This is a very large PR with some non-backwards-compatible changes.
Historically, `codex mcp` (or `codex mcp serve`) started a JSON-RPC-ish
server that had two overlapping responsibilities:
- Running an MCP server, providing some basic tool calls.
- Running the app server used to power experiences such as the VS Code
extension.
This PR aims to separate these into distinct concepts:
- `codex mcp-server` for the MCP server
- `codex app-server` for the "application server"
Note `codex mcp` still exists because it already has its own subcommands
for MCP management (`list`, `add`, etc.)
The MCP logic continues to live in `codex-rs/mcp-server` whereas the
refactored app server logic is in the new `codex-rs/app-server` folder.
Note that most of the existing integration tests in
`codex-rs/mcp-server/tests/suite` were actually for the app server, so
all the tests have been moved with the exception of
`codex-rs/mcp-server/tests/suite/mod.rs`.
Because this is already a large diff, I tried not to change more than I
had to, so `codex-rs/app-server/tests/common/mcp_process.rs` still uses
the name `McpProcess` for now, but I will do some mechanical renamings
to things like `AppServer` in subsequent PRs.
While `mcp-server` and `app-server` share some overlapping functionality
(like reading streams of JSONL and dispatching based on message types)
and some differences (completely different message types), I ended up
doing a bit of copypasta between the two crates, as both have somewhat
similar `message_processor.rs` and `outgoing_message.rs` files for now,
though I expect them to diverge more in the near future.
One material change is that of the initialize handshake for `codex
app-server`, as we no longer use the MCP types for that handshake.
Instead, we update `codex-rs/protocol/src/mcp_protocol.rs` to add an
`Initialize` variant to `ClientRequest`, which takes the `ClientInfo`
object we need to update the `USER_AGENT_SUFFIX` in
`codex-rs/app-server/src/message_processor.rs`.
One other material change is in
`codex-rs/app-server/src/codex_message_processor.rs` where I eliminated
a use of the `send_event_as_notification()` method I am generally trying
to deprecate (because it blindly maps an `EventMsg` into a
`JSONNotification`) in favor of `send_server_notification()`, which
takes a `ServerNotification`, as that is intended to be a custom enum of
all notification types supported by the app server. So to make this
update, I had to introduce a new variant of `ServerNotification`,
`SessionConfigured`, which is a non-backwards compatible change with the
old `codex mcp`, and clients will have to be updated after the next
release that contains this PR. Note that
`codex-rs/app-server/tests/suite/list_resume.rs` also had to be update
to reflect this change.
I introduced `codex-rs/utils/json-to-toml/src/lib.rs` as a small utility
crate to avoid some of the copying between `mcp-server` and
`app-server`.
# External (non-OpenAI) Pull Request Requirements
Before opening this Pull Request, please read the dedicated
"Contributing" markdown file or your PR may be closed:
https://github.com/openai/codex/blob/main/docs/contributing.md
If your PR conforms to our contribution guidelines, replace this text
with a detailed and high quality description of your changes.
# test
```
codex-rs % export CODEX_DEVICE_AUTH_BASE_URL=http://localhost:3007
codex-rs % cargo run --bin codex login --experimental_use-device-code
Compiling codex-login v0.0.0 (/Users/rakesh/code/codex/codex-rs/login)
Compiling codex-mcp-server v0.0.0 (/Users/rakesh/code/codex/codex-rs/mcp-server)
Compiling codex-tui v0.0.0 (/Users/rakesh/code/codex/codex-rs/tui)
Compiling codex-cli v0.0.0 (/Users/rakesh/code/codex/codex-rs/cli)
Finished `dev` profile [unoptimized + debuginfo] target(s) in 2.90s
Running `target/debug/codex login --experimental_use-device-code`
To authenticate, enter this code when prompted: 6Q27-KBVRF with interval 5
^C
```
The error in the last line is since the poll endpoint is not yet
implemented
Fixing the "? for shortcuts"
- Only show the hint when composer is empty
- Don't reset footer on new task updates
- Reorder the elements
- Align the "?" and "/" with overlay on and off
Based on #4364
### Title
## otel
Codex can emit [OpenTelemetry](https://opentelemetry.io/) **log events**
that
describe each run: outbound API requests, streamed responses, user
input,
tool-approval decisions, and the result of every tool invocation. Export
is
**disabled by default** so local runs remain self-contained. Opt in by
adding an
`[otel]` table and choosing an exporter.
```toml
[otel]
environment = "staging" # defaults to "dev"
exporter = "none" # defaults to "none"; set to otlp-http or otlp-grpc to send events
log_user_prompt = false # defaults to false; redact prompt text unless explicitly enabled
```
Codex tags every exported event with `service.name = "codex-cli"`, the
CLI
version, and an `env` attribute so downstream collectors can distinguish
dev/staging/prod traffic. Only telemetry produced inside the
`codex_otel`
crate—the events listed below—is forwarded to the exporter.
### Event catalog
Every event shares a common set of metadata fields: `event.timestamp`,
`conversation.id`, `app.version`, `auth_mode` (when available),
`user.account_id` (when available), `terminal.type`, `model`, and
`slug`.
With OTEL enabled Codex emits the following event types (in addition to
the
metadata above):
- `codex.api_request`
- `cf_ray` (optional)
- `attempt`
- `duration_ms`
- `http.response.status_code` (optional)
- `error.message` (failures)
- `codex.sse_event`
- `event.kind`
- `duration_ms`
- `error.message` (failures)
- `input_token_count` (completion only)
- `output_token_count` (completion only)
- `cached_token_count` (completion only, optional)
- `reasoning_token_count` (completion only, optional)
- `tool_token_count` (completion only)
- `codex.user_prompt`
- `prompt_length`
- `prompt` (redacted unless `log_user_prompt = true`)
- `codex.tool_decision`
- `tool_name`
- `call_id`
- `decision` (`approved`, `approved_for_session`, `denied`, or `abort`)
- `source` (`config` or `user`)
- `codex.tool_result`
- `tool_name`
- `call_id`
- `arguments`
- `duration_ms` (execution time for the tool)
- `success` (`"true"` or `"false"`)
- `output`
### Choosing an exporter
Set `otel.exporter` to control where events go:
- `none` – leaves instrumentation active but skips exporting. This is
the
default.
- `otlp-http` – posts OTLP log records to an OTLP/HTTP collector.
Specify the
endpoint, protocol, and headers your collector expects:
```toml
[otel]
exporter = { otlp-http = {
endpoint = "https://otel.example.com/v1/logs",
protocol = "binary",
headers = { "x-otlp-api-key" = "${OTLP_TOKEN}" }
}}
```
- `otlp-grpc` – streams OTLP log records over gRPC. Provide the endpoint
and any
metadata headers:
```toml
[otel]
exporter = { otlp-grpc = {
endpoint = "https://otel.example.com:4317",
headers = { "x-otlp-meta" = "abc123" }
}}
```
If the exporter is `none` nothing is written anywhere; otherwise you
must run or point to your
own collector. All exporters run on a background batch worker that is
flushed on
shutdown.
If you build Codex from source the OTEL crate is still behind an `otel`
feature
flag; the official prebuilt binaries ship with the feature enabled. When
the
feature is disabled the telemetry hooks become no-ops so the CLI
continues to
function without the extra dependencies.
---------
Co-authored-by: Anton Panasenko <[email protected]>
This PR expands `.github/workflows/rust-release.yml` so that it also
builds and publishes the `npm` module for
`@openai/codex-responses-api-proxy` in addition to `@openai/codex`. Note
both `npm` modules are similar, in that they each contain a single `.js`
file that is a thin launcher around the appropriate native executable.
(Since we have a minimal dependency on Node.js, I also lowered the
minimum version from 20 to 16 and verified that works on my machine.)
As part of this change, we tighten up some of the docs around
`codex-responses-api-proxy` and ensure the details regarding protecting
the `OPENAI_API_KEY` in memory match the implementation.
To test the `npm` build process, I ran:
```
./codex-cli/scripts/build_npm_package.py --package codex-responses-api-proxy --version 0.43.0-alpha.3
```
which stages the `npm` module for `@openai/codex-responses-api-proxy` in
a temp directory, using the binary artifacts from
https://github.com/openai/codex/releases/tag/rust-v0.43.0-alpha.3.
This should make the `codex-responses-api-proxy` binaries available for
all platforms in a GitHub Release as well as a corresponding DotSlash
file.
Making `codex-responses-api-proxy` available as an `npm` module will be
done in a follow-up PR.
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/4404).
* __->__ #4406
* #4404
* #4403
This removes the `codex responses-api-proxy` subcommand in favor of
running it as a standalone CLI.
As part of this change, we:
- remove the dependency on `tokio`/`async/await` as well as `codex_arg0`
- introduce the use of `pre_main_hardening()` so `CODEX_SECURE_MODE=1`
is not required
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/4404).
* #4406
* __->__ #4404
* #4403
This is likely the reason that I saw some conversations "freeze up" when
using the proxy.
Note the client in `core` does not specify a timeout when making
requests to the Responses API, so the proxy should not, either.
This PR adds support for streamable HTTP MCP servers when the
`experimental_use_rmcp_client` is enabled.
To set one up, simply add a new mcp server config with the url:
```
[mcp_servers.figma]
url = "http://127.0.0.1:3845/mcp"
```
It also supports an optional `bearer_token` which will be provided in an
authorization header. The full oauth flow is not supported yet.
The config parsing will throw if it detects that the user mixed and
matched config fields (like command + bearer token or url + env).
The best way to review it is to review `core/src` and then
`rmcp-client/src/rmcp_client.rs` first. The rest is tests and
propagating the `Transport` struct around the codebase.
Example with the Figma MCP:
<img width="5084" height="1614" alt="CleanShot 2025-09-26 at 13 35 40"
src="https://github.com/user-attachments/assets/eaf2771e-df3e-4300-816b-184d7dec5a28"
/>
- Render `send a message to load usage data` in the beginning of the
session
- Render `data not available yet` if received no rate limits
- nit case
- Deleted stall snapshots that were moved to
`codex-rs/tui/src/status/snapshots`
The [official Rust
SDK](https://github.com/modelcontextprotocol/rust-sdk/tree/57fc428c578a1a3fe851ee0838bf068bda120eb3)
has come a long way since we first started our mcp client implementation
5 months ago and, today, it is much more complete than our own
stdio-only implementation.
This PR introduces a new config flag `experimental_use_rmcp_client`
which will use a new mcp client powered by the sdk instead of our own.
To keep this PR simple, I've only implemented the same stdio MCP
functionality that we had but will expand on it with future PRs.
---------
Co-authored-by: pakrym-oai <[email protected]>
Adds a 1-per-turn todo-list item and item.updated event
```jsonl
{"type":"item.started","item":{"id":"item_6","item_type":"todo_list","items":[{"text":"Record initial two-step plan now","completed":false},{"text":"Update progress to next step","completed":false}]}}
{"type":"item.updated","item":{"id":"item_6","item_type":"todo_list","items":[{"text":"Record initial two-step plan now","completed":true},{"text":"Update progress to next step","completed":false}]}}
{"type":"item.completed","item":{"id":"item_6","item_type":"todo_list","items":[{"text":"Record initial two-step plan now","completed":true},{"text":"Update progress to next step","completed":false}]}}
```
Details are in `responses-api-proxy/README.md`, but the key contribution
of this PR is a new subcommand, `codex responses-api-proxy`, which reads
the auth token for use with the OpenAI Responses API from `stdin` at
startup and then proxies `POST` requests to `/v1/responses` over to
`https://api.openai.com/v1/responses`, injecting the auth token as part
of the `Authorization` header.
The expectation is that `codex responses-api-proxy` is launched by a
privileged user who has access to the auth token so that it can be used
by unprivileged users of the Codex CLI on the same host.
If the client only has one user account with `sudo`, one option is to:
- run `sudo codex responses-api-proxy --http-shutdown --server-info
/tmp/server-info.json` to start the server
- record the port written to `/tmp/server-info.json`
- relinquish their `sudo` privileges (which is irreversible!) like so:
```
sudo deluser $USER sudo || sudo gpasswd -d $USER sudo || true
```
- use `codex` with the proxy (see `README.md`)
- when done, make a `GET` request to the server using the `PORT` from
`server-info.json` to shut it down:
```shell
curl --fail --silent --show-error "http://127.0.0.1:$PORT/shutdown"
```
To protect the auth token, we:
- allocate a 1024 byte buffer on the stack and write `"Bearer "` into it
to start
- we then read from `stdin`, copying to the contents into the buffer
after the prefix
- after verifying the input looks good, we create a `String` from that
buffer (so the data is now on the heap)
- we zero out the stack-allocated buffer using
https://crates.io/crates/zeroize so it is not optimized away by the
compiler
- we invoke `.leak()` on the `String` so we can treat its contents as a
`&'static str`, as it will live for the rest of the processs
- on UNIX, we `mlock(2)` the memory backing the `&'static str`
- when using the `&'static str` when building an HTTP request, we use
`HeaderValue::from_static()` to avoid copying the `&str`
- we also invoke `.set_sensitive(true)` on the `HeaderValue`, which in
theory indicates to other parts of the HTTP stack that the header should
be treated with "special care" to avoid leakage:
https://github.com/hyperium/http/blob/439d1c50d71e3be3204b6c4a1bf2255ed78e1f93/src/header/value.rs#L346-L376
