diff --git a/codex-rs/app-server-protocol/schema/json/ServerNotification.json b/codex-rs/app-server-protocol/schema/json/ServerNotification.json
index 23dae42a9d..0dab5a4c57 100644
--- a/codex-rs/app-server-protocol/schema/json/ServerNotification.json
+++ b/codex-rs/app-server-protocol/schema/json/ServerNotification.json
@@ -536,6 +536,13 @@
           ],
           "type": "string"
         },
+        {
+          "description": "[UNSTABLE] FOR OPENAI INTERNAL USE ONLY - DO NOT USE.\n\nCodex backend request headers supplied by the process embedding Codex.",
+          "enum": [
+            "hostProvided"
+          ],
+          "type": "string"
+        },
         {
           "description": "Programmatic Codex auth backed by a registered Agent Identity.",
           "enum": [
diff --git a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
index 341c325b1d..4f56b6fc45 100644
--- a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
+++ b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.schemas.json
@@ -6950,6 +6950,13 @@
             ],
             "type": "string"
           },
+          {
+            "description": "[UNSTABLE] FOR OPENAI INTERNAL USE ONLY - DO NOT USE.\n\nCodex backend request headers supplied by the process embedding Codex.",
+            "enum": [
+              "hostProvided"
+            ],
+            "type": "string"
+          },
           {
             "description": "Programmatic Codex auth backed by a registered Agent Identity.",
             "enum": [
diff --git a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
index 488bd6016e..9db95a2c97 100644
--- a/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
+++ b/codex-rs/app-server-protocol/schema/json/codex_app_server_protocol.v2.schemas.json
@@ -1076,6 +1076,13 @@
           ],
           "type": "string"
         },
+        {
+          "description": "[UNSTABLE] FOR OPENAI INTERNAL USE ONLY - DO NOT USE.\n\nCodex backend request headers supplied by the process embedding Codex.",
+          "enum": [
+            "hostProvided"
+          ],
+          "type": "string"
+        },
         {
           "description": "Programmatic Codex auth backed by a registered Agent Identity.",
           "enum": [
diff --git a/codex-rs/app-server-protocol/schema/json/v2/AccountUpdatedNotification.json b/codex-rs/app-server-protocol/schema/json/v2/AccountUpdatedNotification.json
index 5c1847c56c..cbbed1ce26 100644
--- a/codex-rs/app-server-protocol/schema/json/v2/AccountUpdatedNotification.json
+++ b/codex-rs/app-server-protocol/schema/json/v2/AccountUpdatedNotification.json
@@ -25,6 +25,13 @@
           ],
           "type": "string"
         },
+        {
+          "description": "[UNSTABLE] FOR OPENAI INTERNAL USE ONLY - DO NOT USE.\n\nCodex backend request headers supplied by the process embedding Codex.",
+          "enum": [
+            "hostProvided"
+          ],
+          "type": "string"
+        },
         {
           "description": "Programmatic Codex auth backed by a registered Agent Identity.",
           "enum": [
diff --git a/codex-rs/app-server-protocol/schema/typescript/AuthMode.ts b/codex-rs/app-server-protocol/schema/typescript/AuthMode.ts
index 77bc037ebe..51f390dc71 100644
--- a/codex-rs/app-server-protocol/schema/typescript/AuthMode.ts
+++ b/codex-rs/app-server-protocol/schema/typescript/AuthMode.ts
@@ -5,4 +5,4 @@
 /**
  * Authentication mode for OpenAI-backed providers.
  */
-export type AuthMode = "apikey" | "chatgpt" | "chatgptAuthTokens" | "agentIdentity" | "personalAccessToken" | "bedrockApiKey";
+export type AuthMode = "apikey" | "chatgpt" | "chatgptAuthTokens" | "hostProvided" | "agentIdentity" | "personalAccessToken" | "bedrockApiKey";
diff --git a/codex-rs/app-server-protocol/src/protocol/common.rs b/codex-rs/app-server-protocol/src/protocol/common.rs
index 7b15035575..fe629415d4 100644
--- a/codex-rs/app-server-protocol/src/protocol/common.rs
+++ b/codex-rs/app-server-protocol/src/protocol/common.rs
@@ -31,6 +31,13 @@ pub enum AuthMode {
     #[ts(rename = "chatgptAuthTokens")]
     #[strum(serialize = "chatgptAuthTokens")]
     ChatgptAuthTokens,
+    /// [UNSTABLE] FOR OPENAI INTERNAL USE ONLY - DO NOT USE.
+    ///
+    /// Codex backend request headers supplied by the process embedding Codex.
+    #[serde(rename = "hostProvided")]
+    #[ts(rename = "hostProvided")]
+    #[strum(serialize = "hostProvided")]
+    HostProvided,
     /// Programmatic Codex auth backed by a registered Agent Identity.
     #[serde(rename = "agentIdentity")]
     #[ts(rename = "agentIdentity")]
@@ -53,7 +60,7 @@ impl AuthMode {
     pub fn has_chatgpt_account(self) -> bool {
         match self {
             Self::Chatgpt | Self::ChatgptAuthTokens | Self::PersonalAccessToken => true,
-            Self::ApiKey | Self::AgentIdentity | Self::BedrockApiKey => false,
+            Self::ApiKey | Self::HostProvided | Self::AgentIdentity | Self::BedrockApiKey => false,
         }
     }
 
@@ -62,6 +69,7 @@ impl AuthMode {
         match self {
             Self::Chatgpt
             | Self::ChatgptAuthTokens
+            | Self::HostProvided
             | Self::AgentIdentity
             | Self::PersonalAccessToken => true,
             Self::ApiKey | Self::BedrockApiKey => false,
diff --git a/codex-rs/app-server/src/auth_mode.rs b/codex-rs/app-server/src/auth_mode.rs
index 67d3ee61b9..802249c9a4 100644
--- a/codex-rs/app-server/src/auth_mode.rs
+++ b/codex-rs/app-server/src/auth_mode.rs
@@ -12,6 +12,7 @@ pub(crate) fn auth_mode_to_api(auth_mode: AuthMode) -> ApiAuthMode {
         AuthMode::ApiKey => ApiAuthMode::ApiKey,
         AuthMode::Chatgpt => ApiAuthMode::Chatgpt,
         AuthMode::ChatgptAuthTokens => ApiAuthMode::ChatgptAuthTokens,
+        AuthMode::HostProvided => ApiAuthMode::HostProvided,
         AuthMode::AgentIdentity => ApiAuthMode::AgentIdentity,
         AuthMode::PersonalAccessToken => ApiAuthMode::PersonalAccessToken,
         AuthMode::BedrockApiKey => ApiAuthMode::BedrockApiKey,
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 4691e22204..38f6147d05 100644
--- a/codex-rs/app-server/src/request_processors/account_processor.rs
+++ b/codex-rs/app-server/src/request_processors/account_processor.rs
@@ -812,7 +812,9 @@ impl AccountRequestProcessor {
                     let auth_mode = auth_mode_to_api(auth.api_auth_mode());
                     let (reported_auth_method, token_opt) = if matches!(
                         auth,
-                        CodexAuth::AgentIdentity(_) | CodexAuth::PersonalAccessToken(_)
+                        CodexAuth::HostProvided(_)
+                            | CodexAuth::AgentIdentity(_)
+                            | CodexAuth::PersonalAccessToken(_)
                     ) || include_token
                         && permanent_refresh_failure
                     {
diff --git a/codex-rs/cli/src/doctor.rs b/codex-rs/cli/src/doctor.rs
index ef587cd1d4..37c7653753 100644
--- a/codex-rs/cli/src/doctor.rs
+++ b/codex-rs/cli/src/doctor.rs
@@ -1327,6 +1327,7 @@ fn stored_auth_mode(auth: &codex_login::AuthDotJson) -> &'static str {
         AuthMode::ApiKey => "api_key",
         AuthMode::Chatgpt => "chatgpt",
         AuthMode::ChatgptAuthTokens => "chatgpt_auth_tokens",
+        AuthMode::HostProvided => "host_provided",
         AuthMode::AgentIdentity => "agent_identity",
         AuthMode::PersonalAccessToken => "personal_access_token",
         AuthMode::BedrockApiKey => "bedrock_api_key",
@@ -1397,6 +1398,9 @@ fn stored_auth_issues(
                 issues.push("external ChatGPT auth is missing refresh metadata");
             }
         }
+        AuthMode::HostProvided => {
+            issues.push("host-provided auth cannot be loaded from auth storage");
+        }
         AuthMode::AgentIdentity => {
             if auth
                 .agent_identity
@@ -2466,6 +2470,7 @@ fn auth_mode_name(auth: &CodexAuth) -> &'static str {
         AuthMode::ApiKey => "api_key",
         AuthMode::Chatgpt => "chatgpt",
         AuthMode::ChatgptAuthTokens => "chatgpt_auth_tokens",
+        AuthMode::HostProvided => "host_provided",
         AuthMode::AgentIdentity => "agent_identity",
         AuthMode::PersonalAccessToken => "personal_access_token",
         AuthMode::BedrockApiKey => "bedrock_api_key",
@@ -2605,6 +2610,7 @@ fn provider_auth_reachability_mode_from_auth(
         Some(
             AuthMode::Chatgpt
             | AuthMode::ChatgptAuthTokens
+            | AuthMode::HostProvided
             | AuthMode::AgentIdentity
             | AuthMode::PersonalAccessToken,
         )
diff --git a/codex-rs/cli/src/login.rs b/codex-rs/cli/src/login.rs
index d3f9b7b96b..8f982f9691 100644
--- a/codex-rs/cli/src/login.rs
+++ b/codex-rs/cli/src/login.rs
@@ -449,6 +449,10 @@ pub async fn run_login_status(cli_config_overrides: CliConfigOverrides) -> ! {
                 eprintln!("Logged in using ChatGPT");
                 std::process::exit(0);
             }
+            AuthMode::HostProvided => {
+                eprintln!("Logged in using host-provided auth");
+                std::process::exit(0);
+            }
             AuthMode::AgentIdentity => {
                 eprintln!("Logged in using access token");
                 std::process::exit(0);
diff --git a/codex-rs/codex-mcp/src/connection_manager_tests.rs b/codex-rs/codex-mcp/src/connection_manager_tests.rs
index 1f61ab700e..19ba252331 100644
--- a/codex-rs/codex-mcp/src/connection_manager_tests.rs
+++ b/codex-rs/codex-mcp/src/connection_manager_tests.rs
@@ -26,6 +26,8 @@ use codex_config::McpServerToolConfig;
 use codex_config::types::AuthKeyringBackendKind;
 use codex_config::types::OAuthCredentialsStoreMode;
 use codex_exec_server::EnvironmentManager;
+use codex_login::CodexAuth;
+use codex_login::HostProvidedAuth;
 use codex_protocol::ToolName;
 use codex_protocol::mcp::McpServerInfo;
 use codex_protocol::models::PermissionProfile;
@@ -68,6 +70,34 @@ fn create_test_tool(server_name: &str, tool_name: &str) -> ToolInfo {
     }
 }
 
+#[test]
+fn host_provided_auth_scopes_codex_apps_cache() {
+    let auth = CodexAuth::HostProvided(
+        HostProvidedAuth::new([], "user-123").with_account_id("account-123"),
+    );
+
+    assert_eq!(
+        crate::codex_apps::codex_apps_tools_cache_key(Some(&auth)),
+        CodexAppsToolsCacheKey {
+            account_id: Some("account-123".to_string()),
+            chatgpt_user_id: Some("user-123".to_string()),
+            is_workspace_account: false,
+        }
+    );
+}
+
+fn create_test_tool_with_connector(
+    server_name: &str,
+    tool_name: &str,
+    connector_id: &str,
+    connector_name: Option<&str>,
+) -> ToolInfo {
+    let mut tool = create_test_tool(server_name, tool_name);
+    tool.connector_id = Some(connector_id.to_string());
+    tool.connector_name = connector_name.map(ToOwned::to_owned);
+    tool
+}
+
 fn create_codex_apps_tools_cache_context(
     codex_home: PathBuf,
     account_id: Option<&str>,
diff --git a/codex-rs/core-api/src/lib.rs b/codex-rs/core-api/src/lib.rs
index c7cfff8a92..11e7609ac5 100644
--- a/codex-rs/core-api/src/lib.rs
+++ b/codex-rs/core-api/src/lib.rs
@@ -70,6 +70,7 @@ pub use codex_features::Feature;
 pub use codex_features::Features;
 pub use codex_home::CodexHomeUserInstructionsProvider;
 pub use codex_login::AuthManager;
+pub use codex_login::HostProvidedAuth;
 pub use codex_login::default_client::set_default_originator;
 pub use codex_model_provider_info::OPENAI_PROVIDER_ID;
 pub use codex_model_provider_info::built_in_model_providers;
diff --git a/codex-rs/core/src/client.rs b/codex-rs/core/src/client.rs
index ffa8ae8e20..c1aa8bd369 100644
--- a/codex-rs/core/src/client.rs
+++ b/codex-rs/core/src/client.rs
@@ -2088,6 +2088,7 @@ impl AuthRequestTelemetryContext {
                 AuthMode::ApiKey | AuthMode::BedrockApiKey => "ApiKey",
                 AuthMode::Chatgpt
                 | AuthMode::ChatgptAuthTokens
+                | AuthMode::HostProvided
                 | AuthMode::AgentIdentity
                 | AuthMode::PersonalAccessToken => "Chatgpt",
             }),
diff --git a/codex-rs/ext/mcp/tests/hosted_apps_mcp.rs b/codex-rs/ext/mcp/tests/hosted_apps_mcp.rs
index 3836234b84..28d6d7d865 100644
--- a/codex-rs/ext/mcp/tests/hosted_apps_mcp.rs
+++ b/codex-rs/ext/mcp/tests/hosted_apps_mcp.rs
@@ -10,6 +10,7 @@ use codex_extension_api::McpServerContribution;
 use codex_extension_api::McpServerContributionContext;
 use codex_extension_api::McpServerContributor;
 use codex_login::CodexAuth;
+use codex_login::HostProvidedAuth;
 use codex_mcp::CODEX_APPS_MCP_SERVER_NAME;
 use pretty_assertions::assert_eq;
 
@@ -146,6 +147,24 @@ async fn hosted_apps_mcp_requires_chatgpt_auth() -> TestResult {
     Ok(())
 }
 
+#[tokio::test]
+async fn hosted_apps_mcp_accepts_host_provided_codex_auth() -> TestResult {
+    let codex_home = tempfile::tempdir()?;
+    let config = ConfigBuilder::default()
+        .codex_home(codex_home.path().to_path_buf())
+        .fallback_cwd(Some(codex_home.path().to_path_buf()))
+        .cli_overrides(vec![("features.apps".to_string(), true.into())])
+        .build()
+        .await?;
+    let auth = CodexAuth::HostProvided(HostProvidedAuth::new([], "user-123"));
+    let manager = installed_manager(&config);
+
+    let servers = manager.effective_servers(&config, Some(&auth)).await;
+
+    assert!(servers.contains_key(CODEX_APPS_MCP_SERVER_NAME));
+    Ok(())
+}
+
 #[tokio::test]
 async fn disabled_apps_remove_reserved_server_config_for_all_hosts() -> TestResult {
     let codex_home = tempfile::tempdir()?;
diff --git a/codex-rs/login/src/auth/bedrock_api_key_tests.rs b/codex-rs/login/src/auth/bedrock_api_key_tests.rs
index 1f8fab68b2..83982252df 100644
--- a/codex-rs/login/src/auth/bedrock_api_key_tests.rs
+++ b/codex-rs/login/src/auth/bedrock_api_key_tests.rs
@@ -85,6 +85,7 @@ async fn login_with_bedrock_api_key_replaces_openai_auth() -> anyhow::Result<()>
             CodexAuth::ApiKey(_)
             | CodexAuth::Chatgpt(_)
             | CodexAuth::ChatgptAuthTokens(_)
+            | CodexAuth::HostProvided(_)
             | CodexAuth::AgentIdentity(_)
             | CodexAuth::PersonalAccessToken(_) => None,
         }),
@@ -148,6 +149,7 @@ async fn bedrock_only_auth_storage_creates_primary_auth() -> anyhow::Result<()>
             CodexAuth::ApiKey(_)
             | CodexAuth::Chatgpt(_)
             | CodexAuth::ChatgptAuthTokens(_)
+            | CodexAuth::HostProvided(_)
             | CodexAuth::AgentIdentity(_)
             | CodexAuth::PersonalAccessToken(_) => None,
         }),
diff --git a/codex-rs/login/src/auth/host_provided.rs b/codex-rs/login/src/auth/host_provided.rs
new file mode 100644
index 0000000000..3d95f24189
--- /dev/null
+++ b/codex-rs/login/src/auth/host_provided.rs
@@ -0,0 +1,58 @@
+use std::collections::BTreeMap;
+use std::fmt;
+
+/// Codex backend authentication supplied by the process embedding Codex.
+///
+/// The embedding process owns credential validation, rotation, and persistence.
+/// Codex keeps this snapshot in memory and uses its headers for backend requests.
+#[derive(Clone, PartialEq, Eq)]
+pub struct HostProvidedAuth {
+    headers: BTreeMap<String, String>,
+    account_id: Option<String>,
+    user_id: String,
+}
+
+impl fmt::Debug for HostProvidedAuth {
+    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
+        f.debug_struct("HostProvidedAuth")
+            .field("headers", &"<redacted>")
+            .field("account_id", &self.account_id)
+            .field("user_id", &self.user_id)
+            .finish()
+    }
+}
+
+impl HostProvidedAuth {
+    /// Creates host-provided auth with backend request headers and a stable user identity.
+    pub fn new(
+        headers: impl IntoIterator<Item = (String, String)>,
+        user_id: impl Into<String>,
+    ) -> Self {
+        Self {
+            headers: headers.into_iter().collect(),
+            account_id: None,
+            user_id: user_id.into(),
+        }
+    }
+
+    /// Adds the account selected by the embedding process.
+    pub fn with_account_id(mut self, account_id: impl Into<String>) -> Self {
+        self.account_id = Some(account_id.into());
+        self
+    }
+
+    /// Returns the request headers supplied by the embedding process.
+    pub fn headers(&self) -> &BTreeMap<String, String> {
+        &self.headers
+    }
+
+    /// Returns the selected account ID, when the embedding process supplied one.
+    pub fn account_id(&self) -> Option<&str> {
+        self.account_id.as_deref()
+    }
+
+    /// Returns the stable user ID supplied by the embedding process.
+    pub fn user_id(&self) -> &str {
+        &self.user_id
+    }
+}
diff --git a/codex-rs/login/src/auth/manager.rs b/codex-rs/login/src/auth/manager.rs
index 844410874d..cbeef197fa 100644
--- a/codex-rs/login/src/auth/manager.rs
+++ b/codex-rs/login/src/auth/manager.rs
@@ -41,6 +41,7 @@ use super::revoke::revoke_auth_tokens;
 pub use crate::auth::agent_identity::AgentIdentityAuth;
 pub use crate::auth::agent_identity::AgentIdentityAuthError;
 pub use crate::auth::bedrock_api_key::BedrockApiKeyAuth;
+use crate::auth::host_provided::HostProvidedAuth;
 pub use crate::auth::personal_access_token::PersonalAccessTokenAuth;
 pub use crate::auth::storage::AgentIdentityAuthRecord;
 pub use crate::auth::storage::AgentIdentityStorage;
@@ -71,6 +72,7 @@ pub enum CodexAuth {
     ApiKey(ApiKeyAuth),
     Chatgpt(ChatgptAuth),
     ChatgptAuthTokens(ChatgptAuthTokens),
+    HostProvided(HostProvidedAuth),
     AgentIdentity(AgentIdentityAuth),
     PersonalAccessToken(PersonalAccessTokenAuth),
     BedrockApiKey(BedrockApiKeyAuth),
@@ -145,6 +147,7 @@ impl AgentIdentityBootstrapCooldown {
 impl PartialEq for CodexAuth {
     fn eq(&self, other: &Self) -> bool {
         match (self, other) {
+            (Self::HostProvided(a), Self::HostProvided(b)) => a == b,
             (Self::PersonalAccessToken(a), Self::PersonalAccessToken(b)) => a == b,
             (Self::BedrockApiKey(a), Self::BedrockApiKey(b)) => a == b,
             _ => self.api_auth_mode() == other.api_auth_mode(),
@@ -357,6 +360,11 @@ impl CodexAuth {
             };
             return Ok(Self::BedrockApiKey(auth));
         }
+        if auth_mode == AuthMode::HostProvided {
+            return Err(std::io::Error::other(
+                "host-provided auth cannot be loaded from auth storage.",
+            ));
+        }
 
         let storage_mode = auth_dot_json.storage_mode(auth_credentials_store_mode);
         let client = create_default_auth_client(&refresh_token_endpoint(), auth_route_config)?;
@@ -376,6 +384,9 @@ impl CodexAuth {
             }
             AuthMode::ChatgptAuthTokens => Ok(Self::ChatgptAuthTokens(ChatgptAuthTokens { state })),
             AuthMode::ApiKey => unreachable!("api key mode is handled above"),
+            AuthMode::HostProvided => {
+                unreachable!("host-provided auth is never loaded from auth storage")
+            }
             AuthMode::AgentIdentity => unreachable!("agent identity mode is handled above"),
             AuthMode::PersonalAccessToken => {
                 unreachable!("personal access token mode is handled above")
@@ -458,6 +469,7 @@ impl CodexAuth {
         match self {
             Self::ApiKey(_) => AuthMode::ApiKey,
             Self::Chatgpt(_) | Self::ChatgptAuthTokens(_) => AuthMode::Chatgpt,
+            Self::HostProvided(_) => AuthMode::HostProvided,
             Self::AgentIdentity(_) => AuthMode::AgentIdentity,
             Self::PersonalAccessToken(_) => AuthMode::PersonalAccessToken,
             Self::BedrockApiKey(_) => AuthMode::BedrockApiKey,
@@ -470,6 +482,7 @@ impl CodexAuth {
             Self::ApiKey(_) => AuthMode::ApiKey,
             Self::Chatgpt(_) => AuthMode::Chatgpt,
             Self::ChatgptAuthTokens(_) => AuthMode::ChatgptAuthTokens,
+            Self::HostProvided(_) => AuthMode::HostProvided,
             Self::AgentIdentity(_) => AuthMode::AgentIdentity,
             Self::PersonalAccessToken(_) => AuthMode::PersonalAccessToken,
             Self::BedrockApiKey(_) => AuthMode::BedrockApiKey,
@@ -506,6 +519,7 @@ impl CodexAuth {
             Self::ApiKey(auth) => Some(auth.api_key.as_str()),
             Self::Chatgpt(_)
             | Self::ChatgptAuthTokens(_)
+            | Self::HostProvided(_)
             | Self::AgentIdentity(_)
             | Self::PersonalAccessToken(_)
             | Self::BedrockApiKey(_) => None,
@@ -536,6 +550,9 @@ impl CodexAuth {
             Self::AgentIdentity(_) => Err(std::io::Error::other(
                 "agent identity auth does not expose a bearer token",
             )),
+            Self::HostProvided(_) => Err(std::io::Error::other(
+                "host-provided auth does not expose a bearer token",
+            )),
             Self::PersonalAccessToken(auth) => Ok(auth.access_token().to_string()),
             Self::BedrockApiKey(_) => Err(std::io::Error::other(
                 "Bedrock API key auth does not expose a Codex bearer token",
@@ -546,6 +563,7 @@ impl CodexAuth {
     /// Returns `None` if Codex backend auth does not expose an account id.
     pub fn get_account_id(&self) -> Option<String> {
         match self {
+            Self::HostProvided(auth) => auth.account_id().map(str::to_string),
             Self::AgentIdentity(auth) => Some(auth.account_id().to_string()),
             Self::PersonalAccessToken(auth) => Some(auth.account_id().to_string()),
             _ => self.get_current_token_data().and_then(|t| t.account_id),
@@ -555,6 +573,7 @@ impl CodexAuth {
     /// Returns false if Codex backend auth omits the FedRAMP claim.
     pub fn is_fedramp_account(&self) -> bool {
         match self {
+            Self::HostProvided(_) => false,
             Self::AgentIdentity(auth) => auth.is_fedramp_account(),
             Self::PersonalAccessToken(auth) => auth.is_fedramp_account(),
             _ => self
@@ -566,6 +585,7 @@ impl CodexAuth {
     /// Returns `None` if Codex backend auth does not expose an account email.
     pub fn get_account_email(&self) -> Option<String> {
         match self {
+            Self::HostProvided(_) => None,
             Self::AgentIdentity(auth) => auth.email().map(str::to_string),
             Self::PersonalAccessToken(auth) => auth.email().map(str::to_string),
             _ => self.get_current_token_data().and_then(|t| t.id_token.email),
@@ -575,6 +595,7 @@ impl CodexAuth {
     /// Returns `None` if Codex backend auth does not expose a ChatGPT user id.
     pub fn get_chatgpt_user_id(&self) -> Option<String> {
         match self {
+            Self::HostProvided(auth) => Some(auth.user_id().to_string()),
             Self::AgentIdentity(auth) => Some(auth.chatgpt_user_id().to_string()),
             Self::PersonalAccessToken(auth) => Some(auth.chatgpt_user_id().to_string()),
             _ => self
@@ -587,6 +608,9 @@ impl CodexAuth {
     /// Returns a high-level `AccountPlanType` (e.g., Free/Plus/Pro/Team/…)
     /// for UI or product decisions based on the user's subscription.
     pub fn account_plan_type(&self) -> Option<AccountPlanType> {
+        if matches!(self, Self::HostProvided(_)) {
+            return Some(AccountPlanType::Unknown);
+        }
         if let Self::AgentIdentity(auth) = self {
             return Some(auth.plan_type());
         }
@@ -613,6 +637,7 @@ impl CodexAuth {
             Self::Chatgpt(auth) => &auth.state,
             Self::ChatgptAuthTokens(auth) => &auth.state,
             Self::ApiKey(_)
+            | Self::HostProvided(_)
             | Self::AgentIdentity(_)
             | Self::PersonalAccessToken(_)
             | Self::BedrockApiKey(_) => return None,
@@ -658,6 +683,7 @@ impl CodexAuth {
             Self::AgentIdentity(auth) => Ok(Some(auth.clone())),
             Self::ApiKey(_)
             | Self::ChatgptAuthTokens(_)
+            | Self::HostProvided(_)
             | Self::PersonalAccessToken(_)
             | Self::BedrockApiKey(_) => Ok(None),
             Self::Chatgpt(_) => {
@@ -1086,10 +1112,12 @@ async fn enforce_login_restrictions_with_agent_identity_authapi_base_url(
             | (ForcedLoginMethod::Api, AuthMode::BedrockApiKey) => None,
             (ForcedLoginMethod::Chatgpt, AuthMode::Chatgpt)
             | (ForcedLoginMethod::Chatgpt, AuthMode::ChatgptAuthTokens)
+            | (ForcedLoginMethod::Chatgpt, AuthMode::HostProvided)
             | (ForcedLoginMethod::Chatgpt, AuthMode::AgentIdentity)
             | (ForcedLoginMethod::Chatgpt, AuthMode::PersonalAccessToken) => None,
             (ForcedLoginMethod::Api, AuthMode::Chatgpt)
             | (ForcedLoginMethod::Api, AuthMode::ChatgptAuthTokens)
+            | (ForcedLoginMethod::Api, AuthMode::HostProvided)
             | (ForcedLoginMethod::Api, AuthMode::AgentIdentity)
             | (ForcedLoginMethod::Api, AuthMode::PersonalAccessToken) => Some(
                 "API key login is required, but ChatGPT is currently being used. Logging out."
@@ -1115,9 +1143,9 @@ async fn enforce_login_restrictions_with_agent_identity_authapi_base_url(
     if let Some(expected_account_ids) = config.forced_chatgpt_workspace_id.as_deref() {
         let chatgpt_account_id = match &auth {
             CodexAuth::ApiKey(_) | CodexAuth::BedrockApiKey(_) => return Ok(()),
-            CodexAuth::AgentIdentity(_) | CodexAuth::PersonalAccessToken(_) => {
-                auth.get_account_id()
-            }
+            CodexAuth::HostProvided(_)
+            | CodexAuth::AgentIdentity(_)
+            | CodexAuth::PersonalAccessToken(_) => auth.get_account_id(),
             CodexAuth::Chatgpt(_) | CodexAuth::ChatgptAuthTokens(_) => {
                 let token_data = match auth.get_token_data() {
                     Ok(data) => data,
@@ -2172,6 +2200,7 @@ impl AuthManager {
                 | (AuthMode::ChatgptAuthTokens, AuthMode::ChatgptAuthTokens) => {
                     a.get_current_auth_json() == b.get_current_auth_json()
                 }
+                (AuthMode::HostProvided, AuthMode::HostProvided) => a == b,
                 (AuthMode::AgentIdentity, AuthMode::AgentIdentity) => match (a, b) {
                     (CodexAuth::AgentIdentity(a), CodexAuth::AgentIdentity(b)) => {
                         a.record() == b.record()
@@ -2256,6 +2285,11 @@ impl AuthManager {
         }
     }
 
+    /// Replaces the current auth snapshot with Codex backend auth supplied by the host.
+    pub fn set_host_provided_auth(&self, auth: HostProvidedAuth) {
+        let _ = self.set_cached_auth(Some(CodexAuth::HostProvided(auth)));
+    }
+
     pub fn clear_external_auth(&self) {
         if let Ok(mut guard) = self.external_auth.write() {
             *guard = None;
@@ -2452,6 +2486,7 @@ impl AuthManager {
                     .await
             }
             CodexAuth::ApiKey(_)
+            | CodexAuth::HostProvided(_)
             | CodexAuth::AgentIdentity(_)
             | CodexAuth::PersonalAccessToken(_)
             | CodexAuth::BedrockApiKey(_) => Ok(()),
diff --git a/codex-rs/login/src/auth/mod.rs b/codex-rs/login/src/auth/mod.rs
index d87c7cc6ad..a1528fce8e 100644
--- a/codex-rs/login/src/auth/mod.rs
+++ b/codex-rs/login/src/auth/mod.rs
@@ -8,6 +8,7 @@ mod storage;
 mod util;
 
 mod external_bearer;
+mod host_provided;
 mod manager;
 mod revoke;
 
@@ -15,4 +16,5 @@ pub use bedrock_api_key::BedrockApiKeyAuth;
 pub use bedrock_api_key::login_with_bedrock_api_key;
 pub use error::RefreshTokenFailedError;
 pub use error::RefreshTokenFailedReason;
+pub use host_provided::HostProvidedAuth;
 pub use manager::*;
diff --git a/codex-rs/login/src/lib.rs b/codex-rs/login/src/lib.rs
index 44c2f1c4d3..9382767b63 100644
--- a/codex-rs/login/src/lib.rs
+++ b/codex-rs/login/src/lib.rs
@@ -35,6 +35,7 @@ pub use auth::ExternalAuthFuture;
 pub use auth::ExternalAuthRefreshContext;
 pub use auth::ExternalAuthRefreshReason;
 pub use auth::ExternalAuthTokens;
+pub use auth::HostProvidedAuth;
 pub use auth::OPENAI_API_KEY_ENV_VAR;
 pub use auth::REFRESH_TOKEN_URL_OVERRIDE_ENV_VAR;
 pub use auth::REVOKE_TOKEN_URL_OVERRIDE_ENV_VAR;
diff --git a/codex-rs/model-provider-info/src/lib.rs b/codex-rs/model-provider-info/src/lib.rs
index 65517cbd43..58e1515419 100644
--- a/codex-rs/model-provider-info/src/lib.rs
+++ b/codex-rs/model-provider-info/src/lib.rs
@@ -244,6 +244,7 @@ impl ModelProviderInfo {
             Some(
                 AuthMode::Chatgpt
                     | AuthMode::ChatgptAuthTokens
+                    | AuthMode::HostProvided
                     | AuthMode::AgentIdentity
                     | AuthMode::PersonalAccessToken
             )
diff --git a/codex-rs/model-provider/src/amazon_bedrock/mod.rs b/codex-rs/model-provider/src/amazon_bedrock/mod.rs
index 108308c1bf..aaeebef3f6 100644
--- a/codex-rs/model-provider/src/amazon_bedrock/mod.rs
+++ b/codex-rs/model-provider/src/amazon_bedrock/mod.rs
@@ -69,6 +69,7 @@ impl AmazonBedrockModelProvider {
                 CodexAuth::ApiKey(_)
                 | CodexAuth::Chatgpt(_)
                 | CodexAuth::ChatgptAuthTokens(_)
+                | CodexAuth::HostProvided(_)
                 | CodexAuth::AgentIdentity(_)
                 | CodexAuth::PersonalAccessToken(_) => None,
             })
diff --git a/codex-rs/model-provider/src/auth.rs b/codex-rs/model-provider/src/auth.rs
index 5b667e4549..3adfad6afb 100644
--- a/codex-rs/model-provider/src/auth.rs
+++ b/codex-rs/model-provider/src/auth.rs
@@ -9,6 +9,7 @@ use codex_api::AuthProvider;
 use codex_api::SharedAuthProvider;
 use codex_login::AuthManager;
 use codex_login::CodexAuth;
+use codex_login::HostProvidedAuth;
 use codex_login::auth::AgentIdentityAuth;
 use codex_login::auth::AgentIdentityAuthError;
 use codex_login::auth::AgentIdentityAuthPolicy;
@@ -16,6 +17,7 @@ use codex_model_provider_info::ModelProviderInfo;
 use codex_protocol::error::CodexErr;
 use codex_protocol::protocol::SessionSource;
 use http::HeaderMap;
+use http::HeaderName;
 use http::HeaderValue;
 
 use crate::bearer_auth_provider::BearerAuthProvider;
@@ -109,6 +111,30 @@ impl AuthProvider for AgentIdentityAuthProvider {
     }
 }
 
+#[derive(Clone, Debug)]
+struct HostProvidedAuthProvider {
+    auth: HostProvidedAuth,
+}
+
+impl AuthProvider for HostProvidedAuthProvider {
+    fn add_auth_headers(&self, headers: &mut HeaderMap) {
+        for (name, value) in self.auth.headers() {
+            let Ok(name) = HeaderName::from_bytes(name.as_bytes()) else {
+                continue;
+            };
+            let Ok(value) = HeaderValue::from_str(value) else {
+                continue;
+            };
+            let _ = headers.insert(name, value);
+        }
+        if let Some(account_id) = self.auth.account_id()
+            && let Ok(account_id) = HeaderValue::from_str(account_id)
+        {
+            let _ = headers.insert("ChatGPT-Account-ID", account_id);
+        }
+    }
+}
+
 // Some providers are meant to send no auth headers. Examples include local OSS
 // providers and custom test providers with `requires_openai_auth = false`.
 #[derive(Clone, Debug)]
@@ -240,6 +266,9 @@ fn bearer_auth_for_provider(
 /// Builds request-header auth for a first-party Codex auth snapshot.
 pub fn auth_provider_from_auth(auth: &CodexAuth) -> SharedAuthProvider {
     match auth {
+        CodexAuth::HostProvided(auth) => {
+            Arc::new(HostProvidedAuthProvider { auth: auth.clone() })
+        }
         CodexAuth::AgentIdentity(auth) => {
             Arc::new(AgentIdentityAuthProvider { auth: auth.clone() })
         }
@@ -405,6 +434,35 @@ mod tests {
         }
     }
 
+    #[test]
+    fn host_provided_auth_provider_uses_host_headers() {
+        let auth = CodexAuth::HostProvided(
+            HostProvidedAuth::new(
+                [(
+                    "x-openai-actor-authorization".to_string(),
+                    "actor-token".to_string(),
+                )],
+                "user-123",
+            )
+            .with_account_id("account-123"),
+        );
+
+        let headers = auth_provider_from_auth(&auth).to_auth_headers();
+
+        assert_eq!(
+            headers
+                .get("x-openai-actor-authorization")
+                .and_then(|value| value.to_str().ok()),
+            Some("actor-token")
+        );
+        assert_eq!(
+            headers
+                .get("ChatGPT-Account-ID")
+                .and_then(|value| value.to_str().ok()),
+            Some("account-123")
+        );
+    }
+
     #[tokio::test]
     async fn first_party_run_scope_uses_agent_assertion_and_exposes_telemetry() {
         let auth = CodexAuth::AgentIdentity(
diff --git a/codex-rs/model-provider/src/provider.rs b/codex-rs/model-provider/src/provider.rs
index 5f101e52cd..32e13950a3 100644
--- a/codex-rs/model-provider/src/provider.rs
+++ b/codex-rs/model-provider/src/provider.rs
@@ -286,6 +286,7 @@ impl ModelProvider for ConfiguredModelProvider {
                     }
                     CodexAuth::Chatgpt(_)
                     | CodexAuth::ChatgptAuthTokens(_)
+                    | CodexAuth::HostProvided(_)
                     | CodexAuth::AgentIdentity(_)
                     | CodexAuth::PersonalAccessToken(_) => {
                         let email = auth.get_account_email();
diff --git a/codex-rs/otel/src/lib.rs b/codex-rs/otel/src/lib.rs
index 87ccbbfeee..2cb029c02f 100644
--- a/codex-rs/otel/src/lib.rs
+++ b/codex-rs/otel/src/lib.rs
@@ -59,6 +59,7 @@ impl From<AuthMode> for TelemetryAuthMode {
             AuthMode::ApiKey | AuthMode::BedrockApiKey => Self::ApiKey,
             AuthMode::Chatgpt
             | AuthMode::ChatgptAuthTokens
+            | AuthMode::HostProvided
             | AuthMode::AgentIdentity
             | AuthMode::PersonalAccessToken => Self::Chatgpt,
         }
diff --git a/codex-rs/protocol/src/auth.rs b/codex-rs/protocol/src/auth.rs
index 7c506e87eb..7aad9fd248 100644
--- a/codex-rs/protocol/src/auth.rs
+++ b/codex-rs/protocol/src/auth.rs
@@ -15,6 +15,10 @@ pub enum AuthMode {
     #[serde(rename = "chatgptAuthTokens")]
     #[strum(serialize = "chatgptAuthTokens")]
     ChatgptAuthTokens,
+    /// Codex backend request headers supplied by the process embedding Codex.
+    #[serde(rename = "hostProvided")]
+    #[strum(serialize = "hostProvided")]
+    HostProvided,
     /// Programmatic Codex auth backed by a registered Agent Identity.
     #[serde(rename = "agentIdentity")]
     #[strum(serialize = "agentIdentity")]
@@ -34,7 +38,7 @@ impl AuthMode {
     pub fn has_chatgpt_account(self) -> bool {
         match self {
             Self::Chatgpt | Self::ChatgptAuthTokens | Self::PersonalAccessToken => true,
-            Self::ApiKey | Self::AgentIdentity | Self::BedrockApiKey => false,
+            Self::ApiKey | Self::HostProvided | Self::AgentIdentity | Self::BedrockApiKey => false,
         }
     }
 
@@ -43,6 +47,7 @@ impl AuthMode {
         match self {
             Self::Chatgpt
             | Self::ChatgptAuthTokens
+            | Self::HostProvided
             | Self::AgentIdentity
             | Self::PersonalAccessToken => true,
             Self::ApiKey | Self::BedrockApiKey => false,
diff --git a/codex-rs/tui/src/app/app_server_events.rs b/codex-rs/tui/src/app/app_server_events.rs
index 06ed4320d8..db71884f4f 100644
--- a/codex-rs/tui/src/app/app_server_events.rs
+++ b/codex-rs/tui/src/app/app_server_events.rs
@@ -86,6 +86,7 @@ impl App {
                     Some(
                         AuthMode::Chatgpt
                             | AuthMode::ChatgptAuthTokens
+                            | AuthMode::HostProvided
                             | AuthMode::AgentIdentity
                             | AuthMode::PersonalAccessToken
                     )
diff --git a/codex-rs/tui/src/app_server_session.rs b/codex-rs/tui/src/app_server_session.rs
index aeca17091e..421c4c99db 100644
--- a/codex-rs/tui/src/app_server_session.rs
+++ b/codex-rs/tui/src/app_server_session.rs
@@ -1202,6 +1202,7 @@ pub(crate) fn status_account_display_from_auth_mode(
         Some(AuthMode::ApiKey) => Some(StatusAccountDisplay::ApiKey),
         Some(AuthMode::Chatgpt)
         | Some(AuthMode::ChatgptAuthTokens)
+        | Some(AuthMode::HostProvided)
         | Some(AuthMode::AgentIdentity)
         | Some(AuthMode::PersonalAccessToken) => Some(StatusAccountDisplay::ChatGpt {
             email: None,
diff --git a/codex-rs/tui/src/onboarding/auth.rs b/codex-rs/tui/src/onboarding/auth.rs
index f9392eb2e8..35520dda63 100644
--- a/codex-rs/tui/src/onboarding/auth.rs
+++ b/codex-rs/tui/src/onboarding/auth.rs
@@ -950,6 +950,7 @@ impl AuthModeWidget {
                     ApiAuthMode::ApiKey => AuthMode::ApiKey,
                     ApiAuthMode::Chatgpt => AuthMode::Chatgpt,
                     ApiAuthMode::ChatgptAuthTokens => AuthMode::ChatgptAuthTokens,
+                    ApiAuthMode::HostProvided => AuthMode::HostProvided,
                     ApiAuthMode::AgentIdentity => AuthMode::AgentIdentity,
                     ApiAuthMode::PersonalAccessToken => AuthMode::PersonalAccessToken,
                     ApiAuthMode::BedrockApiKey => AuthMode::BedrockApiKey,