diff --git a/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-stable.json.zst b/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-stable.json.zst
index 7893421a83..c43dd8756d 100644
Binary files a/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-stable.json.zst and b/codex-rs/app-server-protocol/schema/precomputed/app-server-exports-stable.json.zst differ
diff --git a/codex-rs/app-server-protocol/src/protocol/thread_history.rs b/codex-rs/app-server-protocol/src/protocol/thread_history.rs
index 7a1d70c85f..40d3d9fc7e 100644
--- a/codex-rs/app-server-protocol/src/protocol/thread_history.rs
+++ b/codex-rs/app-server-protocol/src/protocol/thread_history.rs
@@ -396,6 +396,7 @@ impl ThreadHistoryBuilder {
             RolloutItem::InterAgentCommunication(_)
             | RolloutItem::InterAgentCommunicationMetadata { .. }
             | RolloutItem::TurnContext(_)
+            | RolloutItem::TokenUsageRecord(_)
             | RolloutItem::WorldState(_)
             | RolloutItem::RealtimeItem(_)
             | RolloutItem::SecurityRiskScore(_)
@@ -4060,6 +4061,8 @@ mod tests {
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
             RolloutItem::EventMsg(EventMsg::TurnComplete(TurnCompleteEvent {
                 turn_id: "turn-compact".into(),
diff --git a/codex-rs/app-server-protocol/src/protocol/thread_history_projection.rs b/codex-rs/app-server-protocol/src/protocol/thread_history_projection.rs
index 6bb1138dc0..7fc8648b32 100644
--- a/codex-rs/app-server-protocol/src/protocol/thread_history_projection.rs
+++ b/codex-rs/app-server-protocol/src/protocol/thread_history_projection.rs
@@ -82,6 +82,7 @@ pub fn project_rollout_line(line: &RolloutLine) -> ThreadHistoryChangeSet {
         | RolloutItem::InterAgentCommunicationMetadata { .. }
         | RolloutItem::Compacted(_)
         | RolloutItem::TurnContext(_)
+        | RolloutItem::TokenUsageRecord(_)
         | RolloutItem::WorldState(_)
         | RolloutItem::RealtimeItem(_)
         | RolloutItem::SecurityRiskScore(_)
diff --git a/codex-rs/app-server-protocol/src/protocol/thread_history_projection_tests.rs b/codex-rs/app-server-protocol/src/protocol/thread_history_projection_tests.rs
index 1c1cda3129..4eb2c02267 100644
--- a/codex-rs/app-server-protocol/src/protocol/thread_history_projection_tests.rs
+++ b/codex-rs/app-server-protocol/src/protocol/thread_history_projection_tests.rs
@@ -205,6 +205,8 @@ fn ignores_legacy_abort_without_turn_id_and_context_only_records() {
         first_window_id: None,
         previous_window_id: None,
         window_id: None,
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     }));
     let security_risk = project(RolloutItem::SecurityRiskScore(SecurityRiskScore {
         scores: BTreeMap::from([("action_risk".to_string(), 0.92)]),
diff --git a/codex-rs/app-server/src/request_processors/feedback_processor.rs b/codex-rs/app-server/src/request_processors/feedback_processor.rs
index d2948c4ade..c68aa1d23e 100644
--- a/codex-rs/app-server/src/request_processors/feedback_processor.rs
+++ b/codex-rs/app-server/src/request_processors/feedback_processor.rs
@@ -704,6 +704,7 @@ mod tests {
                 ordinal: None,
                 item: RolloutItem::TurnContext(TurnContextItem {
                     turn_id: Some((*turn_id).to_string()),
+                    root_turn_id: None,
                     cwd: AbsolutePathBuf::from_absolute_path(tempdir.path())
                         .expect("absolute feedback rollout directory"),
                     workspace_roots: None,
diff --git a/codex-rs/app-server/src/request_processors/persisted_resume_settings_tests.rs b/codex-rs/app-server/src/request_processors/persisted_resume_settings_tests.rs
index 167e770af5..792fc344a1 100644
--- a/codex-rs/app-server/src/request_processors/persisted_resume_settings_tests.rs
+++ b/codex-rs/app-server/src/request_processors/persisted_resume_settings_tests.rs
@@ -62,6 +62,7 @@ fn turn_context_item(
 ) -> RolloutItem {
     RolloutItem::TurnContext(TurnContextItem {
         turn_id: Some(turn_id.to_string()),
+        root_turn_id: None,
         cwd: cwd(),
         workspace_roots: Some(vec![cwd()]),
         current_date: None,
diff --git a/codex-rs/app-server/tests/suite/v2/thread_resume.rs b/codex-rs/app-server/tests/suite/v2/thread_resume.rs
index 6338c57b45..485336edd7 100644
--- a/codex-rs/app-server/tests/suite/v2/thread_resume.rs
+++ b/codex-rs/app-server/tests/suite/v2/thread_resume.rs
@@ -201,6 +201,8 @@ async fn thread_resume_paginated_model_context_preserves_original_metadata() ->
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
     )
     .await?;
@@ -3238,7 +3240,10 @@ async fn thread_goal_keeps_original_root_until_external_objective_edit() -> Resu
         reopened_original_request["client_metadata"]["turn_id"].as_str(),
         Some(original_turn.turn.id.as_str())
     );
-    responses::assert_root_turn(&reopened_original_request, /*expected*/ None)?;
+    responses::assert_root_turn(
+        &reopened_original_request,
+        Some(original_turn.turn.id.as_str()),
+    )?;
     let intervening_request = serde_json::from_slice::<serde_json::Value>(&requests[3])?;
     let intervening_turn_id = intervening_request["client_metadata"]["turn_id"]
         .as_str()
@@ -3265,7 +3270,7 @@ async fn thread_goal_keeps_original_root_until_external_objective_edit() -> Resu
         reopened_request["client_metadata"]["turn_id"].as_str(),
         Some(edited_turn_id)
     );
-    responses::assert_root_turn(&reopened_request, /*expected*/ None)?;
+    responses::assert_root_turn(&reopened_request, Some(original_turn.turn.id.as_str()))?;
     let continuation_request = serde_json::from_slice::<serde_json::Value>(&requests[7])?;
     assert_ne!(
         continuation_request["client_metadata"]["turn_id"].as_str(),
diff --git a/codex-rs/core/src/agent/control.rs b/codex-rs/core/src/agent/control.rs
index 8dbd4d329a..141aaddc6e 100644
--- a/codex-rs/core/src/agent/control.rs
+++ b/codex-rs/core/src/agent/control.rs
@@ -116,8 +116,7 @@ pub(crate) struct ListedAgent {
 /// which keeps the registry scoped to that root thread rather than the entire `ThreadManager`.
 #[derive(Clone)]
 pub(crate) struct AgentControl {
-    /// ID shared by the whole agent control session. This means every sub-agents from a common
-    /// root share the same session ID.
+    /// session_id is equal to the root thread's ID.
     session_id: SessionId,
     /// Weak handle back to the global thread registry/state.
     /// This is `Weak` to avoid reference cycles and shadow persistence of the form
diff --git a/codex-rs/core/src/agent/control/spawn.rs b/codex-rs/core/src/agent/control/spawn.rs
index 2f31539798..b0dbd8a162 100644
--- a/codex-rs/core/src/agent/control/spawn.rs
+++ b/codex-rs/core/src/agent/control/spawn.rs
@@ -96,6 +96,8 @@ fn keep_forked_rollout_item(item: &RolloutItem, preserve_reference_context_item:
         // from the parent's durable baseline. Truncated forks drop part of that prompt,
         // so they must rebuild context on their first child turn.
         RolloutItem::TurnContext(_) | RolloutItem::WorldState(_) => preserve_reference_context_item,
+        // Child threads inherit model context, not the parent's cumulative usage state.
+        RolloutItem::TokenUsageRecord(_) => false,
         RolloutItem::Compacted(_) | RolloutItem::EventMsg(_) | RolloutItem::SessionMeta(_) => true,
     }
 }
@@ -992,6 +994,8 @@ impl AgentControl {
                     retain_forked_item(response_item, &mut replaced_parent_developer_instructions)
                 }
                 RolloutItem::Compacted(compacted) => {
+                    // This checkpoint belongs to the inherited parent prefix.
+                    compacted.latest_token_usage_record = None;
                     if let Some(replacement_history) = compacted.replacement_history.as_mut() {
                         // Matches before this checkpoint cannot survive its replacement history.
                         replaced_parent_developer_instructions = false;
@@ -1016,7 +1020,7 @@ impl AgentControl {
                 | RolloutItem::TurnContext(_)
                 | RolloutItem::InterAgentCommunication(_)
                 | RolloutItem::InterAgentCommunicationMetadata { .. } => true,
-                RolloutItem::SecurityRiskScore(_) => false,
+                RolloutItem::TokenUsageRecord(_) | RolloutItem::SecurityRiskScore(_) => false,
             }
         });
         // Full forks reuse the parent's reference context instead of rebuilding it. If that
diff --git a/codex-rs/core/src/agent/control_tests.rs b/codex-rs/core/src/agent/control_tests.rs
index 99200ac47a..2b2d81eda5 100644
--- a/codex-rs/core/src/agent/control_tests.rs
+++ b/codex-rs/core/src/agent/control_tests.rs
@@ -56,6 +56,8 @@ use codex_protocol::protocol::SubAgentSource;
 use codex_protocol::protocol::ThreadHistoryMode;
 use codex_protocol::protocol::ThreadSettingsAppliedEvent;
 use codex_protocol::protocol::ThreadSettingsSnapshot;
+use codex_protocol::protocol::TokenUsage;
+use codex_protocol::protocol::TokenUsageRecord;
 use codex_protocol::protocol::TurnAbortReason;
 use codex_protocol::protocol::TurnAbortedEvent;
 use codex_protocol::protocol::TurnCompleteEvent;
@@ -276,6 +278,7 @@ async fn persisted_originator(thread: &CodexThread) -> String {
             | RolloutItem::WorldState(_)
             | RolloutItem::RealtimeItem(_)
             | RolloutItem::SecurityRiskScore(_)
+            | RolloutItem::TokenUsageRecord(_)
             | RolloutItem::TurnContext(_) => None,
         })
         .expect("session metadata should be persisted")
@@ -1382,6 +1385,124 @@ async fn spawn_agent_without_fork_from_paginated_parent_stays_fresh_and_paginate
         .expect("parent shutdown should submit");
 }
 
+#[tokio::test]
+async fn spawn_agent_fork_drops_inherited_token_usage_state() {
+    let harness = AgentControlHarness::new().await;
+    let (parent_thread_id, parent_thread) = harness.start_paginated_thread().await;
+    let parent_usage = TokenUsage {
+        total_tokens: 120,
+        ..TokenUsage::default()
+    };
+    let parent_record = TokenUsageRecord {
+        thread_id: parent_thread_id,
+        turn_id: "parent-turn".to_string(),
+        session_id: parent_thread.session.session_id(),
+        root_turn_id: "parent-turn".to_string(),
+        response_id: "parent-response".to_string(),
+        usage: parent_usage.clone(),
+        turn_token_usage: parent_usage.clone(),
+        thread_token_usage: parent_usage,
+    };
+    let parent_spawn_call_id = "spawn-call-token-usage".to_string();
+    parent_thread
+        .session
+        .persist_rollout_items(&[
+            RolloutItem::Compacted(CompactedItem {
+                message: String::new(),
+                replacement_history: Some(vec![user_message("compacted parent context").into()]),
+                mcp_resource_origins: None,
+                window_number: None,
+                first_window_id: None,
+                previous_window_id: None,
+                window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: Some(parent_record.clone()),
+            }),
+            RolloutItem::TokenUsageRecord(parent_record),
+            rollout_response_item(spawn_agent_call(&parent_spawn_call_id)),
+        ])
+        .await;
+
+    let child_thread_id = harness
+        .spawn_anonymous_child(
+            parent_thread_id,
+            SpawnAgentOptions {
+                fork_parent_spawn_call_id: Some(parent_spawn_call_id),
+                fork_mode: Some(SpawnAgentForkMode::FullHistory),
+                ..Default::default()
+            },
+        )
+        .await;
+    let child_thread = harness
+        .manager
+        .get_thread(child_thread_id)
+        .await
+        .expect("child thread should be registered");
+
+    let child_usage = TokenUsage {
+        total_tokens: 80,
+        ..TokenUsage::default()
+    };
+    let turn_context = child_thread.session.new_default_turn().await;
+    child_thread
+        .session
+        .record_observed_response_completed(
+            turn_context.as_ref(),
+            "child-response",
+            Some(&child_usage),
+            /*usage_metadata*/ None,
+        )
+        .await;
+    child_thread
+        .flush_rollout()
+        .await
+        .expect("child rollout should flush");
+    let rollout_path = child_thread
+        .rollout_path()
+        .expect("child rollout should exist");
+    let lines = std::fs::read_to_string(&rollout_path)
+        .expect("read child rollout")
+        .lines()
+        .map(|line| serde_json::from_str::<RolloutLine>(line).expect("parse rollout line"))
+        .collect::<Vec<_>>();
+    assert!(
+        !lines.iter().any(|line| {
+            matches!(
+                &line.item,
+                RolloutItem::TokenUsageRecord(record) if record.thread_id == parent_thread_id
+            )
+        }),
+        "child rollout should not inherit parent token usage records"
+    );
+    assert!(
+        lines.iter().all(|line| {
+            !matches!(
+                &line.item,
+                RolloutItem::Compacted(compacted)
+                    if compacted.latest_token_usage_record.is_some()
+            )
+        }),
+        "child rollout should not inherit parent token usage checkpoints"
+    );
+    let child_record = lines.iter().rev().find_map(|line| match &line.item {
+        RolloutItem::TokenUsageRecord(record) => Some(record),
+        _ => None,
+    });
+    assert_eq!(
+        child_record,
+        Some(&TokenUsageRecord {
+            thread_id: child_thread_id,
+            turn_id: turn_context.sub_id.clone(),
+            session_id: child_thread.session.session_id(),
+            root_turn_id: turn_context.sub_id.clone(),
+            response_id: "child-response".to_string(),
+            usage: child_usage.clone(),
+            turn_token_usage: child_usage.clone(),
+            thread_token_usage: child_usage,
+        })
+    );
+}
+
 #[tokio::test]
 async fn spawn_agent_numeric_fork_from_compacted_paginated_parent_clamps_to_provable_turns() {
     let harness = AgentControlHarness::new().await;
@@ -1409,6 +1530,8 @@ async fn spawn_agent_numeric_fork_from_compacted_paginated_parent_clamps_to_prov
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
             rollout_response_item(ResponseItem::Message {
                 id: None,
@@ -1905,6 +2028,8 @@ async fn spawn_agent_fork_strips_parent_usage_hints_from_compacted_history() {
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
             RolloutItem::TurnContext(turn_context.to_turn_context_item()),
             rollout_response_item(spawn_agent_call(&parent_spawn_call_id)),
@@ -2087,6 +2212,8 @@ async fn spawn_agent_full_fork_restores_instructions_after_compaction_discards_p
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
             RolloutItem::TurnContext(turn_context.to_turn_context_item()),
             rollout_response_item(spawn_agent_call(&parent_spawn_call_id)),
@@ -2240,6 +2367,8 @@ async fn spawn_agent_full_fork_legacy_compaction_rebuilds_child_instructions_onc
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
         ];
         if let Some(instructions) = parent_developer_instructions {
diff --git a/codex-rs/core/src/codex_thread.rs b/codex-rs/core/src/codex_thread.rs
index 563d73c7ec..3ef4c219f9 100644
--- a/codex-rs/core/src/codex_thread.rs
+++ b/codex-rs/core/src/codex_thread.rs
@@ -390,8 +390,15 @@ impl CodexThread {
             trace,
             cyber_access_program,
         } = request;
+        let root_turn_id = self
+            .session
+            .reference_context_item()
+            .await
+            .filter(|context| context.turn_id.as_deref() == Some(turn_id.as_str()))
+            .and_then(|context| context.root_turn_id);
         let start_options = TurnStartOptions {
             cyber_access_program,
+            root_turn_id,
             ..Default::default()
         };
         match self
@@ -514,18 +521,6 @@ impl CodexThread {
         task.turn_context.turn_metadata_state.root_turn_id()
     }
 
-    /// Invalidates the trusted root when the expected turn is currently active.
-    pub async fn invalidate_turn_lineage(&self, expected_turn_id: &str) {
-        let active = self.session.active_turn.lock().await;
-        if let Some(task) = active.as_ref().and_then(|turn| turn.task.as_ref())
-            && task.turn_context.sub_id == expected_turn_id
-        {
-            task.turn_context
-                .turn_metadata_state
-                .mark_root_turn_ambiguous();
-        }
-    }
-
     pub async fn set_app_server_client_info(
         &self,
         app_server_client_name: Option<String>,
diff --git a/codex-rs/core/src/compact.rs b/codex-rs/core/src/compact.rs
index 1651ab1b9e..49306c357c 100644
--- a/codex-rs/core/src/compact.rs
+++ b/codex-rs/core/src/compact.rs
@@ -46,7 +46,6 @@ use codex_protocol::models::InternalChatMessageMetadataPassthrough;
 use codex_protocol::models::ResponseInputItem;
 use codex_protocol::models::ResponseItem;
 use codex_protocol::protocol::EventMsg;
-use codex_protocol::protocol::RawResponseCompletedEvent;
 use codex_protocol::protocol::TurnStartedEvent;
 use codex_protocol::protocol::WarningEvent;
 use codex_protocol::user_input::UserInput;
@@ -86,6 +85,7 @@ pub(crate) struct CompactedHistoryMetadata {
     pub(crate) message: String,
     pub(crate) window_number: u64,
     pub(crate) window_ids: AutoCompactWindowIds,
+    pub(crate) compaction_response_id: Option<String>,
 }
 
 pub(crate) async fn build_compaction_initial_context(
@@ -273,7 +273,7 @@ async fn run_compact_task_inner_impl(
         )
         .await;
 
-    loop {
+    let compaction_response_id = loop {
         // Clone is required because of the loop
         let turn_input = history
             .clone()
@@ -294,8 +294,8 @@ async fn run_compact_task_inner_impl(
         .await;
 
         match attempt_result {
-            Ok(()) => {
-                break;
+            Ok(response_id) => {
+                break response_id;
             }
             Err(err)
                 if matches!(
@@ -347,7 +347,7 @@ async fn run_compact_task_inner_impl(
                 }
             }
         }
-    }
+    };
 
     let history_snapshot = sess.clone_history().await;
     let history_items = history_snapshot.annotated_items();
@@ -384,6 +384,7 @@ async fn run_compact_task_inner_impl(
             message: summary_text,
             window_number,
             window_ids,
+            compaction_response_id: Some(compaction_response_id),
         },
     )
     .await;
@@ -738,7 +739,7 @@ async fn drain_to_completed(
     client_session: &mut ModelClientSession,
     responses_metadata: &CodexResponsesMetadata,
     prompt: &Prompt,
-) -> CodexResult<()> {
+) -> CodexResult<String> {
     let mut stream = client_session
         .stream(
             prompt,
@@ -777,18 +778,16 @@ async fn drain_to_completed(
                 usage_metadata,
                 ..
             }) => {
-                sess.send_event(
+                sess.record_observed_response_completed(
                     turn_context,
-                    EventMsg::RawResponseCompleted(RawResponseCompletedEvent {
-                        response_id,
-                        token_usage: token_usage.clone(),
-                        usage_metadata,
-                    }),
+                    &response_id,
+                    token_usage.as_ref(),
+                    usage_metadata.as_ref(),
                 )
                 .await;
                 sess.update_token_usage_info(turn_context, token_usage.as_ref())
                     .await?;
-                return Ok(());
+                return Ok(response_id);
             }
             Ok(_) => continue,
             Err(e) => return Err(e),
diff --git a/codex-rs/core/src/compact_remote.rs b/codex-rs/core/src/compact_remote.rs
index ea1d5a372d..3d16dafd92 100644
--- a/codex-rs/core/src/compact_remote.rs
+++ b/codex-rs/core/src/compact_remote.rs
@@ -300,6 +300,7 @@ async fn run_remote_compact_task_inner_impl(
             message: String::new(),
             window_number: new_window_number,
             window_ids: new_window_ids,
+            compaction_response_id: None,
         },
     )
     .await;
diff --git a/codex-rs/core/src/compact_remote_v2.rs b/codex-rs/core/src/compact_remote_v2.rs
index e36d11387f..def91ff2f4 100644
--- a/codex-rs/core/src/compact_remote_v2.rs
+++ b/codex-rs/core/src/compact_remote_v2.rs
@@ -38,7 +38,6 @@ use codex_context_fragments::to_annotated_content;
 use codex_features::Feature;
 use codex_history::CodexHarnessMetadata;
 use codex_history::ResponseItemEnvelope;
-use codex_protocol::ResponseUsageMetadata;
 use codex_protocol::error::CodexErr;
 use codex_protocol::error::CodexErrorDetails;
 use codex_protocol::error::Result as CodexResult;
@@ -298,6 +297,7 @@ async fn run_remote_compact_task_inner_impl(
         prompt_input,
         prompt_input_metadata,
         compaction_output,
+        compaction_response_id,
         token_usage,
         owned_client_session: _owned_client_session,
     } = attempt;
@@ -350,6 +350,7 @@ async fn run_remote_compact_task_inner_impl(
             message: String::new(),
             window_number: new_window_number,
             window_ids: new_window_ids,
+            compaction_response_id: Some(compaction_response_id),
         },
     )
     .await;
@@ -364,7 +365,6 @@ struct RemoteCompactionV2Output {
     compaction_output: ResponseItem,
     response_id: String,
     token_usage: Option<TokenUsage>,
-    usage_metadata: Option<ResponseUsageMetadata>,
 }
 
 async fn run_remote_compaction_request_v2(
@@ -395,7 +395,7 @@ async fn run_remote_compaction_request_v2(
             )
             .await
         {
-            Ok(stream) => collect_compaction_output(stream).await,
+            Ok(stream) => collect_compaction_output(sess, turn_context, stream).await,
             Err(err) => Err(err),
         };
 
@@ -419,15 +419,15 @@ async fn run_remote_compaction_request_v2(
 }
 
 async fn collect_compaction_output(
+    sess: &Session,
+    turn_context: &TurnContext,
     mut stream: ResponseStream,
 ) -> CodexResult<RemoteCompactionV2Output> {
     let mut output_item_count = 0usize;
     let mut compaction_count = 0usize;
     let mut compaction_output = None;
-    let mut saw_completed = false;
     let mut completed_response_id = None;
     let mut completed_token_usage = None;
-    let mut completed_usage_metadata = None;
     while let Some(event) = stream.next().await {
         match event? {
             ResponseEvent::OutputItemDone(item) => {
@@ -445,21 +445,26 @@ async fn collect_compaction_output(
                 usage_metadata,
                 ..
             } => {
-                saw_completed = true;
+                sess.record_observed_response_completed(
+                    turn_context,
+                    &response_id,
+                    token_usage.as_ref(),
+                    usage_metadata.as_ref(),
+                )
+                .await;
                 completed_response_id = Some(response_id);
                 completed_token_usage = token_usage;
-                completed_usage_metadata = usage_metadata;
                 break;
             }
             _ => {}
         }
     }
 
-    if !saw_completed {
+    let Some(response_id) = completed_response_id else {
         return Err(CodexErr::Stream(
             "remote compaction v2 stream closed before response.completed".to_string(),
         ));
-    }
+    };
 
     if compaction_count != 1 {
         return Err(CodexErr::Fatal(format!(
@@ -470,14 +475,10 @@ async fn collect_compaction_output(
     let Some(compaction_output) = compaction_output else {
         unreachable!("compaction output must exist when count is exactly one");
     };
-    let Some(response_id) = completed_response_id else {
-        unreachable!("response id must exist after response.completed");
-    };
     Ok(RemoteCompactionV2Output {
         compaction_output,
         response_id,
         token_usage: completed_token_usage,
-        usage_metadata: completed_usage_metadata,
     })
 }
 
@@ -1179,16 +1180,11 @@ mod tests {
             }),
         ]);
 
-        let output = collect_compaction_output(stream)
+        let (sess, turn_context) = crate::session::tests::make_session_and_context().await;
+        let output = collect_compaction_output(&sess, &turn_context, stream)
             .await
             .expect("compaction should be collected");
 
-        assert_eq!(
-            output.usage_metadata,
-            Some(codex_protocol::ResponseUsageMetadata {
-                amount: Some("0.125".to_string()),
-            }),
-        );
         assert_eq!(output.compaction_output, compaction);
         assert_eq!(output.response_id, "resp-compact");
         assert_eq!(
diff --git a/codex-rs/core/src/compact_remote_v2_attempt.rs b/codex-rs/core/src/compact_remote_v2_attempt.rs
index 1c58c7e4c4..8827ba1d21 100644
--- a/codex-rs/core/src/compact_remote_v2_attempt.rs
+++ b/codex-rs/core/src/compact_remote_v2_attempt.rs
@@ -13,8 +13,6 @@ use crate::session::step_context::StepContext;
 use codex_history::CodexHarnessMetadata;
 use codex_protocol::error::Result as CodexResult;
 use codex_protocol::models::ResponseItem;
-use codex_protocol::protocol::EventMsg;
-use codex_protocol::protocol::RawResponseCompletedEvent;
 use codex_protocol::protocol::TokenUsage;
 use codex_rollout_trace::CompactionTraceContext;
 use tracing::info;
@@ -24,6 +22,7 @@ pub(super) struct RemoteCompactV2Attempt {
     pub(super) prompt_input: Vec<ResponseItem>,
     pub(super) prompt_input_metadata: Vec<Option<CodexHarnessMetadata>>,
     pub(super) compaction_output: ResponseItem,
+    pub(super) compaction_response_id: String,
     pub(super) token_usage: Option<TokenUsage>,
     /// Keeps a session created for standalone compaction alive through lifecycle completion.
     pub(super) owned_client_session: Option<ModelClientSession>,
@@ -119,19 +118,7 @@ pub(super) async fn run_remote_compact_v2_attempt(
         compaction_output,
         response_id,
         token_usage,
-        usage_metadata,
     } = compaction_output_result?;
-    // TODO: Emit this before compaction output validation so malformed completed
-    // responses still surface their raw upstream usage.
-    sess.send_event(
-        turn_context,
-        EventMsg::RawResponseCompleted(RawResponseCompletedEvent {
-            response_id,
-            token_usage: token_usage.clone(),
-            usage_metadata,
-        }),
-    )
-    .await;
     let mut prompt_input = prompt.input;
     prompt_input.pop();
     Ok(RemoteCompactV2Attempt {
@@ -139,6 +126,7 @@ pub(super) async fn run_remote_compact_v2_attempt(
         prompt_input,
         prompt_input_metadata,
         compaction_output,
+        compaction_response_id: response_id,
         token_usage,
         owned_client_session,
     })
diff --git a/codex-rs/core/src/context_manager/history_tests.rs b/codex-rs/core/src/context_manager/history_tests.rs
index 2c661588f6..e7c6491db5 100644
--- a/codex-rs/core/src/context_manager/history_tests.rs
+++ b/codex-rs/core/src/context_manager/history_tests.rs
@@ -314,6 +314,7 @@ fn developer_msg_with_fragments(texts: &[&str]) -> ResponseItem {
 fn reference_context_item() -> TurnContextItem {
     TurnContextItem {
         turn_id: Some("reference-turn".to_string()),
+        root_turn_id: None,
         cwd: AbsolutePathBuf::try_from(
             std::env::current_dir()
                 .expect("current directory")
diff --git a/codex-rs/core/src/guardian/tests.rs b/codex-rs/core/src/guardian/tests.rs
index 6ee7fd4bad..fe043d3bab 100644
--- a/codex-rs/core/src/guardian/tests.rs
+++ b/codex-rs/core/src/guardian/tests.rs
@@ -3544,8 +3544,6 @@ async fn guardian_ephemeral_retry_preserves_parallel_trunk_and_fork_history() ->
             )
             .await;
 
-        // A conflicting input removes the known root while the trunk review is in flight.
-        turn.turn_metadata_state.mark_root_turn_ambiguous();
         let third_decision = review_approval_request(
             &session,
             &turn,
@@ -3570,8 +3568,8 @@ async fn guardian_ephemeral_retry_preserves_parallel_trunk_and_fork_history() ->
         for (body, expected_root) in [
             (&first_request_body, Some("causal-root-turn")),
             (&second_request_body, Some("causal-root-turn")),
-            (&failed_ephemeral_request_body, None),
-            (&retried_ephemeral_request_body, None),
+            (&failed_ephemeral_request_body, Some("causal-root-turn")),
+            (&retried_ephemeral_request_body, Some("causal-root-turn")),
         ] {
             assert_parent_turn(body, Some(turn.sub_id.as_str()))?;
             assert_root_turn(body, expected_root)?;
diff --git a/codex-rs/core/src/hook_runtime.rs b/codex-rs/core/src/hook_runtime.rs
index f3a0ec11c9..83711b97f3 100644
--- a/codex-rs/core/src/hook_runtime.rs
+++ b/codex-rs/core/src/hook_runtime.rs
@@ -769,21 +769,10 @@ pub(crate) async fn drain_async_hook_results(
             .collect::<Vec<_>>();
 
         if before_user_prompt {
-            // A fresh user turn owns its root; automatic turns only inherit one.
-            let current_turn_id = Some(turn_context.sub_id.as_str());
-            if !additional_contexts.is_empty()
-                && result.turn_id.as_deref() != current_turn_id
-                && turn_context.turn_metadata_state.root_turn_id().as_deref() != current_turn_id
-            {
-                turn_context.turn_metadata_state.mark_root_turn_ambiguous();
-            }
             record_additional_contexts(sess, turn_context, additional_contexts).await;
         } else if !additional_contexts.is_empty() {
             let _ = sess
-                .inject_hook_context_if_running(
-                    additional_context_messages(additional_contexts),
-                    result.turn_id.as_deref(),
-                )
+                .inject_hook_context_if_running(additional_context_messages(additional_contexts))
                 .await;
         }
 
diff --git a/codex-rs/core/src/session/inject.rs b/codex-rs/core/src/session/inject.rs
index 3c57e7033f..6c103f266c 100644
--- a/codex-rs/core/src/session/inject.rs
+++ b/codex-rs/core/src/session/inject.rs
@@ -35,7 +35,7 @@ impl Session {
         }
     }
 
-    /// Injects hook context while classifying its actual receiving turn atomically.
+    /// Injects hook context into the running turn atomically.
     #[expect(
         clippy::await_holding_invalid_type,
         reason = "active turn provenance and turn state updates must remain atomic"
@@ -43,19 +43,13 @@ impl Session {
     pub(crate) async fn inject_hook_context_if_running(
         &self,
         input: Vec<ResponseItem>,
-        source_turn_id: Option<&str>,
     ) -> Result<(), Vec<ResponseItem>> {
         let mut active = self.active_turn.lock().await;
         let Some(active_turn) = active.as_mut() else {
             return Err(input);
         };
-        let Some(task) = active_turn.task.as_ref() else {
+        if active_turn.task.is_none() {
             return Err(input);
-        };
-        if source_turn_id != Some(task.turn_context.sub_id.as_str()) {
-            task.turn_context
-                .turn_metadata_state
-                .mark_root_turn_ambiguous();
         }
         self.input_queue
             .extend_pending_input_and_accept_mailbox_delivery_for_turn_state(
@@ -86,11 +80,6 @@ impl Session {
             .collect::<Vec<_>>();
         let mut active = self.active_turn.lock().await;
         if let Some(active_turn) = active.as_mut() {
-            if let Some(task) = active_turn.task.as_ref() {
-                task.turn_context
-                    .turn_metadata_state
-                    .mark_root_turn_ambiguous();
-            }
             self.input_queue
                 .extend_pending_input_and_accept_mailbox_delivery_for_turn_state(
                     active_turn.turn_state.as_ref(),
diff --git a/codex-rs/core/src/session/input_queue.rs b/codex-rs/core/src/session/input_queue.rs
index 6e71857aa3..e6bd3ba388 100644
--- a/codex-rs/core/src/session/input_queue.rs
+++ b/codex-rs/core/src/session/input_queue.rs
@@ -169,16 +169,16 @@ impl InputQueue {
             .and_then(|id| id.filter(|id| !id.trim().is_empty()).map(str::to_string));
         start_options.root_turn_id = pending_mails
             .iter()
-            .filter(|mail| mail.communication.trigger_turn)
-            .map(|mail| {
+            .find(|mail| mail.communication.trigger_turn)
+            .and_then(|mail| {
                 mail.start_options
                     .parent_turn_id
                     .as_deref()
                     .filter(|id| !id.trim().is_empty())
                     .and(mail.start_options.root_turn_id.as_deref())
+                    .filter(|id| !id.trim().is_empty())
             })
-            .reduce(|expected, candidate| expected.filter(|id| candidate == Some(*id)))
-            .and_then(|id| id.filter(|id| !id.trim().is_empty()).map(str::to_string));
+            .map(str::to_string);
         let items = pending_mails
             .into_iter()
             .map(|mail| TurnInput::InterAgentCommunication(mail.communication))
@@ -320,17 +320,10 @@ impl InputQueue {
         }
         let (mailbox_items, start_options) = self.drain_mailbox_input_items().await;
         if let Some(active_turn_metadata) = active_turn_metadata
-            && mailbox_items.iter().any(|item| {
-                matches!(
-                    item,
-                    TurnInput::InterAgentCommunication(communication)
-                        if communication.trigger_turn
-                )
-            })
-            && (start_options.root_turn_id.is_none()
-                || active_turn_metadata.root_turn_id() != start_options.root_turn_id)
+            && active_turn_metadata.root_turn_id().is_none()
+            && let Some(root_turn_id) = start_options.root_turn_id.as_ref()
         {
-            active_turn_metadata.mark_root_turn_ambiguous();
+            active_turn_metadata.set_root_turn_id(root_turn_id.clone());
         }
         if pending_input.is_empty() {
             (mailbox_items, start_options)
@@ -561,7 +554,7 @@ mod tests {
     }
 
     #[tokio::test]
-    async fn input_queue_requires_one_unambiguous_trigger_parent() {
+    async fn input_queue_uses_unambiguous_trigger_parent_and_first_root() {
         let (parent, peer, root, root2) = (Some("a"), Some("b"), Some("r"), Some("s"));
         for (pending_mails, expected_parent_turn_id, expected_root_turn_id) in [
             (Vec::new(), None, None),
@@ -572,8 +565,8 @@ mod tests {
             (vec![(true, parent, None)], parent, None),
             (vec![(true, parent, Some(""))], parent, None),
             (vec![(true, parent, root), (true, peer, root)], None, root),
-            (vec![(true, parent, root), (true, peer, root2)], None, None),
-            (vec![(true, parent, root), (true, None, root)], None, None),
+            (vec![(true, parent, root), (true, peer, root2)], None, root),
+            (vec![(true, parent, root), (true, None, root)], None, root),
             (
                 vec![(true, parent, root), (true, parent, root)],
                 parent,
diff --git a/codex-rs/core/src/session/mod.rs b/codex-rs/core/src/session/mod.rs
index c99599b7d6..f7ab1271a0 100644
--- a/codex-rs/core/src/session/mod.rs
+++ b/codex-rs/core/src/session/mod.rs
@@ -90,6 +90,7 @@ use codex_network_proxy::normalize_host;
 use codex_otel::current_span_trace_id;
 use codex_otel::current_span_w3c_trace_context;
 use codex_otel::set_parent_from_w3c_trace_context;
+use codex_protocol::ResponseUsageMetadata;
 use codex_protocol::SessionId;
 use codex_protocol::ThreadId;
 use codex_protocol::approvals::ElicitationRequest;
@@ -349,6 +350,7 @@ use codex_protocol::protocol::ModelVerificationEvent;
 use codex_protocol::protocol::NetworkApprovalContext;
 use codex_protocol::protocol::Op;
 use codex_protocol::protocol::RateLimitSnapshot;
+use codex_protocol::protocol::RawResponseCompletedEvent;
 use codex_protocol::protocol::RequestUserInputEvent;
 use codex_protocol::protocol::ReviewDecision;
 use codex_protocol::protocol::SandboxPolicy;
@@ -360,6 +362,7 @@ use codex_protocol::protocol::ThreadMemoryMode;
 use codex_protocol::protocol::TokenCountEvent;
 use codex_protocol::protocol::TokenUsage;
 use codex_protocol::protocol::TokenUsageInfo;
+use codex_protocol::protocol::TokenUsageRecord;
 use codex_protocol::protocol::TurnModerationMetadataEvent;
 use codex_protocol::protocol::WarningEvent;
 use codex_protocol::turn_input::TurnInputMode;
@@ -1440,6 +1443,8 @@ impl Session {
                     let mut state = self.state.lock().await;
                     state.set_token_info(Some(info));
                 }
+                self.state.lock().await.latest_token_usage_record =
+                    Self::last_token_usage_record_from_rollout(&rollout_items);
 
                 // Defer seeding the session's initial context until the first turn starts so
                 // turn/start overrides can be merged before we write to the rollout.
@@ -1460,6 +1465,8 @@ impl Session {
                     let mut state = self.state.lock().await;
                     state.set_token_info(Some(info));
                 }
+                self.state.lock().await.latest_token_usage_record =
+                    Self::last_token_usage_record_from_rollout(&rollout_items);
 
                 let thread_settings_applied =
                     RolloutItem::EventMsg(thread_settings::applied_event(self).await);
@@ -1624,6 +1631,21 @@ impl Session {
         })
     }
 
+    fn last_token_usage_record_from_rollout(
+        rollout_items: &[RolloutItem],
+    ) -> Option<TokenUsageRecord> {
+        for item in rollout_items.iter().rev() {
+            match item {
+                RolloutItem::TokenUsageRecord(record) => return Some(record.clone()),
+                RolloutItem::Compacted(compacted) => {
+                    return compacted.latest_token_usage_record.clone();
+                }
+                _ => {}
+            }
+        }
+        None
+    }
+
     async fn previous_turn_settings(&self) -> Option<PreviousTurnSettings> {
         let state = self.state.lock().await;
         state.previous_turn_settings()
@@ -3668,6 +3690,8 @@ impl Session {
                 .previous_window_id
                 .map(|id| id.to_string()),
             window_id: Some(metadata.window_ids.window_id.to_string()),
+            compaction_response_id: metadata.compaction_response_id,
+            latest_token_usage_record: self.state.lock().await.latest_token_usage_record.clone(),
         };
         // Wait for accepted updates to finish persisting, then keep later updates from
         // overtaking the current settings snapshot while its checkpoint is written.
@@ -4118,6 +4142,7 @@ impl Session {
                 message: String::new(),
                 window_number,
                 window_ids,
+                compaction_response_id: None,
             },
         )
         .await;
@@ -4232,6 +4257,40 @@ impl Session {
         result
     }
 
+    pub(crate) async fn record_observed_response_completed(
+        &self,
+        turn_context: &TurnContext,
+        response_id: &str,
+        usage: Option<&TokenUsage>,
+        usage_metadata: Option<&ResponseUsageMetadata>,
+    ) {
+        self.send_event(
+            turn_context,
+            EventMsg::RawResponseCompleted(RawResponseCompletedEvent {
+                response_id: response_id.to_string(),
+                token_usage: usage.cloned(),
+                usage_metadata: usage_metadata.cloned(),
+            }),
+        )
+        .await;
+        let Some(usage) = usage else {
+            return;
+        };
+        let record = self.state.lock().await.record_token_usage(
+            self.thread_id,
+            &turn_context.sub_id,
+            self.session_id(),
+            turn_context
+                .turn_metadata_state
+                .root_turn_id()
+                .unwrap_or_else(|| turn_context.sub_id.clone()),
+            response_id.to_string(),
+            usage,
+        );
+        self.persist_rollout_items(&[RolloutItem::TokenUsageRecord(record)])
+            .await;
+    }
+
     pub(crate) async fn record_token_usage_info(
         &self,
         turn_context: &TurnContext,
diff --git a/codex-rs/core/src/session/rollout_reconstruction.rs b/codex-rs/core/src/session/rollout_reconstruction.rs
index e087240ccd..46e94eb6e4 100644
--- a/codex-rs/core/src/session/rollout_reconstruction.rs
+++ b/codex-rs/core/src/session/rollout_reconstruction.rs
@@ -294,6 +294,7 @@ impl Session {
                 | RolloutItem::SessionMeta(_)
                 | RolloutItem::RealtimeItem(_)
                 | RolloutItem::SecurityRiskScore(_)
+                | RolloutItem::TokenUsageRecord(_)
                 | RolloutItem::InterAgentCommunicationMetadata { .. } => {}
             }
 
@@ -385,6 +386,7 @@ impl Session {
                 | RolloutItem::RealtimeItem(_)
                 | RolloutItem::WorldState(_)
                 | RolloutItem::SecurityRiskScore(_)
+                | RolloutItem::TokenUsageRecord(_)
                 | RolloutItem::SessionMeta(_) => {}
             }
         }
@@ -424,6 +426,7 @@ impl Session {
                 | RolloutItem::InterAgentCommunicationMetadata { .. }
                 | RolloutItem::TurnContext(_)
                 | RolloutItem::RealtimeItem(_)
+                | RolloutItem::TokenUsageRecord(_)
                 | RolloutItem::SecurityRiskScore(_)
                 | RolloutItem::EventMsg(_) => {
                     unreachable!("only world-state replay items are collected")
diff --git a/codex-rs/core/src/session/rollout_reconstruction_tests.rs b/codex-rs/core/src/session/rollout_reconstruction_tests.rs
index 3f0b410b9e..6d7f2863e3 100644
--- a/codex-rs/core/src/session/rollout_reconstruction_tests.rs
+++ b/codex-rs/core/src/session/rollout_reconstruction_tests.rs
@@ -265,6 +265,7 @@ async fn record_initial_history_resumed_bare_turn_context_does_not_hydrate_previ
     let previous_model = "previous-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
+        root_turn_id: None,
         #[allow(deprecated)]
         cwd: turn_context.cwd.clone(),
         workspace_roots: None,
@@ -314,6 +315,7 @@ async fn record_initial_history_resumed_hydrates_previous_turn_settings_from_lif
     let previous_model = "previous-rollout-model";
     let mut previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
+        root_turn_id: None,
         #[allow(deprecated)]
         cwd: turn_context.cwd.clone(),
         workspace_roots: None,
@@ -1064,6 +1066,8 @@ async fn record_initial_history_resumed_rollback_drops_incomplete_user_turn_comp
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
         RolloutItem::EventMsg(EventMsg::ThreadRolledBack(
             codex_protocol::protocol::ThreadRolledBackEvent { num_turns: 1 },
@@ -1124,6 +1128,8 @@ async fn record_initial_history_requires_surviving_full_snapshot_without_user_tu
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
         ],
     };
@@ -1156,6 +1162,8 @@ async fn record_initial_history_resumed_does_not_seed_reference_context_item_aft
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
     ];
 
@@ -1226,6 +1234,8 @@ async fn reconstruct_history_prefers_compacted_window_over_session_meta() {
             first_window_id: Some(compacted_first_window_id.to_string()),
             previous_window_id: Some(compacted_previous_window_id.to_string()),
             window_id: Some(compacted_window_id.to_string()),
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
     ];
 
@@ -1262,6 +1272,8 @@ async fn reconstruct_history_replays_world_state_from_latest_compaction_window()
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
             RolloutItem::WorldState(WorldStateItem::full(object!({
                 "environment": {"status": "starting", "cwd": "/workspace"}
@@ -1324,6 +1336,8 @@ async fn bounded_replay_matches_full_replay_after_empty_turn_compactions() {
                     first_window_id: Some(window_ids[0].to_string()),
                     previous_window_id: Some(window_ids[window_number - 1].to_string()),
                     window_id: Some(window_ids[window_number].to_string()),
+                    compaction_response_id: None,
+                    latest_token_usage_record: None,
                 }),
                 RolloutItem::WorldState(WorldStateItem::full(object!({
                     "environment": {"window": window_number, "status": "starting"}
@@ -1420,6 +1434,8 @@ async fn reconstruct_history_preserves_legacy_compaction_count_with_session_meta
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
     ];
 
@@ -1448,6 +1464,8 @@ async fn reconstruct_history_legacy_compaction_without_replacement_history_does_
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
     ];
 
@@ -1484,6 +1502,8 @@ async fn reconstruct_history_legacy_compaction_without_replacement_history_clear
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
         RolloutItem::EventMsg(EventMsg::TurnStarted(
             codex_protocol::protocol::TurnStartedEvent {
@@ -1532,6 +1552,7 @@ async fn record_initial_history_resumed_turn_context_after_compaction_reestablis
     let previous_model = "previous-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
+        root_turn_id: Some("root-turn".to_string()),
         #[allow(deprecated)]
         cwd: turn_context.cwd.clone(),
         workspace_roots: None,
@@ -1588,6 +1609,8 @@ async fn record_initial_history_resumed_turn_context_after_compaction_reestablis
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
         RolloutItem::TurnContext(previous_context_item),
         RolloutItem::EventMsg(EventMsg::TurnComplete(
@@ -1624,6 +1647,7 @@ async fn record_initial_history_resumed_turn_context_after_compaction_reestablis
             .expect("serialize seeded reference context item"),
         serde_json::to_value(Some(TurnContextItem {
             turn_id: Some(turn_context.sub_id.clone()),
+            root_turn_id: Some("root-turn".to_string()),
             #[allow(deprecated)]
             cwd: turn_context.cwd.clone(),
             workspace_roots: None,
@@ -1658,6 +1682,7 @@ async fn record_initial_history_resumed_aborted_turn_without_id_clears_active_tu
     let previous_model = "previous-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
+        root_turn_id: None,
         #[allow(deprecated)]
         cwd: turn_context.cwd.clone(),
         workspace_roots: None,
@@ -1755,6 +1780,8 @@ async fn record_initial_history_resumed_aborted_turn_without_id_clears_active_tu
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
     ];
 
@@ -1791,6 +1818,7 @@ async fn record_initial_history_resumed_unmatched_abort_preserves_active_turn_fo
     let unmatched_abort_turn_id = "other-turn".to_string();
     let current_context_item = TurnContextItem {
         turn_id: Some(current_turn_id.clone()),
+        root_turn_id: None,
         #[allow(deprecated)]
         cwd: turn_context.cwd.clone(),
         workspace_roots: None,
@@ -1920,6 +1948,7 @@ async fn record_initial_history_resumed_trailing_incomplete_turn_compaction_clea
     let previous_model = "previous-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
+        root_turn_id: None,
         #[allow(deprecated)]
         cwd: turn_context.cwd.clone(),
         workspace_roots: None,
@@ -2008,6 +2037,8 @@ async fn record_initial_history_resumed_trailing_incomplete_turn_compaction_clea
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
     ];
 
@@ -2093,6 +2124,7 @@ async fn record_initial_history_resumed_replaced_incomplete_compacted_turn_clear
     let previous_model = "previous-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
+        root_turn_id: None,
         #[allow(deprecated)]
         cwd: turn_context.cwd.clone(),
         workspace_roots: None,
@@ -2182,6 +2214,8 @@ async fn record_initial_history_resumed_replaced_incomplete_compacted_turn_clear
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
         // A newer TurnStarted replaces the incomplete compacted turn without a matching
         // completion/abort for the old one.
diff --git a/codex-rs/core/src/session/session.rs b/codex-rs/core/src/session/session.rs
index 8dbfad88d3..3b3da7440b 100644
--- a/codex-rs/core/src/session/session.rs
+++ b/codex-rs/core/src/session/session.rs
@@ -770,11 +770,12 @@ impl Session {
             }
             InitialHistory::New | InitialHistory::Cleared | InitialHistory::Forked(_) => None,
         };
-        // Legacy subagent rollouts synthesize session_id from their own thread id.
+        // Legacy subagent rollouts synthesized session_id from their own thread ID.
         let resumed_session_id = resumed_session_id.filter(|session_id| {
             !session_configuration.session_source.is_non_root_agent()
                 || *session_id != SessionId::from(thread_id)
         });
+        // session_id is equal to the root thread's ID.
         let session_id = resumed_session_id.unwrap_or_else(|| {
             if session_configuration.session_source.is_non_root_agent() {
                 agent_control.session_id()
@@ -1357,6 +1358,7 @@ impl Session {
                     | RolloutItem::TurnContext(_)
                     | RolloutItem::WorldState(_)
                     | RolloutItem::RealtimeItem(_)
+                    | RolloutItem::TokenUsageRecord(_)
                     | RolloutItem::SecurityRiskScore(_) => {}
                 }
             }
diff --git a/codex-rs/core/src/session/tests.rs b/codex-rs/core/src/session/tests.rs
index e962382eb7..b8d97c87e5 100644
--- a/codex-rs/core/src/session/tests.rs
+++ b/codex-rs/core/src/session/tests.rs
@@ -164,6 +164,7 @@ use codex_protocol::protocol::ThreadSettingsOverrides;
 use codex_protocol::protocol::TokenCountEvent;
 use codex_protocol::protocol::TokenUsage;
 use codex_protocol::protocol::TokenUsageInfo;
+use codex_protocol::protocol::TokenUsageRecord;
 use codex_protocol::protocol::TurnAbortedEvent;
 use codex_protocol::protocol::TurnCompleteEvent;
 use codex_protocol::protocol::TurnStartedEvent;
@@ -2227,6 +2228,8 @@ async fn reconstruct_history_uses_replacement_history_verbatim() {
         first_window_id: Some(first_window_id.to_string()),
         previous_window_id: Some(previous_window_id.to_string()),
         window_id: Some(window_id.to_string()),
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     })];
 
     let reconstructed = session
@@ -2883,6 +2886,49 @@ async fn record_initial_history_seeds_token_info_from_rollout() {
     assert_eq!(actual, Some(info2));
 }
 
+#[test]
+fn latest_token_usage_record_stops_at_compaction_checkpoint() {
+    let thread_id = ThreadId::new();
+    let checkpoint_record = TokenUsageRecord {
+        thread_id,
+        turn_id: "turn-1".to_string(),
+        session_id: SessionId::from(thread_id),
+        root_turn_id: "turn-1".to_string(),
+        response_id: "response-1".to_string(),
+        usage: TokenUsage::default(),
+        turn_token_usage: TokenUsage::default(),
+        thread_token_usage: TokenUsage::default(),
+    };
+    let checkpoint = |latest_token_usage_record| {
+        RolloutItem::Compacted(CompactedItem {
+            message: String::new(),
+            replacement_history: None,
+            mcp_resource_origins: None,
+            window_number: None,
+            first_window_id: None,
+            previous_window_id: None,
+            window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record,
+        })
+    };
+
+    assert_eq!(
+        Session::last_token_usage_record_from_rollout(&[
+            RolloutItem::TokenUsageRecord(checkpoint_record.clone()),
+            checkpoint(Some(checkpoint_record.clone())),
+        ]),
+        Some(checkpoint_record.clone())
+    );
+    assert_eq!(
+        Session::last_token_usage_record_from_rollout(&[
+            RolloutItem::TokenUsageRecord(checkpoint_record),
+            checkpoint(None),
+        ]),
+        None
+    );
+}
+
 #[tokio::test]
 async fn recompute_token_usage_uses_session_base_instructions() {
     let (session, turn_context) = make_session_and_context().await;
@@ -3412,7 +3458,7 @@ async fn record_initial_history_reconstructs_forked_transcript() {
 }
 
 #[tokio::test]
-async fn start_new_context_window_assigns_and_persists_item_ids() {
+async fn start_new_context_window_persists_checkpoint_state() {
     let (mut session, turn_context, _rx) = make_session_and_context_with_auth_and_config_and_rx(
         CodexAuth::from_api_key("Test API Key"),
         Vec::new(),
@@ -3421,6 +3467,18 @@ async fn start_new_context_window_assigns_and_persists_item_ids() {
     .await;
     let rollout_path =
         attach_thread_persistence(Arc::get_mut(&mut session).expect("unique session")).await;
+    let thread_id = ThreadId::new();
+    let token_usage_record = TokenUsageRecord {
+        thread_id,
+        turn_id: "turn-1".to_string(),
+        session_id: SessionId::from(thread_id),
+        root_turn_id: "turn-1".to_string(),
+        response_id: "response-1".to_string(),
+        usage: TokenUsage::default(),
+        turn_token_usage: TokenUsage::default(),
+        thread_token_usage: TokenUsage::default(),
+    };
+    session.state.lock().await.latest_token_usage_record = Some(token_usage_record.clone());
     let step_context = session
         .capture_step_context(Arc::clone(&turn_context), &CancellationToken::new())
         .await
@@ -3447,8 +3505,8 @@ async fn start_new_context_window_assigns_and_persists_item_ids() {
     else {
         panic!("expected resumed rollout history");
     };
-    let persisted_replacement_history = resumed.history.iter().rev().find_map(|item| match item {
-        RolloutItem::Compacted(compacted) => compacted.replacement_history.as_ref(),
+    let persisted_compacted = resumed.history.iter().rev().find_map(|item| match item {
+        RolloutItem::Compacted(compacted) => Some(compacted),
         RolloutItem::SessionMeta(_)
         | RolloutItem::ResponseItem(_)
         | RolloutItem::InterAgentCommunication(_)
@@ -3456,13 +3514,23 @@ async fn start_new_context_window_assigns_and_persists_item_ids() {
         | RolloutItem::TurnContext(_)
         | RolloutItem::WorldState(_)
         | RolloutItem::SecurityRiskScore(_)
+        | RolloutItem::TokenUsageRecord(_)
         | RolloutItem::RealtimeItem(_)
         | RolloutItem::EventMsg(_) => None,
     });
     assert_eq!(
-        persisted_replacement_history.cloned(),
+        persisted_compacted.and_then(|compacted| compacted.replacement_history.clone()),
         Some(live_history.annotated_items().to_vec())
     );
+    assert_eq!(
+        persisted_compacted.map(|compacted| {
+            (
+                compacted.compaction_response_id.as_deref(),
+                compacted.latest_token_usage_record.as_ref(),
+            )
+        }),
+        Some((None, Some(&token_usage_record)))
+    );
 }
 
 #[tokio::test]
@@ -3535,6 +3603,7 @@ async fn record_initial_history_assigns_and_persists_id_for_forked_response_item
         | RolloutItem::TurnContext(_)
         | RolloutItem::WorldState(_)
         | RolloutItem::SecurityRiskScore(_)
+        | RolloutItem::TokenUsageRecord(_)
         | RolloutItem::RealtimeItem(_)
         | RolloutItem::EventMsg(_) => None,
     });
@@ -3691,6 +3760,7 @@ async fn record_initial_history_forked_hydrates_previous_turn_settings() {
     let previous_model = "forked-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
+        root_turn_id: None,
         #[allow(deprecated)]
         cwd: turn_context.cwd.clone(),
         workspace_roots: None,
@@ -4102,6 +4172,8 @@ async fn thread_rollback_restores_cleared_reference_context_item_after_compactio
             first_window_id: Some(first_window_id.to_string()),
             previous_window_id: Some(previous_window_id.to_string()),
             window_id: Some(compacted_window_id.to_string()),
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }),
         RolloutItem::EventMsg(EventMsg::TurnComplete(TurnCompleteEvent {
             turn_id: compact_turn_id,
@@ -5864,6 +5936,7 @@ async fn compaction_checkpoint_waits_for_accepted_settings_persistence() {
                 message: "summary".to_string(),
                 window_number,
                 window_ids,
+                compaction_response_id: None,
             },
         ),
     ));
@@ -11907,6 +11980,66 @@ async fn trigger_turn_mailbox_mail_waits_for_next_turn_after_answer_boundary() {
     assert!(sess.input_queue.has_trigger_turn_mailbox_items().await);
 }
 
+#[tokio::test]
+async fn active_turn_keeps_first_root_when_mail_coalesces() {
+    let (sess, tc, _rx) = make_session_and_context_with_rx().await;
+    tc.turn_metadata_state
+        .set_root_turn_id("root-a".to_string());
+    sess.spawn_task(
+        Arc::clone(&tc),
+        Vec::new(),
+        NeverEndingTask {
+            kind: TaskKind::Regular,
+            listen_to_cancellation_token: true,
+        },
+    )
+    .await;
+    let first = InterAgentCommunication::new(
+        AgentPath::try_from("/root/worker_a").expect("worker path should parse"),
+        AgentPath::root(),
+        Vec::new(),
+        "first".to_string(),
+        /*trigger_turn*/ true,
+    );
+    let second = InterAgentCommunication::new(
+        AgentPath::try_from("/root/worker_b").expect("worker path should parse"),
+        AgentPath::root(),
+        Vec::new(),
+        "second".to_string(),
+        /*trigger_turn*/ true,
+    );
+    for (communication, parent_turn_id, root_turn_id) in [
+        (first.clone(), "parent-a", "root-a"),
+        (second.clone(), "parent-b", "root-b"),
+    ] {
+        sess.input_queue
+            .enqueue_mailbox_communication(
+                communication,
+                codex_protocol::turn_input::TurnStartOptions {
+                    parent_turn_id: Some(parent_turn_id.to_string()),
+                    root_turn_id: Some(root_turn_id.to_string()),
+                    ..Default::default()
+                },
+            )
+            .await;
+    }
+
+    assert_eq!(
+        (sess.input_queue.get_pending_input(&sess.active_turn).await).0,
+        vec![
+            TurnInput::InterAgentCommunication(first),
+            TurnInput::InterAgentCommunication(second),
+        ]
+    );
+    assert_eq!(
+        tc.turn_metadata_state.root_turn_id().as_deref(),
+        Some("root-a")
+    );
+    assert!(!sess.input_queue.has_pending_mailbox_items().await);
+
+    sess.abort_all_tasks(TurnAbortReason::Replaced).await;
+}
+
 #[tokio::test]
 async fn steered_input_reopens_mailbox_delivery_for_current_turn() {
     let (sess, tc, _rx) = make_session_and_context_with_rx().await;
@@ -12271,6 +12404,8 @@ async fn sample_rollout(
         first_window_id: Some(window_ids.first_window_id.to_string()),
         previous_window_id: window_ids.previous_window_id.map(|id| id.to_string()),
         window_id: Some(window_ids.window_id.to_string()),
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     }));
 
     let user2 = user_message("second user");
@@ -12301,6 +12436,8 @@ async fn sample_rollout(
         first_window_id: Some(window_ids.first_window_id.to_string()),
         previous_window_id: window_ids.previous_window_id.map(|id| id.to_string()),
         window_id: Some(window_ids.window_id.to_string()),
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     }));
 
     let user3 = user_message("third user");
diff --git a/codex-rs/core/src/session/turn.rs b/codex-rs/core/src/session/turn.rs
index 9ab25ca151..f43ad3cc35 100644
--- a/codex-rs/core/src/session/turn.rs
+++ b/codex-rs/core/src/session/turn.rs
@@ -100,7 +100,6 @@ use codex_protocol::protocol::ErrorEvent;
 use codex_protocol::protocol::EventMsg;
 use codex_protocol::protocol::InternalSessionSource;
 use codex_protocol::protocol::PlanDeltaEvent;
-use codex_protocol::protocol::RawResponseCompletedEvent;
 use codex_protocol::protocol::ReasoningContentDeltaEvent;
 use codex_protocol::protocol::ReasoningRawContentDeltaEvent;
 use codex_protocol::protocol::SafetyBufferingEvent;
@@ -2590,13 +2589,11 @@ async fn try_run_sampling_request(
                     &mut assistant_message_stream_parsers,
                 )
                 .await;
-                sess.send_event(
+                sess.record_observed_response_completed(
                     &turn_context,
-                    EventMsg::RawResponseCompleted(RawResponseCompletedEvent {
-                        response_id,
-                        token_usage: token_usage.clone(),
-                        usage_metadata,
-                    }),
+                    &response_id,
+                    token_usage.as_ref(),
+                    usage_metadata.as_ref(),
                 )
                 .await;
                 let budget_result = sess
diff --git a/codex-rs/core/src/session/turn_context.rs b/codex-rs/core/src/session/turn_context.rs
index cc3681d420..44c62cac67 100644
--- a/codex-rs/core/src/session/turn_context.rs
+++ b/codex-rs/core/src/session/turn_context.rs
@@ -578,6 +578,7 @@ impl TurnContext {
         let cwd = self.cwd.clone();
         TurnContextItem {
             turn_id: Some(self.sub_id.clone()),
+            root_turn_id: self.turn_metadata_state.root_turn_id(),
             cwd,
             workspace_roots: (!workspace_roots.is_empty()).then_some(workspace_roots),
             current_date: self.current_date.clone(),
diff --git a/codex-rs/core/src/session/turn_input.rs b/codex-rs/core/src/session/turn_input.rs
index b83b175953..2882931bca 100644
--- a/codex-rs/core/src/session/turn_input.rs
+++ b/codex-rs/core/src/session/turn_input.rs
@@ -624,13 +624,17 @@ impl Session {
             input => pending_turn_input(input.clone()),
         };
         pending_input.push(input);
-        if let Some(incoming_root_turn_id) = incoming_root_turn_id
-            && active_task.turn_context.turn_metadata_state.root_turn_id() != incoming_root_turn_id
+        if active_task
+            .turn_context
+            .turn_metadata_state
+            .root_turn_id()
+            .is_none()
+            && let Some(Some(incoming_root_turn_id)) = incoming_root_turn_id
         {
             active_task
                 .turn_context
                 .turn_metadata_state
-                .mark_root_turn_ambiguous();
+                .set_root_turn_id(incoming_root_turn_id);
         }
         self.input_queue
             .extend_pending_input_and_accept_mailbox_delivery_for_turn_state(
diff --git a/codex-rs/core/src/state/session.rs b/codex-rs/core/src/state/session.rs
index c65eafadbd..768e8d9fe3 100644
--- a/codex-rs/core/src/state/session.rs
+++ b/codex-rs/core/src/state/session.rs
@@ -19,9 +19,12 @@ use crate::session::session::SessionConfiguration;
 use crate::session::time_reminder::CurrentTimeReminderState;
 use crate::session_startup_prewarm::SessionStartupPrewarmHandle;
 use codex_history::ResponseItemEnvelope;
+use codex_protocol::SessionId;
+use codex_protocol::ThreadId;
 use codex_protocol::protocol::RateLimitSnapshot;
 use codex_protocol::protocol::TokenUsage;
 use codex_protocol::protocol::TokenUsageInfo;
+use codex_protocol::protocol::TokenUsageRecord;
 use codex_protocol::protocol::TurnContextItem;
 use codex_utils_output_truncation::TruncationPolicy;
 
@@ -32,6 +35,7 @@ pub(crate) struct SessionState {
     pub(crate) base_instructions_provenance: Option<BaseInstructionsProvenance>,
     pub(crate) history: ContextManager,
     pub(crate) latest_rate_limits: Option<RateLimitSnapshot>,
+    pub(crate) latest_token_usage_record: Option<TokenUsageRecord>,
     pub(crate) server_reasoning_included: bool,
     pub(crate) mcp_dependency_prompted: HashSet<String>,
     pub(crate) additional_context: AdditionalContextStore,
@@ -70,6 +74,7 @@ impl SessionState {
             base_instructions_provenance: None,
             history,
             latest_rate_limits: None,
+            latest_token_usage_record: None,
             server_reasoning_included: false,
             mcp_dependency_prompted: HashSet::new(),
             additional_context: AdditionalContextStore::default(),
@@ -148,6 +153,44 @@ impl SessionState {
         self.history.set_token_info(info);
     }
 
+    pub(crate) fn record_token_usage(
+        &mut self,
+        thread_id: ThreadId,
+        turn_id: &str,
+        session_id: SessionId,
+        root_turn_id: String,
+        response_id: String,
+        usage: &TokenUsage,
+    ) -> TokenUsageRecord {
+        let mut turn_token_usage = self
+            .latest_token_usage_record
+            .as_ref()
+            .filter(|record| record.turn_id == turn_id)
+            .map_or_else(TokenUsage::default, |record| {
+                record.turn_token_usage.clone()
+            });
+        turn_token_usage.add_assign(usage);
+        let mut thread_token_usage = self
+            .latest_token_usage_record
+            .as_ref()
+            .map_or_else(TokenUsage::default, |record| {
+                record.thread_token_usage.clone()
+            });
+        thread_token_usage.add_assign(usage);
+        let record = TokenUsageRecord {
+            thread_id,
+            turn_id: turn_id.to_string(),
+            session_id,
+            root_turn_id,
+            response_id,
+            usage: usage.clone(),
+            turn_token_usage,
+            thread_token_usage,
+        };
+        self.latest_token_usage_record = Some(record.clone());
+        record
+    }
+
     pub(crate) fn set_reference_context_item(&mut self, item: Option<TurnContextItem>) {
         self.history.set_reference_context_item(item);
     }
diff --git a/codex-rs/core/src/state/session_tests.rs b/codex-rs/core/src/state/session_tests.rs
index 44011b7d82..533bd2df26 100644
--- a/codex-rs/core/src/state/session_tests.rs
+++ b/codex-rs/core/src/state/session_tests.rs
@@ -1,11 +1,57 @@
 use super::*;
 use crate::session::tests::make_session_configuration_for_tests;
 use crate::state::AutoCompactWindowSnapshot;
+use codex_protocol::SessionId;
+use codex_protocol::ThreadId;
 use codex_protocol::protocol::CreditsSnapshot;
 use codex_protocol::protocol::RateLimitWindow;
 use codex_protocol::protocol::SpendControlLimitSnapshot;
+use codex_protocol::protocol::TokenUsage;
+use codex_protocol::protocol::TokenUsageRecord;
 use pretty_assertions::assert_eq;
 
+#[tokio::test]
+async fn record_token_usage_continues_restored_totals() {
+    let thread_id = ThreadId::new();
+    let session_id = SessionId::from(ThreadId::new());
+    let usage = |total_tokens| TokenUsage {
+        total_tokens,
+        ..TokenUsage::default()
+    };
+    let mut restored = SessionState::new(make_session_configuration_for_tests().await);
+    restored.latest_token_usage_record = Some(TokenUsageRecord {
+        thread_id,
+        turn_id: "turn-b".to_string(),
+        session_id,
+        root_turn_id: "root-turn".to_string(),
+        response_id: "response-c".to_string(),
+        usage: usage(30),
+        turn_token_usage: usage(30),
+        thread_token_usage: usage(230),
+    });
+    let after_resume = restored.record_token_usage(
+        thread_id,
+        "turn-b",
+        session_id,
+        "root-turn".to_string(),
+        "response-d".to_string(),
+        &usage(20),
+    );
+    assert_eq!(
+        after_resume,
+        TokenUsageRecord {
+            thread_id,
+            turn_id: "turn-b".to_string(),
+            session_id,
+            root_turn_id: "root-turn".to_string(),
+            response_id: "response-d".to_string(),
+            usage: usage(20),
+            turn_token_usage: usage(50),
+            thread_token_usage: usage(250),
+        }
+    );
+}
+
 #[tokio::test]
 // Verifies connector merging deduplicates repeated IDs.
 async fn merge_connector_selection_deduplicates_entries() {
diff --git a/codex-rs/core/src/tasks/mod.rs b/codex-rs/core/src/tasks/mod.rs
index c51db874ee..5bf41019d5 100644
--- a/codex-rs/core/src/tasks/mod.rs
+++ b/codex-rs/core/src/tasks/mod.rs
@@ -307,16 +307,13 @@ impl Session {
             .await
             .clear_turn(&turn_context.sub_id);
 
-        // Reserved turn input already has its context; only newly arriving mail can change lineage.
         let (pending_items, start_options) = self.input_queue.drain_mailbox_input_items().await;
-        if pending_items.iter().any(|item| {
-            matches!(
-                item,
-                TurnInput::InterAgentCommunication(communication) if communication.trigger_turn
-            )
-        }) && turn_context.turn_metadata_state.root_turn_id() != start_options.root_turn_id
+        if turn_context.turn_metadata_state.root_turn_id().is_none()
+            && let Some(root_turn_id) = start_options.root_turn_id
         {
-            turn_context.turn_metadata_state.mark_root_turn_ambiguous();
+            turn_context
+                .turn_metadata_state
+                .set_root_turn_id(root_turn_id);
         }
         let turn_state = {
             let mut active = self.active_turn.lock().await;
diff --git a/codex-rs/core/src/tools/registry_tests.rs b/codex-rs/core/src/tools/registry_tests.rs
index 65c19f6ae3..9808432f86 100644
--- a/codex-rs/core/src/tools/registry_tests.rs
+++ b/codex-rs/core/src/tools/registry_tests.rs
@@ -728,7 +728,6 @@ async fn dispatch_uses_canonical_tool_names_for_lifecycle_contributors() -> anyh
             /*terminal_outcome_reached*/ None,
         )
         .await?;
-    turn.turn_metadata_state.mark_root_turn_ambiguous();
     let err = match registry
         .dispatch_any_with_terminal_outcome(
             test_invocation(
@@ -760,7 +759,7 @@ async fn dispatch_uses_canonical_tool_names_for_lifecycle_contributors() -> anyh
         RecordedToolLifecycle::Start {
             call_id: "failing-call".to_string(),
             tool_name: failing_tool.clone(),
-            root_turn_id: None,
+            root_turn_id: Some("root-turn".to_string()),
         },
         RecordedToolLifecycle::Finish {
             call_id: "failing-call".to_string(),
diff --git a/codex-rs/core/src/turn_metadata.rs b/codex-rs/core/src/turn_metadata.rs
index afae92f22f..2f7b540d06 100644
--- a/codex-rs/core/src/turn_metadata.rs
+++ b/codex-rs/core/src/turn_metadata.rs
@@ -129,7 +129,6 @@ pub(crate) struct TurnMetadataState {
     turn_started_at_unix_ms: RwLock<Option<i64>>,
     responses_api_metadata: RwLock<BTreeMap<String, String>>,
     responsesapi_client_metadata: RwLock<BTreeMap<String, String>>,
-    root_turn_ambiguous: AtomicBool,
     user_input_requested_during_turn: AtomicBool,
     enrichment_task: Mutex<Option<JoinHandle<()>>>,
     git_enrichment_complete: watch::Sender<bool>,
@@ -199,7 +198,6 @@ impl TurnMetadataState {
             turn_started_at_unix_ms: RwLock::new(None),
             responses_api_metadata: RwLock::new(BTreeMap::new()),
             responsesapi_client_metadata: RwLock::new(BTreeMap::new()),
-            root_turn_ambiguous: AtomicBool::new(false),
             user_input_requested_during_turn: AtomicBool::new(false),
             enrichment_task: Mutex::new(None),
             git_enrichment_complete: watch::channel(/*init*/ true).0,
@@ -311,14 +309,7 @@ impl TurnMetadataState {
     }
 
     pub(crate) fn root_turn_id(&self) -> Option<String> {
-        self.root_turn_id
-            .get()
-            .filter(|_| !self.root_turn_ambiguous.load(Ordering::Relaxed))
-            .cloned()
-    }
-
-    pub(crate) fn mark_root_turn_ambiguous(&self) {
-        self.root_turn_ambiguous.store(true, Ordering::Relaxed);
+        self.root_turn_id.get().cloned()
     }
 
     pub(crate) fn can_start_root_turn(&self, session_source: &SessionSource) -> bool {
diff --git a/codex-rs/core/tests/suite/compact.rs b/codex-rs/core/tests/suite/compact.rs
index 0a2c462d51..3473e39628 100644
--- a/codex-rs/core/tests/suite/compact.rs
+++ b/codex-rs/core/tests/suite/compact.rs
@@ -989,7 +989,7 @@ async fn manual_compact_uses_custom_prompt() {
 }
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
-async fn manual_compact_emits_api_and_local_token_usage_events() {
+async fn manual_compact_records_durable_and_local_token_usage() {
     skip_if_no_network!();
 
     let server = start_mock_server().await;
@@ -1008,7 +1008,9 @@ async fn manual_compact_emits_api_and_local_token_usage_events() {
         config.model_provider = model_provider;
         set_test_compact_prompt(config);
     });
-    let codex = builder.build(&server).await.unwrap().codex;
+    let test = builder.build(&server).await.unwrap();
+    let rollout_path = test.codex.rollout_path().expect("rollout path");
+    let codex = test.codex;
 
     // Trigger manual compact and collect TokenCount events for the compact turn.
     codex.submit(Op::Compact).await.unwrap();
@@ -1044,6 +1046,36 @@ async fn manual_compact_emits_api_and_local_token_usage_events() {
         last > 0,
         "second TokenCount should reflect a non-zero estimated context size after compaction"
     );
+    let rollout_items = fs::read_to_string(rollout_path)
+        .expect("read rollout")
+        .lines()
+        .filter_map(|line| serde_json::from_str::<RolloutLine>(line).ok())
+        .map(|line| line.item)
+        .collect::<Vec<_>>();
+    let records = rollout_items
+        .iter()
+        .filter_map(|item| match item {
+            RolloutItem::TokenUsageRecord(record) => Some(record),
+            _ => None,
+        })
+        .collect::<Vec<_>>();
+    assert_eq!(records.len(), 1);
+    assert_eq!(records[0].response_id, "r1");
+    assert_eq!(records[0].usage.total_tokens, 0);
+    let compacted = rollout_items
+        .iter()
+        .find_map(|item| match item {
+            RolloutItem::Compacted(compacted) => Some(compacted),
+            _ => None,
+        })
+        .expect("compaction checkpoint");
+    assert_eq!(
+        (
+            compacted.compaction_response_id.as_deref(),
+            compacted.latest_token_usage_record.as_ref(),
+        ),
+        (Some("r1"), records.first().copied())
+    );
 }
 
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
diff --git a/codex-rs/core/tests/suite/compact_remote.rs b/codex-rs/core/tests/suite/compact_remote.rs
index 053ccecb59..dd905d4f67 100644
--- a/codex-rs/core/tests/suite/compact_remote.rs
+++ b/codex-rs/core/tests/suite/compact_remote.rs
@@ -685,6 +685,67 @@ async fn remote_compact_v2_retains_only_client_developer_messages_when_enabled(
         })
         .count();
     assert_eq!(retained_client_developers, usize::from(enabled));
+    Ok(())
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn remote_compact_v2_records_usage_before_output_validation() -> Result<()> {
+    skip_if_no_network!(Ok(()));
+
+    let harness = TestCodexHarness::with_auto_env_builder(
+        test_codex()
+            .with_auth(CodexAuth::create_dummy_chatgpt_auth_for_testing())
+            .with_config(|config| {
+                config
+                    .features
+                    .enable(Feature::RemoteCompactionV2)
+                    .expect("remote compaction v2 should be configurable");
+            }),
+    )
+    .await?;
+    let codex = &harness.test().codex;
+    let rollout_path = codex.rollout_path().context("rollout path")?;
+    responses::mount_sse_sequence(
+        harness.server(),
+        vec![
+            sse(vec![responses::ev_completed("before-compact")]),
+            sse(vec![
+                json!({
+                    "type": "response.output_item.done",
+                    "item": {
+                        "type": "compaction",
+                        "encrypted_content": "FIRST_SUMMARY",
+                    },
+                }),
+                json!({
+                    "type": "response.output_item.done",
+                    "item": {
+                        "type": "compaction",
+                        "encrypted_content": "SECOND_SUMMARY",
+                    },
+                }),
+                responses::ev_completed_with_tokens("invalid-compact", /*total_tokens*/ 8_200),
+            ]),
+        ],
+    )
+    .await;
+
+    harness.test().submit_turn("before compact").await?;
+    codex.submit(Op::Compact).await?;
+    wait_for_event(codex, |event| matches!(event, EventMsg::Error(_))).await;
+    wait_for_event(codex, |event| matches!(event, EventMsg::TurnComplete(_))).await;
+    codex.shutdown_and_wait().await?;
+
+    let record = fs::read_to_string(&rollout_path)?
+        .lines()
+        .filter_map(|line| serde_json::from_str::<RolloutLine>(line).ok())
+        .filter_map(|line| match line.item {
+            RolloutItem::TokenUsageRecord(record) => Some(record),
+            _ => None,
+        })
+        .find(|record| record.response_id == "invalid-compact")
+        .context("remote compaction usage record")?;
+    assert_eq!(record.usage.total_tokens, 8_200);
 
     Ok(())
 }
diff --git a/codex-rs/core/tests/suite/hooks.rs b/codex-rs/core/tests/suite/hooks.rs
index e4874b489c..90f6832481 100644
--- a/codex-rs/core/tests/suite/hooks.rs
+++ b/codex-rs/core/tests/suite/hooks.rs
@@ -1843,7 +1843,11 @@ async fn async_hook_finishing_while_idle_waits_for_the_next_turn(
     assert_ne!(first_turn_id, second_turn_id);
     responses::assert_root_turn(
         &requests[1].body_json(),
-        (!automatic_continuation).then_some(second_turn_id.as_str()),
+        Some(if automatic_continuation {
+            first_turn_id.as_str()
+        } else {
+            second_turn_id.as_str()
+        }),
     )?;
     assert_eq!(
         warning_event
diff --git a/codex-rs/core/tests/suite/mod.rs b/codex-rs/core/tests/suite/mod.rs
index 5fc867a5cb..4d434aed55 100644
--- a/codex-rs/core/tests/suite/mod.rs
+++ b/codex-rs/core/tests/suite/mod.rs
@@ -166,6 +166,7 @@ mod stream_no_completed;
 mod subagent_notifications;
 mod subagent_service_tier;
 mod token_budget;
+mod token_usage_rollout;
 mod tool_harness;
 mod tool_lifecycle;
 mod tool_parallelism;
diff --git a/codex-rs/core/tests/suite/pending_input.rs b/codex-rs/core/tests/suite/pending_input.rs
index 372fab5ce2..a636b2c248 100644
--- a/codex-rs/core/tests/suite/pending_input.rs
+++ b/codex-rs/core/tests/suite/pending_input.rs
@@ -1102,8 +1102,8 @@ async fn injected_response_item_reopens_turn_after_final_answer() {
     responses::assert_root_turn(&first, Some(first_turn_id))
         .expect("initial root should be trusted");
     let second: Value = from_slice(&requests[1]).expect("parse second request");
-    responses::assert_root_turn(&second, /*expected*/ None)
-        .expect("external injection should invalidate the active turn root");
+    responses::assert_root_turn(&second, Some(first_turn_id))
+        .expect("external injection should preserve the active turn root");
     let relevant_user_input = message_input_texts(&second, "user")
         .into_iter()
         .filter(|text| {
diff --git a/codex-rs/core/tests/suite/resume_warning.rs b/codex-rs/core/tests/suite/resume_warning.rs
index 1be835b6fe..e5dd6f61bc 100644
--- a/codex-rs/core/tests/suite/resume_warning.rs
+++ b/codex-rs/core/tests/suite/resume_warning.rs
@@ -30,6 +30,7 @@ fn resume_history(
     let turn_id = "resume-warning-seed-turn".to_string();
     let turn_ctx = TurnContextItem {
         turn_id: Some(turn_id.clone()),
+        root_turn_id: None,
         cwd: config.cwd.clone(),
         workspace_roots: None,
         current_date: None,
diff --git a/codex-rs/core/tests/suite/token_usage_rollout.rs b/codex-rs/core/tests/suite/token_usage_rollout.rs
new file mode 100644
index 0000000000..db9e6c50e1
--- /dev/null
+++ b/codex-rs/core/tests/suite/token_usage_rollout.rs
@@ -0,0 +1,117 @@
+//! Verifies observed Responses API usage is durably recorded in rollout history.
+
+use anyhow::Result;
+use codex_history::RolloutItem;
+use codex_history::RolloutLine;
+use codex_protocol::SessionId;
+use codex_protocol::protocol::TokenUsageRecord;
+use core_test_support::responses::ev_assistant_message;
+use core_test_support::responses::ev_completed_with_tokens;
+use core_test_support::responses::ev_function_call;
+use core_test_support::responses::ev_response_created;
+use core_test_support::responses::mount_sse_sequence;
+use core_test_support::responses::sse;
+use core_test_support::responses::start_mock_server;
+use core_test_support::skip_if_no_network;
+use core_test_support::test_codex::test_codex;
+use pretty_assertions::assert_eq;
+use serde_json::json;
+
+fn token_usage_records(path: &std::path::Path) -> Vec<TokenUsageRecord> {
+    std::fs::read_to_string(path)
+        .expect("read rollout")
+        .lines()
+        .filter_map(|line| serde_json::from_str::<RolloutLine>(line).ok())
+        .filter_map(|line| match line.item {
+            RolloutItem::TokenUsageRecord(record) => Some(record),
+            _ => None,
+        })
+        .collect()
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn observed_response_usage_accumulates_per_turn_and_thread() -> Result<()> {
+    skip_if_no_network!(Ok(()));
+
+    let server = start_mock_server().await;
+    let plan_args = json!({
+        "plan": [{
+            "step": "keep sampling",
+            "status": "in_progress"
+        }]
+    })
+    .to_string();
+    mount_sse_sequence(
+        &server,
+        vec![
+            sse(vec![
+                ev_response_created("response-a"),
+                ev_function_call("call-a", "update_plan", &plan_args),
+                ev_completed_with_tokens("response-a", /*total_tokens*/ 120),
+            ]),
+            sse(vec![
+                ev_response_created("response-b"),
+                ev_assistant_message("message-b", "done"),
+                ev_completed_with_tokens("response-b", /*total_tokens*/ 80),
+            ]),
+            sse(vec![
+                ev_response_created("response-c"),
+                ev_assistant_message("message-c", "next"),
+                ev_completed_with_tokens("response-c", /*total_tokens*/ 30),
+            ]),
+            sse(vec![
+                ev_response_created("response-without-usage"),
+                ev_assistant_message("message-d", "no usage"),
+                json!({
+                    "type": "response.completed",
+                    "response": {
+                        "id": "response-without-usage"
+                    }
+                }),
+            ]),
+        ],
+    )
+    .await;
+    let test = test_codex().build_with_auto_env(&server).await?;
+    let rollout_path = test.codex.rollout_path().expect("rollout path");
+    let home = test.home.clone();
+
+    test.submit_turn("first").await?;
+    test.codex.shutdown_and_wait().await?;
+
+    let resumed = test_codex()
+        .resume(&server, home, rollout_path.clone())
+        .await?;
+    for prompt in ["second", "third"] {
+        resumed.submit_turn(prompt).await?;
+    }
+    resumed.codex.shutdown_and_wait().await?;
+
+    let records = token_usage_records(&rollout_path);
+    assert_eq!(records.len(), 3);
+    assert_eq!(
+        records
+            .iter()
+            .map(|record| {
+                (
+                    record.response_id.as_str(),
+                    record.turn_token_usage.total_tokens,
+                    record.thread_token_usage.total_tokens,
+                )
+            })
+            .collect::<Vec<_>>(),
+        vec![
+            ("response-a", 120, 120),
+            ("response-b", 200, 200),
+            ("response-c", 30, 230),
+        ]
+    );
+    assert_eq!(records[0].turn_id, records[1].turn_id);
+    assert_ne!(records[1].turn_id, records[2].turn_id);
+    assert!(records.iter().all(|record| {
+        record.session_id == SessionId::from(record.thread_id)
+            && record.root_turn_id == record.turn_id
+    }));
+
+    Ok(())
+}
diff --git a/codex-rs/ext/goal/src/api.rs b/codex-rs/ext/goal/src/api.rs
index a643b90ff2..b414e9ccfb 100644
--- a/codex-rs/ext/goal/src/api.rs
+++ b/codex-rs/ext/goal/src/api.rs
@@ -276,7 +276,7 @@ impl GoalService {
         };
 
         if let Some(runtime) = runtime.as_ref() {
-            runtime.invalidate_turn_lineage().await;
+            runtime.clear_pending_turn_start_options().await;
         }
 
         if objective.is_some() {
@@ -321,7 +321,7 @@ impl GoalService {
             })?;
         let cleared = cleared_goal.is_some();
         if cleared && let Some(runtime) = runtime.as_ref() {
-            runtime.invalidate_turn_lineage().await;
+            runtime.clear_pending_turn_start_options().await;
         }
         drop(goal_state_permit);
         drop(runtime);
diff --git a/codex-rs/ext/goal/src/runtime.rs b/codex-rs/ext/goal/src/runtime.rs
index 9a3594b760..84fa4204ba 100644
--- a/codex-rs/ext/goal/src/runtime.rs
+++ b/codex-rs/ext/goal/src/runtime.rs
@@ -135,7 +135,7 @@ impl GoalRuntimeHandle {
         self.inner.root_accounting_state.clone()
     }
 
-    pub(crate) async fn invalidate_turn_lineage(&self) {
+    pub(crate) async fn clear_pending_turn_start_options(&self) {
         let Some(thread_manager) = self.inner.thread_manager.upgrade() else {
             return;
         };
@@ -143,9 +143,6 @@ impl GoalRuntimeHandle {
             return;
         };
         thread.thread_extension_data().remove::<TurnStartOptions>();
-        if let Some(turn_id) = self.inner.accounting_state.current_turn_id() {
-            thread.invalidate_turn_lineage(turn_id.as_str()).await;
-        }
     }
 
     pub(crate) async fn goal_state_permit(&self) -> Result<SemaphorePermit<'_>, String> {
diff --git a/codex-rs/external-agent-migration/src/sessions/append.rs b/codex-rs/external-agent-migration/src/sessions/append.rs
index d76a54b7ce..04dd151279 100644
--- a/codex-rs/external-agent-migration/src/sessions/append.rs
+++ b/codex-rs/external-agent-migration/src/sessions/append.rs
@@ -219,6 +219,7 @@ fn source_model_items(items: &[RolloutItem]) -> Option<Vec<SourceModelItem<'_>>>
         match item {
             RolloutItem::SessionMeta(_)
             | RolloutItem::InterAgentCommunicationMetadata { .. }
+            | RolloutItem::TokenUsageRecord(_)
             | RolloutItem::RealtimeItem(_) => {}
             RolloutItem::ResponseItem(response_item) => {
                 model_items.push(SourceModelItem {
@@ -257,6 +258,7 @@ fn history_model_items(items: &[RolloutItem]) -> Option<Vec<&ResponseItem>> {
         match item {
             RolloutItem::SessionMeta(_)
             | RolloutItem::InterAgentCommunicationMetadata { .. }
+            | RolloutItem::TokenUsageRecord(_)
             | RolloutItem::RealtimeItem(_)
             | RolloutItem::SecurityRiskScore(_) => {}
             RolloutItem::ResponseItem(response_item) => model_items.push(&response_item.item),
diff --git a/codex-rs/history/src/lib.rs b/codex-rs/history/src/lib.rs
index 0241394fcb..a87c83a279 100644
--- a/codex-rs/history/src/lib.rs
+++ b/codex-rs/history/src/lib.rs
@@ -21,6 +21,7 @@ use codex_protocol::protocol::SessionMetaLine;
 use codex_protocol::protocol::SessionSource;
 use codex_protocol::protocol::ThreadHistoryMode;
 use codex_protocol::protocol::ThreadSource;
+use codex_protocol::protocol::TokenUsageRecord;
 use codex_protocol::protocol::TurnContextItem;
 use codex_protocol::protocol::WorldStateItem;
 use codex_protocol::realtime::RealtimeItem;
@@ -107,6 +108,7 @@ pub enum RolloutItem {
     },
     Compacted(CompactedItem),
     TurnContext(TurnContextItem),
+    TokenUsageRecord(TokenUsageRecord),
     WorldState(WorldStateItem),
     SecurityRiskScore(SecurityRiskScore),
     EventMsg(EventMsg),
@@ -157,6 +159,13 @@ pub struct CompactedItem {
     pub first_window_id: Option<String>,
     pub previous_window_id: Option<String>,
     pub window_id: Option<String>,
+    /// Responses API ID for the model-backed compaction request, when one exists.
+    pub compaction_response_id: Option<String>,
+    /// Snapshot of the latest reachable token usage record when this compaction was written.
+    ///
+    /// `thread/resume` can restore token usage totals from this field without scanning arbitrarily
+    /// far past the compaction.
+    pub latest_token_usage_record: Option<TokenUsageRecord>,
 }
 
 impl Serialize for CompactedItem {
@@ -423,6 +432,7 @@ fn multi_agent_version_from_items(
             | RolloutItem::InterAgentCommunication(_)
             | RolloutItem::InterAgentCommunicationMetadata { .. }
             | RolloutItem::Compacted(_)
+            | RolloutItem::TokenUsageRecord(_)
             | RolloutItem::WorldState(_)
             | RolloutItem::SecurityRiskScore(_)
             | RolloutItem::RealtimeItem(_)
diff --git a/codex-rs/history/src/rollout_payload.rs b/codex-rs/history/src/rollout_payload.rs
index 8f65619363..d68f51c3e1 100644
--- a/codex-rs/history/src/rollout_payload.rs
+++ b/codex-rs/history/src/rollout_payload.rs
@@ -11,6 +11,7 @@ use super::ResponseItemEnvelope;
 use super::RolloutItem;
 use super::SecurityRiskScore;
 use super::SessionMetaLine;
+use super::TokenUsageRecord;
 use super::TurnContextItem;
 use super::WorldStateItem;
 use schemars::JsonSchema;
@@ -41,6 +42,9 @@ pub(super) enum RolloutItemWire<'a> {
     TurnContext {
         payload: Cow<'a, TurnContextItem>,
     },
+    TokenUsageRecord {
+        payload: Cow<'a, TokenUsageRecord>,
+    },
     WorldState {
         payload: Cow<'a, WorldStateItem>,
     },
@@ -81,6 +85,9 @@ impl<'a> From<&'a RolloutItem> for RolloutItemWire<'a> {
             RolloutItem::TurnContext(payload) => Self::TurnContext {
                 payload: Cow::Borrowed(payload),
             },
+            RolloutItem::TokenUsageRecord(payload) => Self::TokenUsageRecord {
+                payload: Cow::Borrowed(payload),
+            },
             RolloutItem::WorldState(payload) => Self::WorldState {
                 payload: Cow::Borrowed(payload),
             },
@@ -117,6 +124,9 @@ impl From<RolloutItemWire<'_>> for RolloutItem {
             }
             RolloutItemWire::Compacted { payload } => Self::Compacted(payload.into_owned()),
             RolloutItemWire::TurnContext { payload } => Self::TurnContext(payload.into_owned()),
+            RolloutItemWire::TokenUsageRecord { payload } => {
+                Self::TokenUsageRecord(payload.into_owned())
+            }
             RolloutItemWire::WorldState { payload } => Self::WorldState(payload.into_owned()),
             RolloutItemWire::SecurityRiskScore { payload } => {
                 Self::SecurityRiskScore(payload.into_owned())
@@ -150,6 +160,10 @@ pub(super) struct CompactedItemWire<'a> {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     #[schemars(with = "Option<String>")]
     window_id: Option<WindowIdWire<'a>>,
+    #[serde(default)]
+    compaction_response_id: Option<Cow<'a, str>>,
+    #[serde(default)]
+    latest_token_usage_record: Option<Cow<'a, TokenUsageRecord>>,
 }
 
 impl<'a> From<&'a CompactedItem> for CompactedItemWire<'a> {
@@ -185,6 +199,8 @@ impl<'a> From<&'a CompactedItem> for CompactedItemWire<'a> {
                 .window_id
                 .as_deref()
                 .map(|window_id| WindowIdWire::Id(Cow::Borrowed(window_id))),
+            compaction_response_id: item.compaction_response_id.as_deref().map(Cow::Borrowed),
+            latest_token_usage_record: item.latest_token_usage_record.as_ref().map(Cow::Borrowed),
         }
     }
 }
@@ -246,6 +262,8 @@ impl TryFrom<CompactedItemWire<'_>> for CompactedItem {
             first_window_id: item.first_window_id.map(Cow::into_owned),
             previous_window_id: item.previous_window_id.map(Cow::into_owned),
             window_id,
+            compaction_response_id: item.compaction_response_id.map(Cow::into_owned),
+            latest_token_usage_record: item.latest_token_usage_record.map(Cow::into_owned),
         })
     }
 }
diff --git a/codex-rs/history/src/tests.rs b/codex-rs/history/src/tests.rs
index cca1050cd7..de015b014a 100644
--- a/codex-rs/history/src/tests.rs
+++ b/codex-rs/history/src/tests.rs
@@ -142,8 +142,8 @@ fn response_item_envelope_ignores_unknown_harness_metadata_fields() -> Result<()
 }
 
 #[test]
-/// Keeps legacy compacted replacement histories readable and shape-compatible.
-fn response_item_replacement_history_preserves_shape() -> Result<()> {
+/// Keeps legacy compacted replacement histories readable while adding nullable checkpoints.
+fn response_item_replacement_history_accepts_legacy_shape() -> Result<()> {
     let legacy_item = json!({
         "message": "summary",
         "replacement_history": [{
@@ -166,7 +166,10 @@ fn response_item_replacement_history_preserves_shape() -> Result<()> {
         ResponseItem::Message { .. }
     ));
     assert_eq!(replacement_history[0].metadata, None);
-    assert_eq!(serde_json::to_value(item)?, legacy_item);
+    let mut expected_item = legacy_item;
+    expected_item["compaction_response_id"] = json!(null);
+    expected_item["latest_token_usage_record"] = json!(null);
+    assert_eq!(serde_json::to_value(item)?, expected_item);
     Ok(())
 }
 
@@ -196,6 +199,8 @@ fn compacted_replacement_history_stores_metadata_in_an_aligned_sidecar() -> Resu
         first_window_id: None,
         previous_window_id: None,
         window_id: None,
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     };
 
     let serialized = serde_json::to_value(item)?;
@@ -208,6 +213,8 @@ fn compacted_replacement_history_stores_metadata_in_an_aligned_sidecar() -> Resu
                 { "client_authored": true },
                 { "client_authored": false },
             ],
+            "compaction_response_id": null,
+            "latest_token_usage_record": null,
         })
     );
 
@@ -300,6 +307,8 @@ fn compacted_metadata_remains_compatible_with_legacy_response_item_readers() ->
         first_window_id: None,
         previous_window_id: None,
         window_id: None,
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     }))?;
 
     let LegacyRolloutItem::Compacted(legacy) =
@@ -343,7 +352,11 @@ fn rollout_item_variants_preserve_existing_payload_shapes() -> Result<()> {
         }),
         json!({
             "type": "compacted",
-            "payload": { "message": "summary" },
+            "payload": {
+                "message": "summary",
+                "compaction_response_id": null,
+                "latest_token_usage_record": null,
+            },
         }),
         json!({
             "type": "turn_context",
@@ -355,6 +368,40 @@ fn rollout_item_variants_preserve_existing_payload_shapes() -> Result<()> {
                 "summary": "auto",
             },
         }),
+        json!({
+            "type": "token_usage_record",
+            "payload": {
+                "thread_id": "0195cda5-433d-7f9a-9d7b-a9f15b60c2e2",
+                "turn_id": "turn-1",
+                "session_id": "0195cda5-433d-7f9a-9d7b-a9f15b60c2e2",
+                "root_turn_id": "turn-1",
+                "response_id": "response-1",
+                "usage": {
+                    "input_tokens": 10,
+                    "cached_input_tokens": 2,
+                    "cache_write_input_tokens": 0,
+                    "output_tokens": 3,
+                    "reasoning_output_tokens": 1,
+                    "total_tokens": 13,
+                },
+                "turn_token_usage": {
+                    "input_tokens": 10,
+                    "cached_input_tokens": 2,
+                    "cache_write_input_tokens": 0,
+                    "output_tokens": 3,
+                    "reasoning_output_tokens": 1,
+                    "total_tokens": 13,
+                },
+                "thread_token_usage": {
+                    "input_tokens": 10,
+                    "cached_input_tokens": 2,
+                    "cache_write_input_tokens": 0,
+                    "output_tokens": 3,
+                    "reasoning_output_tokens": 1,
+                    "total_tokens": 13,
+                },
+            },
+        }),
         json!({
             "type": "world_state",
             "payload": { "full": true, "state": { "cwd": "/tmp" } },
@@ -396,7 +443,7 @@ fn rollout_item_variants_preserve_existing_payload_shapes() -> Result<()> {
 fn rollout_item_schema_matches_tagged_payload_and_sibling_metadata() -> Result<()> {
     let schema = serde_json::to_value(schemars::schema_for!(RolloutItem))?;
     let variants = schema["oneOf"].as_array().expect("rollout variants");
-    assert_eq!(variants.len(), 10);
+    assert_eq!(variants.len(), 11);
 
     for variant in variants {
         let required = variant["required"].as_array().expect("required fields");
@@ -452,6 +499,8 @@ fn compacted_item_serializes_window_number_and_id() -> Result<()> {
         first_window_id: Some("019b3f6e-0000-7000-8000-000000000001".to_string()),
         previous_window_id: Some("019b3f6e-0000-7000-8000-000000000002".to_string()),
         window_id: Some("019b3f6e-7a10-7cc3-8b6e-1d09e2f7a001".to_string()),
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     };
 
     assert_eq!(
@@ -462,6 +511,8 @@ fn compacted_item_serializes_window_number_and_id() -> Result<()> {
             "first_window_id": "019b3f6e-0000-7000-8000-000000000001",
             "previous_window_id": "019b3f6e-0000-7000-8000-000000000002",
             "window_id": "019b3f6e-7a10-7cc3-8b6e-1d09e2f7a001",
+            "compaction_response_id": null,
+            "latest_token_usage_record": null,
         })
     );
     Ok(())
@@ -485,6 +536,8 @@ fn compacted_item_migrates_legacy_numeric_window_id() -> Result<()> {
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         }
     );
     Ok(())
diff --git a/codex-rs/memories/write/src/phase1.rs b/codex-rs/memories/write/src/phase1.rs
index 0646979939..f4724201ce 100644
--- a/codex-rs/memories/write/src/phase1.rs
+++ b/codex-rs/memories/write/src/phase1.rs
@@ -417,6 +417,7 @@ mod job {
                 | RolloutItem::InterAgentCommunicationMetadata { .. }
                 | RolloutItem::Compacted(_)
                 | RolloutItem::TurnContext(_)
+                | RolloutItem::TokenUsageRecord(_)
                 | RolloutItem::RealtimeItem(_)
                 | RolloutItem::WorldState(_)
                 | RolloutItem::SecurityRiskScore(_)
diff --git a/codex-rs/protocol/src/protocol.rs b/codex-rs/protocol/src/protocol.rs
index 3a8c087efa..db862f866a 100644
--- a/codex-rs/protocol/src/protocol.rs
+++ b/codex-rs/protocol/src/protocol.rs
@@ -2210,6 +2210,19 @@ pub struct TokenUsage {
     pub codex_rollout_budget_units: Option<serde_json::Number>,
 }
 
+/// Best-effort Responses API usage observed for one completed response.
+#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS)]
+pub struct TokenUsageRecord {
+    pub thread_id: ThreadId,
+    pub turn_id: String,
+    pub session_id: SessionId,
+    pub root_turn_id: String,
+    pub response_id: String,
+    pub usage: TokenUsage,
+    pub turn_token_usage: TokenUsage,
+    pub thread_token_usage: TokenUsage,
+}
+
 #[derive(Debug, Clone, Deserialize, Serialize, PartialEq, Eq, JsonSchema, TS)]
 pub struct TokenUsageInfo {
     pub total_token_usage: TokenUsage,
@@ -2995,6 +3008,7 @@ pub struct HistoryPosition {
 /// and should be used when there is no config override.
 #[derive(Serialize, Deserialize, Clone, Debug, JsonSchema, TS)]
 pub struct SessionMeta {
+    /// session_id is equal to the root thread's ID.
     pub session_id: SessionId,
     pub id: ThreadId,
     #[serde(skip_serializing_if = "Option::is_none")]
@@ -3158,6 +3172,10 @@ pub struct TurnContextNetworkItem {
 pub struct TurnContextItem {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub turn_id: Option<String>,
+    /// Root turn that owns this subagent turn's attribution.
+    /// Only set for subagent turns; persisted so resume keeps the scope frozen at turn start.
+    #[serde(default, skip_serializing_if = "Option::is_none")]
+    pub root_turn_id: Option<String>,
     pub cwd: AbsolutePathBuf,
     /// Effective workspace roots used to materialize symbolic
     /// `:workspace_roots` filesystem permissions in `permission_profile`.
@@ -5957,6 +5975,7 @@ mod tests {
     fn turn_context_item_serializes_network_when_present() -> Result<()> {
         let item = TurnContextItem {
             turn_id: None,
+            root_turn_id: None,
             cwd: test_path_buf("/tmp").abs(),
             workspace_roots: None,
             current_date: None,
diff --git a/codex-rs/rollout/src/list.rs b/codex-rs/rollout/src/list.rs
index 3c775e3124..f01fee8200 100644
--- a/codex-rs/rollout/src/list.rs
+++ b/codex-rs/rollout/src/list.rs
@@ -1174,6 +1174,9 @@ async fn read_head_summary(path: &Path, head_limit: usize) -> io::Result<HeadTai
             RolloutItem::TurnContext(_) => {
                 // Not included in `head`; skip.
             }
+            RolloutItem::TokenUsageRecord(_) => {
+                // Not included in `head`; skip.
+            }
             RolloutItem::WorldState(_) | RolloutItem::SecurityRiskScore(_) => {
                 // Not included in `head`; skip.
             }
@@ -1249,6 +1252,7 @@ pub async fn read_head_for_summary(path: &Path) -> io::Result<Vec<serde_json::Va
                 RolloutItem::InterAgentCommunicationMetadata { .. }
                 | RolloutItem::Compacted(_)
                 | RolloutItem::TurnContext(_)
+                | RolloutItem::TokenUsageRecord(_)
                 | RolloutItem::WorldState(_)
                 | RolloutItem::RealtimeItem(_)
                 | RolloutItem::SecurityRiskScore(_)
@@ -1303,6 +1307,7 @@ pub async fn read_session_meta_line(path: &Path) -> io::Result<SessionMetaLine>
             RolloutItem::InterAgentCommunicationMetadata { .. }
             | RolloutItem::Compacted(_)
             | RolloutItem::TurnContext(_)
+            | RolloutItem::TokenUsageRecord(_)
             | RolloutItem::WorldState(_)
             | RolloutItem::RealtimeItem(_)
             | RolloutItem::SecurityRiskScore(_)
diff --git a/codex-rs/rollout/src/metadata.rs b/codex-rs/rollout/src/metadata.rs
index 3ac5a744cb..f76652329d 100644
--- a/codex-rs/rollout/src/metadata.rs
+++ b/codex-rs/rollout/src/metadata.rs
@@ -77,6 +77,7 @@ pub fn builder_from_items(
         | RolloutItem::TurnContext(_)
         | RolloutItem::WorldState(_)
         | RolloutItem::RealtimeItem(_)
+        | RolloutItem::TokenUsageRecord(_)
         | RolloutItem::SecurityRiskScore(_)
         | RolloutItem::EventMsg(_) => None,
     }) && let Some(builder) = builder_from_session_meta(session_meta, rollout_path)
@@ -167,6 +168,7 @@ pub async fn extract_metadata_from_rollout(
             | RolloutItem::TurnContext(_)
             | RolloutItem::WorldState(_)
             | RolloutItem::RealtimeItem(_)
+            | RolloutItem::TokenUsageRecord(_)
             | RolloutItem::SecurityRiskScore(_)
             | RolloutItem::EventMsg(_) => None,
         }),
diff --git a/codex-rs/rollout/src/metadata_tests.rs b/codex-rs/rollout/src/metadata_tests.rs
index 9ab474b13a..3d493c3327 100644
--- a/codex-rs/rollout/src/metadata_tests.rs
+++ b/codex-rs/rollout/src/metadata_tests.rs
@@ -296,6 +296,8 @@ fn builder_from_items_falls_back_to_filename() {
         first_window_id: None,
         previous_window_id: None,
         window_id: None,
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     })];
 
     let builder = builder_from_items(items.as_slice(), path.as_path()).expect("builder");
diff --git a/codex-rs/rollout/src/model_context.rs b/codex-rs/rollout/src/model_context.rs
index f41021442e..f5328ca608 100644
--- a/codex-rs/rollout/src/model_context.rs
+++ b/codex-rs/rollout/src/model_context.rs
@@ -160,7 +160,8 @@ impl ModelContextScan {
             | RolloutItem::SessionMeta(_)
             | RolloutItem::InterAgentCommunicationMetadata { .. }
             | RolloutItem::RealtimeItem(_)
-            | RolloutItem::SecurityRiskScore(_) => {}
+            | RolloutItem::SecurityRiskScore(_)
+            | RolloutItem::TokenUsageRecord(_) => {}
         }
 
         if self.has_bounded_cutoff() {
diff --git a/codex-rs/rollout/src/persistence_metrics.rs b/codex-rs/rollout/src/persistence_metrics.rs
index 968578b60f..ca046e1f61 100644
--- a/codex-rs/rollout/src/persistence_metrics.rs
+++ b/codex-rs/rollout/src/persistence_metrics.rs
@@ -235,6 +235,7 @@ fn rollout_item_type(item: &RolloutItem) -> String {
         }
         RolloutItem::Compacted(_) => "compacted".to_string(),
         RolloutItem::TurnContext(_) => "turn_context".to_string(),
+        RolloutItem::TokenUsageRecord(_) => "token_usage_record".to_string(),
         RolloutItem::WorldState(_) => "world_state".to_string(),
         RolloutItem::SecurityRiskScore(_) => "security_risk_score".to_string(),
         RolloutItem::RealtimeItem(item) => match &item.content {
diff --git a/codex-rs/rollout/src/policy.rs b/codex-rs/rollout/src/policy.rs
index 56be88b738..cc54ac5554 100644
--- a/codex-rs/rollout/src/policy.rs
+++ b/codex-rs/rollout/src/policy.rs
@@ -17,6 +17,7 @@ pub fn is_persisted_rollout_item(item: &RolloutItem, history_mode: ThreadHistory
         // Persist Codex executive markers so we can analyze flows (e.g., compaction, API turns).
         RolloutItem::Compacted(_)
         | RolloutItem::TurnContext(_)
+        | RolloutItem::TokenUsageRecord(_)
         | RolloutItem::WorldState(_)
         | RolloutItem::SecurityRiskScore(_)
         | RolloutItem::SessionMeta(_) => true,
diff --git a/codex-rs/rollout/src/recorder.rs b/codex-rs/rollout/src/recorder.rs
index 1ca019356e..dff3f52d3a 100644
--- a/codex-rs/rollout/src/recorder.rs
+++ b/codex-rs/rollout/src/recorder.rs
@@ -2092,6 +2092,7 @@ async fn resume_candidate_matches_cwd(
             | RolloutItem::Compacted(_)
             | RolloutItem::WorldState(_)
             | RolloutItem::RealtimeItem(_)
+            | RolloutItem::TokenUsageRecord(_)
             | RolloutItem::SecurityRiskScore(_)
             | RolloutItem::EventMsg(_) => None,
         })
diff --git a/codex-rs/rollout/src/recorder_tests.rs b/codex-rs/rollout/src/recorder_tests.rs
index 0056d0ef77..23afea6153 100644
--- a/codex-rs/rollout/src/recorder_tests.rs
+++ b/codex-rs/rollout/src/recorder_tests.rs
@@ -1718,6 +1718,7 @@ async fn resume_candidate_matches_cwd_reads_latest_turn_context() -> std::io::Re
         ordinal: None,
         item: RolloutItem::TurnContext(TurnContextItem {
             turn_id: Some("turn-1".to_string()),
+            root_turn_id: None,
             cwd: serde_json::from_value(serde_json::json!(&latest_cwd))
                 .expect("absolute latest cwd"),
             workspace_roots: None,
diff --git a/codex-rs/rollout/src/search.rs b/codex-rs/rollout/src/search.rs
index 946e2672fd..cbfd54de8c 100644
--- a/codex-rs/rollout/src/search.rs
+++ b/codex-rs/rollout/src/search.rs
@@ -294,6 +294,7 @@ fn conversation_text_from_item(item: &RolloutItem) -> Option<String> {
         | RolloutItem::Compacted(_)
         | RolloutItem::RealtimeItem(_)
         | RolloutItem::SecurityRiskScore(_)
+        | RolloutItem::TokenUsageRecord(_)
         | RolloutItem::WorldState(_) => None,
     }
 }
diff --git a/codex-rs/state/src/extract.rs b/codex-rs/state/src/extract.rs
index d2bd33bb3e..94370044b8 100644
--- a/codex-rs/state/src/extract.rs
+++ b/codex-rs/state/src/extract.rs
@@ -28,6 +28,7 @@ pub fn apply_rollout_item(
         RolloutItem::WorldState(_) => {}
         RolloutItem::SecurityRiskScore(_) => {}
         RolloutItem::RealtimeItem(_) => {}
+        RolloutItem::TokenUsageRecord(_) => {}
     }
     if metadata.model_provider.is_empty() {
         metadata.model_provider = default_provider.to_string();
@@ -56,6 +57,7 @@ pub fn rollout_item_affects_thread_metadata(item: &RolloutItem) -> bool {
         | RolloutItem::Compacted(_)
         | RolloutItem::RealtimeItem(_)
         | RolloutItem::SecurityRiskScore(_)
+        | RolloutItem::TokenUsageRecord(_)
         | RolloutItem::WorldState(_) => false,
     }
 }
@@ -424,6 +426,7 @@ mod tests {
             &mut metadata,
             &RolloutItem::TurnContext(TurnContextItem {
                 turn_id: Some("turn-1".to_string()),
+                root_turn_id: None,
                 cwd: serde_json::from_value(serde_json::json!(
                     std::env::current_dir()
                         .expect("current directory")
@@ -472,6 +475,7 @@ mod tests {
             &mut metadata,
             &RolloutItem::TurnContext(TurnContextItem {
                 turn_id: Some("turn-1".to_string()),
+                root_turn_id: None,
                 cwd: serde_json::from_value(serde_json::json!(
                     std::env::current_dir()
                         .expect("current directory")
@@ -520,6 +524,7 @@ mod tests {
             &mut metadata,
             &RolloutItem::TurnContext(TurnContextItem {
                 turn_id: Some("turn-1".to_string()),
+                root_turn_id: None,
                 cwd: serde_json::from_value(serde_json::json!(&fallback_cwd))
                     .expect("absolute fallback cwd"),
                 workspace_roots: None,
@@ -557,6 +562,7 @@ mod tests {
             &mut metadata,
             &RolloutItem::TurnContext(TurnContextItem {
                 turn_id: Some("turn-1".to_string()),
+                root_turn_id: None,
                 cwd: serde_json::from_value(serde_json::json!(
                     std::env::current_dir()
                         .expect("current directory")
diff --git a/codex-rs/state/src/runtime/threads.rs b/codex-rs/state/src/runtime/threads.rs
index 3d2e0d923c..a18c051d8e 100644
--- a/codex-rs/state/src/runtime/threads.rs
+++ b/codex-rs/state/src/runtime/threads.rs
@@ -1323,6 +1323,7 @@ pub(super) fn extract_memory_mode(items: &[RolloutItem]) -> Option<String> {
         | RolloutItem::WorldState(_)
         | RolloutItem::RealtimeItem(_)
         | RolloutItem::SecurityRiskScore(_)
+        | RolloutItem::TokenUsageRecord(_)
         | RolloutItem::EventMsg(_) => None,
     })
 }
diff --git a/codex-rs/thread-store/src/local/mod.rs b/codex-rs/thread-store/src/local/mod.rs
index de9f72e618..e83e7ccd46 100644
--- a/codex-rs/thread-store/src/local/mod.rs
+++ b/codex-rs/thread-store/src/local/mod.rs
@@ -933,6 +933,7 @@ mod tests {
         let turn_context = |model: &str, approval_policy| {
             RolloutItem::TurnContext(TurnContextItem {
                 turn_id: Some("turn-1".to_string()),
+                root_turn_id: None,
                 cwd: serde_json::from_value(serde_json::json!(cwd)).expect("absolute cwd"),
                 workspace_roots: None,
                 current_date: None,
diff --git a/codex-rs/thread-store/src/local/model_context_tests.rs b/codex-rs/thread-store/src/local/model_context_tests.rs
index a6ec02169d..73f8274118 100644
--- a/codex-rs/thread-store/src/local/model_context_tests.rs
+++ b/codex-rs/thread-store/src/local/model_context_tests.rs
@@ -729,6 +729,7 @@ fn agent_message(message: &str) -> RolloutItem {
 fn turn_context(root: &Path, turn_id: &str) -> RolloutItem {
     RolloutItem::TurnContext(TurnContextItem {
         turn_id: Some(turn_id.to_string()),
+        root_turn_id: None,
         cwd: serde_json::from_value(serde_json::json!(root)).expect("absolute cwd"),
         workspace_roots: None,
         current_date: None,
@@ -763,5 +764,7 @@ fn compacted(message: &str, replacement_history: Option<Vec<ResponseItem>>) -> R
         first_window_id: None,
         previous_window_id: None,
         window_id: None,
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     })
 }
diff --git a/codex-rs/thread-store/src/local/rollout_migration/canonicalizer.rs b/codex-rs/thread-store/src/local/rollout_migration/canonicalizer.rs
index 9eed043bd0..0607411c6e 100644
--- a/codex-rs/thread-store/src/local/rollout_migration/canonicalizer.rs
+++ b/codex-rs/thread-store/src/local/rollout_migration/canonicalizer.rs
@@ -292,6 +292,7 @@ impl LegacyRolloutCanonicalizer {
             }
             item @ (RolloutItem::InterAgentCommunicationMetadata { .. }
             | RolloutItem::TurnContext(_)
+            | RolloutItem::TokenUsageRecord(_)
             | RolloutItem::RealtimeItem(_)
             | RolloutItem::SecurityRiskScore(_)
             | RolloutItem::WorldState(_)) => {
diff --git a/codex-rs/thread-store/src/local/rollout_migration/rollback_plan.rs b/codex-rs/thread-store/src/local/rollout_migration/rollback_plan.rs
index f8404b6177..f015caaa32 100644
--- a/codex-rs/thread-store/src/local/rollout_migration/rollback_plan.rs
+++ b/codex-rs/thread-store/src/local/rollout_migration/rollback_plan.rs
@@ -219,6 +219,9 @@ impl RollbackPlanner {
                     self.pending_turn_records.push(index);
                 }
             }
+            RolloutItem::TokenUsageRecord(record) => {
+                self.assign_targeted_record(index, Some(record.turn_id.as_str()));
+            }
             RolloutItem::WorldState(_) | RolloutItem::RealtimeItem(_) => {}
             RolloutItem::SecurityRiskScore(_) => self.record_boundaries[index] = None,
         }
diff --git a/codex-rs/thread-store/src/local/rollout_migration/rollback_replay.rs b/codex-rs/thread-store/src/local/rollout_migration/rollback_replay.rs
index b8d47f36bf..80dfdbcac7 100644
--- a/codex-rs/thread-store/src/local/rollout_migration/rollback_replay.rs
+++ b/codex-rs/thread-store/src/local/rollout_migration/rollback_replay.rs
@@ -76,6 +76,7 @@ impl ModelReplayPlanner {
             | RolloutItem::EventMsg(_)
             | RolloutItem::InterAgentCommunicationMetadata { .. }
             | RolloutItem::RealtimeItem(_)
+            | RolloutItem::TokenUsageRecord(_)
             | RolloutItem::SecurityRiskScore(_)
             | RolloutItem::WorldState(_) => return,
         };
diff --git a/codex-rs/thread-store/src/local/rollout_migration_tests.rs b/codex-rs/thread-store/src/local/rollout_migration_tests.rs
index 5f1263d6ed..b1b38ba060 100644
--- a/codex-rs/thread-store/src/local/rollout_migration_tests.rs
+++ b/codex-rs/thread-store/src/local/rollout_migration_tests.rs
@@ -235,6 +235,8 @@ fn compacted(replacement_history: Vec<ResponseItem>) -> RolloutItem {
         first_window_id: None,
         previous_window_id: None,
         window_id: None,
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     })
 }
 
@@ -1411,6 +1413,8 @@ async fn migration_compacts_subagent_prefix_and_does_not_project_it() {
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
             RolloutItem::Compacted(CompactedItem {
                 message: "latest checkpoint".to_string(),
@@ -1431,10 +1435,13 @@ async fn migration_compacts_subagent_prefix_and_does_not_project_it() {
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
             started("child-turn"),
             RolloutItem::TurnContext(TurnContextItem {
                 turn_id: Some("child-turn".to_string()),
+                root_turn_id: None,
                 cwd: serde_json::from_value(json!(home.path())).expect("absolute cwd"),
                 workspace_roots: None,
                 current_date: None,
diff --git a/codex-rs/thread-store/src/thread_metadata_sync.rs b/codex-rs/thread-store/src/thread_metadata_sync.rs
index e2557dbd52..dbfac21ef5 100644
--- a/codex-rs/thread-store/src/thread_metadata_sync.rs
+++ b/codex-rs/thread-store/src/thread_metadata_sync.rs
@@ -305,6 +305,7 @@ impl ThreadMetadataSync {
                 | RolloutItem::InterAgentCommunicationMetadata { .. }
                 | RolloutItem::Compacted(_)
                 | RolloutItem::RealtimeItem(_)
+                | RolloutItem::TokenUsageRecord(_)
                 | RolloutItem::SecurityRiskScore(_)
                 | RolloutItem::WorldState(_) => {}
             }
@@ -587,6 +588,8 @@ mod tests {
             first_window_id: None,
             previous_window_id: None,
             window_id: None,
+            compaction_response_id: None,
+            latest_token_usage_record: None,
         });
 
         let first = sync
diff --git a/codex-rs/tui/src/resume_picker_transcript_preview_tests.rs b/codex-rs/tui/src/resume_picker_transcript_preview_tests.rs
index efc9a4b043..d40ac1565c 100644
--- a/codex-rs/tui/src/resume_picker_transcript_preview_tests.rs
+++ b/codex-rs/tui/src/resume_picker_transcript_preview_tests.rs
@@ -78,6 +78,8 @@ fn legacy_transcript_preview_scans_tail_across_compaction() {
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
             rollout_user_message("recent user"),
             rollout_agent_message("commentary one\ncommentary two"),
@@ -209,6 +211,8 @@ fn legacy_transcript_preview_falls_back_for_oversized_hidden_record() {
                 first_window_id: None,
                 previous_window_id: None,
                 window_id: None,
+                compaction_response_id: None,
+                latest_token_usage_record: None,
             }),
             rollout_agent_message("recent assistant"),
         ],
@@ -236,6 +240,8 @@ fn legacy_transcript_preview_falls_back_when_scan_budget_is_exhausted() {
         first_window_id: None,
         previous_window_id: None,
         window_id: None,
+        compaction_response_id: None,
+        latest_token_usage_record: None,
     });
     let mut items = vec![rollout_user_message("older user")];
     items.extend(std::iter::repeat_n(compacted, 9));