llmx/codex-rs/core/tests/prompt_caching.rs

use codex_core::ConversationManager;
use codex_core::ModelProviderInfo;
use codex_core::built_in_model_providers;
use codex_core::protocol::AskForApproval;
use codex_core::protocol::EventMsg;
use codex_core::protocol::InputItem;
use codex_core::protocol::Op;
use codex_core::protocol::SandboxPolicy;
use codex_core::protocol_config_types::ReasoningEffort;
use codex_core::protocol_config_types::ReasoningSummary;
use codex_core::shell::default_user_shell;
use codex_login::CodexAuth;
use core_test_support::load_default_config_for_test;
use core_test_support::load_sse_fixture_with_id;
use core_test_support::wait_for_event;
use tempfile::TempDir;
use wiremock::Mock;
use wiremock::MockServer;
use wiremock::ResponseTemplate;
use wiremock::matchers::method;
use wiremock::matchers::path;

/// Build minimal SSE stream with completed marker using the JSON fixture.
fn sse_completed(id: &str) -> String {
    load_sse_fixture_with_id("tests/fixtures/completed_template.json", id)
}

#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn default_system_instructions_contain_apply_patch() {
    use pretty_assertions::assert_eq;

    let server = MockServer::start().await;

    let sse = sse_completed("resp");
    let template = ResponseTemplate::new(200)
        .insert_header("content-type", "text/event-stream")
        .set_body_raw(sse, "text/event-stream");

    // Expect two POSTs to /v1/responses
    Mock::given(method("POST"))
        .and(path("/v1/responses"))
        .respond_with(template)
        .expect(2)
        .mount(&server)
        .await;

    let model_provider = ModelProviderInfo {
        base_url: Some(format!("{}/v1", server.uri())),
        ..built_in_model_providers()["openai"].clone()
    };

    let cwd = TempDir::new().unwrap();
    let codex_home = TempDir::new().unwrap();
    let mut config = load_default_config_for_test(&codex_home);
    config.cwd = cwd.path().to_path_buf();
    config.model_provider = model_provider;
    config.user_instructions = Some("be consistent and helpful".to_string());

    let conversation_manager = ConversationManager::default();
    let codex = conversation_manager
        .new_conversation_with_auth(config, Some(CodexAuth::from_api_key("Test API Key")))
        .await
        .expect("create new conversation")
        .conversation;

    codex
        .submit(Op::UserInput {
            items: vec![InputItem::Text {
                text: "hello 1".into(),
            }],
        })
        .await
        .unwrap();
    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;

    codex
        .submit(Op::UserInput {
            items: vec![InputItem::Text {
                text: "hello 2".into(),
            }],
        })
        .await
        .unwrap();
    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;

    let requests = server.received_requests().await.unwrap();
    assert_eq!(requests.len(), 2, "expected two POST requests");

    let expected_instructions = [
        include_str!("../prompt.md"),
        include_str!("../../apply-patch/apply_patch_tool_instructions.md"),
    ]
    .join("\n");

    let body0 = requests[0].body_json::<serde_json::Value>().unwrap();
    assert_eq!(
        body0["instructions"],
        serde_json::json!(expected_instructions),
    );
    let body1 = requests[1].body_json::<serde_json::Value>().unwrap();
    assert_eq!(
        body1["instructions"],
        serde_json::json!(expected_instructions),
    );
}

#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
async fn prompt_tools_are_consistent_across_requests() {
    use pretty_assertions::assert_eq;

    let server = MockServer::start().await;

    let sse = sse_completed("resp");
    let template = ResponseTemplate::new(200)
        .insert_header("content-type", "text/event-stream")
        .set_body_raw(sse, "text/event-stream");

    // Expect two POSTs to /v1/responses
    Mock::given(method("POST"))
        .and(path("/v1/responses"))
        .respond_with(template)
        .expect(2)
        .mount(&server)
        .await;

    let model_provider = ModelProviderInfo {
        base_url: Some(format!("{}/v1", server.uri())),
        ..built_in_model_providers()["openai"].clone()
    };

    let cwd = TempDir::new().unwrap();
    let codex_home = TempDir::new().unwrap();
    let mut config = load_default_config_for_test(&codex_home);
    config.cwd = cwd.path().to_path_buf();
    config.model_provider = model_provider;
    config.user_instructions = Some("be consistent and helpful".to_string());
    config.include_apply_patch_tool = true;
    config.include_plan_tool = true;

    let conversation_manager = ConversationManager::default();
    let codex = conversation_manager
        .new_conversation_with_auth(config, Some(CodexAuth::from_api_key("Test API Key")))
        .await
        .expect("create new conversation")
        .conversation;

    codex
        .submit(Op::UserInput {
            items: vec![InputItem::Text {
                text: "hello 1".into(),
            }],
        })
        .await
        .unwrap();
    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;

    codex
        .submit(Op::UserInput {
            items: vec![InputItem::Text {
                text: "hello 2".into(),
            }],
        })
        .await
        .unwrap();
    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;

    let requests = server.received_requests().await.unwrap();
    assert_eq!(requests.len(), 2, "expected two POST requests");

    let expected_instructions: &str = include_str!("../prompt.md");
    // our internal implementation is responsible for keeping tools in sync
    // with the OpenAI schema, so we just verify the tool presence here
    let expected_tools_names: &[&str] = &["shell", "update_plan", "apply_patch"];
    fn assert_tool_names(body: &serde_json::Value, expected_names: &[&str]) {
        assert_eq!(
            body["tools"]
                .as_array()
                .unwrap()
                .iter()
                .map(|t| t["name"].as_str().unwrap().to_string())
                .collect::<Vec<_>>(),
            expected_names
        );
    }

    let body0 = requests[0].body_json::<serde_json::Value>().unwrap();
    assert_eq!(
        body0["instructions"],
        serde_json::json!(expected_instructions),
    );
    assert_tool_names(&body0, expected_tools_names);

    let body1 = requests[1].body_json::<serde_json::Value>().unwrap();
    assert_eq!(
        body1["instructions"],
        serde_json::json!(expected_instructions),
    );
    assert_tool_names(&body1, expected_tools_names);
}

#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn prefixes_context_and_instructions_once_and_consistently_across_requests() {
    use pretty_assertions::assert_eq;

    let server = MockServer::start().await;

    let sse = sse_completed("resp");
    let template = ResponseTemplate::new(200)
        .insert_header("content-type", "text/event-stream")
        .set_body_raw(sse, "text/event-stream");

    // Expect two POSTs to /v1/responses
    Mock::given(method("POST"))
        .and(path("/v1/responses"))
        .respond_with(template)
        .expect(2)
        .mount(&server)
        .await;

    let model_provider = ModelProviderInfo {
        base_url: Some(format!("{}/v1", server.uri())),
        ..built_in_model_providers()["openai"].clone()
    };

    let cwd = TempDir::new().unwrap();
    let codex_home = TempDir::new().unwrap();
    let mut config = load_default_config_for_test(&codex_home);
    config.cwd = cwd.path().to_path_buf();
    config.model_provider = model_provider;
    config.user_instructions = Some("be consistent and helpful".to_string());

    let conversation_manager = ConversationManager::default();
    let codex = conversation_manager
        .new_conversation_with_auth(config, Some(CodexAuth::from_api_key("Test API Key")))
        .await
        .expect("create new conversation")
        .conversation;

    codex
        .submit(Op::UserInput {
            items: vec![InputItem::Text {
                text: "hello 1".into(),
            }],
        })
        .await
        .unwrap();
    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;

    codex
        .submit(Op::UserInput {
            items: vec![InputItem::Text {
                text: "hello 2".into(),
            }],
        })
        .await
        .unwrap();
    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;

    let requests = server.received_requests().await.unwrap();
    assert_eq!(requests.len(), 2, "expected two POST requests");

    let shell = default_user_shell().await;

    let expected_env_text = format!(
        r#"<environment_context>
  <cwd>{}</cwd>
  <approval_policy>on-request</approval_policy>
  <sandbox_mode>read-only</sandbox_mode>
  <network_access>restricted</network_access>
{}</environment_context>"#,
        cwd.path().to_string_lossy(),
        match shell.name() {
            Some(name) => format!("  <shell>{}</shell>\n", name),
            None => String::new(),
        }
    );
    let expected_ui_text =
        "<user_instructions>\n\nbe consistent and helpful\n\n</user_instructions>";

    let expected_env_msg = serde_json::json!({
        "type": "message",
        "id": serde_json::Value::Null,
        "role": "user",
        "content": [ { "type": "input_text", "text": expected_env_text } ]
    });
    let expected_ui_msg = serde_json::json!({
        "type": "message",
        "id": serde_json::Value::Null,
        "role": "user",
        "content": [ { "type": "input_text", "text": expected_ui_text } ]
    });

    let expected_user_message_1 = serde_json::json!({
        "type": "message",
        "id": serde_json::Value::Null,
        "role": "user",
        "content": [ { "type": "input_text", "text": "hello 1" } ]
    });
    let body1 = requests[0].body_json::<serde_json::Value>().unwrap();
    assert_eq!(
        body1["input"],
        serde_json::json!([expected_ui_msg, expected_env_msg, expected_user_message_1])
    );

    let expected_user_message_2 = serde_json::json!({
        "type": "message",
        "id": serde_json::Value::Null,
        "role": "user",
        "content": [ { "type": "input_text", "text": "hello 2" } ]
    });
    let body2 = requests[1].body_json::<serde_json::Value>().unwrap();
    let expected_body2 = serde_json::json!(
        [
            body1["input"].as_array().unwrap().as_slice(),
            [expected_user_message_2].as_slice(),
        ]
        .concat()
    );
    assert_eq!(body2["input"], expected_body2);
}

#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn overrides_turn_context_but_keeps_cached_prefix_and_key_constant() {
    use pretty_assertions::assert_eq;

    let server = MockServer::start().await;

    let sse = sse_completed("resp");
    let template = ResponseTemplate::new(200)
        .insert_header("content-type", "text/event-stream")
        .set_body_raw(sse, "text/event-stream");

    // Expect two POSTs to /v1/responses
    Mock::given(method("POST"))
        .and(path("/v1/responses"))
        .respond_with(template)
        .expect(2)
        .mount(&server)
        .await;

    let model_provider = ModelProviderInfo {
        base_url: Some(format!("{}/v1", server.uri())),
        ..built_in_model_providers()["openai"].clone()
    };

    let cwd = TempDir::new().unwrap();
    let codex_home = TempDir::new().unwrap();
    let mut config = load_default_config_for_test(&codex_home);
    config.cwd = cwd.path().to_path_buf();
    config.model_provider = model_provider;
    config.user_instructions = Some("be consistent and helpful".to_string());

    let conversation_manager = ConversationManager::default();
    let codex = conversation_manager
        .new_conversation_with_auth(config, Some(CodexAuth::from_api_key("Test API Key")))
        .await
        .expect("create new conversation")
        .conversation;

    // First turn
    codex
        .submit(Op::UserInput {
            items: vec![InputItem::Text {
                text: "hello 1".into(),
            }],
        })
        .await
        .unwrap();
    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;

    let writable = TempDir::new().unwrap();
    codex
        .submit(Op::OverrideTurnContext {
            cwd: None,
            approval_policy: Some(AskForApproval::Never),
            sandbox_policy: Some(SandboxPolicy::WorkspaceWrite {
                writable_roots: vec![writable.path().to_path_buf()],
                network_access: true,
                exclude_tmpdir_env_var: true,
                exclude_slash_tmp: true,
            }),
            model: Some("o3".to_string()),
            effort: Some(ReasoningEffort::High),
            summary: Some(ReasoningSummary::Detailed),
        })
        .await
        .unwrap();

    // Second turn after overrides
    codex
        .submit(Op::UserInput {
            items: vec![InputItem::Text {
                text: "hello 2".into(),
            }],
        })
        .await
        .unwrap();
    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;

    // Verify we issued exactly two requests, and the cached prefix stayed identical.
    let requests = server.received_requests().await.unwrap();
    assert_eq!(requests.len(), 2, "expected two POST requests");

    let body1 = requests[0].body_json::<serde_json::Value>().unwrap();
    let body2 = requests[1].body_json::<serde_json::Value>().unwrap();
    // prompt_cache_key should remain constant across overrides
    assert_eq!(
        body1["prompt_cache_key"], body2["prompt_cache_key"],
        "prompt_cache_key should not change across overrides"
    );

    // The entire prefix from the first request should be identical and reused
    // as the prefix of the second request, ensuring cache hit potential.
    let expected_user_message_2 = serde_json::json!({
        "type": "message",
        "id": serde_json::Value::Null,
        "role": "user",
        "content": [ { "type": "input_text", "text": "hello 2" } ]
    });
    // After overriding the turn context, the environment context should be emitted again
    // reflecting the new approval policy and sandbox settings. Omit cwd because it did
    // not change.
    let expected_env_text_2 = r#"<environment_context>
  <approval_policy>never</approval_policy>
  <sandbox_mode>workspace-write</sandbox_mode>
  <network_access>enabled</network_access>
</environment_context>"#;
    let expected_env_msg_2 = serde_json::json!({
        "type": "message",
        "id": serde_json::Value::Null,
        "role": "user",
        "content": [ { "type": "input_text", "text": expected_env_text_2 } ]
    });
    let expected_body2 = serde_json::json!(
        [
            body1["input"].as_array().unwrap().as_slice(),
            [expected_env_msg_2, expected_user_message_2].as_slice(),
        ]
        .concat()
    );
    assert_eq!(body2["input"], expected_body2);
}

#[tokio::test(flavor = "multi_thread", worker_threads = 2)]
async fn per_turn_overrides_keep_cached_prefix_and_key_constant() {
    use pretty_assertions::assert_eq;

    let server = MockServer::start().await;

    let sse = sse_completed("resp");
    let template = ResponseTemplate::new(200)
        .insert_header("content-type", "text/event-stream")
        .set_body_raw(sse, "text/event-stream");

    // Expect two POSTs to /v1/responses
    Mock::given(method("POST"))
        .and(path("/v1/responses"))
        .respond_with(template)
        .expect(2)
        .mount(&server)
        .await;

    let model_provider = ModelProviderInfo {
        base_url: Some(format!("{}/v1", server.uri())),
        ..built_in_model_providers()["openai"].clone()
    };

    let cwd = TempDir::new().unwrap();
    let codex_home = TempDir::new().unwrap();
    let mut config = load_default_config_for_test(&codex_home);
    config.cwd = cwd.path().to_path_buf();
    config.model_provider = model_provider;
    config.user_instructions = Some("be consistent and helpful".to_string());

    let conversation_manager = ConversationManager::default();
    let codex = conversation_manager
        .new_conversation_with_auth(config, Some(CodexAuth::from_api_key("Test API Key")))
        .await
        .expect("create new conversation")
        .conversation;

    // First turn
    codex
        .submit(Op::UserInput {
            items: vec![InputItem::Text {
                text: "hello 1".into(),
            }],
        })
        .await
        .unwrap();
    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;

    // Second turn using per-turn overrides via UserTurn
    let new_cwd = TempDir::new().unwrap();
    let writable = TempDir::new().unwrap();
    codex
        .submit(Op::UserTurn {
            items: vec![InputItem::Text {
                text: "hello 2".into(),
            }],
            cwd: new_cwd.path().to_path_buf(),
            approval_policy: AskForApproval::Never,
            sandbox_policy: SandboxPolicy::WorkspaceWrite {
                writable_roots: vec![writable.path().to_path_buf()],
                network_access: true,
                exclude_tmpdir_env_var: true,
                exclude_slash_tmp: true,
            },
            model: "o3".to_string(),
            effort: ReasoningEffort::High,
            summary: ReasoningSummary::Detailed,
        })
        .await
        .unwrap();
    wait_for_event(&codex, |ev| matches!(ev, EventMsg::TaskComplete(_))).await;

    // Verify we issued exactly two requests, and the cached prefix stayed identical.
    let requests = server.received_requests().await.unwrap();
    assert_eq!(requests.len(), 2, "expected two POST requests");

    let body1 = requests[0].body_json::<serde_json::Value>().unwrap();
    let body2 = requests[1].body_json::<serde_json::Value>().unwrap();

    // prompt_cache_key should remain constant across per-turn overrides
    assert_eq!(
        body1["prompt_cache_key"], body2["prompt_cache_key"],
        "prompt_cache_key should not change across per-turn overrides"
    );

    // The entire prefix from the first request should be identical and reused
    // as the prefix of the second request.
    let expected_user_message_2 = serde_json::json!({
        "type": "message",
        "id": serde_json::Value::Null,
        "role": "user",
        "content": [ { "type": "input_text", "text": "hello 2" } ]
    });
    let expected_body2 = serde_json::json!(
        [
            body1["input"].as_array().unwrap().as_slice(),
            [expected_user_message_2].as_slice(),
        ]
        .concat()
    );
    assert_eq!(body2["input"], expected_body2);
}