diff --git a/codex-rs/core/src/session/session.rs b/codex-rs/core/src/session/session.rs
index 0734f3090a..7247d267c4 100644
--- a/codex-rs/core/src/session/session.rs
+++ b/codex-rs/core/src/session/session.rs
@@ -116,19 +116,19 @@ impl SessionConfiguration {
         &self.environments.environments
     }
 
-    pub(super) fn workspace_roots(&self) -> Vec<AbsolutePathBuf> {
+    pub(super) fn primary_workspace_roots(&self) -> Vec<AbsolutePathBuf> {
         self.environments
             .environments
             .first()
-            .and_then(|environment| {
+            .map(|environment| {
                 environment
                     .workspace_roots
                     .iter()
                     .map(PathUri::to_abs_path)
                     .collect::<std::io::Result<Vec<_>>>()
-                    .ok()
+                    .unwrap_or_default()
             })
-            .unwrap_or_else(|| vec![self.cwd().clone()])
+            .unwrap_or_default()
     }
 
     pub(crate) fn codex_home(&self) -> &AbsolutePathBuf {
@@ -140,10 +140,12 @@ impl SessionConfiguration {
     }
 
     pub(super) fn permission_profile(&self) -> PermissionProfile {
-        self.permission_profile_state
-            .permission_profile()
-            .clone()
-            .materialize_project_roots_with_workspace_roots(&self.workspace_roots())
+        self.permission_profile_state.permission_profile().clone()
+    }
+
+    fn materialized_permission_profile(&self) -> PermissionProfile {
+        self.permission_profile()
+            .materialize_project_roots_with_workspace_roots(&self.primary_workspace_roots())
     }
 
     pub(super) fn active_permission_profile(&self) -> Option<ActivePermissionProfile> {
@@ -171,7 +173,7 @@ impl SessionConfiguration {
     }
 
     pub(super) fn sandbox_policy(&self) -> SandboxPolicy {
-        let permission_profile = self.permission_profile();
+        let permission_profile = self.materialized_permission_profile();
         codex_sandboxing::compatibility_sandbox_policy_for_permission_profile(
             &permission_profile,
             self.cwd(),
@@ -179,7 +181,8 @@ impl SessionConfiguration {
     }
 
     pub(super) fn file_system_sandbox_policy(&self) -> FileSystemSandboxPolicy {
-        self.permission_profile().file_system_sandbox_policy()
+        self.materialized_permission_profile()
+            .file_system_sandbox_policy()
     }
 
     pub(super) fn network_sandbox_policy(&self) -> NetworkSandboxPolicy {
@@ -198,7 +201,7 @@ impl SessionConfiguration {
             permission_profile: self.permission_profile(),
             active_permission_profile: self.active_permission_profile(),
             environments: self.environments.clone(),
-            workspace_roots: self.workspace_roots(),
+            workspace_roots: self.primary_workspace_roots(),
             profile_workspace_roots: self.profile_workspace_roots().to_vec(),
             ephemeral: self.original_config_do_not_use.ephemeral,
             reasoning_effort: self.collaboration_mode.reasoning_effort(),
diff --git a/codex-rs/core/src/session/tests.rs b/codex-rs/core/src/session/tests.rs
index 9791813dde..041970b012 100644
--- a/codex-rs/core/src/session/tests.rs
+++ b/codex-rs/core/src/session/tests.rs
@@ -4502,7 +4502,9 @@ async fn session_configuration_apply_preserves_profile_file_system_policy_on_cwd
         )
         .expect("set permission profile");
     let expected_file_system_sandbox_policy = file_system_sandbox_policy
-        .materialize_project_roots_with_workspace_roots(&session_configuration.workspace_roots());
+        .materialize_project_roots_with_workspace_roots(
+            &session_configuration.primary_workspace_roots(),
+        );
 
     let updated = session_configuration
         .apply(&SessionSettingsUpdate {
@@ -4564,7 +4566,9 @@ async fn session_configuration_apply_permission_profile_preserves_existing_deny_
         .expect("permission profile update should succeed");
 
     let mut expected_file_system_policy = requested_file_system_policy
-        .materialize_project_roots_with_workspace_roots(&session_configuration.workspace_roots());
+        .materialize_project_roots_with_workspace_roots(
+            &session_configuration.primary_workspace_roots(),
+        );
     expected_file_system_policy.glob_scan_max_depth = Some(2);
     expected_file_system_policy.entries.push(deny_entry);
     assert_eq!(
@@ -4821,59 +4825,6 @@ enabled = false
     );
 }
 
-#[tokio::test]
-async fn session_configuration_apply_retargets_legacy_workspace_root_on_cwd_update() {
-    let mut session_configuration = make_session_configuration_for_tests().await;
-    let workspace = tempfile::tempdir().expect("create temp dir");
-    let original_cwd = workspace.path().join("repo-a").abs();
-    let project_root = workspace.path().join("repo-b").abs();
-    session_configuration.environments =
-        TurnEnvironmentSelections::new(original_cwd.clone(), Vec::new());
-    let sandbox_policy = SandboxPolicy::WorkspaceWrite {
-        writable_roots: Vec::new(),
-        network_access: false,
-        exclude_tmpdir_env_var: true,
-        exclude_slash_tmp: true,
-    };
-    let file_system_sandbox_policy = FileSystemSandboxPolicy::from_legacy_sandbox_policy_for_cwd(
-        &sandbox_policy,
-        session_configuration.cwd(),
-    );
-    session_configuration
-        .set_permission_profile_for_tests(
-            PermissionProfile::from_runtime_permissions_with_enforcement(
-                SandboxEnforcement::from_legacy_sandbox_policy(&sandbox_policy),
-                &file_system_sandbox_policy,
-                NetworkSandboxPolicy::from(&sandbox_policy),
-            ),
-        )
-        .expect("set permission profile");
-
-    let updated = session_configuration
-        .apply(&SessionSettingsUpdate {
-            environments: Some(TurnEnvironmentSelections::new(
-                project_root.clone(),
-                Vec::new(),
-            )),
-            ..Default::default()
-        })
-        .expect("cwd-only update should succeed");
-
-    assert_eq!(updated.workspace_roots(), vec![project_root.clone()]);
-    assert!(
-        updated
-            .file_system_sandbox_policy()
-            .can_write_path_with_cwd(project_root.as_path(), updated.cwd().as_path()),
-        "cwd-only update should keep the new cwd writable"
-    );
-    assert!(
-        !updated
-            .file_system_sandbox_policy()
-            .can_write_path_with_cwd(original_cwd.as_path(), updated.cwd().as_path()),
-        "cwd-only update should not keep the old implicit cwd writable"
-    );
-}
-
 #[tokio::test]
 async fn session_configuration_apply_preserves_absolute_cwd_write_root_on_cwd_update() {
     let mut session_configuration = make_session_configuration_for_tests().await;
@@ -5275,7 +5226,7 @@ pub(crate) async fn make_session_and_context() -> (Session, TurnContext) {
     let per_turn_config = Session::build_per_turn_config(
         &session_configuration,
         session_configuration.cwd().clone(),
-        session_configuration.workspace_roots(),
+        session_configuration.primary_workspace_roots(),
     );
     let model_info = construct_model_info_offline_for_tests(
         session_configuration.collaboration_mode.model(),
@@ -7409,7 +7360,7 @@ where
     let per_turn_config = Session::build_per_turn_config(
         &session_configuration,
         session_configuration.cwd().clone(),
-        session_configuration.workspace_roots(),
+        session_configuration.primary_workspace_roots(),
     );
     let model_info = construct_model_info_offline_for_tests(
         session_configuration.collaboration_mode.model(),
diff --git a/codex-rs/core/src/session/turn_context.rs b/codex-rs/core/src/session/turn_context.rs
index bf50a5b206..65157cde83 100644
--- a/codex-rs/core/src/session/turn_context.rs
+++ b/codex-rs/core/src/session/turn_context.rs
@@ -471,7 +471,7 @@ impl Session {
     pub(crate) fn build_effective_session_config(
         session_configuration: &SessionConfiguration,
     ) -> Config {
-        let workspace_roots = session_configuration.workspace_roots();
+        let workspace_roots = session_configuration.primary_workspace_roots();
         let mut config = Self::build_per_turn_config(
             session_configuration,
             session_configuration.cwd().clone(),
@@ -718,7 +718,7 @@ impl Session {
             .transpose()
             .ok()
             .flatten()
-            .unwrap_or_else(|| session_configuration.workspace_roots());
+            .unwrap_or_default();
         let per_turn_config =
             Self::build_per_turn_config(&session_configuration, cwd.clone(), workspace_roots);
         {