From 9cd8115a6974af34634af9a76077828071ff29f7 Mon Sep 17 00:00:00 2001
From: Adam Perry <anp@openai.com>
Date: Sat, 6 Jun 2026 16:52:25 -0700
Subject: [PATCH] test: cover reviewed instruction edge cases

---
 .../app-server/tests/suite/v2/thread_fork.rs  | 58 ++++++++++++++++++-
 .../core/tests/suite/global_instructions.rs   | 15 +++++
 2 files changed, 72 insertions(+), 1 deletion(-)

diff --git a/codex-rs/app-server/tests/suite/v2/thread_fork.rs b/codex-rs/app-server/tests/suite/v2/thread_fork.rs
index 1dc07963ad..ad6665eaa2 100644
--- a/codex-rs/app-server/tests/suite/v2/thread_fork.rs
+++ b/codex-rs/app-server/tests/suite/v2/thread_fork.rs
@@ -37,6 +37,7 @@ use codex_rollout::append_rollout_item_to_path;
 use codex_rollout::append_thread_name;
 use codex_rollout::read_session_meta_line;
 use codex_utils_absolute_path::AbsolutePathBuf;
+use core_test_support::responses;
 use pretty_assertions::assert_eq;
 use serde_json::Value;
 use serde_json::json;
@@ -252,7 +253,21 @@ async fn thread_fork_creates_new_thread_and_emits_started() -> Result<()> {
 
 #[tokio::test]
 async fn thread_fork_reloads_instruction_sources() -> Result<()> {
-    let server = create_mock_responses_server_repeating_assistant("Done").await;
+    let server = responses::start_mock_server().await;
+    let response_mock = responses::mount_sse_sequence(
+        &server,
+        vec![
+            responses::sse(vec![
+                responses::ev_response_created("parent-response"),
+                responses::ev_completed("parent-response"),
+            ]),
+            responses::sse(vec![
+                responses::ev_response_created("fork-response"),
+                responses::ev_completed("fork-response"),
+            ]),
+        ],
+    )
+    .await;
     let codex_home = TempDir::new()?;
     create_config_toml(codex_home.path(), &server.uri())?;
     let global_agents = codex_home.path().join("AGENTS.md");
@@ -322,6 +337,7 @@ async fn thread_fork_reloads_instruction_sources() -> Result<()> {
     )
     .await??;
     let ThreadForkResponse {
+        thread: forked_thread,
         instruction_sources,
         ..
     } = to_response::<ThreadForkResponse>(fork_resp)?;
@@ -332,6 +348,46 @@ async fn thread_fork_reloads_instruction_sources() -> Result<()> {
         "fork reloads sources after the files have been removed"
     );
 
+    let fork_turn_id = mcp
+        .send_turn_start_request(TurnStartParams {
+            thread_id: forked_thread.id,
+            input: vec![UserInput::Text {
+                text: "inspect inherited instructions".to_string(),
+                text_elements: Vec::new(),
+            }],
+            ..Default::default()
+        })
+        .await?;
+    timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(fork_turn_id)),
+    )
+    .await??;
+    timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_notification_message("turn/completed"),
+    )
+    .await??;
+
+    let expected_instruction = format!(
+        "# AGENTS.md instructions for {}\n\n<INSTRUCTIONS>\nglobal instructions\n\n--- project-doc ---\n\nproject instructions\n</INSTRUCTIONS>",
+        workspace.path().display()
+    );
+    let requests = response_mock.requests();
+    assert_eq!(requests.len(), 2);
+    for request in requests {
+        let instruction_fragments = request
+            .message_input_texts("user")
+            .into_iter()
+            .filter(|text| text.starts_with("# AGENTS.md instructions for "))
+            .collect::<Vec<_>>();
+        assert_eq!(
+            instruction_fragments,
+            vec![expected_instruction.clone()],
+            "parent and fork requests should contain the same historical instruction fragment"
+        );
+    }
+
     Ok(())
 }
 
diff --git a/codex-rs/core/tests/suite/global_instructions.rs b/codex-rs/core/tests/suite/global_instructions.rs
index 8da620d23b..b9fb68ead3 100644
--- a/codex-rs/core/tests/suite/global_instructions.rs
+++ b/codex-rs/core/tests/suite/global_instructions.rs
@@ -176,6 +176,14 @@ async fn fresh_thread_composes_global_before_project_and_reports_sources() -> Re
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn global_loading_warning_surfaces_during_thread_creation() -> Result<()> {
     let server = responses::start_mock_server().await;
+    let response_mock = responses::mount_sse_once(
+        &server,
+        responses::sse(vec![
+            responses::ev_response_created("warning-response"),
+            responses::ev_completed("warning-response"),
+        ]),
+    )
+    .await;
     let home = Arc::new(TempDir::new()?);
     let source = write_global(home.as_ref(), b"global\xFFinstructions")?;
 
@@ -197,10 +205,17 @@ async fn global_loading_warning_surfaces_during_thread_creation() -> Result<()>
         warning.contains("invalid UTF-8"),
         "expected warning to contain \"invalid UTF-8\"; observed: {warning}"
     );
+    test.submit_turn("inspect lossy global instructions")
+        .await?;
+    let expected_fragment =
+        expected_instruction_fragment(&test.config.cwd, "global\u{FFFD}instructions");
+    assert_single_instruction_fragment(&response_mock.single_request(), &expected_fragment);
 
     Ok(())
 }
 
+// TODO(anp): Align cold-resume instruction sources with the historical instructions replayed to
+// the model so the API source list and model-visible context describe the same files.
 #[tokio::test(flavor = "multi_thread", worker_threads = 2)]
 async fn cold_resume_replays_rendered_instructions_but_reports_current_config_sources() -> Result<()>
 {