diff --git a/codex-rs/core/src/session/tests.rs b/codex-rs/core/src/session/tests.rs
index e06dba9b68..176ea9413f 100644
--- a/codex-rs/core/src/session/tests.rs
+++ b/codex-rs/core/src/session/tests.rs
@@ -7009,7 +7009,9 @@ async fn handle_output_item_done_records_image_save_history_message() {
     let mut ctx = HandleOutputCtx {
         sess: Arc::clone(&session),
         turn_context: Arc::clone(&turn_context),
-        turn_store: Arc::new(codex_extension_api::ExtensionData::new()),
+        turn_store: Arc::new(codex_extension_api::ExtensionData::new(
+            turn_context.sub_id.clone(),
+        )),
         tool_runtime: test_tool_runtime(Arc::clone(&session), Arc::clone(&turn_context)),
         cancellation_token: CancellationToken::new(),
     };
@@ -7062,7 +7064,9 @@ async fn handle_output_item_done_skips_image_save_message_when_save_fails() {
     let mut ctx = HandleOutputCtx {
         sess: Arc::clone(&session),
         turn_context: Arc::clone(&turn_context),
-        turn_store: Arc::new(codex_extension_api::ExtensionData::new()),
+        turn_store: Arc::new(codex_extension_api::ExtensionData::new(
+            turn_context.sub_id.clone(),
+        )),
         tool_runtime: test_tool_runtime(Arc::clone(&session), Arc::clone(&turn_context)),
         cancellation_token: CancellationToken::new(),
     };
@@ -8950,7 +8954,7 @@ async fn tool_calls_reopen_mailbox_delivery_for_current_turn() {
     let mut ctx = HandleOutputCtx {
         sess: Arc::clone(&sess),
         turn_context: Arc::clone(&tc),
-        turn_store: Arc::new(codex_extension_api::ExtensionData::new()),
+        turn_store: Arc::new(codex_extension_api::ExtensionData::new(tc.sub_id.clone())),
         tool_runtime: test_tool_runtime(Arc::clone(&sess), Arc::clone(&tc)),
         cancellation_token: CancellationToken::new(),
     };
diff --git a/codex-rs/core/src/session/turn_tests.rs b/codex-rs/core/src/session/turn_tests.rs
index 4f19474d38..f1cf86b46c 100644
--- a/codex-rs/core/src/session/turn_tests.rs
+++ b/codex-rs/core/src/session/turn_tests.rs
@@ -43,7 +43,7 @@ async fn plan_mode_uses_contributed_turn_item_for_last_agent_message() {
     let mut builder = codex_extension_api::ExtensionRegistryBuilder::new();
     builder.turn_item_contributor(Arc::new(RewriteAgentMessageContributor));
     session.services.extensions = Arc::new(builder.build());
-    let turn_store = ExtensionData::new();
+    let turn_store = ExtensionData::new(turn_context.sub_id.clone());
     let mut state = PlanModeStreamState::new(&turn_context.sub_id);
     let mut last_agent_message = None;
     let item = assistant_output_text("original assistant text");
diff --git a/codex-rs/core/src/state/turn.rs b/codex-rs/core/src/state/turn.rs
index 0dd0c09379..70aae74e87 100644
--- a/codex-rs/core/src/state/turn.rs
+++ b/codex-rs/core/src/state/turn.rs
@@ -9,6 +9,7 @@ use tokio::sync::Notify;
 use tokio_util::sync::CancellationToken;
 use tokio_util::task::AbortOnDropHandle;
 
+use codex_extension_api::ExtensionData;
 use codex_protocol::dynamic_tools::DynamicToolResponse;
 use codex_protocol::models::ResponseInputItem;
 use codex_protocol::request_permissions::RequestPermissionProfile;
@@ -75,6 +76,7 @@ pub(crate) struct RunningTask {
     pub(crate) cancellation_token: CancellationToken,
     pub(crate) handle: AbortOnDropHandle<()>,
     pub(crate) turn_context: Arc<TurnContext>,
+    pub(crate) turn_extension_data: Arc<ExtensionData>,
     // Timer recorded when the task drops to capture the full turn duration.
     pub(crate) _timer: Option<codex_otel::Timer>,
 }
diff --git a/codex-rs/core/src/stream_events_utils_tests.rs b/codex-rs/core/src/stream_events_utils_tests.rs
index 46c7ffed19..2d095906ed 100644
--- a/codex-rs/core/src/stream_events_utils_tests.rs
+++ b/codex-rs/core/src/stream_events_utils_tests.rs
@@ -214,7 +214,7 @@ async fn handle_non_tool_response_item_runs_turn_item_contributors_only_when_req
     let mut builder = codex_extension_api::ExtensionRegistryBuilder::new();
     builder.turn_item_contributor(Arc::new(TestTurnItemContributor));
     session.services.extensions = Arc::new(builder.build());
-    let turn_store = ExtensionData::new();
+    let turn_store = ExtensionData::new(turn_context.sub_id.clone());
     let item = assistant_output_text(
         "hello<oai-mem-citation>ignored by memory parser</oai-mem-citation> world",
     );
@@ -288,8 +288,8 @@ async fn handle_output_item_done_returns_contributed_last_agent_message() {
     let item = assistant_output_text("original assistant text");
     let mut ctx = HandleOutputCtx {
         sess: session,
-        turn_context,
-        turn_store: Arc::new(ExtensionData::new()),
+        turn_context: Arc::clone(&turn_context),
+        turn_store: Arc::new(ExtensionData::new(turn_context.sub_id.clone())),
         tool_runtime,
         cancellation_token: CancellationToken::new(),
     };
@@ -310,7 +310,7 @@ async fn finalized_turn_item_defers_mailbox_for_contributed_visible_text() {
     let mut builder = codex_extension_api::ExtensionRegistryBuilder::new();
     builder.turn_item_contributor(Arc::new(RewriteAgentMessageContributor));
     session.services.extensions = Arc::new(builder.build());
-    let turn_store = ExtensionData::new();
+    let turn_store = ExtensionData::new(turn_context.sub_id.clone());
     let item = assistant_output_text("<oai-mem-citation>hidden only</oai-mem-citation>");
 
     let finalized = finalize_non_tool_response_item(
@@ -336,7 +336,7 @@ async fn finalized_turn_item_keeps_mailbox_open_for_commentary_text() {
     let mut builder = codex_extension_api::ExtensionRegistryBuilder::new();
     builder.turn_item_contributor(Arc::new(RewriteAgentMessageContributor));
     session.services.extensions = Arc::new(builder.build());
-    let turn_store = ExtensionData::new();
+    let turn_store = ExtensionData::new(turn_context.sub_id.clone());
     let item = assistant_output_text_with_phase("still working", Some(MessagePhase::Commentary));
 
     let finalized = finalize_non_tool_response_item(
diff --git a/codex-rs/core/src/tasks/mod.rs b/codex-rs/core/src/tasks/mod.rs
index 5e6b931500..58ead0fd25 100644
--- a/codex-rs/core/src/tasks/mod.rs
+++ b/codex-rs/core/src/tasks/mod.rs
@@ -367,6 +367,7 @@ impl Session {
         }
         self.emit_turn_start_lifecycle(turn_context.extension_data.as_ref());
 
+        let turn_extension_data = Arc::clone(&turn_context.extension_data);
         let mut active = self.active_turn.lock().await;
         let turn = active.get_or_insert_with(ActiveTurn::default);
         debug_assert!(turn.tasks.is_empty());
@@ -439,6 +440,7 @@ impl Session {
             task,
             cancellation_token,
             turn_context: Arc::clone(&turn_context),
+            turn_extension_data,
             _timer: timer,
         };
         turn.add_task(running_task);