Support end_turn flag (#9698)

Experimental flag that signals the end of the turn.

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

@@ -194,6 +194,7 @@ async fn resume_includes_initial_messages_and_sends_prior_items() {
         content: vec![codex_protocol::models::ContentItem::InputText {
             text: "resumed user message".to_string(),
         }],
+        end_turn: None,
     };
     let prior_user_json = serde_json::to_value(&prior_user).unwrap();
     writeln!(
@@ -214,6 +215,7 @@ async fn resume_includes_initial_messages_and_sends_prior_items() {
         content: vec![codex_protocol::models::ContentItem::OutputText {
             text: "resumed system instruction".to_string(),
         }],
+        end_turn: None,
     };
     let prior_system_json = serde_json::to_value(&prior_system).unwrap();
     writeln!(
@@ -234,6 +236,7 @@ async fn resume_includes_initial_messages_and_sends_prior_items() {
         content: vec![codex_protocol::models::ContentItem::OutputText {
             text: "resumed assistant message".to_string(),
         }],
+        end_turn: None,
     };
     let prior_item_json = serde_json::to_value(&prior_item).unwrap();
     writeln!(
@@ -1275,6 +1278,7 @@ async fn azure_responses_request_includes_store_and_reasoning_ids() {
         content: vec![ContentItem::OutputText {
             text: "message".into(),
         }],
+        end_turn: None,
     });
     prompt.input.push(ResponseItem::WebSearchCall {
         id: Some("web-search-id".into()),

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

@@ -170,6 +170,7 @@ fn message_item(text: &str) -> ResponseItem {
         id: None,
         role: "user".into(),
         content: vec![ContentItem::InputText { text: text.into() }],
+        end_turn: None,
     }
 }
 

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

@@ -1221,6 +1221,7 @@ async fn auto_compact_runs_after_resume_when_token_usage_is_over_limit() {
             content: vec![codex_protocol::models::ContentItem::OutputText {
                 text: remote_summary.to_string(),
             }],
+            end_turn: None,
         },
         codex_protocol::models::ResponseItem::Compaction {
             encrypted_content: "ENCRYPTED_COMPACTION_SUMMARY".to_string(),
@@ -2071,6 +2072,7 @@ async fn auto_compact_counts_encrypted_reasoning_before_last_user() {
             content: vec![codex_protocol::models::ContentItem::OutputText {
                 text: "REMOTE_COMPACT_SUMMARY".to_string(),
             }],
+            end_turn: None,
         },
         codex_protocol::models::ResponseItem::Compaction {
             encrypted_content: "ENCRYPTED_COMPACTION_SUMMARY".to_string(),
@@ -2190,6 +2192,7 @@ async fn auto_compact_runs_when_reasoning_header_clears_between_turns() {
             content: vec![codex_protocol::models::ContentItem::OutputText {
                 text: "REMOTE_COMPACT_SUMMARY".to_string(),
             }],
+            end_turn: None,
         },
         codex_protocol::models::ResponseItem::Compaction {
             encrypted_content: "ENCRYPTED_COMPACTION_SUMMARY".to_string(),

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

@@ -58,6 +58,7 @@ async fn remote_compact_replaces_history_for_followups() -> Result<()> {
             content: vec![ContentItem::InputText {
                 text: "REMOTE_COMPACTED_SUMMARY".to_string(),
             }],
+            end_turn: None,
         },
         ResponseItem::Compaction {
             encrypted_content: "ENCRYPTED_COMPACTION_SUMMARY".to_string(),
@@ -179,6 +180,7 @@ async fn remote_compact_runs_automatically() -> Result<()> {
             content: vec![ContentItem::InputText {
                 text: "REMOTE_COMPACTED_SUMMARY".to_string(),
             }],
+            end_turn: None,
         },
         ResponseItem::Compaction {
             encrypted_content: "ENCRYPTED_COMPACTION_SUMMARY".to_string(),
@@ -246,6 +248,7 @@ async fn remote_compact_persists_replacement_history_in_rollout() -> Result<()>
             content: vec![ContentItem::InputText {
                 text: "COMPACTED_USER_SUMMARY".to_string(),
             }],
+            end_turn: None,
         },
         ResponseItem::Compaction {
             encrypted_content: "ENCRYPTED_COMPACTION_SUMMARY".to_string(),
@@ -256,6 +259,7 @@ async fn remote_compact_persists_replacement_history_in_rollout() -> Result<()>
             content: vec![ContentItem::OutputText {
                 text: "COMPACTED_ASSISTANT_NOTE".to_string(),
             }],
+            end_turn: None,
         },
     ];
     let compact_mock = responses::mount_compact_json_once(

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

@@ -156,6 +156,7 @@ async fn copy_paste_local_image_persists_rollout_request_shape() -> anyhow::Resu
                 text: "pasted image".to_string(),
             },
         ],
+        end_turn: None,
     };
 
     assert_eq!(actual, expected);
@@ -235,6 +236,7 @@ async fn drag_drop_image_persists_rollout_request_shape() -> anyhow::Result<()>
                 text: "dropped image".to_string(),
             },
         ],
+        end_turn: None,
     };
 
     assert_eq!(actual, expected);

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

@@ -532,6 +532,7 @@ async fn review_input_isolated_from_parent_history() {
             content: vec![codex_protocol::models::ContentItem::InputText {
                 text: "parent: earlier user message".to_string(),
             }],
+            end_turn: None,
         };
         let user_json = serde_json::to_value(&user).unwrap();
         let user_line = serde_json::json!({
@@ -550,6 +551,7 @@ async fn review_input_isolated_from_parent_history() {
             content: vec![codex_protocol::models::ContentItem::OutputText {
                 text: "parent: assistant reply".to_string(),
             }],
+            end_turn: None,
         };
         let assistant_json = serde_json::to_value(&assistant).unwrap();
         let assistant_line = serde_json::json!({