Use optional default environment for disabled mode

Restore CODEX_EXEC_SERVER_URL=none semantics by making EnvironmentManager::default_environment return None when environment access is disabled. Remove the separate disabled-for-agent flag and derive tool availability from the optional default environment.

Add an end-to-end tool exposure test for CODEX_EXEC_SERVER_URL=none.

Co-authored-by: Codex <noreply@openai.com>

codex-rs/core/src/session/mod.rs

@@ -461,7 +461,9 @@ impl Codex {
         let (tx_event, rx_event) = async_channel::unbounded();
 
         let environment = environment_manager.default_environment();
-        let fs = Some(environment.get_filesystem());
+        let fs = environment
+            .as_ref()
+            .map(|environment| environment.get_filesystem());
         let plugin_outcome = plugins_manager.plugins_for_config(&config).await;
         let effective_skill_roots = plugin_outcome.effective_skill_roots();
         let skills_input = skills_load_input_from_config(&config, effective_skill_roots);

codex-rs/core/src/session/session.rs

@@ -641,8 +641,6 @@ impl Session {
             Arc::clone(&auth_manager),
             session_configuration.session_source.clone(),
         ));
-        let environment = environment_manager.default_environment();
-        let allows_agent_environment_access = environment_manager.allows_agent_environment_access();
         let services = SessionServices {
             // Initialize the MCP connection manager with an uninitialized
             // instance. It will be replaced with one created via
@@ -698,8 +696,6 @@ impl Session {
                 config.js_repl_node_path.clone(),
             ),
             environment_manager,
-            environment: Some(environment),
-            allows_agent_environment_access,
         };
         services
             .model_client

codex-rs/core/src/session/tests.rs

@@ -3245,8 +3245,6 @@ pub(crate) async fn make_session_and_context() -> (Session, TurnContext) {
             config.js_repl_node_path.clone(),
         ),
         environment_manager: Arc::new(codex_exec_server::EnvironmentManager::default()),
-        environment: Some(Arc::clone(&environment)),
-        allows_agent_environment_access: true,
     };
     let js_repl = Arc::new(JsReplHandle::with_node_path(
         config.js_repl_node_path.clone(),
@@ -3280,7 +3278,6 @@ pub(crate) async fn make_session_and_context() -> (Session, TurnContext) {
         model_info,
         &models_manager,
         /*network*/ None,
-        /*allows_agent_environment_access*/ true,
         Some(environment),
         "turn_id".to_string(),
         Arc::clone(&js_repl),
@@ -4346,8 +4343,6 @@ where
             config.js_repl_node_path.clone(),
         ),
         environment_manager: Arc::new(codex_exec_server::EnvironmentManager::default()),
-        environment: Some(Arc::clone(&environment)),
-        allows_agent_environment_access: true,
     };
     let js_repl = Arc::new(JsReplHandle::with_node_path(
         config.js_repl_node_path.clone(),
@@ -4381,7 +4376,6 @@ where
         model_info,
         &models_manager,
         /*network*/ None,
-        /*allows_agent_environment_access*/ true,
         Some(environment),
         "turn_id".to_string(),
         Arc::clone(&js_repl),

codex-rs/core/src/session/turn_context.rs

@@ -345,7 +345,6 @@ impl Session {
         model_info: ModelInfo,
         models_manager: &ModelsManager,
         network: Option<NetworkProxy>,
-        allows_agent_environment_access: bool,
         environment: Option<Arc<Environment>>,
         sub_id: String,
         js_repl: Arc<JsReplHandle>,
@@ -382,7 +381,7 @@ impl Session {
         )
         .with_web_search_config(per_turn_config.web_search_config.clone())
         .with_allow_login_shell(per_turn_config.permissions.allow_login_shell)
-        .with_has_environment(allows_agent_environment_access)
+        .with_has_environment(environment.is_some())
         .with_spawn_agent_usage_hint(per_turn_config.multi_agent_v2.usage_hint_enabled)
         .with_spawn_agent_usage_hint_text(per_turn_config.multi_agent_v2.usage_hint_text.clone())
         .with_hide_spawn_agent_metadata(per_turn_config.multi_agent_v2.hide_spawn_agent_metadata)
@@ -545,9 +544,8 @@ impl Session {
             .await;
         let effective_skill_roots = plugin_outcome.effective_skill_roots();
         let skills_input = skills_load_input_from_config(&per_turn_config, effective_skill_roots);
-        let fs = self
-            .services
-            .environment
+        let environment = self.services.environment_manager.default_environment();
+        let fs = environment
             .as_ref()
             .map(|environment| environment.get_filesystem());
         let skills_outcome = Arc::new(
@@ -577,8 +575,7 @@ impl Session {
                     )
                     .then(|| started_proxy.proxy())
                 }),
-            self.services.allows_agent_environment_access,
-            self.services.environment.clone(),
+            environment,
             sub_id,
             Arc::clone(&self.js_repl),
             skills_outcome,

codex-rs/core/src/state/service.rs

@@ -17,7 +17,6 @@ use crate::tools::network_approval::NetworkApprovalService;
 use crate::tools::sandboxing::ApprovalStore;
 use crate::unified_exec::UnifiedExecProcessManager;
 use codex_analytics::AnalyticsEventsClient;
-use codex_exec_server::Environment;
 use codex_exec_server::EnvironmentManager;
 use codex_hooks::Hooks;
 use codex_login::AuthManager;
@@ -68,6 +67,4 @@ pub(crate) struct SessionServices {
     /// Shared process-level environment registry. Sessions carry an `Arc` handle so they can pass
     /// the same manager through child-thread spawn paths without reconstructing it.
     pub(crate) environment_manager: Arc<EnvironmentManager>,
-    pub(crate) environment: Option<Arc<Environment>>,
-    pub(crate) allows_agent_environment_access: bool,
 }

codex-rs/core/src/thread_manager.rs

@@ -923,8 +923,8 @@ impl ThreadManagerState {
         user_shell_override: Option<crate::shell::Shell>,
     ) -> CodexResult<NewThread> {
         let environment = self.environment_manager.default_environment();
-        let watch_registration = match environment.is_remote() {
-            false => {
+        let watch_registration = match environment.as_ref() {
+            Some(environment) if !environment.is_remote() => {
                 self.skills_watcher
                     .register_config(
                         &config,
@@ -934,7 +934,7 @@ impl ThreadManagerState {
                     )
                     .await
             }
-            true => crate::file_watcher::WatchRegistration::default(),
+            Some(_) | None => crate::file_watcher::WatchRegistration::default(),
         };
         let CodexSpawnOk {
             codex, thread_id, ..