[codex] Trim unused TurnContextItem fields (#22709)

## Why

`TurnContextItem` is the durable baseline used to reconstruct context
diffs across resume/fork. Most of the old persisted-only fields on it
are no longer read, so keeping them in rollout snapshots adds schema
surface and state that can drift without affecting reconstruction.

`summary` is the exception: older Codex versions require it to
deserialize `turn_context` records, so keep writing a default
compatibility value until that schema surface can be removed safely.

## What changed

- Removed the unused persisted fields from `TurnContextItem`: trace ids,
user/developer instructions, output schema, and truncation policy.
- Kept `summary` with a compatibility comment and made
`TurnContext::to_turn_context_item` write `ReasoningSummary::Auto`
instead of live turn state.
- Updated rollout/context reconstruction fixtures for the retained
summary field.

## Verification

- `cargo test -p codex-protocol --lib turn_context_item`
- `cargo test -p codex-rollout
resume_candidate_matches_cwd_reads_latest_turn_context`
- `cargo test -p codex-state turn_context`
- `cargo test -p codex-core --lib
new_default_turn_captures_current_span_trace_id`
- `cargo test -p codex-core --lib
record_initial_history_resumed_turn_context_after_compaction_reestablishes_reference_context_item`
- `cargo test -p codex-core --test all
emits_warning_when_resumed_model_differs`
- `git diff --check`

codex-rs/core/src/context_manager/history_tests.rs

@@ -2,7 +2,6 @@ use super::*;
 use base64::Engine;
 use base64::engine::general_purpose::STANDARD as BASE64_STANDARD;
 use codex_protocol::AgentPath;
-use codex_protocol::config_types::ReasoningSummary;
 use codex_protocol::models::BaseInstructions;
 use codex_protocol::models::ContentItem;
 use codex_protocol::models::DEFAULT_IMAGE_DETAIL;
@@ -121,7 +120,6 @@ fn developer_msg_with_fragments(texts: &[&str]) -> ResponseItem {
 fn reference_context_item() -> TurnContextItem {
     TurnContextItem {
         turn_id: Some("reference-turn".to_string()),
-        trace_id: None,
         cwd: PathBuf::from("/tmp/reference-cwd"),
         current_date: Some("2026-03-23".to_string()),
         timezone: Some("America/Los_Angeles".to_string()),
@@ -135,11 +133,7 @@ fn reference_context_item() -> TurnContextItem {
         collaboration_mode: None,
         realtime_active: Some(false),
         effort: None,
-        summary: ReasoningSummary::Auto,
+        summary: codex_protocol::config_types::ReasoningSummary::Auto,
-        user_instructions: None,
-        developer_instructions: None,
-        final_output_json_schema: None,
-        truncation_policy: Some(codex_protocol::protocol::TruncationPolicy::Tokens(10_000)),
     }
 }
 

codex-rs/core/src/session/rollout_reconstruction_tests.rs

@@ -59,7 +59,6 @@ async fn record_initial_history_resumed_bare_turn_context_does_not_hydrate_previ
     let previous_model = "previous-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
-        trace_id: turn_context.trace_id.clone(),
         #[allow(deprecated)]
         cwd: turn_context.cwd.to_path_buf(),
         current_date: turn_context.current_date.clone(),
@@ -74,11 +73,7 @@ async fn record_initial_history_resumed_bare_turn_context_does_not_hydrate_previ
         collaboration_mode: Some(turn_context.collaboration_mode.clone()),
         realtime_active: Some(turn_context.realtime_active),
         effort: turn_context.reasoning_effort,
-        summary: turn_context.reasoning_summary,
+        summary: codex_protocol::config_types::ReasoningSummary::Auto,
-        user_instructions: None,
-        developer_instructions: None,
-        final_output_json_schema: None,
-        truncation_policy: Some(turn_context.truncation_policy),
     };
     let rollout_items = vec![RolloutItem::TurnContext(previous_context_item)];
 
@@ -101,7 +96,6 @@ async fn record_initial_history_resumed_hydrates_previous_turn_settings_from_lif
     let previous_model = "previous-rollout-model";
     let mut previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
-        trace_id: turn_context.trace_id.clone(),
         #[allow(deprecated)]
         cwd: turn_context.cwd.to_path_buf(),
         current_date: turn_context.current_date.clone(),
@@ -116,11 +110,7 @@ async fn record_initial_history_resumed_hydrates_previous_turn_settings_from_lif
         collaboration_mode: Some(turn_context.collaboration_mode.clone()),
         realtime_active: Some(turn_context.realtime_active),
         effort: turn_context.reasoning_effort,
-        summary: turn_context.reasoning_summary,
+        summary: codex_protocol::config_types::ReasoningSummary::Auto,
-        user_instructions: None,
-        developer_instructions: None,
-        final_output_json_schema: None,
-        truncation_policy: Some(turn_context.truncation_policy),
     };
     let turn_id = previous_context_item
         .turn_id
@@ -925,7 +915,6 @@ async fn record_initial_history_resumed_turn_context_after_compaction_reestablis
     let previous_model = "previous-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
-        trace_id: turn_context.trace_id.clone(),
         #[allow(deprecated)]
         cwd: turn_context.cwd.to_path_buf(),
         current_date: turn_context.current_date.clone(),
@@ -940,11 +929,7 @@ async fn record_initial_history_resumed_turn_context_after_compaction_reestablis
         collaboration_mode: Some(turn_context.collaboration_mode.clone()),
         realtime_active: Some(turn_context.realtime_active),
         effort: turn_context.reasoning_effort,
-        summary: turn_context.reasoning_summary,
+        summary: codex_protocol::config_types::ReasoningSummary::Auto,
-        user_instructions: None,
-        developer_instructions: None,
-        final_output_json_schema: None,
-        truncation_policy: Some(turn_context.truncation_policy),
     };
     let previous_turn_id = previous_context_item
         .turn_id
@@ -1005,7 +990,6 @@ async fn record_initial_history_resumed_turn_context_after_compaction_reestablis
             .expect("serialize seeded reference context item"),
         serde_json::to_value(Some(TurnContextItem {
             turn_id: Some(turn_context.sub_id.clone()),
-            trace_id: turn_context.trace_id.clone(),
             #[allow(deprecated)]
             cwd: turn_context.cwd.to_path_buf(),
             current_date: turn_context.current_date.clone(),
@@ -1020,11 +1004,7 @@ async fn record_initial_history_resumed_turn_context_after_compaction_reestablis
             collaboration_mode: Some(turn_context.collaboration_mode.clone()),
             realtime_active: Some(turn_context.realtime_active),
             effort: turn_context.reasoning_effort,
-            summary: turn_context.reasoning_summary,
+            summary: codex_protocol::config_types::ReasoningSummary::Auto,
-            user_instructions: None,
-            developer_instructions: None,
-            final_output_json_schema: None,
-            truncation_policy: Some(turn_context.truncation_policy),
         }))
         .expect("serialize expected reference context item")
     );
@@ -1037,7 +1017,6 @@ async fn record_initial_history_resumed_aborted_turn_without_id_clears_active_tu
     let previous_model = "previous-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
-        trace_id: turn_context.trace_id.clone(),
         #[allow(deprecated)]
         cwd: turn_context.cwd.to_path_buf(),
         current_date: turn_context.current_date.clone(),
@@ -1052,11 +1031,7 @@ async fn record_initial_history_resumed_aborted_turn_without_id_clears_active_tu
         collaboration_mode: Some(turn_context.collaboration_mode.clone()),
         realtime_active: Some(turn_context.realtime_active),
         effort: turn_context.reasoning_effort,
-        summary: turn_context.reasoning_summary,
+        summary: codex_protocol::config_types::ReasoningSummary::Auto,
-        user_instructions: None,
-        developer_instructions: None,
-        final_output_json_schema: None,
-        truncation_policy: Some(turn_context.truncation_policy),
     };
     let previous_turn_id = previous_context_item
         .turn_id
@@ -1155,7 +1130,6 @@ async fn record_initial_history_resumed_unmatched_abort_preserves_active_turn_fo
     let unmatched_abort_turn_id = "other-turn".to_string();
     let current_context_item = TurnContextItem {
         turn_id: Some(current_turn_id.clone()),
-        trace_id: turn_context.trace_id.clone(),
         #[allow(deprecated)]
         cwd: turn_context.cwd.to_path_buf(),
         current_date: turn_context.current_date.clone(),
@@ -1170,11 +1144,7 @@ async fn record_initial_history_resumed_unmatched_abort_preserves_active_turn_fo
         collaboration_mode: Some(turn_context.collaboration_mode.clone()),
         realtime_active: Some(turn_context.realtime_active),
         effort: turn_context.reasoning_effort,
-        summary: turn_context.reasoning_summary,
+        summary: codex_protocol::config_types::ReasoningSummary::Auto,
-        user_instructions: None,
-        developer_instructions: None,
-        final_output_json_schema: None,
-        truncation_policy: Some(turn_context.truncation_policy),
     };
 
     let rollout_items = vec![
@@ -1272,7 +1242,6 @@ async fn record_initial_history_resumed_trailing_incomplete_turn_compaction_clea
     let previous_model = "previous-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
-        trace_id: turn_context.trace_id.clone(),
         #[allow(deprecated)]
         cwd: turn_context.cwd.to_path_buf(),
         current_date: turn_context.current_date.clone(),
@@ -1287,11 +1256,7 @@ async fn record_initial_history_resumed_trailing_incomplete_turn_compaction_clea
         collaboration_mode: Some(turn_context.collaboration_mode.clone()),
         realtime_active: Some(turn_context.realtime_active),
         effort: turn_context.reasoning_effort,
-        summary: turn_context.reasoning_summary,
+        summary: codex_protocol::config_types::ReasoningSummary::Auto,
-        user_instructions: None,
-        developer_instructions: None,
-        final_output_json_schema: None,
-        truncation_policy: Some(turn_context.truncation_policy),
     };
     let previous_turn_id = previous_context_item
         .turn_id
@@ -1428,7 +1393,6 @@ async fn record_initial_history_resumed_replaced_incomplete_compacted_turn_clear
     let previous_model = "previous-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
-        trace_id: turn_context.trace_id.clone(),
         #[allow(deprecated)]
         cwd: turn_context.cwd.to_path_buf(),
         current_date: turn_context.current_date.clone(),
@@ -1443,11 +1407,7 @@ async fn record_initial_history_resumed_replaced_incomplete_compacted_turn_clear
         collaboration_mode: Some(turn_context.collaboration_mode.clone()),
         realtime_active: Some(turn_context.realtime_active),
         effort: turn_context.reasoning_effort,
-        summary: turn_context.reasoning_summary,
+        summary: codex_protocol::config_types::ReasoningSummary::Auto,
-        user_instructions: None,
-        developer_instructions: None,
-        final_output_json_schema: None,
-        truncation_policy: Some(turn_context.truncation_policy),
     };
     let previous_turn_id = previous_context_item
         .turn_id

codex-rs/core/src/session/tests.rs

@@ -2317,7 +2317,6 @@ async fn record_initial_history_forked_hydrates_previous_turn_settings() {
     let previous_model = "forked-rollout-model";
     let previous_context_item = TurnContextItem {
         turn_id: Some(turn_context.sub_id.clone()),
-        trace_id: turn_context.trace_id.clone(),
         #[allow(deprecated)]
         cwd: turn_context.cwd.to_path_buf(),
         current_date: turn_context.current_date.clone(),
@@ -2332,11 +2331,7 @@ async fn record_initial_history_forked_hydrates_previous_turn_settings() {
         collaboration_mode: Some(turn_context.collaboration_mode.clone()),
         realtime_active: Some(turn_context.realtime_active),
         effort: turn_context.reasoning_effort,
-        summary: turn_context.reasoning_summary,
+        summary: codex_protocol::config_types::ReasoningSummary::Auto,
-        user_instructions: None,
-        developer_instructions: None,
-        final_output_json_schema: None,
-        truncation_policy: Some(turn_context.truncation_policy),
     };
     let turn_id = previous_context_item
         .turn_id
@@ -5125,7 +5120,7 @@ async fn new_default_turn_captures_current_span_trace_id() {
         &request_parent
     ));
 
-    let turn_context_item = async {
+    let turn_trace_id = async {
         let expected_trace_id = Span::current()
             .context()
             .span()
@@ -5133,15 +5128,14 @@ async fn new_default_turn_captures_current_span_trace_id() {
             .trace_id()
             .to_string();
         let turn_context = session.new_default_turn().await;
-        let turn_context_item = turn_context.to_turn_context_item();
+        assert_eq!(turn_context.trace_id, Some(expected_trace_id));
-        assert_eq!(turn_context_item.trace_id, Some(expected_trace_id));
+        turn_context.trace_id.clone()
-        turn_context_item
     }
     .instrument(request_span)
     .await;
 
     assert_eq!(
-        turn_context_item.trace_id.as_deref(),
+        turn_trace_id.as_deref(),
         Some("00000000000000000000000000000011")
     );
 }

codex-rs/core/src/session/turn_context.rs

@@ -368,7 +368,6 @@ impl TurnContext {
     pub(crate) fn to_turn_context_item(&self) -> TurnContextItem {
         TurnContextItem {
             turn_id: Some(self.sub_id.clone()),
-            trace_id: self.trace_id.clone(),
             #[allow(deprecated)]
             cwd: self.cwd.to_path_buf(),
             current_date: self.current_date.clone(),
@@ -383,11 +382,7 @@ impl TurnContext {
             collaboration_mode: Some(self.collaboration_mode.clone()),
             realtime_active: Some(self.realtime_active),
             effort: self.reasoning_effort,
-            summary: self.reasoning_summary,
+            summary: ReasoningSummaryConfig::Auto,
-            user_instructions: self.user_instructions.clone(),
-            developer_instructions: self.developer_instructions.clone(),
-            final_output_json_schema: self.final_output_json_schema.clone(),
-            truncation_policy: Some(self.truncation_policy),
         }
     }
 

codex-rs/core/tests/suite/resume_warning.rs

@@ -27,7 +27,6 @@ fn resume_history(
     let turn_id = "resume-warning-seed-turn".to_string();
     let turn_ctx = TurnContextItem {
         turn_id: Some(turn_id.clone()),
-        trace_id: None,
         cwd: config.cwd.to_path_buf(),
         current_date: None,
         timezone: None,
@@ -44,10 +43,6 @@ fn resume_history(
         summary: config
             .model_reasoning_summary
             .unwrap_or(ReasoningSummary::Auto),
-        user_instructions: None,
-        developer_instructions: None,
-        final_output_json_schema: None,
-        truncation_policy: None,
     };
 
     InitialHistory::Resumed(ResumedHistory {

codex-rs/protocol/src/protocol.rs

@@ -2824,8 +2824,6 @@ pub struct TurnContextNetworkItem {
 pub struct TurnContextItem {
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub turn_id: Option<String>,
-    #[serde(default, skip_serializing_if = "Option::is_none")]
-    pub trace_id: Option<String>,
     pub cwd: PathBuf,
     #[serde(default, skip_serializing_if = "Option::is_none")]
     pub current_date: Option<String>,
@@ -2848,15 +2846,11 @@ pub struct TurnContextItem {
     pub realtime_active: Option<bool>,
     #[serde(skip_serializing_if = "Option::is_none")]
     pub effort: Option<ReasoningEffortConfig>,
+    // Compatibility-only field written with a default value so older Codex
+    // versions can deserialize turn-context rollout items. It is no longer
+    // read by context reconstruction and should be removed in a future schema
+    // cleanup.
     pub summary: ReasoningSummaryConfig,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub user_instructions: Option<String>,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub developer_instructions: Option<String>,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub final_output_json_schema: Option<Value>,
-    #[serde(skip_serializing_if = "Option::is_none")]
-    pub truncation_policy: Option<TruncationPolicy>,
 }
 
 impl TurnContextItem {
@@ -5246,7 +5240,6 @@ mod tests {
             "summary": "auto",
         }))?;
 
-        assert_eq!(item.trace_id, None);
         assert_eq!(item.network, None);
         assert_eq!(item.file_system_sandbox_policy, None);
         Ok(())
@@ -5256,7 +5249,6 @@ mod tests {
     fn turn_context_item_serializes_network_when_present() -> Result<()> {
         let item = TurnContextItem {
             turn_id: None,
-            trace_id: None,
             cwd: test_path_buf("/tmp"),
             current_date: None,
             timezone: None,
@@ -5281,10 +5273,6 @@ mod tests {
             realtime_active: None,
             effort: None,
             summary: ReasoningSummaryConfig::Auto,
-            user_instructions: None,
-            developer_instructions: None,
-            final_output_json_schema: None,
-            truncation_policy: None,
         };
 
         let value = serde_json::to_value(item)?;
@@ -5308,6 +5296,7 @@ mod tests {
                 }]
             })
         );
+        assert_eq!(value["summary"], json!("auto"));
         Ok(())
     }
 

codex-rs/rollout/src/recorder_tests.rs

@@ -4,7 +4,6 @@ use super::*;
 use crate::config::RolloutConfig;
 use chrono::TimeZone;
 use codex_protocol::ThreadId;
-use codex_protocol::config_types::ReasoningSummary as ReasoningSummaryConfig;
 use codex_protocol::models::ResponseItem;
 use codex_protocol::protocol::AgentMessageEvent;
 use codex_protocol::protocol::AskForApproval;
@@ -1127,7 +1126,6 @@ async fn resume_candidate_matches_cwd_reads_latest_turn_context() -> std::io::Re
         timestamp: "2025-01-03T13:00:01Z".to_string(),
         item: RolloutItem::TurnContext(TurnContextItem {
             turn_id: Some("turn-1".to_string()),
-            trace_id: None,
             cwd: latest_cwd.clone(),
             current_date: None,
             timezone: None,
@@ -1141,11 +1139,7 @@ async fn resume_candidate_matches_cwd_reads_latest_turn_context() -> std::io::Re
             collaboration_mode: None,
             realtime_active: None,
             effort: None,
-            summary: ReasoningSummaryConfig::Auto,
+            summary: codex_protocol::config_types::ReasoningSummary::Auto,
-            user_instructions: None,
-            developer_instructions: None,
-            final_output_json_schema: None,
-            truncation_policy: None,
         }),
     };
     writeln!(file, "{}", serde_json::to_string(&turn_context)?)?;

codex-rs/state/src/extract.rs

@@ -156,7 +156,6 @@ mod tests {
     use chrono::DateTime;
     use chrono::Utc;
     use codex_protocol::ThreadId;
-    use codex_protocol::config_types::ReasoningSummary;
     use codex_protocol::models::ContentItem;
     use codex_protocol::models::ResponseItem;
     use codex_protocol::openai_models::ReasoningEffort;
@@ -339,7 +338,6 @@ mod tests {
             &mut metadata,
             &RolloutItem::TurnContext(TurnContextItem {
                 turn_id: Some("turn-1".to_string()),
-                trace_id: None,
                 cwd: PathBuf::from("/parent/workspace"),
                 current_date: None,
                 timezone: None,
@@ -353,11 +351,7 @@ mod tests {
                 collaboration_mode: None,
                 realtime_active: None,
                 effort: None,
-                summary: ReasoningSummary::Auto,
+                summary: codex_protocol::config_types::ReasoningSummary::Auto,
-                user_instructions: None,
-                developer_instructions: None,
-                final_output_json_schema: None,
-                truncation_policy: None,
             }),
             "test-provider",
         );
@@ -379,7 +373,6 @@ mod tests {
             &mut metadata,
             &RolloutItem::TurnContext(TurnContextItem {
                 turn_id: Some("turn-1".to_string()),
-                trace_id: None,
                 cwd: PathBuf::from("/fallback/workspace"),
                 current_date: None,
                 timezone: None,
@@ -393,11 +386,7 @@ mod tests {
                 collaboration_mode: None,
                 realtime_active: None,
                 effort: Some(ReasoningEffort::High),
-                summary: ReasoningSummary::Auto,
+                summary: codex_protocol::config_types::ReasoningSummary::Auto,
-                user_instructions: None,
-                developer_instructions: None,
-                final_output_json_schema: None,
-                truncation_policy: None,
             }),
             "test-provider",
         );
@@ -413,7 +402,6 @@ mod tests {
             &mut metadata,
             &RolloutItem::TurnContext(TurnContextItem {
                 turn_id: Some("turn-1".to_string()),
-                trace_id: None,
                 cwd: PathBuf::from("/fallback/workspace"),
                 current_date: None,
                 timezone: None,
@@ -427,11 +415,7 @@ mod tests {
                 collaboration_mode: None,
                 realtime_active: None,
                 effort: Some(ReasoningEffort::High),
-                summary: ReasoningSummary::Auto,
+                summary: codex_protocol::config_types::ReasoningSummary::Auto,
-                user_instructions: None,
-                developer_instructions: None,
-                final_output_json_schema: None,
-                truncation_policy: None,
             }),
             "test-provider",
         );