Preserve assistant phase for replayed messages (#19832)

codex-rs/protocol/src/models.rs

@@ -609,6 +609,9 @@ pub enum ResponseInputItem {
     Message {
         role: String,
         content: Vec<ContentItem>,
+        #[serde(default, skip_serializing_if = "Option::is_none")]
+        #[ts(optional)]
+        phase: Option<MessagePhase>,
     },
     FunctionCallOutput {
         call_id: String,
@@ -1034,11 +1037,15 @@ pub fn local_image_content_items_with_label_number(
 impl From<ResponseInputItem> for ResponseItem {
     fn from(item: ResponseInputItem) -> Self {
         match item {
-            ResponseInputItem::Message { role, content } => Self::Message {
+            ResponseInputItem::Message {
+                role,
+                content,
+                phase,
+            } => Self::Message {
                 role,
                 content,
                 id: None,
-                phase: None,
+                phase,
             },
             ResponseInputItem::FunctionCallOutput { call_id, output } => {
                 Self::FunctionCallOutput { call_id, output }
@@ -1176,6 +1183,7 @@ impl From<Vec<UserInput>> for ResponseInputItem {
                     UserInput::Skill { .. } | UserInput::Mention { .. } => Vec::new(), // Tool bodies are injected later in core
                 })
                 .collect::<Vec<ContentItem>>(),
+            phase: None,
         }
     }
 }
@@ -1581,6 +1589,29 @@ mod tests {
     use std::path::PathBuf;
     use tempfile::tempdir;
 
+    #[test]
+    fn response_input_message_conversion_preserves_phase() {
+        let item = ResponseItem::from(ResponseInputItem::Message {
+            role: "assistant".to_string(),
+            content: vec![ContentItem::OutputText {
+                text: "still working".to_string(),
+            }],
+            phase: Some(MessagePhase::Commentary),
+        });
+
+        assert_eq!(
+            item,
+            ResponseItem::Message {
+                id: None,
+                role: "assistant".to_string(),
+                content: vec![ContentItem::OutputText {
+                    text: "still working".to_string(),
+                }],
+                phase: Some(MessagePhase::Commentary),
+            }
+        );
+    }
+
     #[test]
     fn sandbox_permissions_helpers_match_documented_semantics() {
         let cases = [

codex-rs/protocol/src/protocol.rs

@@ -855,6 +855,7 @@ impl InterAgentCommunication {
             content: vec![ContentItem::OutputText {
                 text: serde_json::to_string(self).unwrap_or_default(),
             }],
+            phase: Some(MessagePhase::Commentary),
         }
     }