diff --git a/codex-rs/app-server/tests/suite/v2/history_notes_extension.rs b/codex-rs/app-server/tests/suite/v2/history_notes_extension.rs
index d49545f70d..14aaddae38 100644
--- a/codex-rs/app-server/tests/suite/v2/history_notes_extension.rs
+++ b/codex-rs/app-server/tests/suite/v2/history_notes_extension.rs
@@ -9,10 +9,8 @@ use codex_app_server_protocol::ThreadStartParams;
 use codex_app_server_protocol::TurnStartParams;
 use codex_app_server_protocol::UserInput;
 use codex_config::types::AuthCredentialsStoreMode;
-use codex_features::Feature;
 use core_test_support::load_default_config_for_test;
 use core_test_support::responses;
-use core_test_support::skip_if_wine_exec;
 use pretty_assertions::assert_eq;
 use serde_json::Value;
 use serde_json::json;
@@ -223,181 +221,6 @@ async fn app_server_uses_configured_notes_backend_for_context_window_hints(
     Ok(())
 }
 
-#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-async fn guardian_can_read_parent_history_without_inheriting_notes_tools() -> Result<()> {
-    // TODO: Remove after Guardian accepts executor-native cwd across host operating systems.
-    skip_if_wine_exec!(
-        Ok(()),
-        "Guardian approval currently rejects a Windows executor cwd on the Linux host"
-    );
-
-    let server = responses::start_mock_server().await;
-    Mock::given(method("POST"))
-        .and(path("/backend-api/codex/alpha/notes/v2/thread_hint"))
-        .respond_with(ResponseTemplate::new(200).set_body_json(json!({"text": ""})))
-        .expect(1)
-        .mount(&server)
-        .await;
-    Mock::given(method("POST"))
-        .and(path("/backend-api/codex/alpha/history/v2/list_items"))
-        .respond_with(ResponseTemplate::new(200).set_body_json(json!({
-            "results": [],
-            "n_returned": 0,
-        })))
-        .expect(1)
-        .mount(&server)
-        .await;
-    let response_mock = responses::mount_sse_sequence(
-        &server,
-        vec![
-            responses::sse(vec![
-                responses::ev_response_created("resp-parent-command"),
-                responses::ev_function_call(
-                    "parent-shell-call",
-                    "exec_command",
-                    &json!({
-                        "cmd": "echo guardian",
-                        "sandbox_permissions": "require_escalated",
-                        "justification": "Review a command using parent history.",
-                    })
-                    .to_string(),
-                ),
-                responses::ev_completed("resp-parent-command"),
-            ]),
-            responses::sse(vec![
-                responses::ev_response_created("resp-guardian-history"),
-                responses::ev_function_call_with_namespace(
-                    "guardian-history-call",
-                    "history",
-                    "list_items",
-                    &json!({"role": "user"}).to_string(),
-                ),
-                responses::ev_completed("resp-guardian-history"),
-            ]),
-            responses::sse(vec![
-                responses::ev_response_created("resp-guardian-review"),
-                responses::ev_assistant_message(
-                    "guardian-review",
-                    &json!({
-                        "outcome": "deny",
-                        "rationale": "The original user instructions do not authorize this command.",
-                    })
-                    .to_string(),
-                ),
-                responses::ev_completed("resp-guardian-review"),
-            ]),
-            responses::sse(vec![
-                responses::ev_response_created("resp-parent-done"),
-                responses::ev_assistant_message("parent-done", "Done"),
-                responses::ev_completed("resp-parent-done"),
-            ]),
-        ],
-    )
-    .await;
-
-    let codex_home = TempDir::new()?;
-    MockResponsesConfig::new(&server.uri())
-        .with_model_provider("openai-custom")
-        .with_provider_name("OpenAI")
-        .with_provider_base_url(&format!("{}/backend-api/codex", server.uri()))
-        .with_provider_config("supports_websockets = false\nrequires_openai_auth = true")
-        .with_approval_policy("on-request")
-        .with_root_config("approvals_reviewer = \"auto_review\"")
-        .enable_feature(Feature::GuardianApproval)
-        .with_extra_config(
-            "[features.token_budget]\nenabled = true\nuse_history_notes_extension = true",
-        )
-        .write(codex_home.path())?;
-    write_chatgpt_auth(
-        codex_home.path(),
-        ChatGptAuthFixture::new("access-chatgpt"),
-        AuthCredentialsStoreMode::File,
-    )?;
-
-    let mut app_server = TestAppServer::builder()
-        .with_codex_home(codex_home.path())
-        .with_env_overrides(&[("OPENAI_API_KEY", None)])
-        .build_initialized()
-        .await?;
-    let thread = app_server
-        .start_thread(ThreadStartParams::default())
-        .await?
-        .thread;
-    timeout(
-        DEFAULT_READ_TIMEOUT,
-        app_server.start_turn_and_wait_for_completion(TurnStartParams {
-            thread_id: thread.id.clone(),
-            input: vec![UserInput::Text {
-                text: "Review a command using the original user instructions".to_string(),
-                text_elements: Vec::new(),
-            }],
-            ..Default::default()
-        }),
-    )
-    .await??;
-
-    let requests = response_mock.requests();
-    assert_eq!(requests.len(), 4);
-    let guardian_request = &requests[1];
-    let guardian_body = guardian_request.body_json();
-    assert_eq!(
-        guardian_body["client_metadata"]["x-openai-subagent"],
-        "guardian"
-    );
-    let guardian_tools = guardian_body.get("tools").or_else(|| {
-        guardian_body["input"]
-            .as_array()?
-            .iter()
-            .find(|item| item["type"] == "additional_tools")?
-            .get("tools")
-    });
-    let guardian_tools = json!({"tools": guardian_tools.expect("Guardian tool definitions")});
-    for tool_name in ["list_windows", "list_items", "read_item", "search_contents"] {
-        assert!(
-            responses::namespace_child_tool(&guardian_tools, "history", tool_name).is_some(),
-            "Guardian should expose history.{tool_name}"
-        );
-    }
-    for tool_name in [
-        "list_files_by_prefix",
-        "read_file",
-        "search_contents",
-        "append_to_file",
-        "write_file",
-    ] {
-        assert!(
-            requests[0].tool_by_name("notes", tool_name).is_some(),
-            "the parent should retain notes.{tool_name}"
-        );
-        assert!(
-            responses::namespace_child_tool(&guardian_tools, "notes", tool_name).is_none(),
-            "Guardian must not inherit notes.{tool_name}"
-        );
-    }
-    assert_eq!(
-        requests[2].function_call_output_text("guardian-history-call"),
-        Some(json!({"results": [], "n_returned": 0}).to_string())
-    );
-
-    let backend_requests = server.received_requests().await.expect("recorded requests");
-    let history_request = backend_requests
-        .iter()
-        .find(|request| request.url.path() == "/backend-api/codex/alpha/history/v2/list_items")
-        .expect("Guardian history request");
-    assert_eq!(
-        history_request.body_json::<Value>()?,
-        json!({
-            "role": "user",
-            "context": {
-                "session_id": thread.id,
-                "current_agent_name": "/root",
-            },
-        })
-    );
-
-    Ok(())
-}
-
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn history_notes_and_async_message_emit_control_tool_analytics() -> Result<()> {
     let encrypted_query = format!("enc_query_{}", "x".repeat(1_001));
diff --git a/codex-rs/core/src/codex_delegate.rs b/codex-rs/core/src/codex_delegate.rs
index 969a6298ff..047a054b89 100644
--- a/codex-rs/core/src/codex_delegate.rs
+++ b/codex-rs/core/src/codex_delegate.rs
@@ -42,10 +42,6 @@ use codex_protocol::turn_input::TurnStartOptions;
 #[cfg(test)]
 use crate::session::completed_session_loop_termination;
 
-pub(crate) struct GuardianReadOnlyHistoryTools(
-    pub(crate) Vec<Arc<dyn for<'call> codex_tools::ToolExecutor<codex_tools::ToolCall<'call>>>>,
-);
-
 /// Start an interactive sub-Codex thread and return its runtime and IO channels.
 ///
 /// Delegates never request approvals, and the returned IO yields their public events.
@@ -85,27 +81,6 @@ pub(crate) async fn run_codex_thread_interactive(
     };
     let session_source = SessionSource::SubAgent(subagent_source.clone());
     let is_guardian_reviewer = crate::guardian::is_basic_session_source(&session_source);
-    let mut thread_extension_init = codex_extension_api::ExtensionDataInit::default();
-    if is_guardian_reviewer {
-        let history_tools = crate::tools::spec_plan::extension_tool_executors(
-            parent_session.as_ref(),
-            parent_ctx.extension_data.as_ref(),
-        )
-        .filter(|executor| {
-            let name = executor.tool_name();
-            matches!(
-                (name.namespace.as_deref(), name.name.as_str()),
-                (
-                    Some("history"),
-                    "list_windows" | "list_items" | "read_item" | "search_contents"
-                )
-            )
-        })
-        .collect::<Vec<_>>();
-        if !history_tools.is_empty() {
-            thread_extension_init.insert(GuardianReadOnlyHistoryTools(history_tools));
-        }
-    }
     let extensions = if is_guardian_reviewer {
         codex_extension_api::empty_extension_registry()
     } else {
@@ -148,7 +123,7 @@ pub(crate) async fn run_codex_thread_interactive(
         parent_rollout_thread_trace: codex_rollout_trace::ThreadTraceContext::disabled(),
         parent_trace: None,
         environment_selections: parent_environments.to_selections(),
-        thread_extension_init,
+        thread_extension_init: codex_extension_api::ExtensionDataInit::default(),
         client_mcp_extensions: parent_session.services.client_mcp_extensions.clone(),
         reserved_thread_id: None,
         analytics_events_client: Some(parent_session.services.analytics_events_client.clone()),
diff --git a/codex-rs/core/src/tools/spec_plan.rs b/codex-rs/core/src/tools/spec_plan.rs
index 082bb8f0b2..d5729387d6 100644
--- a/codex-rs/core/src/tools/spec_plan.rs
+++ b/codex-rs/core/src/tools/spec_plan.rs
@@ -153,18 +153,6 @@ pub(crate) fn build_tool_router(
     add_core_tool_sources(&context, &mut registry);
 
     let hosted_specs = if crate::guardian::is_basic_session_source(&turn_context.session_source) {
-        if let Some(history_tools) = session
-            .services
-            .thread_extension_data
-            .get::<crate::codex_delegate::GuardianReadOnlyHistoryTools>()
-        {
-            append_extension_tool_executors(
-                turn_context,
-                model_info,
-                history_tools.0.iter().cloned(),
-                &mut registry,
-            );
-        }
         Vec::new()
     } else {
         let registered_mcp_tools = session.services.mcp_handler_cache.append_mcp_tools(