Merge branch 'main' into dev/mzeng/hot_reload_config

codex-rs/app-server/tests/common/models_cache.rs

@@ -1,6 +1,7 @@
 use chrono::DateTime;
 use chrono::Utc;
 use codex_core::test_support::all_model_presets;
+use codex_protocol::config_types::ReasoningSummary;
 use codex_protocol::openai_models::ConfigShellToolType;
 use codex_protocol::openai_models::ModelInfo;
 use codex_protocol::openai_models::ModelPreset;
@@ -30,8 +31,10 @@ fn preset_to_info(preset: &ModelPreset, priority: i32) -> ModelInfo {
         base_instructions: "base instructions".to_string(),
         model_messages: None,
         supports_reasoning_summaries: false,
+        default_reasoning_summary: ReasoningSummary::Auto,
         support_verbosity: false,
         default_verbosity: None,
+        availability_nux: None,
         apply_patch_tool_type: None,
         truncation_policy: TruncationPolicyConfig::bytes(10_000),
         supports_parallel_tool_calls: false,

codex-rs/app-server/tests/suite/output_schema.rs

@@ -1,8 +1,11 @@
 use anyhow::Result;
 use app_test_support::McpProcess;
 use app_test_support::to_response;
+use codex_app_server::INPUT_TOO_LARGE_ERROR_CODE;
+use codex_app_server::INVALID_PARAMS_ERROR_CODE;
 use codex_app_server_protocol::AddConversationListenerParams;
 use codex_app_server_protocol::InputItem;
+use codex_app_server_protocol::JSONRPCError;
 use codex_app_server_protocol::JSONRPCResponse;
 use codex_app_server_protocol::NewConversationParams;
 use codex_app_server_protocol::NewConversationResponse;
@@ -13,6 +16,7 @@ use codex_protocol::config_types::ReasoningSummary;
 use codex_protocol::openai_models::ReasoningEffort;
 use codex_protocol::protocol::AskForApproval;
 use codex_protocol::protocol::SandboxPolicy;
+use codex_protocol::user_input::MAX_USER_INPUT_TEXT_CHARS;
 use core_test_support::responses;
 use core_test_support::skip_if_no_network;
 use pretty_assertions::assert_eq;
@@ -124,6 +128,85 @@ async fn send_user_turn_accepts_output_schema_v1() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn send_user_turn_rejects_oversized_input_v1() -> Result<()> {
+    let server = responses::start_mock_server().await;
+    let body = responses::sse(vec![
+        responses::ev_response_created("resp-1"),
+        responses::ev_assistant_message("msg-1", "Done"),
+        responses::ev_completed("resp-1"),
+    ]);
+    let _response_mock = responses::mount_sse_once(&server, body).await;
+
+    let codex_home = TempDir::new()?;
+    create_config_toml(codex_home.path(), &server.uri())?;
+
+    let mut mcp = McpProcess::new(codex_home.path()).await?;
+    timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
+
+    let new_conv_id = mcp
+        .send_new_conversation_request(NewConversationParams {
+            ..Default::default()
+        })
+        .await?;
+    let new_conv_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(new_conv_id)),
+    )
+    .await??;
+    let NewConversationResponse {
+        conversation_id, ..
+    } = to_response::<NewConversationResponse>(new_conv_resp)?;
+
+    let listener_id = mcp
+        .send_add_conversation_listener_request(AddConversationListenerParams {
+            conversation_id,
+            experimental_raw_events: false,
+        })
+        .await?;
+    timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(listener_id)),
+    )
+    .await??;
+
+    let oversized_input = "x".repeat(MAX_USER_INPUT_TEXT_CHARS + 1);
+    let send_turn_id = mcp
+        .send_send_user_turn_request(SendUserTurnParams {
+            conversation_id,
+            items: vec![InputItem::Text {
+                text: oversized_input.clone(),
+                text_elements: Vec::new(),
+            }],
+            cwd: codex_home.path().to_path_buf(),
+            approval_policy: AskForApproval::Never,
+            sandbox_policy: SandboxPolicy::DangerFullAccess,
+            model: "mock-model".to_string(),
+            effort: Some(ReasoningEffort::Low),
+            summary: ReasoningSummary::Auto,
+            output_schema: None,
+        })
+        .await?;
+
+    let err: JSONRPCError = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_error_message(RequestId::Integer(send_turn_id)),
+    )
+    .await??;
+
+    assert_eq!(err.error.code, INVALID_PARAMS_ERROR_CODE);
+    assert_eq!(
+        err.error.message,
+        format!("Input exceeds the maximum length of {MAX_USER_INPUT_TEXT_CHARS} characters.")
+    );
+    let data = err.error.data.expect("expected structured error data");
+    assert_eq!(data["input_error_code"], INPUT_TOO_LARGE_ERROR_CODE);
+    assert_eq!(data["max_chars"], MAX_USER_INPUT_TEXT_CHARS);
+    assert_eq!(data["actual_chars"], oversized_input.chars().count());
+
+    Ok(())
+}
+
 #[tokio::test]
 async fn send_user_turn_output_schema_is_per_turn_v1() -> Result<()> {
     skip_if_no_network!(Ok(()));

codex-rs/app-server/tests/suite/send_message.rs

@@ -3,9 +3,12 @@ use app_test_support::McpProcess;
 use app_test_support::create_fake_rollout;
 use app_test_support::rollout_path;
 use app_test_support::to_response;
+use codex_app_server::INPUT_TOO_LARGE_ERROR_CODE;
+use codex_app_server::INVALID_PARAMS_ERROR_CODE;
 use codex_app_server_protocol::AddConversationListenerParams;
 use codex_app_server_protocol::AddConversationSubscriptionResponse;
 use codex_app_server_protocol::InputItem;
+use codex_app_server_protocol::JSONRPCError;
 use codex_app_server_protocol::JSONRPCNotification;
 use codex_app_server_protocol::JSONRPCResponse;
 use codex_app_server_protocol::NewConversationParams;
@@ -27,6 +30,7 @@ use codex_protocol::protocol::RolloutItem;
 use codex_protocol::protocol::RolloutLine;
 use codex_protocol::protocol::SandboxPolicy;
 use codex_protocol::protocol::TurnContextItem;
+use codex_protocol::user_input::MAX_USER_INPUT_TEXT_CHARS;
 use core_test_support::responses;
 use pretty_assertions::assert_eq;
 use std::io::Write;
@@ -210,17 +214,13 @@ async fn test_send_message_raw_notifications_opt_in() -> Result<()> {
         })
         .await?;
 
-    let permissions = read_raw_response_item(&mut mcp, conversation_id).await;
-    assert_permissions_message(&permissions);
-
     let developer = read_raw_response_item(&mut mcp, conversation_id).await;
+    assert_permissions_message(&developer);
     assert_developer_message(&developer, "Use the test harness tools.");
 
-    let instructions = read_raw_response_item(&mut mcp, conversation_id).await;
-    assert_instructions_message(&instructions);
-
-    let environment = read_raw_response_item(&mut mcp, conversation_id).await;
-    assert_environment_message(&environment);
+    let contextual_user = read_raw_response_item(&mut mcp, conversation_id).await;
+    assert_instructions_message(&contextual_user);
+    assert_environment_message(&contextual_user);
 
     let response: JSONRPCResponse = timeout(
         DEFAULT_READ_TIMEOUT,
@@ -272,6 +272,66 @@ async fn test_send_message_session_not_found() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn test_send_message_rejects_oversized_input() -> Result<()> {
+    let server = responses::start_mock_server().await;
+    let body = responses::sse(vec![
+        responses::ev_response_created("resp-1"),
+        responses::ev_assistant_message("msg-1", "Done"),
+        responses::ev_completed("resp-1"),
+    ]);
+    let _response_mock = responses::mount_sse_once(&server, body).await;
+
+    let codex_home = TempDir::new()?;
+    create_config_toml(codex_home.path(), &server.uri())?;
+
+    let mut mcp = McpProcess::new(codex_home.path()).await?;
+    timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
+
+    let new_conv_id = mcp
+        .send_new_conversation_request(NewConversationParams {
+            ..Default::default()
+        })
+        .await?;
+    let new_conv_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(new_conv_id)),
+    )
+    .await??;
+    let NewConversationResponse {
+        conversation_id, ..
+    } = to_response::<_>(new_conv_resp)?;
+
+    let oversized_input = "x".repeat(MAX_USER_INPUT_TEXT_CHARS + 1);
+    let req_id = mcp
+        .send_send_user_message_request(SendUserMessageParams {
+            conversation_id,
+            items: vec![InputItem::Text {
+                text: oversized_input.clone(),
+                text_elements: Vec::new(),
+            }],
+        })
+        .await?;
+
+    let err: JSONRPCError = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_error_message(RequestId::Integer(req_id)),
+    )
+    .await??;
+
+    assert_eq!(err.error.code, INVALID_PARAMS_ERROR_CODE);
+    assert_eq!(
+        err.error.message,
+        format!("Input exceeds the maximum length of {MAX_USER_INPUT_TEXT_CHARS} characters.")
+    );
+    let data = err.error.data.expect("expected structured error data");
+    assert_eq!(data["input_error_code"], INPUT_TOO_LARGE_ERROR_CODE);
+    assert_eq!(data["max_chars"], MAX_USER_INPUT_TEXT_CHARS);
+    assert_eq!(data["actual_chars"], oversized_input.chars().count());
+
+    Ok(())
+}
+
 #[tokio::test]
 async fn resume_with_model_mismatch_appends_model_switch_once() -> Result<()> {
     let server = responses::start_mock_server().await;
@@ -481,9 +541,8 @@ fn assert_permissions_message(item: &ResponseItem) {
                 false,
             )
             .into_text();
-            assert_eq!(
-                texts,
-                vec![expected.as_str()],
+            assert!(
+                texts.iter().any(|text| *text == expected),
                 "expected permissions developer message, got {texts:?}"
             );
         }
@@ -496,9 +555,8 @@ fn assert_developer_message(item: &ResponseItem, expected_text: &str) {
         ResponseItem::Message { role, content, .. } => {
             assert_eq!(role, "developer");
             let texts = content_texts(content);
-            assert_eq!(
-                texts,
-                vec![expected_text],
+            assert!(
+                texts.contains(&expected_text),
                 "expected developer instructions message, got {texts:?}"
             );
         }
@@ -562,6 +620,8 @@ fn append_rollout_turn_context(path: &Path, timestamp: &str, model: &str) -> std
         item: RolloutItem::TurnContext(TurnContextItem {
             turn_id: None,
             cwd: PathBuf::from("/"),
+            current_date: None,
+            timezone: None,
             approval_policy: AskForApproval::Never,
             sandbox_policy: SandboxPolicy::DangerFullAccess,
             network: None,

codex-rs/app-server/tests/suite/v2/app_list.rs

@@ -1027,6 +1027,41 @@ async fn list_apps_force_refetch_patches_updates_from_cached_snapshots() -> Resu
     let first_update = read_app_list_updated_notification(&mut mcp).await?;
     assert_eq!(
         first_update.data,
+        vec![
+            AppInfo {
+                id: "beta".to_string(),
+                name: "Beta App".to_string(),
+                description: Some("Beta v1".to_string()),
+                logo_url: None,
+                logo_url_dark: None,
+                distribution_channel: None,
+                branding: None,
+                app_metadata: None,
+                labels: None,
+                install_url: Some("https://chatgpt.com/apps/beta-app/beta".to_string()),
+                is_accessible: true,
+                is_enabled: true,
+            },
+            AppInfo {
+                id: "alpha".to_string(),
+                name: "Alpha".to_string(),
+                description: Some("Alpha v1".to_string()),
+                logo_url: None,
+                logo_url_dark: None,
+                distribution_channel: None,
+                branding: None,
+                app_metadata: None,
+                labels: None,
+                install_url: Some("https://chatgpt.com/apps/alpha/alpha".to_string()),
+                is_accessible: false,
+                is_enabled: true,
+            },
+        ]
+    );
+
+    let second_update = read_app_list_updated_notification(&mut mcp).await?;
+    assert_eq!(
+        second_update.data,
         vec![
             AppInfo {
                 id: "alpha".to_string(),
@@ -1073,8 +1108,8 @@ async fn list_apps_force_refetch_patches_updates_from_cached_snapshots() -> Resu
         is_accessible: false,
         is_enabled: true,
     }];
-    let second_update = read_app_list_updated_notification(&mut mcp).await?;
-    assert_eq!(second_update.data, expected_final);
+    let third_update = read_app_list_updated_notification(&mut mcp).await?;
+    assert_eq!(third_update.data, expected_final);
 
     let refetch_response: JSONRPCResponse = timeout(
         DEFAULT_TIMEOUT,

codex-rs/app-server/tests/suite/v2/initialize.rs

@@ -1,16 +1,24 @@
 use anyhow::Result;
 use app_test_support::McpProcess;
+use app_test_support::create_final_assistant_message_sse_response;
 use app_test_support::create_mock_responses_server_sequence_unchecked;
 use app_test_support::to_response;
 use codex_app_server_protocol::ClientInfo;
 use codex_app_server_protocol::InitializeCapabilities;
 use codex_app_server_protocol::InitializeResponse;
 use codex_app_server_protocol::JSONRPCMessage;
+use codex_app_server_protocol::JSONRPCResponse;
 use codex_app_server_protocol::RequestId;
 use codex_app_server_protocol::ThreadStartParams;
 use codex_app_server_protocol::ThreadStartResponse;
+use codex_app_server_protocol::TurnStartParams;
+use codex_app_server_protocol::TurnStartResponse;
+use codex_app_server_protocol::UserInput as V2UserInput;
+use core_test_support::fs_wait;
 use pretty_assertions::assert_eq;
+use serde_json::Value;
 use std::path::Path;
+use std::time::Duration;
 use tempfile::TempDir;
 use tokio::time::timeout;
 
@@ -178,11 +186,103 @@ async fn initialize_opt_out_notification_methods_filters_notifications() -> Resu
     Ok(())
 }
 
+#[tokio::test]
+async fn turn_start_notify_payload_includes_initialize_client_name() -> Result<()> {
+    let responses = vec![create_final_assistant_message_sse_response("Done")?];
+    let server = create_mock_responses_server_sequence_unchecked(responses).await;
+    let codex_home = TempDir::new()?;
+    let notify_script = codex_home.path().join("notify.py");
+    std::fs::write(
+        &notify_script,
+        r#"from pathlib import Path
+import sys
+
+payload_path = Path(__file__).with_name("notify.json")
+tmp_path = payload_path.with_suffix(".json.tmp")
+tmp_path.write_text(sys.argv[-1], encoding="utf-8")
+tmp_path.replace(payload_path)
+"#,
+    )?;
+    let notify_file = codex_home.path().join("notify.json");
+    let notify_script = notify_script
+        .to_str()
+        .expect("notify script path should be valid UTF-8");
+    create_config_toml_with_extra(
+        codex_home.path(),
+        &server.uri(),
+        "never",
+        &format!(
+            "notify = [\"python3\", {}]",
+            toml_basic_string(notify_script)
+        ),
+    )?;
+
+    let mut mcp = McpProcess::new(codex_home.path()).await?;
+    timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.initialize_with_client_info(ClientInfo {
+            name: "xcode".to_string(),
+            title: Some("Xcode".to_string()),
+            version: "1.0.0".to_string(),
+        }),
+    )
+    .await??;
+
+    let thread_req = mcp
+        .send_thread_start_request(ThreadStartParams::default())
+        .await?;
+    let thread_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(thread_req)),
+    )
+    .await??;
+    let ThreadStartResponse { thread, .. } = to_response(thread_resp)?;
+
+    let turn_req = mcp
+        .send_turn_start_request(TurnStartParams {
+            thread_id: thread.id,
+            input: vec![V2UserInput::Text {
+                text: "Hello".to_string(),
+                text_elements: Vec::new(),
+            }],
+            ..Default::default()
+        })
+        .await?;
+    let turn_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(turn_req)),
+    )
+    .await??;
+    let _: TurnStartResponse = to_response(turn_resp)?;
+
+    timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_notification_message("turn/completed"),
+    )
+    .await??;
+
+    fs_wait::wait_for_path_exists(&notify_file, Duration::from_secs(5)).await?;
+    let payload_raw = tokio::fs::read_to_string(&notify_file).await?;
+    let payload: Value = serde_json::from_str(&payload_raw)?;
+    assert_eq!(payload["client"], "xcode");
+
+    Ok(())
+}
+
 // Helper to create a config.toml pointing at the mock model server.
 fn create_config_toml(
     codex_home: &Path,
     server_uri: &str,
     approval_policy: &str,
+) -> std::io::Result<()> {
+    create_config_toml_with_extra(codex_home, server_uri, approval_policy, "")
+}
+
+fn create_config_toml_with_extra(
+    codex_home: &Path,
+    server_uri: &str,
+    approval_policy: &str,
+    extra: &str,
 ) -> std::io::Result<()> {
     let config_toml = codex_home.join("config.toml");
     std::fs::write(
@@ -195,6 +295,8 @@ sandbox_mode = "read-only"
 
 model_provider = "mock_provider"
 
+{extra}
+
 [model_providers.mock_provider]
 name = "Mock provider for test"
 base_url = "{server_uri}/v1"
@@ -205,3 +307,7 @@ stream_max_retries = 0
         ),
     )
 }
+
+fn toml_basic_string(value: &str) -> String {
+    format!("\"{}\"", value.replace('\\', "\\\\").replace('"', "\\\""))
+}

codex-rs/app-server/tests/suite/v2/mod.rs

@@ -19,7 +19,6 @@ mod realtime_conversation;
 mod request_user_input;
 mod review;
 mod safety_check_downgrade;
-mod skill_approval;
 mod skills_list;
 mod thread_archive;
 mod thread_fork;

codex-rs/app-server/tests/suite/v2/model_list.rs

@@ -9,6 +9,7 @@ use codex_app_server_protocol::JSONRPCResponse;
 use codex_app_server_protocol::Model;
 use codex_app_server_protocol::ModelListParams;
 use codex_app_server_protocol::ModelListResponse;
+use codex_app_server_protocol::ModelUpgradeInfo;
 use codex_app_server_protocol::ReasoningEffortOption;
 use codex_app_server_protocol::RequestId;
 use codex_protocol::openai_models::ModelPreset;
@@ -24,6 +25,13 @@ fn model_from_preset(preset: &ModelPreset) -> Model {
         id: preset.id.clone(),
         model: preset.model.clone(),
         upgrade: preset.upgrade.as_ref().map(|upgrade| upgrade.id.clone()),
+        upgrade_info: preset.upgrade.as_ref().map(|upgrade| ModelUpgradeInfo {
+            model: upgrade.id.clone(),
+            upgrade_copy: upgrade.upgrade_copy.clone(),
+            model_link: upgrade.model_link.clone(),
+            migration_markdown: upgrade.migration_markdown.clone(),
+        }),
+        availability_nux: preset.availability_nux.clone().map(Into::into),
         display_name: preset.display_name.clone(),
         description: preset.description.clone(),
         hidden: !preset.show_in_picker,

codex-rs/app-server/tests/suite/v2/skill_approval.rs

@@ -1,109 +0,0 @@
-use anyhow::Result;
-use app_test_support::McpProcess;
-use app_test_support::create_final_assistant_message_sse_response;
-use app_test_support::create_mock_responses_server_sequence;
-use app_test_support::to_response;
-use codex_app_server_protocol::JSONRPCResponse;
-use codex_app_server_protocol::RequestId;
-use codex_app_server_protocol::ServerRequest;
-use codex_app_server_protocol::ThreadStartParams;
-use codex_app_server_protocol::ThreadStartResponse;
-use codex_app_server_protocol::TurnStartParams;
-use codex_app_server_protocol::TurnStartResponse;
-use codex_app_server_protocol::UserInput as V2UserInput;
-use tokio::time::timeout;
-
-const DEFAULT_READ_TIMEOUT: std::time::Duration = std::time::Duration::from_secs(10);
-
-#[tokio::test(flavor = "multi_thread", worker_threads = 4)]
-async fn skill_request_approval_round_trip() -> Result<()> {
-    let codex_home = tempfile::TempDir::new()?;
-    let server =
-        create_mock_responses_server_sequence(vec![create_final_assistant_message_sse_response(
-            "done",
-        )?])
-        .await;
-    create_config_toml(codex_home.path(), &server.uri())?;
-
-    let mut mcp = McpProcess::new(codex_home.path()).await?;
-    timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
-
-    let thread_start_id = mcp
-        .send_thread_start_request(ThreadStartParams {
-            model: Some("mock-model".to_string()),
-            ..Default::default()
-        })
-        .await?;
-    let thread_start_resp: JSONRPCResponse = timeout(
-        DEFAULT_READ_TIMEOUT,
-        mcp.read_stream_until_response_message(RequestId::Integer(thread_start_id)),
-    )
-    .await??;
-    let ThreadStartResponse { thread, .. } = to_response(thread_start_resp)?;
-
-    let turn_start_id = mcp
-        .send_turn_start_request(TurnStartParams {
-            thread_id: thread.id.clone(),
-            input: vec![V2UserInput::Text {
-                text: "ask something".to_string(),
-                text_elements: Vec::new(),
-            }],
-            model: Some("mock-model".to_string()),
-            ..Default::default()
-        })
-        .await?;
-    let turn_start_resp: JSONRPCResponse = timeout(
-        DEFAULT_READ_TIMEOUT,
-        mcp.read_stream_until_response_message(RequestId::Integer(turn_start_id)),
-    )
-    .await??;
-    let TurnStartResponse { turn, .. } = to_response(turn_start_resp)?;
-
-    let server_req = timeout(
-        DEFAULT_READ_TIMEOUT,
-        mcp.read_stream_until_request_message(),
-    )
-    .await??;
-    let ServerRequest::SkillRequestApproval { request_id, params } = server_req else {
-        panic!("expected SkillRequestApproval request, got: {server_req:?}");
-    };
-
-    assert_eq!(params.item_id, turn.id);
-    assert_eq!(params.skill_name, "test-skill");
-
-    mcp.send_response(request_id, serde_json::json!({ "decision": "approve" }))
-        .await?;
-
-    timeout(
-        DEFAULT_READ_TIMEOUT,
-        mcp.read_stream_until_notification_message("turn/completed"),
-    )
-    .await??;
-
-    Ok(())
-}
-
-fn create_config_toml(codex_home: &std::path::Path, server_uri: &str) -> std::io::Result<()> {
-    let config_toml = codex_home.join("config.toml");
-    std::fs::write(
-        config_toml,
-        format!(
-            r#"
-model = "mock-model"
-approval_policy = "never"
-sandbox_mode = "read-only"
-
-model_provider = "mock_provider"
-
-[features]
-skill_approval = true
-
-[model_providers.mock_provider]
-name = "Mock provider for test"
-base_url = "{server_uri}/v1"
-request_max_retries = 0
-stream_max_retries = 0
-"#
-        ),
-    )
-}

codex-rs/app-server/tests/suite/v2/turn_start.rs

@@ -9,6 +9,8 @@ use app_test_support::create_mock_responses_server_sequence_unchecked;
 use app_test_support::create_shell_command_sse_response;
 use app_test_support::format_with_current_shell_display;
 use app_test_support::to_response;
+use codex_app_server::INPUT_TOO_LARGE_ERROR_CODE;
+use codex_app_server::INVALID_PARAMS_ERROR_CODE;
 use codex_app_server_protocol::ByteRange;
 use codex_app_server_protocol::ClientInfo;
 use codex_app_server_protocol::CommandExecutionApprovalDecision;
@@ -19,6 +21,7 @@ use codex_app_server_protocol::FileChangeOutputDeltaNotification;
 use codex_app_server_protocol::FileChangeRequestApprovalResponse;
 use codex_app_server_protocol::ItemCompletedNotification;
 use codex_app_server_protocol::ItemStartedNotification;
+use codex_app_server_protocol::JSONRPCError;
 use codex_app_server_protocol::JSONRPCNotification;
 use codex_app_server_protocol::JSONRPCResponse;
 use codex_app_server_protocol::PatchApplyStatus;
@@ -45,6 +48,7 @@ use codex_protocol::config_types::Personality;
 use codex_protocol::config_types::ReasoningSummary;
 use codex_protocol::config_types::Settings;
 use codex_protocol::openai_models::ReasoningEffort;
+use codex_protocol::user_input::MAX_USER_INPUT_TEXT_CHARS;
 use core_test_support::responses;
 use core_test_support::skip_if_no_network;
 use pretty_assertions::assert_eq;
@@ -223,6 +227,143 @@ async fn turn_start_emits_user_message_item_with_text_elements() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn turn_start_accepts_text_at_limit_with_mention_item() -> Result<()> {
+    let responses = vec![create_final_assistant_message_sse_response("Done")?];
+    let server = create_mock_responses_server_sequence_unchecked(responses).await;
+
+    let codex_home = TempDir::new()?;
+    create_config_toml(
+        codex_home.path(),
+        &server.uri(),
+        "never",
+        &BTreeMap::from([(Feature::Personality, true)]),
+    )?;
+
+    let mut mcp = McpProcess::new(codex_home.path()).await?;
+    timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
+
+    let thread_req = mcp
+        .send_thread_start_request(ThreadStartParams {
+            model: Some("mock-model".to_string()),
+            ..Default::default()
+        })
+        .await?;
+    let thread_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(thread_req)),
+    )
+    .await??;
+    let ThreadStartResponse { thread, .. } = to_response::<ThreadStartResponse>(thread_resp)?;
+
+    let turn_req = mcp
+        .send_turn_start_request(TurnStartParams {
+            thread_id: thread.id,
+            input: vec![
+                V2UserInput::Text {
+                    text: "x".repeat(MAX_USER_INPUT_TEXT_CHARS),
+                    text_elements: Vec::new(),
+                },
+                V2UserInput::Mention {
+                    name: "Demo App".to_string(),
+                    path: "app://demo-app".to_string(),
+                },
+            ],
+            ..Default::default()
+        })
+        .await?;
+    let turn_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(turn_req)),
+    )
+    .await??;
+    let TurnStartResponse { turn } = to_response::<TurnStartResponse>(turn_resp)?;
+    assert_eq!(turn.status, TurnStatus::InProgress);
+
+    timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_notification_message("turn/completed"),
+    )
+    .await??;
+
+    Ok(())
+}
+
+#[tokio::test]
+async fn turn_start_rejects_combined_oversized_text_input() -> Result<()> {
+    let codex_home = TempDir::new()?;
+    create_config_toml(
+        codex_home.path(),
+        "http://localhost/unused",
+        "never",
+        &BTreeMap::from([(Feature::Personality, true)]),
+    )?;
+
+    let mut mcp = McpProcess::new(codex_home.path()).await?;
+    timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
+
+    let thread_req = mcp
+        .send_thread_start_request(ThreadStartParams {
+            model: Some("mock-model".to_string()),
+            ..Default::default()
+        })
+        .await?;
+    let thread_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(thread_req)),
+    )
+    .await??;
+    let ThreadStartResponse { thread, .. } = to_response::<ThreadStartResponse>(thread_resp)?;
+
+    let first = "x".repeat(MAX_USER_INPUT_TEXT_CHARS / 2);
+    let second = "y".repeat(MAX_USER_INPUT_TEXT_CHARS / 2 + 1);
+    let actual_chars = first.chars().count() + second.chars().count();
+
+    let turn_req = mcp
+        .send_turn_start_request(TurnStartParams {
+            thread_id: thread.id,
+            input: vec![
+                V2UserInput::Text {
+                    text: first,
+                    text_elements: Vec::new(),
+                },
+                V2UserInput::Text {
+                    text: second,
+                    text_elements: Vec::new(),
+                },
+            ],
+            ..Default::default()
+        })
+        .await?;
+    let err: JSONRPCError = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_error_message(RequestId::Integer(turn_req)),
+    )
+    .await??;
+
+    assert_eq!(err.error.code, INVALID_PARAMS_ERROR_CODE);
+    assert_eq!(
+        err.error.message,
+        format!("Input exceeds the maximum length of {MAX_USER_INPUT_TEXT_CHARS} characters.")
+    );
+    let data = err.error.data.expect("expected structured error data");
+    assert_eq!(data["input_error_code"], INPUT_TOO_LARGE_ERROR_CODE);
+    assert_eq!(data["max_chars"], MAX_USER_INPUT_TEXT_CHARS);
+    assert_eq!(data["actual_chars"], actual_chars);
+
+    let turn_started = tokio::time::timeout(
+        std::time::Duration::from_millis(250),
+        mcp.read_stream_until_notification_message("turn/started"),
+    )
+    .await;
+    assert!(
+        turn_started.is_err(),
+        "did not expect a turn/started notification for rejected input"
+    );
+
+    Ok(())
+}
+
 #[tokio::test]
 async fn turn_start_emits_notifications_and_accepts_model_override() -> Result<()> {
     // Provide a mock server and config so model wiring is valid.

codex-rs/app-server/tests/suite/v2/turn_steer.rs

@@ -6,6 +6,8 @@ use app_test_support::create_mock_responses_server_sequence;
 use app_test_support::create_mock_responses_server_sequence_unchecked;
 use app_test_support::create_shell_command_sse_response;
 use app_test_support::to_response;
+use codex_app_server::INPUT_TOO_LARGE_ERROR_CODE;
+use codex_app_server::INVALID_PARAMS_ERROR_CODE;
 use codex_app_server_protocol::JSONRPCError;
 use codex_app_server_protocol::JSONRPCNotification;
 use codex_app_server_protocol::JSONRPCResponse;
@@ -17,6 +19,7 @@ use codex_app_server_protocol::TurnStartResponse;
 use codex_app_server_protocol::TurnSteerParams;
 use codex_app_server_protocol::TurnSteerResponse;
 use codex_app_server_protocol::UserInput as V2UserInput;
+use codex_protocol::user_input::MAX_USER_INPUT_TEXT_CHARS;
 use tempfile::TempDir;
 use tokio::time::timeout;
 
@@ -67,6 +70,109 @@ async fn turn_steer_requires_active_turn() -> Result<()> {
     Ok(())
 }
 
+#[tokio::test]
+async fn turn_steer_rejects_oversized_text_input() -> Result<()> {
+    #[cfg(target_os = "windows")]
+    let shell_command = vec![
+        "powershell".to_string(),
+        "-Command".to_string(),
+        "Start-Sleep -Seconds 10".to_string(),
+    ];
+    #[cfg(not(target_os = "windows"))]
+    let shell_command = vec!["sleep".to_string(), "10".to_string()];
+
+    let tmp = TempDir::new()?;
+    let codex_home = tmp.path().join("codex_home");
+    std::fs::create_dir(&codex_home)?;
+    let working_directory = tmp.path().join("workdir");
+    std::fs::create_dir(&working_directory)?;
+
+    let server =
+        create_mock_responses_server_sequence_unchecked(vec![create_shell_command_sse_response(
+            shell_command.clone(),
+            Some(&working_directory),
+            Some(10_000),
+            "call_sleep",
+        )?])
+        .await;
+    create_config_toml(&codex_home, &server.uri())?;
+
+    let mut mcp = McpProcess::new(&codex_home).await?;
+    timeout(DEFAULT_READ_TIMEOUT, mcp.initialize()).await??;
+
+    let thread_req = mcp
+        .send_thread_start_request(ThreadStartParams {
+            model: Some("mock-model".to_string()),
+            ..Default::default()
+        })
+        .await?;
+    let thread_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(thread_req)),
+    )
+    .await??;
+    let ThreadStartResponse { thread, .. } = to_response::<ThreadStartResponse>(thread_resp)?;
+
+    let turn_req = mcp
+        .send_turn_start_request(TurnStartParams {
+            thread_id: thread.id.clone(),
+            input: vec![V2UserInput::Text {
+                text: "run sleep".to_string(),
+                text_elements: Vec::new(),
+            }],
+            cwd: Some(working_directory.clone()),
+            ..Default::default()
+        })
+        .await?;
+    let turn_resp: JSONRPCResponse = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_response_message(RequestId::Integer(turn_req)),
+    )
+    .await??;
+    let TurnStartResponse { turn } = to_response::<TurnStartResponse>(turn_resp)?;
+
+    let _task_started: JSONRPCNotification = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_notification_message("codex/event/task_started"),
+    )
+    .await??;
+
+    let oversized_input = "x".repeat(MAX_USER_INPUT_TEXT_CHARS + 1);
+    let steer_req = mcp
+        .send_turn_steer_request(TurnSteerParams {
+            thread_id: thread.id.clone(),
+            input: vec![V2UserInput::Text {
+                text: oversized_input.clone(),
+                text_elements: Vec::new(),
+            }],
+            expected_turn_id: turn.id.clone(),
+        })
+        .await?;
+    let steer_err: JSONRPCError = timeout(
+        DEFAULT_READ_TIMEOUT,
+        mcp.read_stream_until_error_message(RequestId::Integer(steer_req)),
+    )
+    .await??;
+
+    assert_eq!(steer_err.error.code, INVALID_PARAMS_ERROR_CODE);
+    assert_eq!(
+        steer_err.error.message,
+        format!("Input exceeds the maximum length of {MAX_USER_INPUT_TEXT_CHARS} characters.")
+    );
+    let data = steer_err
+        .error
+        .data
+        .expect("expected structured error data");
+    assert_eq!(data["input_error_code"], INPUT_TOO_LARGE_ERROR_CODE);
+    assert_eq!(data["max_chars"], MAX_USER_INPUT_TEXT_CHARS);
+    assert_eq!(data["actual_chars"], oversized_input.chars().count());
+
+    mcp.interrupt_turn_and_wait_for_aborted(thread.id, turn.id, DEFAULT_READ_TIMEOUT)
+        .await?;
+
+    Ok(())
+}
+
 #[tokio::test]
 async fn turn_steer_returns_active_turn_id() -> Result<()> {
     #[cfg(target_os = "windows")]