diff --git a/codex-rs/app-server/tests/suite/v2/thread_inject_items.rs b/codex-rs/app-server/tests/suite/v2/thread_inject_items.rs
index 95ad84b2c4..384137b95a 100644
--- a/codex-rs/app-server/tests/suite/v2/thread_inject_items.rs
+++ b/codex-rs/app-server/tests/suite/v2/thread_inject_items.rs
@@ -228,24 +228,37 @@ async fn thread_inject_items_adds_raw_response_items_to_thread_history(
         .iter()
         .filter_map(|item| match item {
             RolloutItem::ResponseItem(envelope) => {
-                let ResponseItem::Message { role, content, .. } = &envelope.item else {
-                    return None;
+                let context_kind = match &envelope.item {
+                    ResponseItem::Message { role, content, .. } => {
+                        content.iter().find_map(|item| {
+                            let ContentItem::InputText { text } = item else {
+                                return None;
+                            };
+                            text.contains(application_context_text)
+                                .then_some(role.as_str())
+                        })
+                    }
+                    ResponseItem::FunctionCallOutput {
+                        name,
+                        namespace,
+                        output,
+                        ..
+                    } if name.as_deref() == Some("untrusted_context")
+                        && namespace.as_deref() == Some("agent")
+                        && output.text_content() == Some(untrusted_context_text) =>
+                    {
+                        Some("function_call_output")
+                    }
+                    _ => None,
                 };
-                content.iter().find_map(|item| {
-                    let ContentItem::InputText { text } = item else {
-                        return None;
-                    };
-                    (text.contains(application_context_text)
-                        || text.contains(untrusted_context_text))
-                    .then(|| {
-                        (
-                            role.as_str(),
-                            envelope
-                                .metadata
-                                .as_ref()
-                                .map(|metadata| metadata.client_authored),
-                        )
-                    })
+                context_kind.map(|kind| {
+                    (
+                        kind,
+                        envelope
+                            .metadata
+                            .as_ref()
+                            .map(|metadata| metadata.client_authored),
+                    )
                 })
             }
             _ => None,
@@ -253,7 +266,10 @@ async fn thread_inject_items_adds_raw_response_items_to_thread_history(
         .collect::<Vec<_>>();
     assert_eq!(
         persisted_additional_context,
-        vec![("developer", Some(true)), ("user", Some(false))]
+        vec![
+            ("developer", Some(true)),
+            ("function_call_output", Some(false))
+        ]
     );
 
     let injected_value = serde_json::to_value(&injected_item)?;
diff --git a/codex-rs/app-server/tests/suite/v2/turn_start.rs b/codex-rs/app-server/tests/suite/v2/turn_start.rs
index dfa244926f..34e9d2dc45 100644
--- a/codex-rs/app-server/tests/suite/v2/turn_start.rs
+++ b/codex-rs/app-server/tests/suite/v2/turn_start.rs
@@ -815,10 +815,9 @@ async fn turn_start_additional_context_flows_to_model_input(
     let ThreadStartResponse { thread, .. } = mcp
         .start_thread(ThreadStartParams {
             model: Some("mock-model".to_string()),
-            config: Some(HashMap::from([(
-                "features.untrusted_as_tool_output".to_owned(),
-                json!(tool_outputs),
-            )])),
+            config: (!tool_outputs).then(|| {
+                HashMap::from([("features.untrusted_as_tool_output".to_owned(), json!(false))])
+            }),
             ..Default::default()
         })
         .await?;
diff --git a/codex-rs/app-server/tests/suite/v2/turn_steer.rs b/codex-rs/app-server/tests/suite/v2/turn_steer.rs
index 38f5cace78..477497b9c2 100644
--- a/codex-rs/app-server/tests/suite/v2/turn_steer.rs
+++ b/codex-rs/app-server/tests/suite/v2/turn_steer.rs
@@ -557,11 +557,7 @@ async fn turn_steer_rejects_context_only_input_without_merging_context() -> Resu
     let body = response_requests[1]
         .body_json::<Value>()
         .context("request body should be JSON")?;
-    assert!(
-        !body
-            .to_string()
-            .contains("<external_browser_info>tab one</external_browser_info>")
-    );
+    assert!(!body.to_string().contains("tab one"));
 
     Ok(())
 }
diff --git a/codex-rs/core/tests/suite/additional_context.rs b/codex-rs/core/tests/suite/additional_context.rs
index 8f4b4518f3..be86847741 100644
--- a/codex-rs/core/tests/suite/additional_context.rs
+++ b/codex-rs/core/tests/suite/additional_context.rs
@@ -34,6 +34,8 @@ use core_test_support::responses::mount_sse_sequence;
 use core_test_support::responses::received_responses_requests;
 use core_test_support::responses::sse;
 use core_test_support::responses::start_mock_server;
+use core_test_support::responses::strip_metadata_from_json;
+use core_test_support::responses::strip_response_item_ids_from_json;
 use core_test_support::skip_if_no_network;
 use core_test_support::skip_if_wine_exec;
 use core_test_support::test_codex::test_codex;
@@ -113,7 +115,9 @@ async fn additional_context_is_model_visible_but_not_a_user_message_item() -> Re
 
     let request = request.single_request();
     assert!(request.has_content_kinds(&["additional_content.automation_info"]));
-    assert!(request.has_content_kinds(&["additional_content.browser_info"]));
+    let outputs = request.inputs_of_type("function_call_output");
+    assert_eq!(outputs.len(), 1);
+    assert_browser_context_actor_output(&outputs[0]);
     assert!(request.has_content_kinds(&["user.text"]));
     insta::assert_snapshot!(
         "additional_context_simple_input",
@@ -134,10 +138,7 @@ async fn additional_context_is_model_visible_but_not_a_user_message_item() -> Re
     );
     assert_eq!(
         request.message_input_texts("user"),
-        vec![
-            "<external_browser_info>tab one</external_browser_info>",
-            "inspect the active tab",
-        ]
+        vec!["inspect the active tab"]
     );
 
     Ok(())
@@ -639,20 +640,47 @@ async fn additional_context_is_deduplicated_between_turns_while_retained(
     })
     .await;
 
+    let first_request = first_request.single_request();
+    let second_request = second_request.single_request();
     assert_eq!(
-        first_request.single_request().message_input_texts("user"),
-        vec![
-            "<external_browser_info>same tab</external_browser_info>",
-            "first turn",
-        ]
+        first_request.message_input_texts("user"),
+        vec!["first turn"]
     );
     assert_eq!(
-        second_request.single_request().message_input_texts("user"),
-        vec![
-            "<external_browser_info>same tab</external_browser_info>",
-            "first turn",
-            "second turn",
-        ]
+        second_request.message_input_texts("user"),
+        vec!["first turn", "second turn"]
+    );
+    let mut expected_outputs = vec![json!({
+        "type": "function_call_output",
+        "namespace": "agent",
+        "name": first_name.unwrap_or("browser_info"),
+        "output": "same tab",
+    })];
+    assert_eq!(
+        first_request
+            .inputs_of_type("function_call_output")
+            .into_iter()
+            .map(strip_response_item_ids_from_json)
+            .map(strip_metadata_from_json)
+            .collect::<Vec<_>>(),
+        expected_outputs,
+    );
+    if first_name != second_name {
+        expected_outputs.push(json!({
+            "type": "function_call_output",
+            "namespace": "agent",
+            "name": second_name.unwrap_or("browser_info"),
+            "output": "same tab",
+        }));
+    }
+    assert_eq!(
+        second_request
+            .inputs_of_type("function_call_output")
+            .into_iter()
+            .map(strip_response_item_ids_from_json)
+            .map(strip_metadata_from_json)
+            .collect::<Vec<_>>(),
+        expected_outputs,
     );
 
     Ok(())
diff --git a/codex-rs/core/tests/suite/context_annotations.rs b/codex-rs/core/tests/suite/context_annotations.rs
index fc982c9b12..7e47cb0cc4 100644
--- a/codex-rs/core/tests/suite/context_annotations.rs
+++ b/codex-rs/core/tests/suite/context_annotations.rs
@@ -214,7 +214,7 @@ async fn first_request_item_types_roles_and_content_annotations() -> Result<()>
     message developer ["multi_agent.mode_instructions"]
     message user ["environments.environment_context"]
     message developer ["additional_content.automation_info"]
-    message user ["additional_content.browser_info"]
+    function_call_output - null
     message user ["user.text","user.image","user.audio"]
     message developer ["rollout_budget.remaining_tokens"]
     message developer ["current_time.reminder"]
diff --git a/codex-rs/core/tests/suite/scenarios.rs b/codex-rs/core/tests/suite/scenarios.rs
index b5b8074c8c..727e806a93 100644
--- a/codex-rs/core/tests/suite/scenarios.rs
+++ b/codex-rs/core/tests/suite/scenarios.rs
@@ -572,10 +572,12 @@ async fn additional_context_tool_outputs(tool_outputs: bool) -> Result<()> {
         .with_config(move |config| {
             configure_scenario_catalog(config);
             config.include_environment_context = false;
-            config
-                .features
-                .set_enabled(Feature::UntrustedAsToolOutput, tool_outputs)
-                .expect("test config should allow feature update");
+            if !tool_outputs {
+                config
+                    .features
+                    .disable(Feature::UntrustedAsToolOutput)
+                    .expect("test config should allow feature update");
+            }
         })
         .build_with_auto_env(&server)
         .await?;
diff --git a/codex-rs/core/tests/suite/snapshots/all__suite__additional_context__additional_context_simple_input.snap b/codex-rs/core/tests/suite/snapshots/all__suite__additional_context__additional_context_simple_input.snap
index 00b33de5ba..bdfe03a4fa 100644
--- a/codex-rs/core/tests/suite/snapshots/all__suite__additional_context__additional_context_simple_input.snap
+++ b/codex-rs/core/tests/suite/snapshots/all__suite__additional_context__additional_context_simple_input.snap
@@ -16,7 +16,6 @@ Scenario: additional context is inserted before the user turn input.
         </tools>
 02:message/developer:
     <automation_info>run one</automation_info>
-03:message/user:
-    <external_browser_info>tab one</external_browser_info>
+03:function_call_output/agent.browser_info:tab one
 04:message/user:
     inspect the active tab
diff --git a/codex-rs/features/src/lib.rs b/codex-rs/features/src/lib.rs
index b3edf15ae1..ad9c53372a 100644
--- a/codex-rs/features/src/lib.rs
+++ b/codex-rs/features/src/lib.rs
@@ -1283,8 +1283,8 @@ pub const FEATURES: &[FeatureSpec] = &[
     FeatureSpec {
         id: Feature::UntrustedAsToolOutput,
         key: "untrusted_as_tool_output",
-        stage: Stage::UnderDevelopment,
-        default_enabled: false,
+        stage: Stage::Stable,
+        default_enabled: true,
     },
     FeatureSpec {
         id: Feature::ExecutedToolCallMetadata,
diff --git a/codex-rs/tui/src/app/tests/safety_buffering.rs b/codex-rs/tui/src/app/tests/safety_buffering.rs
index 62f376ddda..15d4059907 100644
--- a/codex-rs/tui/src/app/tests/safety_buffering.rs
+++ b/codex-rs/tui/src/app/tests/safety_buffering.rs
@@ -1441,9 +1441,16 @@ goals = true
         retry_request_index + 1
     };
     assert!(
-        user_input_texts(&request_bodies[goal_continuation_request_index])
+        request_bodies[goal_continuation_request_index]["input"]
+            .as_array()
+            .expect("goal continuation model input")
             .iter()
-            .any(|text| text.contains(RETRY_GOAL)),
+            .any(|item| {
+                item["type"] == "function_call_output"
+                    && item["namespace"] == "agent"
+                    && item["name"] == "goal_objective"
+                    && item["output"] == RETRY_GOAL
+            }),
         "inherited goal continuation should resume after the explicit retry"
     );
 
diff --git a/sdk/python/tests/test_app_server_goal_operations.py b/sdk/python/tests/test_app_server_goal_operations.py
index 388aada8b7..ee064dcb25 100644
--- a/sdk/python/tests/test_app_server_goal_operations.py
+++ b/sdk/python/tests/test_app_server_goal_operations.py
@@ -74,9 +74,12 @@ def test_private_goal_operation_coalesces_runtime_continuations(tmp_path) -> Non
         "result": (result.id, result.status, result.final_response),
         "messages": agent_message_texts(events),
         "request_count": len(requests),
-        "objective_reached_model": (
-            "<external_goal_objective>Improve benchmark coverage</external_goal_objective>"
-            in requests[0].message_input_texts("user")
+        "objective_reached_model": any(
+            item.get("type") == "function_call_output"
+            and item.get("namespace") == "agent"
+            and item.get("name") == "goal_objective"
+            and item.get("output") == "Improve benchmark coverage"
+            for item in requests[0].input()
         ),
         "steering_reached_model": any(
             "Continue working toward the active thread goal." in text