diff --git a/codex-rs/core/src/agent/agent_resolver.rs b/codex-rs/core/src/agent/agent_resolver.rs
index 115739c2f..fff2d7afd 100644
--- a/codex-rs/core/src/agent/agent_resolver.rs
+++ b/codex-rs/core/src/agent/agent_resolver.rs
@@ -18,7 +18,7 @@ pub(crate) async fn resolve_agent_target(
     session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, target)
+        .resolve_agent_reference(session.thread_id, &turn.session_source, target)
         .await
         .map_err(|err| match err {
             codex_protocol::error::CodexErr::UnsupportedOperation(message) => {
@@ -32,5 +32,5 @@ fn register_session_root(session: &Arc<Session>, turn: &Arc<TurnContext>) {
     session
         .services
         .agent_control
-        .register_session_root(session.conversation_id, turn.parent_thread_id);
+        .register_session_root(session.thread_id, turn.parent_thread_id);
 }
diff --git a/codex-rs/core/src/codex_delegate.rs b/codex-rs/core/src/codex_delegate.rs
index 678a6e5d1..5a1473b05 100644
--- a/codex-rs/core/src/codex_delegate.rs
+++ b/codex-rs/core/src/codex_delegate.rs
@@ -92,7 +92,7 @@ pub(crate) async fn run_codex_thread_interactive(
         conversation_history,
         session_source: SessionSource::SubAgent(subagent_source.clone()),
         forked_from_thread_id,
-        parent_thread_id: Some(parent_session.conversation_id),
+        parent_thread_id: Some(parent_session.thread_id),
         thread_source: Some(ThreadSource::Subagent),
         agent_control: parent_session.services.agent_control.clone(),
         dynamic_tools: Vec::new(),
@@ -116,8 +116,8 @@ pub(crate) async fn run_codex_thread_interactive(
         &parent_session.services.analytics_events_client,
         client_metadata,
         codex.session.session_id(),
-        codex.session.conversation_id,
-        Some(parent_session.conversation_id),
+        codex.session.thread_id,
+        Some(parent_session.thread_id),
         thread_config,
         subagent_source,
     );
diff --git a/codex-rs/core/src/compact.rs b/codex-rs/core/src/compact.rs
index a002ce20d..4ff35c09e 100644
--- a/codex-rs/core/src/compact.rs
+++ b/codex-rs/core/src/compact.rs
@@ -327,7 +327,7 @@ impl CompactionAnalyticsAttempt {
     ) -> Self {
         let active_context_tokens_before = sess.get_total_token_usage().await;
         Self {
-            thread_id: sess.conversation_id.to_string(),
+            thread_id: sess.thread_id.to_string(),
             turn_id: turn_context.sub_id.clone(),
             trigger,
             reason,
diff --git a/codex-rs/core/src/goals.rs b/codex-rs/core/src/goals.rs
index ca92f8bec..6e0663655 100644
--- a/codex-rs/core/src/goals.rs
+++ b/codex-rs/core/src/goals.rs
@@ -403,7 +403,7 @@ impl Session {
         let state_db = self.require_state_db_for_thread_goals().await?;
         state_db
             .thread_goals()
-            .get_thread_goal(self.conversation_id)
+            .get_thread_goal(self.thread_id)
             .await
             .map(|goal| goal.map(protocol_goal_from_state))
     }
@@ -442,14 +442,14 @@ impl Session {
         let goal = if let Some(objective) = objective.as_deref() {
             let existing_goal = state_db
                 .thread_goals()
-                .get_thread_goal(self.conversation_id)
+                .get_thread_goal(self.thread_id)
                 .await?;
             previous_status = existing_goal.as_ref().map(|goal| goal.status);
             if let Some(existing_goal) = existing_goal.as_ref() {
                 state_db
                     .thread_goals()
                     .update_thread_goal(
-                        self.conversation_id,
+                        self.thread_id,
                         codex_state::GoalUpdate {
                             objective: Some(objective.to_string()),
                             status: status.map(state_goal_status_from_protocol),
@@ -461,7 +461,7 @@ impl Session {
                     .ok_or_else(|| {
                         anyhow::anyhow!(
                             "cannot update goal for thread {}: no goal exists",
-                            self.conversation_id
+                            self.thread_id
                         )
                     })?
             } else {
@@ -469,7 +469,7 @@ impl Session {
                 state_db
                     .thread_goals()
                     .replace_thread_goal(
-                        self.conversation_id,
+                        self.thread_id,
                         objective,
                         status
                             .map(state_goal_status_from_protocol)
@@ -481,7 +481,7 @@ impl Session {
         } else {
             let existing_goal = state_db
                 .thread_goals()
-                .get_thread_goal(self.conversation_id)
+                .get_thread_goal(self.thread_id)
                 .await?;
             previous_status = existing_goal.as_ref().map(|goal| goal.status);
             let expected_goal_id = existing_goal.map(|goal| goal.goal_id);
@@ -489,7 +489,7 @@ impl Session {
             state_db
                 .thread_goals()
                 .update_thread_goal(
-                    self.conversation_id,
+                    self.thread_id,
                     codex_state::GoalUpdate {
                         objective: None,
                         status,
@@ -501,7 +501,7 @@ impl Session {
                 .ok_or_else(|| {
                     anyhow::anyhow!(
                         "cannot update goal for thread {}: no goal exists",
-                        self.conversation_id
+                        self.thread_id
                     )
                 })?
         };
@@ -509,7 +509,7 @@ impl Session {
         if objective.is_some() {
             set_thread_preview_from_goal_objective(
                 &state_db,
-                self.conversation_id,
+                self.thread_id,
                 goal.objective.as_str(),
             )
             .await;
@@ -546,7 +546,7 @@ impl Session {
         self.send_event(
             turn_context,
             EventMsg::ThreadGoalUpdated(ThreadGoalUpdatedEvent {
-                thread_id: self.conversation_id,
+                thread_id: self.thread_id,
                 turn_id: Some(turn_context.sub_id.clone()),
                 goal: goal.clone(),
             }),
@@ -582,7 +582,7 @@ impl Session {
         let goal = state_db
             .thread_goals()
             .insert_thread_goal(
-                self.conversation_id,
+                self.thread_id,
                 objective,
                 codex_state::ThreadGoalStatus::Active,
                 token_budget,
@@ -591,16 +591,12 @@ impl Session {
             .ok_or_else(|| {
                 anyhow::anyhow!(
                     "cannot create a new goal because thread {} already has a goal",
-                    self.conversation_id
+                    self.thread_id
                 )
             })?;
 
-        set_thread_preview_from_goal_objective(
-            &state_db,
-            self.conversation_id,
-            goal.objective.as_str(),
-        )
-        .await;
+        set_thread_preview_from_goal_objective(&state_db, self.thread_id, goal.objective.as_str())
+            .await;
         let goal_id = goal.goal_id.clone();
         self.emit_goal_created_metric();
         let goal = protocol_goal_from_state(goal);
@@ -617,7 +613,7 @@ impl Session {
         self.send_event(
             turn_context,
             EventMsg::ThreadGoalUpdated(ThreadGoalUpdatedEvent {
-                thread_id: self.conversation_id,
+                thread_id: self.thread_id,
                 turn_id: Some(turn_context.sub_id.clone()),
                 goal: goal.clone(),
             }),
@@ -799,7 +795,7 @@ impl Session {
     ) -> anyhow::Result<Option<codex_state::ThreadGoalStatus>> {
         let goal = state_db
             .thread_goals()
-            .get_thread_goal(self.conversation_id)
+            .get_thread_goal(self.thread_id)
             .await?;
         Ok(goal.and_then(|goal| {
             expected_goal_id
@@ -843,7 +839,7 @@ impl Session {
         };
         match state_db
             .thread_goals()
-            .get_thread_goal(self.conversation_id)
+            .get_thread_goal(self.thread_id)
             .await
         {
             Ok(Some(goal))
@@ -981,7 +977,7 @@ impl Session {
         let outcome = state_db
             .thread_goals()
             .account_thread_goal_usage(
-                self.conversation_id,
+                self.thread_id,
                 time_delta_seconds,
                 token_delta,
                 codex_state::GoalAccountingMode::ActiveOnly,
@@ -1043,7 +1039,7 @@ impl Session {
         self.send_event(
             turn_context,
             EventMsg::ThreadGoalUpdated(ThreadGoalUpdatedEvent {
-                thread_id: self.conversation_id,
+                thread_id: self.thread_id,
                 turn_id: Some(turn_context.sub_id.clone()),
                 goal: goal.clone(),
             }),
@@ -1106,7 +1102,7 @@ impl Session {
         match state_db
             .thread_goals()
             .account_thread_goal_usage(
-                self.conversation_id,
+                self.thread_id,
                 time_delta_seconds,
                 /*token_delta*/ 0,
                 mode,
@@ -1174,7 +1170,7 @@ impl Session {
             .await?;
         let Some(goal) = state_db
             .thread_goals()
-            .usage_limit_active_thread_goal(self.conversation_id)
+            .usage_limit_active_thread_goal(self.thread_id)
             .await?
         else {
             return Ok(());
@@ -1186,7 +1182,7 @@ impl Session {
         self.send_event(
             turn_context,
             EventMsg::ThreadGoalUpdated(ThreadGoalUpdatedEvent {
-                thread_id: self.conversation_id,
+                thread_id: self.thread_id,
                 turn_id: Some(turn_context.sub_id.clone()),
                 goal,
             }),
@@ -1217,7 +1213,7 @@ impl Session {
         };
         let Some(goal) = state_db
             .thread_goals()
-            .get_thread_goal(self.conversation_id)
+            .get_thread_goal(self.thread_id)
             .await?
         else {
             self.clear_stopped_thread_goal_runtime_state().await;
@@ -1269,7 +1265,7 @@ impl Session {
         let goal_is_current = match self.state_db_for_thread_goals().await {
             Ok(Some(state_db)) => match state_db
                 .thread_goals()
-                .get_thread_goal(self.conversation_id)
+                .get_thread_goal(self.thread_id)
                 .await
             {
                 Ok(Some(goal))
@@ -1367,7 +1363,7 @@ impl Session {
         };
         let goal = match state_db
             .thread_goals()
-            .get_thread_goal(self.conversation_id)
+            .get_thread_goal(self.thread_id)
             .await
         {
             Ok(Some(goal)) => goal,
@@ -1430,7 +1426,7 @@ impl Session {
         };
 
         let thread_metadata_present = state_db
-            .get_thread(self.conversation_id)
+            .get_thread(self.thread_id)
             .await
             .context("failed to read thread metadata before reconciling thread goals")?
             .is_some();
@@ -1453,7 +1449,7 @@ impl Session {
             )
             .await;
             let thread_metadata_present = state_db
-                .get_thread(self.conversation_id)
+                .get_thread(self.thread_id)
                 .await
                 .context("failed to read thread metadata after reconciling thread goals")?
                 .is_some();
diff --git a/codex-rs/core/src/guardian/prompt.rs b/codex-rs/core/src/guardian/prompt.rs
index 062a21dee..008e97957 100644
--- a/codex-rs/core/src/guardian/prompt.rs
+++ b/codex-rs/core/src/guardian/prompt.rs
@@ -186,7 +186,7 @@ pub(crate) async fn build_guardian_prompt_items_with_parent_turn(
     push_text(headings.transcript_end.to_string());
     push_text(format!(
         "Reviewed Codex session id: {}\n",
-        session.conversation_id
+        session.thread_id
     ));
     if let Some(note) = omission_note {
         push_text(format!("\n{note}\n"));
diff --git a/codex-rs/core/src/guardian/review.rs b/codex-rs/core/src/guardian/review.rs
index 167b153e2..06d1a7893 100644
--- a/codex-rs/core/src/guardian/review.rs
+++ b/codex-rs/core/src/guardian/review.rs
@@ -265,7 +265,7 @@ async fn run_guardian_review(
     let action_summary = guardian_assessment_action(&request);
     let reviewed_action = guardian_reviewed_action(&request);
     let review_tracking = GuardianReviewTrackContext::new(
-        session.conversation_id.to_string(),
+        session.thread_id.to_string(),
         assessment_turn_id.clone(),
         review_id.clone(),
         target_item_id.clone(),
diff --git a/codex-rs/core/src/guardian/review_session.rs b/codex-rs/core/src/guardian/review_session.rs
index b8c5c9807..c139a910a 100644
--- a/codex-rs/core/src/guardian/review_session.rs
+++ b/codex-rs/core/src/guardian/review_session.rs
@@ -662,7 +662,7 @@ async fn run_review_on_session(
         None
     };
     let mut analytics_result = GuardianReviewAnalyticsResult::from_session(
-        review_session.codex.session.conversation_id.to_string(),
+        review_session.codex.session.thread_id.to_string(),
         guardian_session_kind,
         params.model.clone(),
         guardian_reasoning_effort.map(|effort| effort.to_string()),
diff --git a/codex-rs/core/src/guardian/tests.rs b/codex-rs/core/src/guardian/tests.rs
index aba67d850..ffadd801c 100644
--- a/codex-rs/core/src/guardian/tests.rs
+++ b/codex-rs/core/src/guardian/tests.rs
@@ -176,7 +176,7 @@ async fn guardian_test_session_and_turn_with_base_url(
     base_url: &str,
 ) -> (Arc<Session>, Arc<TurnContext>) {
     let (mut session, mut turn) = crate::session::tests::make_session_and_context().await;
-    session.conversation_id = fixed_guardian_parent_session_id();
+    session.thread_id = fixed_guardian_parent_session_id();
     let mut config = (*turn.config).clone();
     config.model_provider.base_url = Some(format!("{base_url}/v1"));
     config.user_instructions = None;
@@ -365,7 +365,7 @@ async fn build_guardian_prompt_full_mode_preserves_initial_review_format() -> an
 #[tokio::test(flavor = "current_thread")]
 async fn build_guardian_prompt_includes_parent_turn_denied_reads() -> anyhow::Result<()> {
     let (mut session, mut turn) = crate::session::tests::make_session_and_context().await;
-    session.conversation_id = fixed_guardian_parent_session_id();
+    session.thread_id = fixed_guardian_parent_session_id();
     let denied_root = test_path_buf("/repo/private").abs();
     let denied_glob = test_path_buf("/repo/private/**").display().to_string();
     turn.permission_profile = PermissionProfile::from_runtime_permissions(
@@ -1415,7 +1415,7 @@ async fn guardian_review_request_layout_matches_model_visible_request_snapshot()
     .await;
 
     let (mut session, mut turn) = crate::session::tests::make_session_and_context().await;
-    session.conversation_id = fixed_guardian_parent_session_id();
+    session.thread_id = fixed_guardian_parent_session_id();
     let temp_cwd = TempDir::new()?;
     let mut config = (*turn.config).clone();
     config.cwd = temp_cwd.abs();
@@ -1464,7 +1464,7 @@ async fn guardian_review_request_layout_matches_model_visible_request_snapshot()
         .as_deref()
         .expect("guardian thread id");
     assert_eq!(assessment.outcome, GuardianAssessmentOutcome::Allow);
-    assert_ne!(guardian_thread_id, session.conversation_id.to_string());
+    assert_ne!(guardian_thread_id, session.thread_id.to_string());
     ThreadId::from_string(guardian_thread_id).expect("guardian thread id should be a valid UUID");
     assert!(matches!(
         metadata.guardian_session_kind,
@@ -1567,7 +1567,7 @@ async fn build_guardian_prompt_items_includes_parent_session_id() -> anyhow::Res
     assert!(
         prompt_text.contains(&format!(
             ">>> TRANSCRIPT END\nReviewed Codex session id: {}\n",
-            session.conversation_id
+            session.thread_id
         )),
         "guardian prompt should expose the parent session id immediately after the transcript end"
     );
diff --git a/codex-rs/core/src/hook_runtime.rs b/codex-rs/core/src/hook_runtime.rs
index 336433fe1..6e2d4fe33 100644
--- a/codex-rs/core/src/hook_runtime.rs
+++ b/codex-rs/core/src/hook_runtime.rs
@@ -451,7 +451,7 @@ pub(crate) async fn run_legacy_after_agent_hook(
             triggered_at: chrono::Utc::now(),
             hook_event: codex_hooks::HookEvent::AfterAgent {
                 event: codex_hooks::HookEventAfterAgent {
-                    thread_id: sess.conversation_id,
+                    thread_id: sess.thread_id,
                     turn_id: turn_context.sub_id.clone(),
                     input_messages,
                     last_assistant_message,
@@ -655,7 +655,7 @@ fn track_hook_completed_analytics(
     completed: &HookCompletedEvent,
 ) {
     let (tracking, hook) =
-        hook_run_analytics_payload(sess.conversation_id.to_string(), turn_context, completed);
+        hook_run_analytics_payload(sess.thread_id.to_string(), turn_context, completed);
     sess.services
         .analytics_events_client
         .track_hook_run(tracking, hook);
diff --git a/codex-rs/core/src/mcp_tool_call.rs b/codex-rs/core/src/mcp_tool_call.rs
index 9c00ba2be..b9a8d4ff0 100644
--- a/codex-rs/core/src/mcp_tool_call.rs
+++ b/codex-rs/core/src/mcp_tool_call.rs
@@ -468,8 +468,8 @@ fn mcp_tool_call_span(
         mcp.connector.name = fields.connector_name.unwrap_or(""),
         tool.name = fields.tool_name,
         tool.call_id = fields.call_id,
-        conversation.id = %session.conversation_id,
-        session.id = %session.conversation_id,
+        conversation.id = %session.thread_id,
+        session.id = %session.thread_id,
         turn.id = turn_context.sub_id.as_str(),
         server.address = Empty,
         server.port = Empty,
@@ -554,8 +554,7 @@ async fn execute_mcp_tool_call(
     metadata: Option<&McpToolApprovalMetadata>,
     request_meta: Option<JsonValue>,
 ) -> Result<CallToolResult, String> {
-    let request_meta =
-        with_mcp_tool_call_thread_id_meta(request_meta, &sess.conversation_id.to_string());
+    let request_meta = with_mcp_tool_call_thread_id_meta(request_meta, &sess.thread_id.to_string());
     let request_meta = augment_mcp_tool_request_meta_with_sandbox_state(
         sess,
         turn_context,
@@ -645,7 +644,7 @@ async fn maybe_request_codex_apps_auth_elicitation(
 
     let request_id = rmcp::model::RequestId::String(plan.elicitation.elicitation_id.clone().into());
     let params = McpServerElicitationRequestParams {
-        thread_id: sess.conversation_id.to_string(),
+        thread_id: sess.thread_id.to_string(),
         turn_id: Some(turn_context.sub_id.clone()),
         server_name: CODEX_APPS_MCP_SERVER_NAME.to_string(),
         request: McpServerElicitationRequest::Url {
@@ -766,7 +765,7 @@ async fn maybe_mark_thread_memory_mode_polluted(
     }
     state_db::mark_thread_memory_mode_polluted(
         sess.services.state_db.as_deref(),
-        sess.conversation_id,
+        sess.thread_id,
         "mcp_tool_call",
     )
     .await;
@@ -945,7 +944,7 @@ async fn maybe_track_codex_app_used(
 
     let tracking = build_track_events_context(
         turn_context.model_info.slug.clone(),
-        sess.conversation_id.to_string(),
+        sess.thread_id.to_string(),
         turn_context.sub_id.clone(),
     );
     sess.services.analytics_events_client.track_app_used(
@@ -1615,7 +1614,7 @@ fn build_mcp_tool_approval_elicitation_request(
         .unwrap_or_else(|| request.question.question.clone());
 
     McpServerElicitationRequestParams {
-        thread_id: sess.conversation_id.to_string(),
+        thread_id: sess.thread_id.to_string(),
         turn_id: Some(turn_context.sub_id.clone()),
         server_name: request.server.to_string(),
         request: McpServerElicitationRequest::Form {
diff --git a/codex-rs/core/src/mcp_tool_call_tests.rs b/codex-rs/core/src/mcp_tool_call_tests.rs
index c9259b8f2..bd71c3a05 100644
--- a/codex-rs/core/src/mcp_tool_call_tests.rs
+++ b/codex-rs/core/src/mcp_tool_call_tests.rs
@@ -138,7 +138,7 @@ async fn execute_mcp_tool_call_records_replayable_correlation() -> anyhow::Resul
         .rollout_thread_trace
         .start_tool_dispatch_trace(|| {
             Some(ToolDispatchInvocation {
-                thread_id: session.conversation_id.to_string(),
+                thread_id: session.thread_id.to_string(),
                 codex_turn_id: turn_context.sub_id.clone(),
                 tool_call_id: "mcp-call".to_string(),
                 tool_name: "search".to_string(),
@@ -280,7 +280,7 @@ fn attach_trace_bundle(
         codex_rollout_trace::ThreadTraceContext::start_root_in_root_for_test(
             root,
             ThreadStartedTraceMetadata {
-                thread_id: session.conversation_id.to_string(),
+                thread_id: session.thread_id.to_string(),
                 agent_path: "/root".to_string(),
                 task_name: None,
                 nickname: None,
@@ -646,7 +646,7 @@ async fn approval_elicitation_request_uses_message_override_and_preserves_tool_p
     assert_eq!(
         request,
         McpServerElicitationRequestParams {
-            thread_id: session.conversation_id.to_string(),
+            thread_id: session.thread_id.to_string(),
             turn_id: Some(turn_context.sub_id),
             server_name: CODEX_APPS_MCP_SERVER_NAME.to_string(),
             request: McpServerElicitationRequest::Form {
diff --git a/codex-rs/core/src/realtime_conversation.rs b/codex-rs/core/src/realtime_conversation.rs
index 7f71142e1..9f35fb2fa 100644
--- a/codex-rs/core/src/realtime_conversation.rs
+++ b/codex-rs/core/src/realtime_conversation.rs
@@ -716,7 +716,7 @@ pub(crate) async fn build_realtime_session_config(
     Ok(RealtimeSessionConfig {
         instructions: prompt,
         model,
-        session_id: Some(realtime_session_id.unwrap_or_else(|| sess.conversation_id.to_string())),
+        session_id: Some(realtime_session_id.unwrap_or_else(|| sess.thread_id.to_string())),
         event_parser,
         session_mode,
         output_modality,
diff --git a/codex-rs/core/src/session/mod.rs b/codex-rs/core/src/session/mod.rs
index 5a92c9c82..8ce16de74 100644
--- a/codex-rs/core/src/session/mod.rs
+++ b/codex-rs/core/src/session/mod.rs
@@ -654,7 +654,7 @@ impl Codex {
             error!("Failed to create session: {e:#}");
             map_session_init_error(&e, &config.codex_home)
         })?;
-        let thread_id = session.conversation_id;
+        let thread_id = session.thread_id;
 
         // This task will run until Op::Shutdown is received.
         let session_for_loop = Arc::clone(&session);
@@ -1369,7 +1369,7 @@ impl Session {
 
         ShellSnapshot::refresh_snapshot(
             codex_home.clone(),
-            self.conversation_id,
+            self.thread_id,
             next_cwd.clone(),
             self.services.user_shell.as_ref().clone(),
             self.services.shell_snapshot_tx.clone(),
@@ -1640,7 +1640,7 @@ impl Session {
         self.services
             .analytics_events_client
             .track_turn_codex_error(TurnCodexErrorFact::from_codex_err(
-                self.conversation_id.to_string(),
+                self.thread_id.to_string(),
                 turn_context.sub_id.clone(),
                 error,
             ));
@@ -1819,7 +1819,7 @@ impl Session {
         self.send_event(
             turn_context,
             EventMsg::ItemStarted(ItemStartedEvent {
-                thread_id: self.conversation_id,
+                thread_id: self.thread_id,
                 turn_id: turn_context.sub_id.clone(),
                 item: item.clone(),
                 started_at_ms: now_unix_timestamp_ms(),
@@ -1837,7 +1837,7 @@ impl Session {
         self.send_event(
             turn_context,
             EventMsg::ItemCompleted(ItemCompletedEvent {
-                thread_id: self.conversation_id,
+                thread_id: self.thread_id,
                 turn_id: turn_context.sub_id.clone(),
                 item,
                 completed_at_ms: now_unix_timestamp_ms(),
@@ -2900,7 +2900,7 @@ impl Session {
             let subagents = self
                 .services
                 .agent_control
-                .format_environment_context_subagents(self.conversation_id)
+                .format_environment_context_subagents(self.thread_id)
                 .await;
             contextual_user_sections.push(
                 crate::context::EnvironmentContext::from_turn_context(turn_context, shell.as_ref())
diff --git a/codex-rs/core/src/session/session.rs b/codex-rs/core/src/session/session.rs
index 05773abb8..6ab7e86f3 100644
--- a/codex-rs/core/src/session/session.rs
+++ b/codex-rs/core/src/session/session.rs
@@ -19,7 +19,7 @@ use tokio::sync::Semaphore;
 ///
 /// A session has at most 1 running task at a time, and can be interrupted by user input.
 pub(crate) struct Session {
-    pub(crate) conversation_id: ThreadId,
+    pub(crate) thread_id: ThreadId,
     pub(crate) installation_id: String,
     pub(super) tx_event: Sender<Event>,
     pub(super) agent_status: watch::Sender<AgentStatus>,
@@ -471,7 +471,7 @@ async fn warm_plugins_and_skills_for_session_init(
 impl Session {
     /// Returns the concrete identity for this thread.
     pub(crate) fn thread_id(&self) -> ThreadId {
-        self.conversation_id
+        self.thread_id
     }
 
     /// Returns the identity shared by the root thread and all descendant threads.
@@ -1061,7 +1061,7 @@ impl Session {
                 watch::channel(false);
 
             let sess = Arc::new(Session {
-                conversation_id: thread_id,
+                thread_id,
                 installation_id,
                 tx_event: tx_event.clone(),
                 agent_status,
diff --git a/codex-rs/core/src/session/tests.rs b/codex-rs/core/src/session/tests.rs
index a3e555897..4d4709e65 100644
--- a/codex-rs/core/src/session/tests.rs
+++ b/codex-rs/core/src/session/tests.rs
@@ -344,7 +344,7 @@ async fn request_mcp_server_elicitation_auto_accepts_when_auto_deny_is_enabled()
             turn_context.as_ref(),
             RequestId::String("request-1".into()),
             McpServerElicitationRequestParams {
-                thread_id: session.conversation_id.to_string(),
+                thread_id: session.thread_id.to_string(),
                 turn_id: Some(turn_context.sub_id.clone()),
                 server_name: "codex_apps".to_string(),
                 request: McpServerElicitationRequest::Form {
@@ -1333,7 +1333,7 @@ async fn reload_user_config_layer_refreshes_hooks() -> anyhow::Result<()> {
     }))?;
 
     let request = codex_hooks::SessionStartRequest {
-        session_id: session.conversation_id,
+        session_id: session.thread_id,
         cwd: session.get_config().await.cwd.clone(),
         transcript_path: None,
         model: "gpt-5.2".to_string(),
@@ -1440,7 +1440,7 @@ async fn refresh_runtime_config_refreshes_hooks() -> anyhow::Result<()> {
     std::fs::write(&config_toml_path, toml::to_string(&trusted_user_config)?)?;
 
     let request = codex_hooks::SessionStartRequest {
-        session_id: session.conversation_id,
+        session_id: session.thread_id,
         cwd: session.get_config().await.cwd.clone(),
         transcript_path: None,
         model: "gpt-5.2".to_string(),
@@ -1999,7 +1999,7 @@ async fn record_token_usage_info_notifies_extension_contributors() {
     let expected = vec![
         RecordedTokenUsage {
             session_level_id: session.session_id().to_string(),
-            thread_level_id: session.conversation_id.to_string(),
+            thread_level_id: session.thread_id.to_string(),
             turn_level_id: turn_context.sub_id.clone(),
             token_usage: TokenUsageInfo {
                 total_token_usage: first_usage.clone(),
@@ -2011,7 +2011,7 @@ async fn record_token_usage_info_notifies_extension_contributors() {
         },
         RecordedTokenUsage {
             session_level_id: session.session_id().to_string(),
-            thread_level_id: session.conversation_id.to_string(),
+            thread_level_id: session.thread_id.to_string(),
             turn_level_id: turn_context.sub_id.clone(),
             token_usage: TokenUsageInfo {
                 total_token_usage: expected_total_usage,
@@ -2100,7 +2100,7 @@ async fn turn_start_lifecycle_exposes_turn_metadata_and_token_baseline() {
 
     let expected = RecordedTurnStart {
         session_level_id: session.session_id().to_string(),
-        thread_level_id: session.conversation_id.to_string(),
+        thread_level_id: session.thread_id.to_string(),
         turn_level_id: turn_context.sub_id.clone(),
         turn_id: turn_context.sub_id.clone(),
         collaboration_mode: turn_context.collaboration_mode.clone(),
@@ -2188,7 +2188,7 @@ async fn turn_error_lifecycle_exposes_error_and_stores() {
 
     let expected = RecordedTurnError {
         session_level_id: session.session_id().to_string(),
-        thread_level_id: session.conversation_id.to_string(),
+        thread_level_id: session.thread_id.to_string(),
         turn_level_id: turn_context.sub_id.clone(),
         turn_id: turn_context.sub_id.clone(),
         error: CodexErrorInfo::UsageLimitExceeded,
@@ -3539,7 +3539,7 @@ async fn attach_thread_persistence(session: &mut Session) -> PathBuf {
     let live_thread = LiveThread::create(
         Arc::clone(&session.services.thread_store),
         CreateThreadParams {
-            thread_id: session.conversation_id,
+            thread_id: session.thread_id,
             forked_from_id: None,
             parent_thread_id: None,
             source: SessionSource::Exec,
@@ -4820,7 +4820,7 @@ pub(crate) async fn make_session_and_context() -> (Session, TurnContext) {
     );
 
     let session = Session {
-        conversation_id: thread_id,
+        thread_id,
         installation_id: "11111111-1111-4111-8111-111111111111".to_string(),
         tx_event,
         agent_status: agent_status_tx,
@@ -6282,7 +6282,7 @@ async fn shutdown_complete_does_not_append_to_thread_store_after_shutdown() {
     let live_thread = LiveThread::create(
         Arc::clone(&thread_store),
         CreateThreadParams {
-            thread_id: session.conversation_id,
+            thread_id: session.thread_id,
             forked_from_id: None,
             parent_thread_id: None,
             source: SessionSource::Exec,
@@ -6347,7 +6347,7 @@ async fn submission_loop_channel_close_emits_thread_stop_lifecycle() {
     let mut builder = codex_extension_api::ExtensionRegistryBuilder::<crate::config::Config>::new();
     builder.thread_lifecycle_contributor(Arc::new(ThreadStopRecorder {
         calls: Arc::clone(&calls),
-        expected_thread_id: session.conversation_id,
+        expected_thread_id: session.thread_id,
     }));
     session.services.extensions = Arc::new(builder.build());
     session
@@ -6409,7 +6409,7 @@ async fn submission_loop_channel_close_aborts_active_turn_before_thread_stop_lif
     let calls = Arc::new(std::sync::Mutex::new(Vec::new()));
     let recorder = Arc::new(LifecycleRecorder {
         calls: Arc::clone(&calls),
-        expected_thread_id: session.conversation_id,
+        expected_thread_id: session.thread_id,
         expected_turn_id: turn_context.sub_id.clone(),
     });
     let mut builder = codex_extension_api::ExtensionRegistryBuilder::<crate::config::Config>::new();
@@ -6910,7 +6910,7 @@ where
     ));
 
     let session = Arc::new(Session {
-        conversation_id: thread_id,
+        thread_id,
         installation_id: "11111111-1111-4111-8111-111111111111".to_string(),
         tx_event,
         agent_status: agent_status_tx,
@@ -6976,7 +6976,7 @@ async fn upsert_goal_test_thread(session: &Session) {
         .state_db()
         .expect("goal test session should have a state db");
     let mut builder = codex_state::ThreadMetadataBuilder::new(
-        session.conversation_id,
+        session.thread_id,
         config
             .codex_home
             .join("goal-test-rollout.jsonl")
@@ -7797,7 +7797,7 @@ async fn handle_output_item_done_records_image_save_history_message() {
     let call_id = "ig_history_records_message";
     let expected_saved_path = crate::stream_events_utils::image_generation_artifact_path(
         &turn_context.config.codex_home,
-        &session.conversation_id.to_string(),
+        &session.thread_id.to_string(),
         call_id,
     );
     let _ = std::fs::remove_file(&expected_saved_path);
@@ -7824,7 +7824,7 @@ async fn handle_output_item_done_records_image_save_history_message() {
     let history = session.clone_history().await;
     let image_output_path = crate::stream_events_utils::image_generation_artifact_path(
         &turn_context.config.codex_home,
-        &session.conversation_id.to_string(),
+        &session.thread_id.to_string(),
         "<image_id>",
     );
     let image_output_dir = image_output_path
@@ -7852,7 +7852,7 @@ async fn handle_output_item_done_skips_image_save_message_when_save_fails() {
     let call_id = "ig_history_no_message";
     let expected_saved_path = crate::stream_events_utils::image_generation_artifact_path(
         &turn_context.config.codex_home,
-        &session.conversation_id.to_string(),
+        &session.thread_id.to_string(),
         call_id,
     );
     let _ = std::fs::remove_file(&expected_saved_path);
@@ -8698,7 +8698,7 @@ async fn task_finish_emits_thread_idle_lifecycle_after_active_turn_clears() {
     builder.thread_lifecycle_contributor(Arc::new(ThreadIdleRecorder {
         calls: Arc::clone(&calls),
         idle_tx,
-        expected_thread_id: session.conversation_id,
+        expected_thread_id: session.thread_id,
     }));
     session.services.extensions = Arc::new(builder.build());
 
@@ -9321,7 +9321,7 @@ async fn create_thread_goal_fills_empty_thread_preview() -> anyhow::Result<()> {
         .iter()
         .map(|thread| thread.id)
         .collect::<Vec<_>>();
-    assert_eq!(vec![sess.conversation_id], ids);
+    assert_eq!(vec![sess.thread_id], ids);
     assert_eq!(
         Some("Keep improving the benchmark"),
         page.items[0].preview.as_deref()
@@ -9401,7 +9401,7 @@ async fn budget_limited_accounting_steers_active_turn_without_aborting() -> anyh
     let state_db = goal_test_state_db(sess.as_ref()).await?;
     let goal = state_db
         .thread_goals()
-        .get_thread_goal(sess.conversation_id)
+        .get_thread_goal(sess.thread_id)
         .await?
         .expect("goal should remain persisted after accounting");
     assert_eq!(codex_state::ThreadGoalStatus::BudgetLimited, goal.status);
@@ -9425,7 +9425,7 @@ async fn budget_limited_accounting_steers_active_turn_without_aborting() -> anyh
 
     let goal = state_db
         .thread_goals()
-        .get_thread_goal(sess.conversation_id)
+        .get_thread_goal(sess.thread_id)
         .await?
         .expect("goal should remain persisted after follow-up accounting");
     assert_eq!(codex_state::ThreadGoalStatus::BudgetLimited, goal.status);
@@ -9473,7 +9473,7 @@ async fn usage_limit_runtime_stops_active_goal_and_prevents_idle_continuation()
     let state_db = goal_test_state_db(sess.as_ref()).await?;
     let goal = state_db
         .thread_goals()
-        .get_thread_goal(sess.conversation_id)
+        .get_thread_goal(sess.thread_id)
         .await?
         .expect("goal should remain persisted after usage limiting");
     assert_eq!(codex_state::ThreadGoalStatus::UsageLimited, goal.status);
@@ -9516,7 +9516,7 @@ async fn external_goal_mutation_accounts_active_turn_before_status_change() -> a
     let state_db = goal_test_state_db(sess.as_ref()).await?;
     let goal = state_db
         .thread_goals()
-        .get_thread_goal(sess.conversation_id)
+        .get_thread_goal(sess.thread_id)
         .await?
         .expect("goal should remain persisted");
     assert_eq!(70, goal.tokens_used);
@@ -9526,7 +9526,7 @@ async fn external_goal_mutation_accounts_active_turn_before_status_change() -> a
     let updated_goal = state_db
         .thread_goals()
         .update_thread_goal(
-            sess.conversation_id,
+            sess.thread_id,
             codex_state::GoalUpdate {
                 objective: None,
                 status: Some(codex_state::ThreadGoalStatus::Complete),
@@ -9547,7 +9547,7 @@ async fn external_goal_mutation_accounts_active_turn_before_status_change() -> a
     assert!(sess.active_turn.lock().await.is_some());
     let goal = state_db
         .thread_goals()
-        .get_thread_goal(sess.conversation_id)
+        .get_thread_goal(sess.thread_id)
         .await?
         .expect("goal should remain persisted");
     assert_eq!(codex_state::ThreadGoalStatus::Complete, goal.status);
@@ -9575,7 +9575,7 @@ async fn external_objective_change_steers_active_turn() -> anyhow::Result<()> {
     let old_goal = state_db
         .thread_goals()
         .replace_thread_goal(
-            sess.conversation_id,
+            sess.thread_id,
             "Keep improving the benchmark",
             codex_state::ThreadGoalStatus::Active,
             /*token_budget*/ Some(10_000),
@@ -9584,7 +9584,7 @@ async fn external_objective_change_steers_active_turn() -> anyhow::Result<()> {
     let new_goal = state_db
         .thread_goals()
         .replace_thread_goal(
-            sess.conversation_id,
+            sess.thread_id,
             "Write a concise benchmark summary",
             codex_state::ThreadGoalStatus::Active,
             /*token_budget*/ Some(10_000),
@@ -9642,7 +9642,7 @@ async fn external_active_goal_set_marks_current_turn_for_accounting() -> anyhow:
     let goal = state_db
         .thread_goals()
         .replace_thread_goal(
-            sess.conversation_id,
+            sess.thread_id,
             "Keep improving the benchmark",
             codex_state::ThreadGoalStatus::Active,
             /*token_budget*/ None,
@@ -9675,7 +9675,7 @@ async fn external_active_goal_set_marks_current_turn_for_accounting() -> anyhow:
 
     let goal = state_db
         .thread_goals()
-        .get_thread_goal(sess.conversation_id)
+        .get_thread_goal(sess.thread_id)
         .await?
         .expect("goal should remain persisted");
     assert_eq!(codex_state::ThreadGoalStatus::Active, goal.status);
diff --git a/codex-rs/core/src/session/turn.rs b/codex-rs/core/src/session/turn.rs
index e301a9c04..42d609561 100644
--- a/codex-rs/core/src/session/turn.rs
+++ b/codex-rs/core/src/session/turn.rs
@@ -469,7 +469,7 @@ async fn build_skills_and_plugins(
         .collect::<Vec<_>>();
     let tracking = build_track_events_context(
         turn_context.model_info.slug.clone(),
-        sess.conversation_id.to_string(),
+        sess.thread_id.to_string(),
         turn_context.sub_id.clone(),
     );
     let loaded_plugins = sess
@@ -665,7 +665,7 @@ async fn track_turn_resolved_config_analytics(
         .analytics_events_client
         .track_turn_resolved_config(TurnResolvedConfigFact {
             turn_id: turn_context.sub_id.clone(),
-            thread_id: sess.conversation_id.to_string(),
+            thread_id: sess.thread_id.to_string(),
             num_input_images: input
                 .iter()
                 .filter_map(|item| match item {
@@ -1306,7 +1306,7 @@ impl ProposedPlanItemState {
             return;
         }
         let event = PlanDeltaEvent {
-            thread_id: sess.conversation_id.to_string(),
+            thread_id: sess.thread_id.to_string(),
             turn_id: turn_context.sub_id.clone(),
             item_id: self.item_id.clone(),
             delta: delta.to_string(),
@@ -1482,7 +1482,7 @@ async fn handle_plan_segments(
                 maybe_emit_pending_agent_message_start(sess, turn_context, state, item_id).await;
 
                 let event = AgentMessageContentDeltaEvent {
-                    thread_id: sess.conversation_id.to_string(),
+                    thread_id: sess.thread_id.to_string(),
                     turn_id: turn_context.sub_id.clone(),
                     item_id: item_id.to_string(),
                     delta,
@@ -1536,7 +1536,7 @@ async fn emit_streamed_assistant_text_delta(
         return;
     }
     let event = AgentMessageContentDeltaEvent {
-        thread_id: sess.conversation_id.to_string(),
+        thread_id: sess.thread_id.to_string(),
         turn_id: turn_context.sub_id.clone(),
         item_id: item_id.to_string(),
         delta: parsed.visible_text,
@@ -2102,7 +2102,7 @@ async fn try_run_sampling_request(
                         .await;
                     } else {
                         let event = AgentMessageContentDeltaEvent {
-                            thread_id: sess.conversation_id.to_string(),
+                            thread_id: sess.thread_id.to_string(),
                             turn_id: turn_context.sub_id.clone(),
                             item_id,
                             delta,
@@ -2141,7 +2141,7 @@ async fn try_run_sampling_request(
                         continue;
                     }
                     let event = ReasoningContentDeltaEvent {
-                        thread_id: sess.conversation_id.to_string(),
+                        thread_id: sess.thread_id.to_string(),
                         turn_id: turn_context.sub_id.clone(),
                         item_id: active.id(),
                         delta,
@@ -2177,7 +2177,7 @@ async fn try_run_sampling_request(
                         continue;
                     }
                     let event = ReasoningRawContentDeltaEvent {
-                        thread_id: sess.conversation_id.to_string(),
+                        thread_id: sess.thread_id.to_string(),
                         turn_id: turn_context.sub_id.clone(),
                         item_id: active.id(),
                         delta,
diff --git a/codex-rs/core/src/skills.rs b/codex-rs/core/src/skills.rs
index d540cd6d4..b11f79260 100644
--- a/codex-rs/core/src/skills.rs
+++ b/codex-rs/core/src/skills.rs
@@ -100,7 +100,7 @@ pub(crate) async fn maybe_emit_implicit_skill_invocation(
         .track_skill_invocations(
             build_track_events_context(
                 turn_context.model_info.slug.clone(),
-                sess.conversation_id.to_string(),
+                sess.thread_id.to_string(),
                 turn_context.sub_id.clone(),
             ),
             vec![invocation],
diff --git a/codex-rs/core/src/stream_events_utils.rs b/codex-rs/core/src/stream_events_utils.rs
index 7914c8d48..20fc6787a 100644
--- a/codex-rs/core/src/stream_events_utils.rs
+++ b/codex-rs/core/src/stream_events_utils.rs
@@ -132,7 +132,7 @@ pub(crate) async fn persist_image_generation_item(
     image_item: &mut ImageGenerationItem,
 ) -> Option<AbsolutePathBuf> {
     image_item.saved_path = None;
-    let session_id = sess.conversation_id.to_string();
+    let session_id = sess.thread_id.to_string();
     match save_image_generation_result(
         &turn_context.config.codex_home,
         &session_id,
@@ -172,7 +172,7 @@ async fn record_image_generation_instructions(
     if image_item.saved_path.is_none() {
         return;
     }
-    let session_id = sess.conversation_id.to_string();
+    let session_id = sess.thread_id.to_string();
     let image_output_path =
         image_generation_artifact_path(&turn_context.config.codex_home, &session_id, "<image_id>");
     let image_output_dir = image_output_path
@@ -263,7 +263,7 @@ pub(crate) async fn mark_thread_memory_mode_polluted_if_external_context(
     }
     state_db::mark_thread_memory_mode_polluted(
         sess.services.state_db.as_deref(),
-        sess.conversation_id,
+        sess.thread_id,
         "record_completed_response_item",
     )
     .await;
@@ -422,7 +422,7 @@ pub(crate) async fn handle_output_item_done(
 
             let payload_preview = call.payload.log_payload().into_owned();
             tracing::info!(
-                thread_id = %ctx.sess.conversation_id,
+                thread_id = %ctx.sess.thread_id,
                 "ToolCall: {} {}",
                 call.tool_name,
                 payload_preview
diff --git a/codex-rs/core/src/tasks/mod.rs b/codex-rs/core/src/tasks/mod.rs
index 76d5e6478..ef2ba0f16 100644
--- a/codex-rs/core/src/tasks/mod.rs
+++ b/codex-rs/core/src/tasks/mod.rs
@@ -383,7 +383,7 @@ impl Session {
         let task_span = info_span!(
             "turn",
             otel.name = span_name,
-            thread.id = %self.conversation_id,
+            thread.id = %self.thread_id,
             turn.id = %turn_context.sub_id,
             model = %turn_context.model_info.slug,
             codex.turn.reasoning_effort = %reasoning_effort,
@@ -708,7 +708,7 @@ impl Session {
                 .analytics_events_client
                 .track_turn_token_usage(TurnTokenUsageFact {
                     turn_id: turn_context.sub_id.clone(),
-                    thread_id: self.conversation_id.to_string(),
+                    thread_id: self.thread_id.to_string(),
                     token_usage: turn_token_usage.clone(),
                 });
             self.services.session_telemetry.histogram(
diff --git a/codex-rs/core/src/tasks/user_shell.rs b/codex-rs/core/src/tasks/user_shell.rs
index 15778b64d..e016a725c 100644
--- a/codex-rs/core/src/tasks/user_shell.rs
+++ b/codex-rs/core/src/tasks/user_shell.rs
@@ -126,7 +126,7 @@ pub(crate) async fn execute_user_shell_command(
     let display_command = session_shell.derive_exec_args(&command, use_login_shell);
     let mut exec_env_map = create_env(
         &turn_context.shell_environment_policy,
-        Some(session.conversation_id),
+        Some(session.thread_id),
     );
     if exec_env_map.contains_key(PROXY_ACTIVE_ENV_KEY) {
         strip_managed_proxy_env(&mut exec_env_map);
diff --git a/codex-rs/core/src/tools/handlers/agent_jobs.rs b/codex-rs/core/src/tools/handlers/agent_jobs.rs
index 48ba08743..25c8f9c4c 100644
--- a/codex-rs/core/src/tools/handlers/agent_jobs.rs
+++ b/codex-rs/core/src/tools/handlers/agent_jobs.rs
@@ -211,7 +211,7 @@ async fn run_agent_job_loop(
                             "agent_job:{job_id}"
                         )))),
                         SpawnAgentOptions {
-                            parent_thread_id: Some(session.conversation_id),
+                            parent_thread_id: Some(session.thread_id),
                             environments: Some(turn.environments.to_selections()),
                             ..Default::default()
                         },
diff --git a/codex-rs/core/src/tools/handlers/agent_jobs/report_agent_job_result.rs b/codex-rs/core/src/tools/handlers/agent_jobs/report_agent_job_result.rs
index 6f4463c6e..c7adb2761 100644
--- a/codex-rs/core/src/tools/handlers/agent_jobs/report_agent_job_result.rs
+++ b/codex-rs/core/src/tools/handlers/agent_jobs/report_agent_job_result.rs
@@ -61,7 +61,7 @@ pub async fn handle(
         ));
     }
     let db = required_state_db(&session)?;
-    let reporting_thread_id = session.conversation_id.to_string();
+    let reporting_thread_id = session.thread_id.to_string();
     let accepted = db
         .report_agent_job_item_result(
             args.job_id.as_str(),
diff --git a/codex-rs/core/src/tools/handlers/extension_tools.rs b/codex-rs/core/src/tools/handlers/extension_tools.rs
index 0a1e2e58c..ecbf772e9 100644
--- a/codex-rs/core/src/tools/handlers/extension_tools.rs
+++ b/codex-rs/core/src/tools/handlers/extension_tools.rs
@@ -486,7 +486,7 @@ mod tests {
         let (session, turn, rx) = crate::session::tests::make_session_and_context_with_rx().await;
         let expected_path = crate::stream_events_utils::image_generation_artifact_path(
             &turn.config.codex_home,
-            &session.conversation_id.to_string(),
+            &session.thread_id.to_string(),
             "call-image",
         );
         let invocation = ToolInvocation {
diff --git a/codex-rs/core/src/tools/handlers/multi_agents/close_agent.rs b/codex-rs/core/src/tools/handlers/multi_agents/close_agent.rs
index 2007e3df7..0d4e17447 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents/close_agent.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents/close_agent.rs
@@ -53,7 +53,7 @@ async fn handle_close_agent(
             CollabCloseBeginEvent {
                 call_id: call_id.clone(),
                 started_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 receiver_thread_id: agent_id,
             }
             .into(),
@@ -77,7 +77,7 @@ async fn handle_close_agent(
                     CollabCloseEndEvent {
                         call_id: call_id.clone(),
                         completed_at_ms: now_unix_timestamp_ms(),
-                        sender_thread_id: session.conversation_id,
+                        sender_thread_id: session.thread_id(),
                         receiver_thread_id: agent_id,
                         receiver_agent_nickname: receiver_agent.agent_nickname.clone(),
                         receiver_agent_role: receiver_agent.agent_role.clone(),
@@ -99,7 +99,7 @@ async fn handle_close_agent(
             CollabCloseEndEvent {
                 call_id,
                 completed_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 receiver_thread_id: agent_id,
                 receiver_agent_nickname: receiver_agent.agent_nickname,
                 receiver_agent_role: receiver_agent.agent_role,
diff --git a/codex-rs/core/src/tools/handlers/multi_agents/resume_agent.rs b/codex-rs/core/src/tools/handlers/multi_agents/resume_agent.rs
index 78b6aafb9..8f95abe4e 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents/resume_agent.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents/resume_agent.rs
@@ -66,7 +66,7 @@ async fn handle_resume_agent(
             CollabResumeBeginEvent {
                 call_id: call_id.clone(),
                 started_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 receiver_thread_id,
                 receiver_agent_nickname: receiver_agent.agent_nickname.clone(),
                 receiver_agent_role: receiver_agent.agent_role.clone(),
@@ -122,7 +122,7 @@ async fn handle_resume_agent(
             CollabResumeEndEvent {
                 call_id,
                 completed_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id(),
                 receiver_thread_id,
                 receiver_agent_nickname: receiver_agent.agent_nickname,
                 receiver_agent_role: receiver_agent.agent_role,
@@ -186,7 +186,7 @@ async fn try_resume_closed_agent(
         config,
         receiver_thread_id,
         thread_spawn_source(
-            session.conversation_id,
+            session.thread_id(),
             &turn.session_source,
             child_depth,
             /*agent_role*/ None,
diff --git a/codex-rs/core/src/tools/handlers/multi_agents/send_input.rs b/codex-rs/core/src/tools/handlers/multi_agents/send_input.rs
index d7f316ba3..1b7018939 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents/send_input.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents/send_input.rs
@@ -58,7 +58,7 @@ impl ToolExecutor<ToolInvocation> for Handler {
                 CollabAgentInteractionBeginEvent {
                     call_id: call_id.clone(),
                     started_at_ms: now_unix_timestamp_ms(),
-                    sender_thread_id: session.conversation_id,
+                    sender_thread_id: session.thread_id,
                     receiver_thread_id,
                     prompt: prompt.clone(),
                 }
@@ -81,7 +81,7 @@ impl ToolExecutor<ToolInvocation> for Handler {
                 CollabAgentInteractionEndEvent {
                     call_id,
                     completed_at_ms: now_unix_timestamp_ms(),
-                    sender_thread_id: session.conversation_id,
+                    sender_thread_id: session.thread_id,
                     receiver_thread_id,
                     receiver_agent_nickname: receiver_agent.agent_nickname,
                     receiver_agent_role: receiver_agent.agent_role,
diff --git a/codex-rs/core/src/tools/handlers/multi_agents/spawn.rs b/codex-rs/core/src/tools/handlers/multi_agents/spawn.rs
index 108ddd336..004dc973b 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents/spawn.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents/spawn.rs
@@ -80,7 +80,7 @@ async fn handle_spawn_agent(
             CollabAgentSpawnBeginEvent {
                 call_id: call_id.clone(),
                 started_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 prompt: prompt.clone(),
                 model: args.model.clone().unwrap_or_default(),
                 reasoning_effort: args.reasoning_effort.unwrap_or_default(),
@@ -121,7 +121,7 @@ async fn handle_spawn_agent(
         config,
         input_items,
         Some(thread_spawn_source(
-            session.conversation_id,
+            session.thread_id,
             &turn.session_source,
             child_depth,
             role_name,
@@ -130,7 +130,7 @@ async fn handle_spawn_agent(
         SpawnAgentOptions {
             fork_parent_spawn_call_id: args.fork_context.then(|| call_id.clone()),
             fork_mode: args.fork_context.then_some(SpawnAgentForkMode::FullHistory),
-            parent_thread_id: Some(session.conversation_id),
+            parent_thread_id: Some(session.thread_id),
             environments: Some(turn.environments.to_selections()),
         },
     ))
@@ -183,7 +183,7 @@ async fn handle_spawn_agent(
             CollabAgentSpawnEndEvent {
                 call_id,
                 completed_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 new_thread_id,
                 new_agent_nickname,
                 new_agent_role,
diff --git a/codex-rs/core/src/tools/handlers/multi_agents/wait.rs b/codex-rs/core/src/tools/handlers/multi_agents/wait.rs
index 063b06457..525ee7f2e 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents/wait.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents/wait.rs
@@ -96,7 +96,7 @@ impl ToolExecutor<ToolInvocation> for Handler {
                 &turn,
                 CollabWaitingBeginEvent {
                     started_at_ms: now_unix_timestamp_ms(),
-                    sender_thread_id: session.conversation_id,
+                    sender_thread_id: session.thread_id,
                     receiver_thread_ids: receiver_thread_ids.clone(),
                     receiver_agents: receiver_agents.clone(),
                     call_id: call_id.clone(),
@@ -126,7 +126,7 @@ impl ToolExecutor<ToolInvocation> for Handler {
                         .send_event(
                             &turn,
                             CollabWaitingEndEvent {
-                                sender_thread_id: session.conversation_id,
+                                sender_thread_id: session.thread_id,
                                 call_id: call_id.clone(),
                                 completed_at_ms: now_unix_timestamp_ms(),
                                 agent_statuses: build_wait_agent_statuses(
@@ -195,7 +195,7 @@ impl ToolExecutor<ToolInvocation> for Handler {
             .send_event(
                 &turn,
                 CollabWaitingEndEvent {
-                    sender_thread_id: session.conversation_id,
+                    sender_thread_id: session.thread_id,
                     call_id,
                     completed_at_ms: now_unix_timestamp_ms(),
                     agent_statuses,
diff --git a/codex-rs/core/src/tools/handlers/multi_agents_tests.rs b/codex-rs/core/src/tools/handlers/multi_agents_tests.rs
index 3d8e8401b..868847414 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents_tests.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents_tests.rs
@@ -310,7 +310,7 @@ async fn spawn_agent_fork_context_rejects_agent_type_override() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let err = SpawnAgentHandler::default()
         .handle(invocation(
             Arc::new(session),
@@ -343,7 +343,7 @@ async fn spawn_agent_fork_context_rejects_child_model_overrides() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
 
     let err = SpawnAgentHandler::default()
         .handle(invocation(
@@ -379,7 +379,7 @@ async fn multi_agent_v2_spawn_fork_turns_all_rejects_agent_type_override() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -424,7 +424,7 @@ async fn multi_agent_v2_spawn_defaults_to_full_fork_and_rejects_child_model_over
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -471,7 +471,7 @@ async fn spawn_agent_service_tier_override_validates_the_effective_child_model()
             .await
             .expect("root thread should start");
         session.services.agent_control = manager.agent_control();
-        session.conversation_id = root.thread_id;
+        session.thread_id = root.thread_id;
 
         let output = SpawnAgentHandler::default()
             .handle(invocation(
@@ -576,7 +576,7 @@ async fn spawn_agent_service_tier_inheritance_preserves_supported_or_configured_
             .await
             .expect("root thread should start");
         session.services.agent_control = manager.agent_control();
-        session.conversation_id = root.thread_id;
+        session.thread_id = root.thread_id;
 
         let output = SpawnAgentHandler::default()
             .handle(invocation(
@@ -617,7 +617,7 @@ async fn spawn_agent_service_tier_inheritance_preserves_supported_or_configured_
             .await
             .expect("root thread should start");
         session.services.agent_control = manager.agent_control();
-        session.conversation_id = root.thread_id;
+        session.thread_id = root.thread_id;
 
         let output = SpawnAgentHandler::default()
             .handle(invocation(
@@ -680,7 +680,7 @@ service_tier = "priority"
             .await
             .expect("root thread should start");
         session.services.agent_control = manager.agent_control();
-        session.conversation_id = root.thread_id;
+        session.thread_id = root.thread_id;
 
         let output = SpawnAgentHandler::default()
             .handle(invocation(
@@ -753,7 +753,7 @@ service_tier = "turbo"
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
 
     let output = SpawnAgentHandler::default()
         .handle(invocation(
@@ -850,7 +850,7 @@ async fn spawn_agent_full_history_fork_accepts_explicit_service_tier() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
 
     let output = SpawnAgentHandler::default()
         .handle(invocation(
@@ -904,7 +904,7 @@ async fn multi_agent_v2_full_history_fork_accepts_explicit_service_tier() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let session = Arc::new(session);
     let turn = Arc::new(turn);
 
@@ -928,7 +928,7 @@ async fn multi_agent_v2_full_history_fork_accepts_explicit_service_tier() {
         .services
         .agent_control
         .resolve_agent_reference(
-            session.conversation_id,
+            session.thread_id,
             &turn.session_source,
             result.task_name.as_str(),
         )
@@ -957,7 +957,7 @@ async fn multi_agent_v2_spawn_partial_fork_turns_allows_agent_type_override() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -1041,7 +1041,7 @@ async fn multi_agent_v2_spawn_requires_task_name() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -1075,7 +1075,7 @@ async fn multi_agent_v2_spawn_rejects_legacy_items_field() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -1135,7 +1135,7 @@ async fn multi_agent_v2_spawn_returns_path_and_send_message_accepts_relative_pat
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -1166,11 +1166,7 @@ async fn multi_agent_v2_spawn_returns_path_and_send_message_accepts_relative_pat
     let child_thread_id = session
         .services
         .agent_control
-        .resolve_agent_reference(
-            session.conversation_id,
-            &turn.session_source,
-            "test_process",
-        )
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "test_process")
         .await
         .expect("relative path should resolve");
     let child_snapshot = manager
@@ -1232,7 +1228,7 @@ async fn multi_agent_v2_spawn_rejects_legacy_fork_context() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -1272,7 +1268,7 @@ async fn multi_agent_v2_spawn_rejects_invalid_fork_turns_string() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -1312,7 +1308,7 @@ async fn multi_agent_v2_spawn_rejects_zero_fork_turns() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -1358,7 +1354,7 @@ async fn multi_agent_v2_send_message_accepts_root_target_from_child() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
 
     let child_path = AgentPath::try_from("/root/worker").expect("agent path");
     let child_thread_id = session
@@ -1383,7 +1379,7 @@ async fn multi_agent_v2_send_message_accepts_root_target_from_child() {
         .await
         .expect("worker spawn should succeed")
         .thread_id;
-    session.conversation_id = child_thread_id;
+    session.thread_id = child_thread_id;
     turn.session_source = SessionSource::SubAgent(SubAgentSource::ThreadSpawn {
         parent_thread_id: root.thread_id,
         depth: 1,
@@ -1434,7 +1430,7 @@ async fn multi_agent_v2_followup_task_rejects_root_target_from_child() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
 
     let child_path = AgentPath::try_from("/root/worker").expect("agent path");
     let child_thread_id = session
@@ -1459,7 +1455,7 @@ async fn multi_agent_v2_followup_task_rejects_root_target_from_child() {
         .await
         .expect("worker spawn should succeed")
         .thread_id;
-    session.conversation_id = child_thread_id;
+    session.thread_id = child_thread_id;
     turn.session_source = SessionSource::SubAgent(SubAgentSource::ThreadSpawn {
         parent_thread_id: root.thread_id,
         depth: 1,
@@ -1511,7 +1507,7 @@ async fn multi_agent_v2_list_agents_returns_completed_status_and_last_task_messa
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     let _ = config.features.enable(Feature::MultiAgentV2);
     set_turn_config(&mut turn, config);
@@ -1535,7 +1531,7 @@ async fn multi_agent_v2_list_agents_returns_completed_status_and_last_task_messa
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker path should resolve");
     let child_thread = manager
@@ -1608,7 +1604,7 @@ async fn multi_agent_v2_list_agents_filters_by_relative_path_prefix() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
 
     let researcher_path = AgentPath::from_string("/root/researcher".to_string()).expect("path");
     let worker_path = AgentPath::from_string("/root/researcher/worker".to_string()).expect("path");
@@ -1692,7 +1688,7 @@ async fn multi_agent_v2_list_agents_omits_closed_agents() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     let _ = config.features.enable(Feature::MultiAgentV2);
     set_turn_config(&mut turn, config);
@@ -1716,7 +1712,7 @@ async fn multi_agent_v2_list_agents_omits_closed_agents() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker path should resolve");
     session
@@ -1756,7 +1752,7 @@ async fn multi_agent_v2_send_message_rejects_legacy_items_field() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = turn.config.as_ref().clone();
     let _ = config.features.enable(Feature::MultiAgentV2);
     set_turn_config(&mut turn, config);
@@ -1778,7 +1774,7 @@ async fn multi_agent_v2_send_message_rejects_legacy_items_field() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker should resolve");
     let invocation = invocation(
@@ -1812,7 +1808,7 @@ async fn multi_agent_v2_send_message_rejects_interrupt_parameter() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = turn.config.as_ref().clone();
     let _ = config.features.enable(Feature::MultiAgentV2);
     set_turn_config(&mut turn, config);
@@ -1834,7 +1830,7 @@ async fn multi_agent_v2_send_message_rejects_interrupt_parameter() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker should resolve");
 
@@ -1891,7 +1887,7 @@ async fn multi_agent_v2_followup_task_completion_notifies_parent_on_every_turn()
     // and stored its runtime; mirror that before using the synthetic handler.
     root.thread.codex.session.new_default_turn().await;
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let session = Arc::new(session);
     let turn = Arc::new(turn);
 
@@ -1910,7 +1906,7 @@ async fn multi_agent_v2_followup_task_completion_notifies_parent_on_every_turn()
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker should resolve");
     let thread = manager
@@ -2023,7 +2019,7 @@ async fn multi_agent_v2_followup_task_rejects_legacy_items_field() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = turn.config.as_ref().clone();
     let _ = config.features.enable(Feature::MultiAgentV2);
     set_turn_config(&mut turn, config);
@@ -2045,7 +2041,7 @@ async fn multi_agent_v2_followup_task_rejects_legacy_items_field() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker should resolve");
     let invocation = invocation(
@@ -2076,7 +2072,7 @@ async fn multi_agent_v2_interrupted_turn_does_not_notify_parent() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = turn.config.as_ref().clone();
     let _ = config.features.enable(Feature::MultiAgentV2);
     set_turn_config(&mut turn, config);
@@ -2098,7 +2094,7 @@ async fn multi_agent_v2_interrupted_turn_does_not_notify_parent() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker should resolve");
     let thread = manager
@@ -2153,7 +2149,7 @@ async fn multi_agent_v2_spawn_omits_agent_id_when_named() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -2192,7 +2188,7 @@ async fn multi_agent_v2_spawn_surfaces_task_name_validation_errors() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -2316,7 +2312,7 @@ async fn spawn_agent_rejects_when_depth_limit_exceeded() {
 
     let max_depth = turn.config.agent_max_depth;
     turn.session_source = SessionSource::SubAgent(SubAgentSource::ThreadSpawn {
-        parent_thread_id: session.conversation_id,
+        parent_thread_id: session.thread_id,
         depth: max_depth,
         agent_path: None,
         agent_nickname: None,
@@ -2356,7 +2352,7 @@ async fn spawn_agent_allows_depth_up_to_configured_max_depth() {
     config.agent_max_depth = DEFAULT_AGENT_MAX_DEPTH + 1;
     turn.config = Arc::new(config);
     turn.session_source = SessionSource::SubAgent(SubAgentSource::ThreadSpawn {
-        parent_thread_id: session.conversation_id,
+        parent_thread_id: session.thread_id,
         depth: DEFAULT_AGENT_MAX_DEPTH,
         agent_path: None,
         agent_nickname: None,
@@ -2407,7 +2403,7 @@ async fn multi_agent_v2_spawn_agent_ignores_configured_max_depth() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     set_turn_config(&mut turn, config);
     let parent_path = AgentPath::try_from("/root/parent").expect("agent path");
     turn.session_source = SessionSource::SubAgent(SubAgentSource::ThreadSpawn {
@@ -2785,7 +2781,7 @@ async fn resume_agent_rejects_when_depth_limit_exceeded() {
 
     let max_depth = turn.config.agent_max_depth;
     turn.session_source = SessionSource::SubAgent(SubAgentSource::ThreadSpawn {
-        parent_thread_id: session.conversation_id,
+        parent_thread_id: session.thread_id,
         depth: max_depth,
         agent_path: None,
         agent_nickname: None,
@@ -2875,7 +2871,7 @@ async fn multi_agent_v2_wait_agent_accepts_timeout_only_argument() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -2900,7 +2896,7 @@ async fn multi_agent_v2_wait_agent_accepts_timeout_only_argument() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker should resolve");
     let worker_path = session
@@ -3358,7 +3354,7 @@ async fn multi_agent_v2_wait_agent_returns_summary_for_mailbox_activity() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -3385,11 +3381,7 @@ async fn multi_agent_v2_wait_agent_returns_summary_for_mailbox_activity() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(
-            session.conversation_id,
-            &turn.session_source,
-            "test_process",
-        )
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "test_process")
         .await
         .expect("relative path should resolve");
     let worker_path = session
@@ -3452,7 +3444,7 @@ async fn multi_agent_v2_wait_agent_returns_for_already_queued_mail() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -3477,7 +3469,7 @@ async fn multi_agent_v2_wait_agent_returns_for_already_queued_mail() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker should resolve");
     let worker_path = session
@@ -3533,7 +3525,7 @@ async fn multi_agent_v2_wait_agent_wakes_on_any_mailbox_notification() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -3560,7 +3552,7 @@ async fn multi_agent_v2_wait_agent_wakes_on_any_mailbox_notification() {
     let worker_b_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker_b")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker_b")
         .await
         .expect("worker_b should resolve");
     let worker_b_path = session
@@ -3624,7 +3616,7 @@ async fn multi_agent_v2_wait_agent_does_not_return_completed_content() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -3649,7 +3641,7 @@ async fn multi_agent_v2_wait_agent_does_not_return_completed_content() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker should resolve");
     let worker_path = session
@@ -3713,7 +3705,7 @@ async fn multi_agent_v2_close_agent_accepts_task_name_target() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
@@ -3739,7 +3731,7 @@ async fn multi_agent_v2_close_agent_accepts_task_name_target() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker path should resolve");
 
@@ -3791,7 +3783,7 @@ async fn multi_agent_v2_close_agent_reaps_stale_task_name_target() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     set_turn_config(&mut turn, config.clone());
 
     let session = Arc::new(session);
@@ -3812,7 +3804,7 @@ async fn multi_agent_v2_close_agent_reaps_stale_task_name_target() {
     let agent_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "worker")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "worker")
         .await
         .expect("worker path should resolve");
     let stale_thread = manager
@@ -3872,7 +3864,7 @@ async fn multi_agent_v2_close_agent_reaps_stale_task_name_target() {
     let replacement_id = session
         .services
         .agent_control
-        .resolve_agent_reference(session.conversation_id, &turn.session_source, "replacement")
+        .resolve_agent_reference(session.thread_id, &turn.session_source, "replacement")
         .await
         .expect("replacement path should resolve");
     let _ = session
@@ -3892,7 +3884,7 @@ async fn multi_agent_v2_close_agent_rejects_root_target_and_id() {
         .await
         .expect("root thread should start");
     session.services.agent_control = manager.agent_control();
-    session.conversation_id = root.thread_id;
+    session.thread_id = root.thread_id;
     let mut config = (*turn.config).clone();
     config
         .features
diff --git a/codex-rs/core/src/tools/handlers/multi_agents_v2/close_agent.rs b/codex-rs/core/src/tools/handlers/multi_agents_v2/close_agent.rs
index 0f7238cdb..756a1862b 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents_v2/close_agent.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents_v2/close_agent.rs
@@ -61,7 +61,7 @@ async fn handle_close_agent(
             CollabCloseBeginEvent {
                 call_id: call_id.clone(),
                 started_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 receiver_thread_id: agent_id,
             }
             .into(),
@@ -85,7 +85,7 @@ async fn handle_close_agent(
                     CollabCloseEndEvent {
                         call_id: call_id.clone(),
                         completed_at_ms: now_unix_timestamp_ms(),
-                        sender_thread_id: session.conversation_id,
+                        sender_thread_id: session.thread_id,
                         receiver_thread_id: agent_id,
                         receiver_agent_nickname: receiver_agent.agent_nickname.clone(),
                         receiver_agent_role: receiver_agent.agent_role.clone(),
@@ -110,7 +110,7 @@ async fn handle_close_agent(
             CollabCloseEndEvent {
                 call_id,
                 completed_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 receiver_thread_id: agent_id,
                 receiver_agent_nickname: receiver_agent.agent_nickname,
                 receiver_agent_role: receiver_agent.agent_role,
diff --git a/codex-rs/core/src/tools/handlers/multi_agents_v2/list_agents.rs b/codex-rs/core/src/tools/handlers/multi_agents_v2/list_agents.rs
index 6abf9a30c..46b29bdf1 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents_v2/list_agents.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents_v2/list_agents.rs
@@ -30,7 +30,7 @@ impl ToolExecutor<ToolInvocation> for Handler {
         session
             .services
             .agent_control
-            .register_session_root(session.conversation_id, turn.parent_thread_id);
+            .register_session_root(session.thread_id, turn.parent_thread_id);
         let agents = session
             .services
             .agent_control
diff --git a/codex-rs/core/src/tools/handlers/multi_agents_v2/message_tool.rs b/codex-rs/core/src/tools/handlers/multi_agents_v2/message_tool.rs
index 3226c4532..258d80c85 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents_v2/message_tool.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents_v2/message_tool.rs
@@ -91,7 +91,7 @@ pub(crate) async fn handle_message_string_tool(
             CollabAgentInteractionBeginEvent {
                 call_id: call_id.clone(),
                 started_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 receiver_thread_id,
                 prompt: prompt.clone(),
             }
@@ -127,7 +127,7 @@ pub(crate) async fn handle_message_string_tool(
             CollabAgentInteractionEndEvent {
                 call_id,
                 completed_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 receiver_thread_id,
                 receiver_agent_nickname: receiver_agent.agent_nickname,
                 receiver_agent_role: receiver_agent.agent_role,
diff --git a/codex-rs/core/src/tools/handlers/multi_agents_v2/spawn.rs b/codex-rs/core/src/tools/handlers/multi_agents_v2/spawn.rs
index ed85d329b..d0fb6c515 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents_v2/spawn.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents_v2/spawn.rs
@@ -72,7 +72,7 @@ async fn handle_spawn_agent(
             CollabAgentSpawnBeginEvent {
                 call_id: call_id.clone(),
                 started_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 prompt: prompt.clone(),
                 model: args.model.clone().unwrap_or_default(),
                 reasoning_effort: args.reasoning_effort.unwrap_or_default(),
@@ -110,7 +110,7 @@ async fn handle_spawn_agent(
     apply_spawn_agent_runtime_overrides(&mut config, turn.as_ref())?;
 
     let spawn_source = thread_spawn_source(
-        session.conversation_id,
+        session.thread_id,
         &turn.session_source,
         child_depth,
         role_name,
@@ -143,7 +143,7 @@ async fn handle_spawn_agent(
             SpawnAgentOptions {
                 fork_parent_spawn_call_id: fork_mode.as_ref().map(|_| call_id.clone()),
                 fork_mode,
-                parent_thread_id: Some(session.conversation_id),
+                parent_thread_id: Some(session.thread_id),
                 environments: Some(turn.environments.to_selections()),
             },
         ),
@@ -197,7 +197,7 @@ async fn handle_spawn_agent(
             CollabAgentSpawnEndEvent {
                 call_id,
                 completed_at_ms: now_unix_timestamp_ms(),
-                sender_thread_id: session.conversation_id,
+                sender_thread_id: session.thread_id,
                 new_thread_id,
                 new_agent_nickname,
                 new_agent_role,
diff --git a/codex-rs/core/src/tools/handlers/multi_agents_v2/wait.rs b/codex-rs/core/src/tools/handlers/multi_agents_v2/wait.rs
index 0aba86782..5e37725b7 100644
--- a/codex-rs/core/src/tools/handlers/multi_agents_v2/wait.rs
+++ b/codex-rs/core/src/tools/handlers/multi_agents_v2/wait.rs
@@ -67,7 +67,7 @@ impl ToolExecutor<ToolInvocation> for Handler {
                 &turn,
                 CollabWaitingBeginEvent {
                     started_at_ms: now_unix_timestamp_ms(),
-                    sender_thread_id: session.conversation_id,
+                    sender_thread_id: session.thread_id,
                     receiver_thread_ids: Vec::new(),
                     receiver_agents: Vec::new(),
                     call_id: call_id.clone(),
@@ -84,7 +84,7 @@ impl ToolExecutor<ToolInvocation> for Handler {
             .send_event(
                 &turn,
                 CollabWaitingEndEvent {
-                    sender_thread_id: session.conversation_id,
+                    sender_thread_id: session.thread_id,
                     call_id,
                     completed_at_ms: now_unix_timestamp_ms(),
                     agent_statuses: Vec::new(),
diff --git a/codex-rs/core/src/tools/handlers/request_plugin_install.rs b/codex-rs/core/src/tools/handlers/request_plugin_install.rs
index 51032b27c..3f7bd92d2 100644
--- a/codex-rs/core/src/tools/handlers/request_plugin_install.rs
+++ b/codex-rs/core/src/tools/handlers/request_plugin_install.rs
@@ -121,7 +121,7 @@ impl ToolExecutor<ToolInvocation> for RequestPluginInstallHandler {
         let request_id = RequestId::String(format!("request_plugin_install_{call_id}").into());
         let params = build_request_plugin_install_elicitation_request(
             CODEX_APPS_MCP_SERVER_NAME,
-            session.conversation_id.to_string(),
+            session.thread_id.to_string(),
             turn.sub_id.clone(),
             &args,
             suggest_reason,
diff --git a/codex-rs/core/src/tools/handlers/shell/shell_command.rs b/codex-rs/core/src/tools/handlers/shell/shell_command.rs
index 8a501c711..b4b60997d 100644
--- a/codex-rs/core/src/tools/handlers/shell/shell_command.rs
+++ b/codex-rs/core/src/tools/handlers/shell/shell_command.rs
@@ -179,7 +179,7 @@ impl ToolExecutor<ToolInvocation> for ShellCommandHandler {
             &params,
             session.as_ref(),
             turn.as_ref(),
-            session.conversation_id,
+            session.thread_id,
             turn.config.permissions.allow_login_shell,
         )?;
         let shell_type = Some(session.user_shell().shell_type.clone());
diff --git a/codex-rs/core/src/tools/handlers/shell_tests.rs b/codex-rs/core/src/tools/handlers/shell_tests.rs
index eda23533a..792eb2bb1 100644
--- a/codex-rs/core/src/tools/handlers/shell_tests.rs
+++ b/codex-rs/core/src/tools/handlers/shell_tests.rs
@@ -92,7 +92,7 @@ async fn shell_command_handler_to_exec_params_uses_session_shell_and_turn_contex
     let expected_cwd = turn_context.resolve_path(workdir.clone());
     let expected_env = create_env(
         &turn_context.shell_environment_policy,
-        Some(session.conversation_id),
+        Some(session.thread_id),
     );
 
     let params = ShellCommandToolCallParams {
@@ -110,7 +110,7 @@ async fn shell_command_handler_to_exec_params_uses_session_shell_and_turn_contex
         &params,
         &session,
         &turn_context,
-        session.conversation_id,
+        session.thread_id,
         /*allow_login_shell*/ true,
     )
     .expect("login shells should be allowed");
@@ -177,7 +177,7 @@ async fn shell_command_handler_defaults_to_non_login_when_disallowed() {
         &params,
         &session,
         &turn_context,
-        session.conversation_id,
+        session.thread_id,
         /*allow_login_shell*/ false,
     )
     .expect("non-login shells should still be allowed");
diff --git a/codex-rs/core/src/tools/tool_dispatch_trace.rs b/codex-rs/core/src/tools/tool_dispatch_trace.rs
index 522e3cd1d..098dc8dde 100644
--- a/codex-rs/core/src/tools/tool_dispatch_trace.rs
+++ b/codex-rs/core/src/tools/tool_dispatch_trace.rs
@@ -74,7 +74,7 @@ fn tool_dispatch_invocation(invocation: &ToolInvocation) -> Option<ToolDispatchI
     };
 
     Some(ToolDispatchInvocation {
-        thread_id: invocation.session.conversation_id.to_string(),
+        thread_id: invocation.session.thread_id.to_string(),
         codex_turn_id: invocation.turn.sub_id.clone(),
         tool_call_id: invocation.call_id.clone(),
         tool_name: invocation.tool_name.name.clone(),
diff --git a/codex-rs/core/src/tools/tool_dispatch_trace_tests.rs b/codex-rs/core/src/tools/tool_dispatch_trace_tests.rs
index 774a393aa..69dc8ab58 100644
--- a/codex-rs/core/src/tools/tool_dispatch_trace_tests.rs
+++ b/codex-rs/core/src/tools/tool_dispatch_trace_tests.rs
@@ -284,7 +284,7 @@ fn test_invocation_with_payload(
 }
 
 fn attach_test_trace(session: &mut Session, turn: &TurnContext, root: &Path) -> anyhow::Result<()> {
-    let thread_id = session.conversation_id;
+    let thread_id = session.thread_id;
     let rollout_thread_trace =
         codex_rollout_trace::ThreadTraceContext::start_root_in_root_for_test(
             root,
diff --git a/codex-rs/core/src/unified_exec/process_manager.rs b/codex-rs/core/src/unified_exec/process_manager.rs
index 563d486c6..66b8b49a8 100644
--- a/codex-rs/core/src/unified_exec/process_manager.rs
+++ b/codex-rs/core/src/unified_exec/process_manager.rs
@@ -1002,7 +1002,7 @@ impl UnifiedExecProcessManager {
         let mut env = local_policy_env.clone();
         env.insert(
             CODEX_THREAD_ID_ENV_VAR.to_string(),
-            context.session.conversation_id.to_string(),
+            context.session.thread_id.to_string(),
         );
         let env = apply_unified_exec_env(env);
         let exec_server_env_config = ExecServerEnvConfig {