Add hierarchical agent prompt (#8996)

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

@@ -0,0 +1,71 @@
+use codex_core::features::Feature;
+use core_test_support::load_sse_fixture_with_id;
+use core_test_support::responses::mount_sse_once;
+use core_test_support::responses::start_mock_server;
+use core_test_support::test_codex::test_codex;
+
+const HIERARCHICAL_AGENTS_SNIPPET: &str =
+    "Files called AGENTS.md commonly appear in many places inside a container";
+
+fn sse_completed(id: &str) -> String {
+    load_sse_fixture_with_id("../fixtures/completed_template.json", id)
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn hierarchical_agents_appends_to_project_doc_in_user_instructions() {
+    let server = start_mock_server().await;
+    let resp_mock = mount_sse_once(&server, sse_completed("resp1")).await;
+
+    let mut builder = test_codex().with_config(|config| {
+        config.features.enable(Feature::HierarchicalAgents);
+        std::fs::write(config.cwd.join("AGENTS.md"), "be nice").expect("write AGENTS.md");
+    });
+    let test = builder.build(&server).await.expect("build test codex");
+
+    test.submit_turn("hello").await.expect("submit turn");
+
+    let request = resp_mock.single_request();
+    let user_messages = request.message_input_texts("user");
+    let instructions = user_messages
+        .iter()
+        .find(|text| text.starts_with("# AGENTS.md instructions for "))
+        .expect("instructions message");
+    assert!(
+        instructions.contains("be nice"),
+        "expected AGENTS.md text included: {instructions}"
+    );
+    let snippet_pos = instructions
+        .find(HIERARCHICAL_AGENTS_SNIPPET)
+        .expect("expected hierarchical agents snippet");
+    let base_pos = instructions
+        .find("be nice")
+        .expect("expected AGENTS.md text");
+    assert!(
+        snippet_pos > base_pos,
+        "expected hierarchical agents message appended after base instructions: {instructions}"
+    );
+}
+
+#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
+async fn hierarchical_agents_emits_when_no_project_doc() {
+    let server = start_mock_server().await;
+    let resp_mock = mount_sse_once(&server, sse_completed("resp1")).await;
+
+    let mut builder = test_codex().with_config(|config| {
+        config.features.enable(Feature::HierarchicalAgents);
+    });
+    let test = builder.build(&server).await.expect("build test codex");
+
+    test.submit_turn("hello").await.expect("submit turn");
+
+    let request = resp_mock.single_request();
+    let user_messages = request.message_input_texts("user");
+    let instructions = user_messages
+        .iter()
+        .find(|text| text.starts_with("# AGENTS.md instructions for "))
+        .expect("instructions message");
+    assert!(
+        instructions.contains(HIERARCHICAL_AGENTS_SNIPPET),
+        "expected hierarchical agents message appended: {instructions}"
+    );
+}