diff --git a/codex-rs/core/src/client.rs b/codex-rs/core/src/client.rs
index 3c21552dcb..14c068e31b 100644
--- a/codex-rs/core/src/client.rs
+++ b/codex-rs/core/src/client.rs
@@ -244,7 +244,12 @@ impl ModelClient {
         let max_attempts = self.provider.request_max_retries();
         for attempt in 0..=max_attempts {
             match self
-                .attempt_stream_responses(attempt, &payload_json, &auth_manager)
+                .attempt_stream_responses(
+                    attempt,
+                    &payload_json,
+                    &auth_manager,
+                    prompt.is_review_turn,
+                )
                 .await
             {
                 Ok(stream) => {
@@ -272,6 +277,7 @@ impl ModelClient {
         attempt: u64,
         payload_json: &Value,
         auth_manager: &Option<Arc<AuthManager>>,
+        is_review_turn: bool,
     ) -> std::result::Result<ResponseStream, StreamAttemptError> {
         // Always fetch the latest auth in case a prior attempt refreshed the token.
         let auth = auth_manager.as_ref().and_then(|m| m.auth());
@@ -293,6 +299,10 @@ impl ModelClient {
             // Send session_id for compatibility.
             .header("conversation_id", self.conversation_id.to_string())
             .header("session_id", self.conversation_id.to_string())
+            .header(
+                "action_kind",
+                if is_review_turn { "review" } else { "turn" },
+            )
             .header(reqwest::header::ACCEPT, "text/event-stream")
             .json(payload_json);
 
diff --git a/codex-rs/core/src/client_common.rs b/codex-rs/core/src/client_common.rs
index d30da5192a..4a97dafdd4 100644
--- a/codex-rs/core/src/client_common.rs
+++ b/codex-rs/core/src/client_common.rs
@@ -41,6 +41,9 @@ pub struct Prompt {
 
     /// Optional the output schema for the model's response.
     pub output_schema: Option<Value>,
+
+    /// Marks whether this prompt is part of a review turn.
+    pub is_review_turn: bool,
 }
 
 impl Prompt {
diff --git a/codex-rs/core/src/codex.rs b/codex-rs/core/src/codex.rs
index d11a53b59a..225117d66b 100644
--- a/codex-rs/core/src/codex.rs
+++ b/codex-rs/core/src/codex.rs
@@ -1950,6 +1950,7 @@ async fn run_turn(
         parallel_tool_calls,
         base_instructions_override: turn_context.base_instructions.clone(),
         output_schema: turn_context.final_output_json_schema.clone(),
+        is_review_turn: turn_context.is_review_mode,
     };
 
     let mut retries = 0;
diff --git a/codex-rs/core/tests/suite/client.rs b/codex-rs/core/tests/suite/client.rs
index eb14dabb81..29dc5f6b81 100644
--- a/codex-rs/core/tests/suite/client.rs
+++ b/codex-rs/core/tests/suite/client.rs
@@ -349,12 +349,14 @@ async fn includes_conversation_id_and_model_headers_in_request() {
     let request_conversation_id = request.headers.get("conversation_id").unwrap();
     let request_authorization = request.headers.get("authorization").unwrap();
     let request_originator = request.headers.get("originator").unwrap();
+    let turn_kind = request.headers.get("action_kind").unwrap();
 
     assert_eq!(
         request_conversation_id.to_str().unwrap(),
         conversation_id.to_string()
     );
     assert_eq!(request_originator.to_str().unwrap(), "codex_cli_rs");
+    assert_eq!(turn_kind.to_str().unwrap(), "turn");
     assert_eq!(
         request_authorization.to_str().unwrap(),
         "Bearer Test API Key"
diff --git a/codex-rs/core/tests/suite/review.rs b/codex-rs/core/tests/suite/review.rs
index f3eeb3a310..cdab96b77a 100644
--- a/codex-rs/core/tests/suite/review.rs
+++ b/codex-rs/core/tests/suite/review.rs
@@ -118,6 +118,14 @@ async fn review_op_emits_lifecycle_and_review_output() {
     assert_eq!(expected, review);
     let _complete = wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;
 
+    // Assert header marks this as a review turn.
+    let request = &server.received_requests().await.unwrap()[0];
+    let turn_kind = request
+        .headers
+        .get("action_kind")
+        .expect("missing action_kind header");
+    assert_eq!(turn_kind.to_str().unwrap(), "review");
+
     // Also verify that a user message with the header and a formatted finding
     // was recorded back in the parent session's rollout.
     codex.submit(Op::GetPath).await.unwrap();