diff --git a/codex-rs/core/src/codex.rs b/codex-rs/core/src/codex.rs
index a6af372136..c05f3e8a77 100644
--- a/codex-rs/core/src/codex.rs
+++ b/codex-rs/core/src/codex.rs
@@ -625,6 +625,10 @@ impl Session {
         Ok(sess)
     }
 
+    pub(crate) fn get_prompt_cache_key(&self) -> String {
+        self.prompt_cache_key.clone()
+    }
+
     pub(crate) fn get_conversation_id(&self) -> ConversationId {
         self.conversation_id
     }
diff --git a/codex-rs/core/src/codex_delegate.rs b/codex-rs/core/src/codex_delegate.rs
index 27774bcb84..987cc0a0c1 100644
--- a/codex-rs/core/src/codex_delegate.rs
+++ b/codex-rs/core/src/codex_delegate.rs
@@ -45,7 +45,7 @@ pub(crate) async fn run_codex_conversation_interactive(
         auth_manager,
         InitialHistory::New,
         SessionSource::SubAgent(SubAgentSource::Review),
-        Some(parent_session.get_conversation_id().to_string()),
+        Some(parent_session.get_prompt_cache_key()),
     )
     .await?;
     let codex = Arc::new(codex);