Send AGENTS.md as a separate user message (#1737)

codex-rs/core/src/chat_completions.rs

@@ -40,6 +40,10 @@ pub(crate) async fn stream_chat_completions(
     let full_instructions = prompt.get_full_instructions(model);
     messages.push(json!({"role": "system", "content": full_instructions}));
 
+    if let Some(instr) = &prompt.user_instructions {
+        messages.push(json!({"role": "user", "content": instr}));
+    }
+
     for item in &prompt.input {
         match item {
             ResponseItem::Message { role, content, .. } => {

codex-rs/core/src/client.rs

@@ -35,6 +35,7 @@ use crate::error::Result;
 use crate::flags::CODEX_RS_SSE_FIXTURE;
 use crate::model_provider_info::ModelProviderInfo;
 use crate::model_provider_info::WireApi;
+use crate::models::ContentItem;
 use crate::models::ResponseItem;
 use crate::openai_tools::create_tools_json_for_responses_api;
 use crate::protocol::TokenUsage;
@@ -156,10 +157,20 @@ impl ModelClient {
             vec![]
         };
 
+        let mut input_with_instructions = Vec::with_capacity(prompt.input.len() + 1);
+        if let Some(ui) = &prompt.user_instructions {
+            input_with_instructions.push(ResponseItem::Message {
+                id: None,
+                role: "user".to_string(),
+                content: vec![ContentItem::InputText { text: ui.clone() }],
+            });
+        }
+        input_with_instructions.extend(prompt.input.clone());
+
         let payload = ResponsesApiRequest {
             model: &self.config.model,
             instructions: &full_instructions,
-            input: &prompt.input,
+            input: &input_with_instructions,
             tools: &tools_json,
             tool_choice: "auto",
             parallel_tool_calls: false,

codex-rs/core/src/client_common.rs

@@ -44,9 +44,6 @@ impl Prompt {
             .as_deref()
             .unwrap_or(BASE_INSTRUCTIONS);
         let mut sections: Vec<&str> = vec![base];
-        if let Some(ref user) = self.user_instructions {
-            sections.push(user);
-        }
         if model.starts_with("gpt-4.1") {
             sections.push(APPLY_PATCH_TOOL_INSTRUCTIONS);
         }
@@ -188,3 +185,19 @@ impl Stream for ResponseStream {
         self.rx_event.poll_recv(cx)
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn get_full_instructions_no_user_content() {
+        let prompt = Prompt {
+            user_instructions: Some("custom instruction".to_string()),
+            ..Default::default()
+        };
+        let expected = format!("{BASE_INSTRUCTIONS}\n{APPLY_PATCH_TOOL_INSTRUCTIONS}");
+        let full = prompt.get_full_instructions("gpt-4.1");
+        assert_eq!(full, expected);
+    }
+}