diff --git a/codex-rs/code-mode/src/lib.rs b/codex-rs/code-mode/src/lib.rs
index 841e568be3..27488d4707 100644
--- a/codex-rs/code-mode/src/lib.rs
+++ b/codex-rs/code-mode/src/lib.rs
@@ -22,9 +22,11 @@ pub use runtime::DEFAULT_WAIT_YIELD_TIME_MS;
 pub use runtime::ExecuteRequest;
 pub use runtime::RuntimeResponse;
 pub use runtime::WaitRequest;
+pub use service::CodeModeRuntime;
 pub use service::CodeModeService;
 pub use service::CodeModeTurnHost;
 pub use service::CodeModeTurnWorker;
+pub use service::CodeModeTurnWorkerHandle;
 
 pub const PUBLIC_TOOL_NAME: &str = "exec";
 pub const WAIT_TOOL_NAME: &str = "wait";
diff --git a/codex-rs/code-mode/src/service.rs b/codex-rs/code-mode/src/service.rs
index 5b67dd17b8..3d7d8b63a0 100644
--- a/codex-rs/code-mode/src/service.rs
+++ b/codex-rs/code-mode/src/service.rs
@@ -34,6 +34,22 @@ pub trait CodeModeTurnHost: Send + Sync {
     async fn notify(&self, call_id: String, cell_id: String, text: String) -> Result<(), String>;
 }
 
+#[async_trait]
+pub trait CodeModeRuntime: Send + Sync {
+    async fn stored_values(&self) -> HashMap<String, JsonValue>;
+
+    async fn replace_stored_values(&self, values: HashMap<String, JsonValue>);
+
+    async fn execute(&self, request: ExecuteRequest) -> Result<RuntimeResponse, String>;
+
+    async fn wait(&self, request: WaitRequest) -> Result<RuntimeResponse, String>;
+
+    fn start_turn_worker(
+        &self,
+        host: Arc<dyn CodeModeTurnHost>,
+    ) -> Box<dyn CodeModeTurnWorkerHandle>;
+}
+
 #[derive(Clone)]
 struct SessionHandle {
     control_tx: mpsc::UnboundedSender<SessionControlCommand>,
@@ -219,6 +235,10 @@ pub struct CodeModeTurnWorker {
     shutdown_tx: Option<oneshot::Sender<()>>,
 }
 
+pub trait CodeModeTurnWorkerHandle: Send {}
+
+impl CodeModeTurnWorkerHandle for CodeModeTurnWorker {}
+
 impl Drop for CodeModeTurnWorker {
     fn drop(&mut self) {
         if let Some(shutdown_tx) = self.shutdown_tx.take() {
@@ -227,6 +247,32 @@ impl Drop for CodeModeTurnWorker {
     }
 }
 
+#[async_trait]
+impl CodeModeRuntime for CodeModeService {
+    async fn stored_values(&self) -> HashMap<String, JsonValue> {
+        CodeModeService::stored_values(self).await
+    }
+
+    async fn replace_stored_values(&self, values: HashMap<String, JsonValue>) {
+        CodeModeService::replace_stored_values(self, values).await;
+    }
+
+    async fn execute(&self, request: ExecuteRequest) -> Result<RuntimeResponse, String> {
+        CodeModeService::execute(self, request).await
+    }
+
+    async fn wait(&self, request: WaitRequest) -> Result<RuntimeResponse, String> {
+        CodeModeService::wait(self, request).await
+    }
+
+    fn start_turn_worker(
+        &self,
+        host: Arc<dyn CodeModeTurnHost>,
+    ) -> Box<dyn CodeModeTurnWorkerHandle> {
+        Box::new(CodeModeService::start_turn_worker(self, host))
+    }
+}
+
 enum SessionControlCommand {
     Poll {
         yield_time_ms: u64,
diff --git a/codex-rs/core/src/codex.rs b/codex-rs/core/src/codex.rs
index 7137bf4d3a..a26e2e50e7 100644
--- a/codex-rs/core/src/codex.rs
+++ b/codex-rs/core/src/codex.rs
@@ -422,6 +422,7 @@ pub(crate) struct CodexSpawnArgs {
     pub(crate) inherited_shell_snapshot: Option<Arc<ShellSnapshot>>,
     pub(crate) inherited_exec_policy: Option<Arc<ExecPolicyManager>>,
     pub(crate) user_shell_override: Option<shell::Shell>,
+    pub(crate) code_mode_runtime: Option<Arc<dyn codex_code_mode::CodeModeRuntime>>,
     pub(crate) parent_trace: Option<W3cTraceContext>,
 }
 
@@ -476,6 +477,7 @@ impl Codex {
             inherited_shell_snapshot,
             user_shell_override,
             inherited_exec_policy,
+            code_mode_runtime,
             parent_trace: _,
         } = args;
         let (tx_sub, rx_sub) = async_channel::bounded(SUBMISSION_CHANNEL_CAPACITY);
@@ -660,6 +662,7 @@ impl Codex {
             mcp_manager.clone(),
             skills_watcher,
             agent_control,
+            code_mode_runtime,
         )
         .await
         .map_err(|e| {
@@ -1478,6 +1481,7 @@ impl Session {
         mcp_manager: Arc<McpManager>,
         skills_watcher: Arc<SkillsWatcher>,
         agent_control: AgentControl,
+        code_mode_runtime: Option<Arc<dyn codex_code_mode::CodeModeRuntime>>,
     ) -> anyhow::Result<Arc<Self>> {
         debug!(
             "Configuring session: model={}; provider={:?}",
@@ -1903,8 +1907,9 @@ impl Session {
                 config.features.enabled(Feature::RuntimeMetrics),
                 Self::build_model_client_beta_features_header(config.as_ref()),
             ),
-            code_mode_service: crate::tools::code_mode::CodeModeService::new(
-                config.js_repl_node_path.clone(),
+            code_mode_service: code_mode_runtime.map_or_else(
+                || crate::tools::code_mode::CodeModeService::new(config.js_repl_node_path.clone()),
+                crate::tools::code_mode::CodeModeService::from_runtime,
             ),
             environment: environment_manager.current().await?,
         };
diff --git a/codex-rs/core/src/codex_delegate.rs b/codex-rs/core/src/codex_delegate.rs
index 3f1508cca1..453f59c322 100644
--- a/codex-rs/core/src/codex_delegate.rs
+++ b/codex-rs/core/src/codex_delegate.rs
@@ -93,6 +93,7 @@ pub(crate) async fn run_codex_thread_interactive(
         inherited_shell_snapshot: None,
         user_shell_override: None,
         inherited_exec_policy: Some(Arc::clone(&parent_session.services.exec_policy)),
+        code_mode_runtime: None,
         parent_trace: None,
     })
     .await?;
diff --git a/codex-rs/core/src/codex_tests_guardian.rs b/codex-rs/core/src/codex_tests_guardian.rs
index f5698d58ff..d90a9443d1 100644
--- a/codex-rs/core/src/codex_tests_guardian.rs
+++ b/codex-rs/core/src/codex_tests_guardian.rs
@@ -456,6 +456,7 @@ async fn guardian_subagent_does_not_inherit_parent_exec_policy_rules() {
         inherited_shell_snapshot: None,
         inherited_exec_policy: Some(Arc::new(parent_exec_policy)),
         user_shell_override: None,
+        code_mode_runtime: None,
         parent_trace: None,
     })
     .await
diff --git a/codex-rs/core/src/lib.rs b/codex-rs/core/src/lib.rs
index cc2861ccdd..40af3a032a 100644
--- a/codex-rs/core/src/lib.rs
+++ b/codex-rs/core/src/lib.rs
@@ -201,6 +201,7 @@ pub use client_common::Prompt;
 pub use client_common::REVIEW_PROMPT;
 pub use client_common::ResponseEvent;
 pub use client_common::ResponseStream;
+pub use codex_code_mode::CodeModeRuntime;
 pub use codex_sandboxing::get_platform_sandbox;
 pub use codex_tools::parse_tool_input_schema;
 pub use compact::content_items_to_text;
diff --git a/codex-rs/core/src/thread_manager.rs b/codex-rs/core/src/thread_manager.rs
index 7f272f9595..9e2131deda 100644
--- a/codex-rs/core/src/thread_manager.rs
+++ b/codex-rs/core/src/thread_manager.rs
@@ -447,6 +447,27 @@ impl ThreadManager {
             persist_extended_history,
             metrics_service_name,
             parent_trace,
+            /*code_mode_runtime*/ None,
+            /*user_shell_override*/ None,
+        ))
+        .await
+    }
+
+    pub async fn start_thread_with_code_mode_runtime(
+        &self,
+        config: Config,
+        code_mode_runtime: Arc<dyn crate::CodeModeRuntime>,
+    ) -> CodexResult<NewThread> {
+        Box::pin(self.state.spawn_thread(
+            config,
+            InitialHistory::New,
+            Arc::clone(&self.state.auth_manager),
+            self.agent_control(),
+            Vec::new(),
+            /*persist_extended_history*/ false,
+            /*metrics_service_name*/ None,
+            /*parent_trace*/ None,
+            Some(code_mode_runtime),
             /*user_shell_override*/ None,
         ))
         .await
@@ -487,6 +508,7 @@ impl ThreadManager {
             persist_extended_history,
             /*metrics_service_name*/ None,
             parent_trace,
+            /*code_mode_runtime*/ None,
             /*user_shell_override*/ None,
         ))
         .await
@@ -506,6 +528,7 @@ impl ThreadManager {
             /*persist_extended_history*/ false,
             /*metrics_service_name*/ None,
             /*parent_trace*/ None,
+            /*code_mode_runtime*/ None,
             /*user_shell_override*/ Some(user_shell_override),
         ))
         .await
@@ -528,6 +551,7 @@ impl ThreadManager {
             /*persist_extended_history*/ false,
             /*metrics_service_name*/ None,
             /*parent_trace*/ None,
+            /*code_mode_runtime*/ None,
             /*user_shell_override*/ Some(user_shell_override),
         ))
         .await
@@ -635,6 +659,7 @@ impl ThreadManager {
             persist_extended_history,
             /*metrics_service_name*/ None,
             parent_trace,
+            /*code_mode_runtime*/ None,
             /*user_shell_override*/ None,
         ))
         .await
@@ -736,6 +761,7 @@ impl ThreadManagerState {
             inherited_shell_snapshot,
             inherited_exec_policy,
             /*parent_trace*/ None,
+            /*code_mode_runtime*/ None,
             /*user_shell_override*/ None,
         ))
         .await
@@ -763,6 +789,7 @@ impl ThreadManagerState {
             inherited_shell_snapshot,
             inherited_exec_policy,
             /*parent_trace*/ None,
+            /*code_mode_runtime*/ None,
             /*user_shell_override*/ None,
         ))
         .await
@@ -791,6 +818,7 @@ impl ThreadManagerState {
             inherited_shell_snapshot,
             inherited_exec_policy,
             /*parent_trace*/ None,
+            /*code_mode_runtime*/ None,
             /*user_shell_override*/ None,
         ))
         .await
@@ -808,6 +836,7 @@ impl ThreadManagerState {
         persist_extended_history: bool,
         metrics_service_name: Option<String>,
         parent_trace: Option<W3cTraceContext>,
+        code_mode_runtime: Option<Arc<dyn codex_code_mode::CodeModeRuntime>>,
         user_shell_override: Option<crate::shell::Shell>,
     ) -> CodexResult<NewThread> {
         Box::pin(self.spawn_thread_with_source(
@@ -822,6 +851,7 @@ impl ThreadManagerState {
             /*inherited_shell_snapshot*/ None,
             /*inherited_exec_policy*/ None,
             parent_trace,
+            code_mode_runtime,
             user_shell_override,
         ))
         .await
@@ -841,6 +871,7 @@ impl ThreadManagerState {
         inherited_shell_snapshot: Option<Arc<ShellSnapshot>>,
         inherited_exec_policy: Option<Arc<crate::exec_policy::ExecPolicyManager>>,
         parent_trace: Option<W3cTraceContext>,
+        code_mode_runtime: Option<Arc<dyn codex_code_mode::CodeModeRuntime>>,
         user_shell_override: Option<crate::shell::Shell>,
     ) -> CodexResult<NewThread> {
         let watch_registration = self.skills_watcher.register_config(
@@ -868,6 +899,7 @@ impl ThreadManagerState {
             inherited_shell_snapshot,
             inherited_exec_policy,
             user_shell_override,
+            code_mode_runtime,
             parent_trace,
         })
         .await?;
diff --git a/codex-rs/core/src/tools/code_mode/mod.rs b/codex-rs/core/src/tools/code_mode/mod.rs
index c8f16ca602..ec896d2828 100644
--- a/codex-rs/core/src/tools/code_mode/mod.rs
+++ b/codex-rs/core/src/tools/code_mode/mod.rs
@@ -6,7 +6,9 @@ use std::path::PathBuf;
 use std::sync::Arc;
 use std::time::Duration;
 
+use codex_code_mode::CodeModeRuntime;
 use codex_code_mode::CodeModeTurnHost;
+use codex_code_mode::CodeModeTurnWorkerHandle;
 use codex_code_mode::RuntimeResponse;
 use codex_protocol::models::FunctionCallOutputContentItem;
 use codex_protocol::models::FunctionCallOutputPayload;
@@ -48,14 +50,16 @@ pub(crate) struct ExecContext {
 }
 
 pub(crate) struct CodeModeService {
-    inner: codex_code_mode::CodeModeService,
+    inner: Arc<dyn CodeModeRuntime>,
 }
 
 impl CodeModeService {
     pub(crate) fn new(_js_repl_node_path: Option<PathBuf>) -> Self {
-        Self {
-            inner: codex_code_mode::CodeModeService::new(),
-        }
+        Self::from_runtime(Arc::new(codex_code_mode::CodeModeService::new()))
+    }
+
+    pub(crate) fn from_runtime(inner: Arc<dyn CodeModeRuntime>) -> Self {
+        Self { inner }
     }
 
     pub(crate) async fn stored_values(&self) -> std::collections::HashMap<String, JsonValue> {
@@ -89,7 +93,7 @@ impl CodeModeService {
         turn: &Arc<TurnContext>,
         router: Arc<ToolRouter>,
         tracker: SharedTurnDiffTracker,
-    ) -> Option<codex_code_mode::CodeModeTurnWorker> {
+    ) -> Option<Box<dyn CodeModeTurnWorkerHandle>> {
         if !turn.features.enabled(Feature::CodeMode) {
             return None;
         }