diff --git a/codex-rs/core/src/config/mod.rs b/codex-rs/core/src/config/mod.rs
index 897a07cc00..56aeec9903 100644
--- a/codex-rs/core/src/config/mod.rs
+++ b/codex-rs/core/src/config/mod.rs
@@ -97,6 +97,7 @@ use codex_model_provider_info::GCP_PROVIDER_ID;
 use codex_model_provider_info::LEGACY_OLLAMA_CHAT_PROVIDER_ID;
 use codex_model_provider_info::ModelProviderInfo;
 use codex_model_provider_info::OLLAMA_CHAT_PROVIDER_REMOVED_ERROR;
+use codex_model_provider_info::OPENAI_PROVIDER_ID;
 use codex_model_provider_info::built_in_model_providers;
 use codex_model_provider_info::merge_configured_model_providers;
 use codex_models_manager::ModelsManagerConfig;
@@ -1711,6 +1712,14 @@ impl Config {
             .unwrap_or(model_messages.auto_review().policy)
     }
 
+    /// Native Guardian agent history requires the reviewed thread's OpenAI provider.
+    pub fn guardian_native_multi_agent_history_enabled(&self) -> bool {
+        self.model_provider_id == OPENAI_PROVIDER_ID
+            && self
+                .features
+                .enabled(Feature::GuardianNativeMultiAgentHistory)
+    }
+
     pub(crate) fn multi_agent_version_override(&self) -> Option<MultiAgentVersion> {
         if self.features.enabled(Feature::MultiAgentV2) {
             Some(MultiAgentVersion::V2)
diff --git a/codex-rs/core/src/guardian/prompt.rs b/codex-rs/core/src/guardian/prompt.rs
index a4afaae26a..b05088d7ab 100644
--- a/codex-rs/core/src/guardian/prompt.rs
+++ b/codex-rs/core/src/guardian/prompt.rs
@@ -1,5 +1,4 @@
 use codex_extension_api::ConversationHistorySnapshot;
-use codex_features::Feature;
 use codex_guardian_context::CollectedContext;
 use codex_guardian_context::ContextProfile;
 use codex_guardian_context::GuardianRootMessage;
@@ -145,9 +144,7 @@ pub(super) async fn collect_guardian_prompt_items_with_parent_turn(
     profile.transcript.options.native_multi_agent_namespace = parent_context
         .is_some_and(|context| {
             let turn = context.turn();
-            turn.config
-                .features
-                .enabled(Feature::GuardianNativeMultiAgentHistory)
+            turn.config.guardian_native_multi_agent_history_enabled()
                 && turn.multi_agent_version == codex_protocol::protocol::MultiAgentVersion::V2
         })
         .then(|| {
diff --git a/codex-rs/core/src/tools/spec_plan.rs b/codex-rs/core/src/tools/spec_plan.rs
index 56a716bc04..6274bc6fb7 100644
--- a/codex-rs/core/src/tools/spec_plan.rs
+++ b/codex-rs/core/src/tools/spec_plan.rs
@@ -1500,8 +1500,7 @@ fn add_collaboration_tools(context: &CoreToolPlanContext<'_>, registry: &mut Too
             let tool_namespace = turn_context.config.multi_agent_v2.tool_namespace.as_deref();
             let native_review = if turn_context
                 .config
-                .features
-                .enabled(Feature::GuardianNativeMultiAgentHistory)
+                .guardian_native_multi_agent_history_enabled()
             {
                 NativeReview::Required
             } else {
diff --git a/codex-rs/core/tests/suite/scenarios_guardian_agent_messages_tests.rs b/codex-rs/core/tests/suite/scenarios_guardian_agent_messages_tests.rs
index 61f2ef6d24..514b914504 100644
--- a/codex-rs/core/tests/suite/scenarios_guardian_agent_messages_tests.rs
+++ b/codex-rs/core/tests/suite/scenarios_guardian_agent_messages_tests.rs
@@ -1,4 +1,4 @@
-//! Guardian retains native encrypted messages and historical calls across incremental reviews.
+//! OpenAI-only native agent review preserves encrypted history across reviews and resumes.
 
 use codex_core::config::Constrained;
 use codex_features::Feature;
@@ -21,6 +21,102 @@ use pretty_assertions::assert_eq;
 use serde_json::json;
 use test_case::test_case;
 
+#[test_case("openai", true, true; "openai_treatment")]
+#[test_case("openai", false, false; "openai_control")]
+#[test_case("amazon-bedrock-runtime", true, false; "bedrock")]
+#[test_case("litellm-hybrid", true, false; "litellm")]
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn native_agent_review_requires_openai_on_start_and_resume(
+    provider_id: &'static str,
+    requested: bool,
+    expected_review: bool,
+) -> anyhow::Result<()> {
+    skip_if_no_network!(Ok(()));
+    let server = responses::start_mock_server().await;
+    let mut previous = None;
+    for phase in ["fresh", "resumed"] {
+        let mut builder = test_codex()
+            .with_model("gpt-5.5")
+            .with_config(move |config| {
+                super::configure_scenario_catalog(config);
+                config.model_provider_id = provider_id.to_owned();
+                // Keep the mock Responses transport and OpenAI display name for every provider ID.
+                config
+                    .model_providers
+                    .insert(provider_id.to_owned(), config.model_provider.clone());
+                for feature in [Feature::Collab, Feature::MultiAgentV2] {
+                    config
+                        .features
+                        .enable(feature)
+                        .expect("enable multi-agent feature");
+                }
+                config
+                    .features
+                    .set_enabled(Feature::GuardianNativeMultiAgentHistory, requested)
+                    .expect("set native agent review flag");
+                config.multi_agent_v2.tool_namespace = Some("collaboration".to_owned());
+                config.approvals_reviewer = ApprovalsReviewer::AutoReview;
+                config.permissions.approval_policy =
+                    Constrained::allow_any(AskForApproval::OnRequest);
+                config
+                    .permissions
+                    .set_permission_profile(PermissionProfile::read_only())
+                    .expect("set read-only permissions");
+            });
+        let test = if let Some(previous) = &previous {
+            builder.restart_with_auto_env(&server, previous).await?
+        } else {
+            builder.build_with_auto_env(&server).await?
+        };
+        let call_id = format!("send-{phase}");
+        let mut call = responses::ev_function_call_with_namespace(
+            &call_id,
+            "collaboration",
+            "send_message",
+            r#"{"target":"/root/missing","message":"opaque-message"}"#,
+        );
+        call["item"]["encrypted_content"] = json!("opaque-replay");
+        call["item"]["encrypted_function_args"] = json!(["message"]);
+        let mut stream = vec![responses::sse(vec![call, responses::ev_completed("send")])];
+        if expected_review {
+            stream.push(responses::sse(vec![
+                responses::ev_assistant_message("assessment", r#"{"outcome":"allow","rationale":"Mock approval.","risk_level":"low","user_authorization":"high"}"#),
+                responses::ev_completed("review"),
+            ]));
+        }
+        stream.push(responses::sse(vec![
+            responses::ev_assistant_message("done", "The worker is unavailable."),
+            responses::ev_completed("done"),
+        ]));
+        let mock = responses::mount_sse_sequence(&server, stream).await;
+        test.submit_text_turn("Ask the missing worker to confirm receipt.")
+            .await?;
+        let requests = mock.requests();
+        let reviews = requests
+            .iter()
+            .filter(|request| {
+                request.body_json()["client_metadata"]["x-openai-subagent"] == "guardian"
+            })
+            .collect::<Vec<_>>();
+        assert_eq!(
+            reviews.len(),
+            usize::from(expected_review),
+            "{phase}: {provider_id}"
+        );
+        if let Some(review) = reviews.first() {
+            assert!(
+                review
+                    .inputs_of_type("function_call")
+                    .iter()
+                    .any(|call| call["call_id"] == call_id),
+                "{phase}: native review evidence"
+            );
+        }
+        previous = Some(test);
+    }
+    Ok(())
+}
+
 #[cfg_attr(not(target_os = "windows"), test_case(None; "agent_reply"))]
 #[test_case(Some("functions"); "native_default_namespace")]
 #[test_case(Some("team"); "native_custom_namespace")]
diff --git a/codex-rs/ext/guardian-v2/src/async_scorer/config.rs b/codex-rs/ext/guardian-v2/src/async_scorer/config.rs
index 6cc765638c..0d3454eade 100644
--- a/codex-rs/ext/guardian-v2/src/async_scorer/config.rs
+++ b/codex-rs/ext/guardian-v2/src/async_scorer/config.rs
@@ -80,9 +80,7 @@ impl GuardianV2Config {
             ..configured
         });
         resolved.policy = GuardianPolicyLoader::new(Some(&legacy));
-        resolved.review_multi_agent_calls = config
-            .features
-            .enabled(codex_features::Feature::GuardianNativeMultiAgentHistory);
+        resolved.review_multi_agent_calls = config.guardian_native_multi_agent_history_enabled();
         resolved.multi_agent_namespace = config.multi_agent_v2.tool_namespace.clone();
         Ok(resolved)
     }