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Enforce user input length cap (#12823)

Browse source 
Currently there is no bound on the length of a user message submitted in
the TUI or through the app server interface. That means users can paste
many megabytes of text, which can lead to bad performance, hangs, and
crashes. In extreme cases, it can lead to a [kernel
panic](https://github.com/openai/codex/issues/12323).

This PR limits the length of a user input to 2**20 (about 1M)
characters. This value was chosen because it fills the entire context
window on the latest models, so accepting longer inputs wouldn't make
sense anyway.

Summary
- add a shared `MAX_USER_INPUT_TEXT_CHARS` constant in codex-protocol
and surface it in TUI and app server code
- block oversized submissions in the TUI submit flow and emit error
history cells when validation fails
- reject heavy app-server requests with JSON-RPC `-32602` and structured
`input_too_large` data, plus document the behavior

Testing
- ran the IDE extension with this change and verified that when I
attempt to paste a user message that's several MB long, it correctly
reports an error instead of crashing or making my computer hot.
This commit is contained in:
Eric Traut 2026-02-25 22:23:51 -08:00 • committed by GitHub
parent 9a96b6f509
commit 28bfbb8f2b
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GPG key ID: B5690EEEBB952194
13 changed files with 676 additions and 0 deletions
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9
codex-rs/app-server-protocol/src/protocol/v1.rs
View file

@ -531,6 +531,15 @@ impl From<V1TextElement> for CoreTextElement {
}
}
impl InputItem {
pub fn text_char_count(&self) -> usize {
match self {
InputItem::Text { text, .. } => text.chars().count(),
InputItem::Image { .. } | InputItem::LocalImage { .. } => 0,
}
}
}
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
#[serde(rename_all = "camelCase")]
/// Deprecated in favor of AccountLoginCompletedNotification.

12
codex-rs/app-server-protocol/src/protocol/v2.rs
View file

@ -3052,6 +3052,18 @@ impl From<CoreUserInput> for UserInput {
}
}
impl UserInput {
pub fn text_char_count(&self) -> usize {
match self {
UserInput::Text { text, .. } => text.chars().count(),
UserInput::Image { .. }
| UserInput::LocalImage { .. }
| UserInput::Skill { .. }
| UserInput::Mention { .. } => 0,
}
}
}
#[derive(Serialize, Deserialize, Debug, Clone, PartialEq, JsonSchema, TS)]
#[serde(tag = "type", rename_all = "camelCase")]
#[ts(tag = "type")]

49
codex-rs/app-server/src/codex_message_processor.rs
View file

@ -1,5 +1,7 @@
use crate::bespoke_event_handling::apply_bespoke_event_handling;
use crate::error_code::INPUT_TOO_LARGE_ERROR_CODE;
use crate::error_code::INTERNAL_ERROR_CODE;
use crate::error_code::INVALID_PARAMS_ERROR_CODE;
use crate::error_code::INVALID_REQUEST_ERROR_CODE;
use crate::fuzzy_file_search::FuzzyFileSearchSession;
use crate::fuzzy_file_search::run_fuzzy_file_search;
@ -267,6 +269,7 @@ use codex_protocol::protocol::RolloutItem;
use codex_protocol::protocol::SessionConfiguredEvent;
use codex_protocol::protocol::SessionMetaLine;
use codex_protocol::protocol::USER_MESSAGE_BEGIN;
use codex_protocol::user_input::MAX_USER_INPUT_TEXT_CHARS;
use codex_protocol::user_input::UserInput as CoreInputItem;
use codex_rmcp_client::perform_oauth_login_return_url;
use codex_utils_json_to_toml::json_to_toml;
@ -4735,6 +4738,36 @@ impl CodexMessageProcessor {
self.outgoing.send_error(request_id, error).await;
}
fn input_too_large_error(actual_chars: usize) -> JSONRPCErrorError {
JSONRPCErrorError {
code: INVALID_PARAMS_ERROR_CODE,
message: format!(
"Input exceeds the maximum length of {MAX_USER_INPUT_TEXT_CHARS} characters."
),
data: Some(serde_json::json!({
"input_error_code": INPUT_TOO_LARGE_ERROR_CODE,
"max_chars": MAX_USER_INPUT_TEXT_CHARS,
"actual_chars": actual_chars,
})),
}
}
fn validate_v1_input_limit(items: &[WireInputItem]) -> Result<(), JSONRPCErrorError> {
let actual_chars: usize = items.iter().map(WireInputItem::text_char_count).sum();
if actual_chars > MAX_USER_INPUT_TEXT_CHARS {
return Err(Self::input_too_large_error(actual_chars));
}
Ok(())
}
fn validate_v2_input_limit(items: &[V2UserInput]) -> Result<(), JSONRPCErrorError> {
let actual_chars: usize = items.iter().map(V2UserInput::text_char_count).sum();
if actual_chars > MAX_USER_INPUT_TEXT_CHARS {
return Err(Self::input_too_large_error(actual_chars));
}
Ok(())
}
async fn send_internal_error(&self, request_id: ConnectionRequestId, message: String) {
let error = JSONRPCErrorError {
code: INTERNAL_ERROR_CODE,
@ -5034,6 +5067,10 @@ impl CodexMessageProcessor {
conversation_id,
items,
} = params;
if let Err(error) = Self::validate_v1_input_limit(&items) {
self.outgoing.send_error(request_id, error).await;
return;
}
let Ok(conversation) = self.thread_manager.get_thread(conversation_id).await else {
let error = JSONRPCErrorError {
code: INVALID_REQUEST_ERROR_CODE,
@ -5085,6 +5122,10 @@ impl CodexMessageProcessor {
summary,
output_schema,
} = params;
if let Err(error) = Self::validate_v1_input_limit(&items) {
self.outgoing.send_error(request_id, error).await;
return;
}
let Ok(conversation) = self.thread_manager.get_thread(conversation_id).await else {
let error = JSONRPCErrorError {
@ -5567,6 +5608,10 @@ impl CodexMessageProcessor {
}
async fn turn_start(&self, request_id: ConnectionRequestId, params: TurnStartParams) {
if let Err(error) = Self::validate_v2_input_limit(&params.input) {
self.outgoing.send_error(request_id, error).await;
return;
}
let (_, thread) = match self.load_thread(&params.thread_id).await {
Ok(v) => v,
Err(error) => {
@ -5672,6 +5717,10 @@ impl CodexMessageProcessor {
.await;
return;
}
if let Err(error) = Self::validate_v2_input_limit(&params.input) {
self.outgoing.send_error(request_id, error).await;
return;
}
let mapped_items: Vec<CoreInputItem> = params
.input

2
codex-rs/app-server/src/error_code.rs
View file

@ -1,3 +1,5 @@
pub(crate) const INVALID_REQUEST_ERROR_CODE: i64 = -32600;
pub const INVALID_PARAMS_ERROR_CODE: i64 = -32602;
pub(crate) const INTERNAL_ERROR_CODE: i64 = -32603;
pub(crate) const OVERLOADED_ERROR_CODE: i64 = -32001;
pub const INPUT_TOO_LARGE_ERROR_CODE: &str = "input_too_large";

2
codex-rs/app-server/src/lib.rs
View file

@ -67,6 +67,8 @@ mod thread_state;
mod thread_status;
mod transport;
pub use crate::error_code::INPUT_TOO_LARGE_ERROR_CODE;
pub use crate::error_code::INVALID_PARAMS_ERROR_CODE;
pub use crate::transport::AppServerTransport;
const LOG_FORMAT_ENV_VAR: &str = "LOG_FORMAT";

83
codex-rs/app-server/tests/suite/output_schema.rs
View file

@ -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(()));

64
codex-rs/app-server/tests/suite/send_message.rs
View file

@ -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;
@ -272,6 +276,66 @@ 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;

141
codex-rs/app-server/tests/suite/v2/turn_start.rs
View file

@ -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.

106
codex-rs/app-server/tests/suite/v2/turn_steer.rs
View file

@ -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")]

3
codex-rs/protocol/src/user_input.rs
View file

@ -3,6 +3,9 @@ use serde::Deserialize;
use serde::Serialize;
use ts_rs::TS;
/// Conservative cap so one user message cannot monopolize a large context window.
pub const MAX_USER_INPUT_TEXT_CHARS: usize = 1 << 20;
/// User input
#[non_exhaustive]
#[derive(Debug, Clone, Deserialize, Serialize, PartialEq, TS, JsonSchema)]

190
codex-rs/tui/src/bottom_pane/chat_composer.rs
View file

@ -189,6 +189,7 @@ use codex_protocol::custom_prompts::CustomPrompt;
use codex_protocol::custom_prompts::PROMPTS_CMD_PREFIX;
use codex_protocol::models::local_image_label_text;
use codex_protocol::user_input::ByteRange;
use codex_protocol::user_input::MAX_USER_INPUT_TEXT_CHARS;
use codex_protocol::user_input::TextElement;
use codex_utils_fuzzy_match::fuzzy_match;
@ -229,6 +230,12 @@ use tokio::runtime::Handle;
/// placeholder in the UI.
const LARGE_PASTE_CHAR_THRESHOLD: usize = 1000;
fn user_input_too_large_message(actual_chars: usize) -> String {
format!(
"Message exceeds the maximum length of {MAX_USER_INPUT_TEXT_CHARS} characters ({actual_chars} provided)."
)
}
/// Result returned when the user interacts with the text area.
#[derive(Debug, PartialEq)]
pub enum InputResult {
@ -570,6 +577,10 @@ impl ChatComposer {
self.realtime_conversation_enabled = enabled;
}
/// Compatibility shim for tests that still toggle the removed steer mode flag.
#[cfg(test)]
pub fn set_steer_enabled(&mut self, _enabled: bool) {}
pub fn set_voice_transcription_enabled(&mut self, enabled: bool) {
self.voice_state.transcription_enabled = enabled;
if !enabled {
@ -2309,6 +2320,22 @@ impl ChatComposer {
text_elements = expanded.text_elements;
}
}
let actual_chars = text.chars().count();
if actual_chars > MAX_USER_INPUT_TEXT_CHARS {
let message = user_input_too_large_message(actual_chars);
self.app_event_tx.send(AppEvent::InsertHistoryCell(Box::new(
history_cell::new_error_event(message),
)));
self.set_text_content_with_mention_bindings(
original_input.clone(),
original_text_elements,
original_local_image_paths,
original_mention_bindings,
);
self.pending_pastes.clone_from(&original_pending_pastes);
self.textarea.set_cursor(original_input.len());
return None;
}
// Custom prompt expansion can remove or rewrite image placeholders, so prune any
// attachments that no longer have a corresponding placeholder in the expanded text.
self.prune_attached_images_for_submission(&text, &text_elements);
@ -5921,6 +5948,118 @@ mod tests {
assert!(composer.pending_pastes.is_empty());
}
#[test]
fn submit_at_character_limit_succeeds() {
use crossterm::event::KeyCode;
use crossterm::event::KeyEvent;
use crossterm::event::KeyModifiers;
let (tx, _rx) = unbounded_channel::<AppEvent>();
let sender = AppEventSender::new(tx);
let mut composer = ChatComposer::new(
true,
sender,
false,
"Ask Codex to do anything".to_string(),
false,
);
composer.set_steer_enabled(true);
let input = "x".repeat(MAX_USER_INPUT_TEXT_CHARS);
composer.textarea.set_text_clearing_elements(&input);
let (result, _needs_redraw) =
composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
assert!(matches!(
result,
InputResult::Submitted { text, .. } if text == input
));
}
#[test]
fn oversized_submit_reports_error_and_restores_draft() {
use crossterm::event::KeyCode;
use crossterm::event::KeyEvent;
use crossterm::event::KeyModifiers;
let (tx, mut rx) = unbounded_channel::<AppEvent>();
let sender = AppEventSender::new(tx);
let mut composer = ChatComposer::new(
true,
sender,
false,
"Ask Codex to do anything".to_string(),
false,
);
composer.set_steer_enabled(true);
let input = "x".repeat(MAX_USER_INPUT_TEXT_CHARS + 1);
composer.textarea.set_text_clearing_elements(&input);
let (result, _needs_redraw) =
composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
assert_eq!(InputResult::None, result);
assert_eq!(composer.textarea.text(), input);
let mut found_error = false;
while let Ok(event) = rx.try_recv() {
if let AppEvent::InsertHistoryCell(cell) = event {
let message = cell
.display_lines(80)
.into_iter()
.map(|line| line.to_string())
.collect::<Vec<_>>()
.join("\n");
assert!(message.contains(&user_input_too_large_message(input.chars().count())));
found_error = true;
break;
}
}
assert!(found_error, "expected oversized-input error history cell");
}
#[test]
fn oversized_queued_submission_reports_error_and_restores_draft() {
use crossterm::event::KeyCode;
use crossterm::event::KeyEvent;
use crossterm::event::KeyModifiers;
let (tx, mut rx) = unbounded_channel::<AppEvent>();
let sender = AppEventSender::new(tx);
let mut composer = ChatComposer::new(
true,
sender,
false,
"Ask Codex to do anything".to_string(),
false,
);
composer.set_steer_enabled(false);
let input = "x".repeat(MAX_USER_INPUT_TEXT_CHARS + 1);
composer.textarea.set_text_clearing_elements(&input);
let (result, _needs_redraw) =
composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
assert_eq!(InputResult::None, result);
assert_eq!(composer.textarea.text(), input);
let mut found_error = false;
while let Ok(event) = rx.try_recv() {
if let AppEvent::InsertHistoryCell(cell) = event {
let message = cell
.display_lines(80)
.into_iter()
.map(|line| line.to_string())
.collect::<Vec<_>>()
.join("\n");
assert!(message.contains(&user_input_too_large_message(input.chars().count())));
found_error = true;
break;
}
}
assert!(found_error, "expected oversized-input error history cell");
}
/// Behavior: editing that removes a paste placeholder should also clear the associated
/// `pending_pastes` entry so it cannot be submitted accidentally.
#[test]
@ -8521,6 +8660,57 @@ mod tests {
);
}
#[test]
fn prompt_expansion_over_character_limit_reports_error_and_restores_draft() {
let (tx, mut rx) = unbounded_channel::<AppEvent>();
let sender = AppEventSender::new(tx);
let mut composer = ChatComposer::new(
true,
sender,
false,
"Ask Codex to do anything".to_string(),
false,
);
composer.set_steer_enabled(true);
composer.set_custom_prompts(vec![CustomPrompt {
name: "my-prompt".to_string(),
path: "/tmp/my-prompt.md".to_string().into(),
content: "Echo: $1".to_string(),
description: None,
argument_hint: None,
}]);
let oversized_arg = "x".repeat(MAX_USER_INPUT_TEXT_CHARS);
let original_input = format!("/prompts:my-prompt {oversized_arg}");
composer
.textarea
.set_text_clearing_elements(&original_input);
let (result, _needs_redraw) =
composer.handle_key_event(KeyEvent::new(KeyCode::Enter, KeyModifiers::NONE));
assert_eq!(InputResult::None, result);
assert_eq!(composer.textarea.text(), original_input);
let actual_chars = format!("Echo: {oversized_arg}").chars().count();
let mut found_error = false;
while let Ok(event) = rx.try_recv() {
if let AppEvent::InsertHistoryCell(cell) = event {
let message = cell
.display_lines(80)
.into_iter()
.map(|line| line.to_string())
.collect::<Vec<_>>()
.join("\n");
assert!(message.contains(&user_input_too_large_message(actual_chars)));
found_error = true;
break;
}
}
assert!(found_error, "expected oversized-input error history cell");
}
#[test]
fn selecting_custom_prompt_with_positional_args_submits_numeric_expansion() {
let prompt_text = "Header: $1\nArgs: $ARGUMENTS\n";

10
codex-rs/tui/src/history_cell.rs
View file

@ -2602,6 +2602,16 @@ mod tests {
insta::assert_snapshot!(rendered);
}
#[test]
fn error_event_oversized_input_snapshot() {
let cell = new_error_event(
"Message exceeds the maximum length of 1048576 characters (1048577 provided)."
.to_string(),
);
let rendered = render_lines(&cell.display_lines(120)).join("\n");
insta::assert_snapshot!(rendered);
}
#[tokio::test]
async fn mcp_tools_output_masks_sensitive_values() {
let mut config = test_config().await;

5
codex-rs/tui/src/snapshots/codex_tui__history_cell__tests__error_event_oversized_input_snapshot.snap Normal file
View file

@ -0,0 +1,5 @@
---
source: tui/src/history_cell.rs
expression: rendered
---
■ Message exceeds the maximum length of 1048576 characters (1048577 provided).