata: None,
         client_id: codex_login::CLIENT_ID.to_string(),
         issuer,
         port: 0,
@@ -190,6 +191,7 @@ async fn hosted_login_redirects_to_configured_open_app_url() -> Result<()> {
         codex_home: tmp.path().to_path_buf(),
         cli_auth_credentials_store_mode: AuthCredentialsStoreMode::File,
         auth_route_config: None,
+        device_auth_metadata: None,
         client_id: codex_login::CLIENT_ID.to_string(),
         issuer,
         port: 0,
@@ -243,6 +245,7 @@ async fn creates_missing_codex_home_dir() -> Result<()> {
         codex_home: server_home,
         cli_auth_credentials_store_mode: AuthCredentialsStoreMode::File,
         auth_route_config: None,
+        device_auth_metadata: None,
         client_id: codex_login::CLIENT_ID.to_string(),
         issuer,
         port: 0,
@@ -286,6 +289,7 @@ async fn login_server_includes_forced_workspaces_as_one_query_param() -> Result<
         codex_home,
         cli_auth_credentials_store_mode: AuthCredentialsStoreMode::File,
         auth_route_config: None,
+        device_auth_metadata: None,
         client_id: codex_login::CLIENT_ID.to_string(),
         issuer,
         port: 0,
@@ -330,6 +334,7 @@ async fn forced_chatgpt_workspace_id_mismatch_blocks_login() -> Result<()> {
         codex_home: codex_home.clone(),
         cli_auth_credentials_store_mode: AuthCredentialsStoreMode::File,
         auth_route_config: None,
+        device_auth_metadata: None,
         client_id: codex_login::CLIENT_ID.to_string(),
         issuer,
         port: 0,
@@ -393,6 +398,7 @@ async fn oauth_access_denied_missing_entitlement_blocks_login_with_clear_error()
         codex_home: codex_home.clone(),
         cli_auth_credentials_store_mode: AuthCredentialsStoreMode::File,
         auth_route_config: None,
+        device_auth_metadata: None,
         client_id: codex_login::CLIENT_ID.to_string(),
         issuer,
         port: 0,
@@ -464,6 +470,7 @@ async fn oauth_access_denied_unknown_reason_uses_generic_error_page() -> Result<
         codex_home: codex_home.clone(),
         cli_auth_credentials_store_mode: AuthCredentialsStoreMode::File,
         auth_route_config: None,
+        device_auth_metadata: None,
         client_id: codex_login::CLIENT_ID.to_string(),
         issuer,
         port: 0,
@@ -614,6 +621,7 @@ async fn cancels_previous_login_server_when_port_is_in_use() -> Result<()> {
         codex_home: first_codex_home,
         cli_auth_credentials_store_mode: AuthCredentialsStoreMode::File,
         auth_route_config: None,
+        device_auth_metadata: None,
         client_id: codex_login::CLIENT_ID.to_string(),
         issuer: issuer.clone(),
         port: 0,
@@ -638,6 +646,7 @@ async fn cancels_previous_login_server_when_port_is_in_use() -> Result<()> {
         codex_home: second_codex_home,
         cli_auth_credentials_store_mode: AuthCredentialsStoreMode::File,
         auth_route_config: None,
+        device_auth_metadata: None,
         client_id: codex_login::CLIENT_ID.to_string(),
         issuer,
         port: login_port,