Previously, users could supply their API key directly via:
```shell
codex login --api-key KEY
```
but this has the drawback that `KEY` is more likely to end up in shell
history, can be read from `/proc`, etc.
This PR removes support for `--api-key` and replaces it with
`--with-api-key`, which reads the key from stdin, so either of these are
better options:
```
printenv OPENAI_API_KEY | codex login --with-api-key
codex login --with-api-key < my_key.txt
```
Other CLIs, such as `gh auth login --with-token`, follow the same
practice.
We continue the separation between `codex app-server` and `codex
mcp-server`.
In particular, we introduce a new crate, `codex-app-server-protocol`,
and migrate `codex-rs/protocol/src/mcp_protocol.rs` into it, renaming it
`codex-rs/app-server-protocol/src/protocol.rs`.
Because `ConversationId` was defined in `mcp_protocol.rs`, we move it
into its own file, `codex-rs/protocol/src/conversation_id.rs`, and
because it is referenced in a ton of places, we have to touch a lot of
files as part of this PR.
We also decide to get away from proper JSON-RPC 2.0 semantics, so we
also introduce `codex-rs/app-server-protocol/src/jsonrpc_lite.rs`, which
is basically the same `JSONRPCMessage` type defined in `mcp-types`
except with all of the `"jsonrpc": "2.0"` removed.
Getting rid of `"jsonrpc": "2.0"` makes our serialization logic
considerably simpler, as we can lean heavier on serde to serialize
directly into the wire format that we use now.
I don't believe there is any upside in making process hardening opt-in
for Codex CLI releases. If you want to tinker with Codex CLI, then build
from source (or run as `root`)?
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
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 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"
/>
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
Because the `codex` process could contain sensitive information in
memory, such as API keys, we add logic so that when
`CODEX_SECURE_MODE=1` is specified, we avail ourselves of whatever the
operating system provides to restrict observability/tampering, which
includes:
- disabling `ptrace(2)`, so it is not possible to attach to the process
with a debugger, such as `gdb`
- disabling core dumps
Admittedly, a user with root privileges can defeat these safeguards.
For now, we only add support for this in the `codex` multitool, but we
may ultimately want to support this in some of the smaller CLIs that are
buildable out of our Cargo workspace.
Ensure the completion helper always emits the new code command prefix and add a regression test to prevent the legacy codex name from resurfacing. Fixes#197.
- Preserved fork in codex-rs/tui/** and core openai_tools/codex.rs per policy
- Adopted upstream CLI resume flow, adapted to our TUI Cli
- Ran scripts/upstream-merge/verify.sh: PASS
- Ran ./build-fast.sh: PASS (no warnings)
James Peter