## Summary
- Add an MCP server environment setting with local as the default.
- Thread the default through config serialization, schema generation,
and existing config fixtures.
## Stack
```text
o #18027 [8/8] Fail exec client operations after disconnect
│
o #18025 [7/8] Cover MCP stdio tests with executor placement
│
o #18089 [6/8] Wire remote MCP stdio through executor
│
o #18088 [5/8] Add executor process transport for MCP stdio
│
o #18087 [4/8] Abstract MCP stdio server launching
│
o #18020 [3/8] Add pushed exec process events
│
o #18086 [2/8] Support piped stdin in exec process API
│
@ #18085 [1/8] Add MCP server environment config
│
o main
```
Co-authored-by: Codex <noreply@openai.com>
- [x] Add resource uri meta to tool call item so that the app-server
client can start prefetching resources immediately without loading mcp
server status.
## Summary
- honor `_meta["codex/imageDetail"] == "original"` on MCP image content
and map it to `detail: "original"` where supported
- strip that detail back out when the active model does not support
original-detail image inputs
- update code-mode `image(...)` to accept individual MCP image blocks
- teach `js_repl` / `codex.emitImage(...)` to preserve the same hint
from raw MCP image outputs
- document the new `_meta` contract and add generic RMCP-backed coverage
across protocol, core, code-mode, and js_repl paths
stacked on #17402.
MCP tools returned by `tool_search` (deferred tools) get registered in
our `ToolRegistry` with a different format than directly available
tools. this leads to two different ways of accessing MCP tools from our
tool catalog, only one of which works for each. fix this by registering
all MCP tools with the namespace format, since this info is already
available.
also, direct MCP tools are registered to responsesapi without a
namespace, while deferred MCP tools have a namespace. this means we can
receive MCP `FunctionCall`s in both formats from namespaces. fix this by
always registering MCP tools with namespace, regardless of deferral
status.
make code mode track `ToolName` provenance of tools so it can map the
literal JS function name string to the correct `ToolName` for
invocation, rather than supporting both in core.
this lets us unify to a single canonical `ToolName` representation for
each MCP tool and force everywhere to use that one, without supporting
fallbacks.
## Changes
Allows MCPs to opt in to receiving sandbox config info through `_meta`
on model-initiated tool calls. This lets MCPs adhere to the thread's
sandbox if they choose to.
## Details
- Adds the `codex/sandbox-state-meta` experimental MCP capability.
- Tracks whether each MCP server advertises that capability.
- When a server opts in, `codex-core` injects the current `SandboxState`
into model-initiated MCP tool-call request `_meta`.
## Verification
- added an integration test for the capability
## Why
For more advanced MCP usage, we want the model to be able to emit
parallel MCP tool calls and have Codex execute eligible ones
concurrently, instead of forcing all MCP calls through the serial block.
The main design choice was where to thread the config. I made this
server-level because parallel safety depends on the MCP server
implementation. Codex reads the flag from `mcp_servers`, threads the
opted-in server names into `ToolRouter`, and checks the parsed
`ToolPayload::Mcp { server, .. }` at execution time. That avoids relying
on model-visible tool names, which can be incomplete in
deferred/search-tool paths or ambiguous for similarly named
servers/tools.
## What was added
Added `supports_parallel_tool_calls` for MCP servers.
Before:
```toml
[mcp_servers.docs]
command = "docs-server"
```
After:
```toml
[mcp_servers.docs]
command = "docs-server"
supports_parallel_tool_calls = true
```
MCP calls remain serial by default. Only tools from opted-in servers are
eligible to run in parallel. Docs also now warn to enable this only when
the server’s tools are safe to run concurrently, especially around
shared state or read/write races.
## Testing
Tested with a local stdio MCP server exposing real delay tools. The
model/Responses side was mocked only to deterministically emit two MCP
calls in the same turn.
Each test called `query_with_delay` and `query_with_delay_2` with `{
"seconds": 25 }`.
| Build/config | Observed | Wall time |
| --- | --- | --- |
| main with flag enabled | serial | `58.79s` |
| PR with flag enabled | parallel | `31.73s` |
| PR without flag | serial | `56.70s` |
PR with flag enabled showed both tools start before either completed;
main and PR-without-flag completed the first delay before starting the
second.
Also added an integration test.
Additional checks:
- `cargo test -p codex-tools` passed
- `cargo test -p codex-core
mcp_parallel_support_uses_exact_payload_server` passed
- `git diff --check` passed
Fast Mode status was still tied to one model name in the TUI and
model-list plumbing. This changes the model metadata shape so a model
can advertise additional speed tiers, carries that field through the
app-server model list, and uses it to decide when to show Fast Mode
status.
For people using Codex, the behavior is intended to stay the same for
existing models. Fast Mode still requires the existing signed-in /
feature-gated path; the difference is that the UI can now recognize any
model the model list marks as Fast-capable, instead of requiring a new
client-side slug check.
Stacked on #16508.
This removes the temporary `codex-core` / `codex-login` re-export shims
from the ownership split and rewrites callsites to import directly from
`codex-model-provider-info`, `codex-models-manager`, `codex-api`,
`codex-protocol`, `codex-feedback`, and `codex-response-debug-context`.
No behavior change intended; this is the mechanical import cleanup layer
split out from the ownership move.
---------
Co-authored-by: Codex <noreply@openai.com>
## Why
This finishes the config-type move out of `codex-core` by removing the
temporary compatibility shim in `codex_core::config::types`. Callers now
depend on `codex-config` directly, which keeps these config model types
owned by the config crate instead of re-expanding `codex-core` as a
transitive API surface.
## What Changed
- Removed the `codex-rs/core/src/config/types.rs` re-export shim and the
`core::config::ApprovalsReviewer` re-export.
- Updated `codex-core`, `codex-cli`, `codex-tui`, `codex-app-server`,
`codex-mcp-server`, and `codex-linux-sandbox` call sites to import
`codex_config::types` directly.
- Added explicit `codex-config` dependencies to downstream crates that
previously relied on the `codex-core` re-export.
- Regenerated `codex-rs/core/config.schema.json` after updating the
config docs path reference.
## Why
`codex-core` was re-exporting APIs owned by sibling `codex-*` crates,
which made downstream crates depend on `codex-core` as a proxy module
instead of the actual owner crate.
Removing those forwards makes crate boundaries explicit and lets leaf
crates drop unnecessary `codex-core` dependencies. In this PR, this
reduces the dependency on `codex-core` to `codex-login` in the following
files:
```
codex-rs/backend-client/Cargo.toml
codex-rs/mcp-server/tests/common/Cargo.toml
```
## What
- Remove `codex-rs/core/src/lib.rs` re-exports for symbols owned by
`codex-login`, `codex-mcp`, `codex-rollout`, `codex-analytics`,
`codex-protocol`, `codex-shell-command`, `codex-sandboxing`,
`codex-tools`, and `codex-utils-path`.
- Delete the `default_client` forwarding shim in `codex-rs/core`.
- Update in-crate and downstream callsites to import directly from the
owning `codex-*` crate.
- Add direct Cargo dependencies where callsites now target the owner
crate, and remove `codex-core` from `codex-rs/backend-client`.
## Why
`argument-comment-lint` was green in CI even though the repo still had
many uncommented literal arguments. The main gap was target coverage:
the repo wrapper did not force Cargo to inspect test-only call sites, so
examples like the `latest_session_lookup_params(true, ...)` tests in
`codex-rs/tui_app_server/src/lib.rs` never entered the blocking CI path.
This change cleans up the existing backlog, makes the default repo lint
path cover all Cargo targets, and starts rolling that stricter CI
enforcement out on the platform where it is currently validated.
## What changed
- mechanically fixed existing `argument-comment-lint` violations across
the `codex-rs` workspace, including tests, examples, and benches
- updated `tools/argument-comment-lint/run-prebuilt-linter.sh` and
`tools/argument-comment-lint/run.sh` so non-`--fix` runs default to
`--all-targets` unless the caller explicitly narrows the target set
- fixed both wrappers so forwarded cargo arguments after `--` are
preserved with a single separator
- documented the new default behavior in
`tools/argument-comment-lint/README.md`
- updated `rust-ci` so the macOS lint lane keeps the plain wrapper
invocation and therefore enforces `--all-targets`, while Linux and
Windows temporarily pass `-- --lib --bins`
That temporary CI split keeps the stricter all-targets check where it is
already cleaned up, while leaving room to finish the remaining Linux-
and Windows-specific target-gated cleanup before enabling
`--all-targets` on those runners. The Linux and Windows failures on the
intermediate revision were caused by the wrapper forwarding bug, not by
additional lint findings in those lanes.
## Validation
- `bash -n tools/argument-comment-lint/run.sh`
- `bash -n tools/argument-comment-lint/run-prebuilt-linter.sh`
- shell-level wrapper forwarding check for `-- --lib --bins`
- shell-level wrapper forwarding check for `-- --tests`
- `just argument-comment-lint`
- `cargo test` in `tools/argument-comment-lint`
- `cargo test -p codex-terminal-detection`
## Follow-up
- Clean up remaining Linux-only target-gated callsites, then switch the
Linux lint lane back to the plain wrapper invocation.
- Clean up remaining Windows-only target-gated callsites, then switch
the Windows lint lane back to the plain wrapper invocation.
## Summary
Adds support for approvals_reviewer to `Op::UserTurn` so we can migrate
`[CodexMessageProcessor::turn_start]` to use Op::UserTurn
## Testing
- [x] Adds quick test for the new field
Co-authored-by: Codex <noreply@openai.com>
## What changed
- The RMCP streamable HTTP tests now wait for metadata and tool
readiness before issuing tool calls.
- OAuth state is isolated per test home.
- The helper server startup path now uses bounded bind retries so
transient `AddrInUse` collisions do not fail the test immediately.
## Why this fixes the flake
- The old tests could begin issuing tool requests before the helper
server had finished advertising its metadata and tools, so the first
request sometimes raced the server startup sequence.
- On top of that, shared OAuth state and occasional bind collisions on
CI runners introduced cross-test environmental noise unrelated to the
functionality under test.
- Readiness polling makes the client wait for an observable “server is
ready” signal, while isolated state and bounded bind retries remove
external contention that was causing intermittent failures.
## Scope
- Test-only change.
add `web_search_tool_type` on model_info that can be populated from
backend. will be used to filter which models can use `web_search` with
images and which cant.
added small unit test.
## Summary
Add original-resolution support for `view_image` behind the
under-development `view_image_original_resolution` feature flag.
When the flag is enabled and the target model is `gpt-5.3-codex` or
newer, `view_image` now preserves original PNG/JPEG/WebP bytes and sends
`detail: "original"` to the Responses API instead of using the legacy
resize/compress path.
## What changed
- Added `view_image_original_resolution` as an under-development feature
flag.
- Added `ImageDetail` to the protocol models and support for serializing
`detail: "original"` on tool-returned images.
- Added `PromptImageMode::Original` to `codex-utils-image`.
- Preserves original PNG/JPEG/WebP bytes.
- Keeps legacy behavior for the resize path.
- Updated `view_image` to:
- use the shared `local_image_content_items_with_label_number(...)`
helper in both code paths
- select original-resolution mode only when:
- the feature flag is enabled, and
- the model slug parses as `gpt-5.3-codex` or newer
- Kept local user image attachments on the existing resize path; this
change is specific to `view_image`.
- Updated history/image accounting so only `detail: "original"` images
use the docs-based GPT-5 image cost calculation; legacy images still use
the old fixed estimate.
- Added JS REPL guidance, gated on the same feature flag, to prefer JPEG
at 85% quality unless lossless is required, while still allowing other
formats when explicitly requested.
- Updated tests and helper code that construct
`FunctionCallOutputContentItem::InputImage` to carry the new `detail`
field.
## Behavior
### Feature off
- `view_image` keeps the existing resize/re-encode behavior.
- History estimation keeps the existing fixed-cost heuristic.
### Feature on + `gpt-5.3-codex+`
- `view_image` sends original-resolution images with `detail:
"original"`.
- PNG/JPEG/WebP source bytes are preserved when possible.
- History estimation uses the GPT-5 docs-based image-cost calculation
for those `detail: "original"` images.
#### [git stack](https://github.com/magus/git-stack-cli)
- 👉 `1` https://github.com/openai/codex/pull/13050
- ⏳ `2` https://github.com/openai/codex/pull/13331
- ⏳ `3` https://github.com/openai/codex/pull/13049
- add a local Fast mode setting in codex-core (similar to how model id
is currently stored on disk locally)
- send `service_tier=priority` on requests when Fast is enabled
- add `/fast` in the TUI and persist it locally
- feature flag
- replace show_nux with structured availability_nux model metadata
- expose availability NUX data through the app-server model API
- update shared fixtures and tests for the new field
Addresses bug https://github.com/openai/codex/issues/12589
Builds on community PR #12763.
This adds `oauth_resource` support for MCP `streamable_http` servers and
wires it through the relevant config and login paths. It fixes the bug
where the configured OAuth resource was not reliably included in the
authorization request, causing MCP login to omit the expected
`resource` parameter.
Summary is a required parameter on UserTurn. Ideally we'd like the core
to decide the appropriate summary level.
Make the summary optional and don't send it when not needed.
## Summary
- make `Config.model_reasoning_summary` optional so unset means use
model default
- resolve the optional config value to a concrete summary when building
`TurnContext`
- add protocol support for `default_reasoning_summary` in model metadata
## Validation
- `cargo test -p codex-core --lib client::tests -- --nocapture`
---------
Co-authored-by: Codex <noreply@openai.com>
## Why
`codex-rs/core/src/lib.rs` re-exported a broad set of types and modules
from `codex-protocol` and `codex-shell-command`. That made it easy for
workspace crates to import those APIs through `codex-core`, which in
turn hides dependency edges and makes it harder to reduce compile-time
coupling over time.
This change removes those public re-exports so call sites must import
from the source crates directly. Even when a crate still depends on
`codex-core` today, this makes dependency boundaries explicit and
unblocks future work to drop `codex-core` dependencies where possible.
## What Changed
- Removed public re-exports from `codex-rs/core/src/lib.rs` for:
- `codex_protocol::protocol` and related protocol/model types (including
`InitialHistory`)
- `codex_protocol::config_types` (`protocol_config_types`)
- `codex_shell_command::{bash, is_dangerous_command, is_safe_command,
parse_command, powershell}`
- Migrated workspace Rust call sites to import directly from:
- `codex_protocol::protocol`
- `codex_protocol::config_types`
- `codex_protocol::models`
- `codex_shell_command`
- Added explicit `Cargo.toml` dependencies (`codex-protocol` /
`codex-shell-command`) in crates that now import those crates directly.
- Kept `codex-core` internal modules compiling by using `pub(crate)`
aliases in `core/src/lib.rs` (internal-only, not part of the public
API).
- Updated the two utility crates that can already drop a `codex-core`
dependency edge entirely:
- `codex-utils-approval-presets`
- `codex-utils-cli`
## Verification
- `cargo test -p codex-utils-approval-presets`
- `cargo test -p codex-utils-cli`
- `cargo check --workspace --all-targets`
- `just clippy`
## Summary
Implements a configurable MCP OAuth callback URL override for `codex mcp
login` and app-server OAuth login flows, including support for non-local
callback endpoints (for example, devbox ingress URLs).
## What changed
- Added new config key: `mcp_oauth_callback_url` in
`~/.codex/config.toml`.
- OAuth authorization now uses `mcp_oauth_callback_url` as
`redirect_uri` when set.
- Callback handling validates the callback path against the configured
redirect URI path.
- Listener bind behavior is now host-aware:
- local callback URL hosts (`localhost`, `127.0.0.1`, `::1`) bind to
`127.0.0.1`
- non-local callback URL hosts bind to `0.0.0.0`
- `mcp_oauth_callback_port` remains supported and is used for the
listener port.
- Wired through:
- CLI MCP login flow
- App-server MCP OAuth login flow
- Skill dependency OAuth login flow
- Updated config schema and config tests.
## Why
Some environments need OAuth callbacks to land on a specific reachable
URL (for example ingress in remote devboxes), not loopback. This change
allows that while preserving local defaults for existing users.
## Backward compatibility
- No behavior change when `mcp_oauth_callback_url` is unset.
- Existing `mcp_oauth_callback_port` behavior remains intact.
- Local callback flows continue binding to loopback by default.
## Testing
- `cargo test -p codex-rmcp-client callback -- --nocapture`
- `cargo test -p codex-core --lib mcp_oauth_callback -- --nocapture`
- `cargo check -p codex-cli -p codex-app-server -p codex-rmcp-client`
## Example config
```toml
mcp_oauth_callback_port = 5555
mcp_oauth_callback_url = "https://<devbox>-<namespace>.gateway.<cluster>.internal.api.openai.org/callback"
rm `remote_models` feature flag.
We see issues like #11527 when a user has `remote_models` disabled, as
we always use the default fallback `ModelInfo`. This causes issues with
model performance.
Builds on #11690, which helps by warning the user when they are using
the default fallback. This PR will make that happen much less frequently
as an accidental consequence of disabling `remote_models`.
### What
It's currently unclear when the harness falls back to the default,
generic `ModelInfo`. This happens when the `remote_models` feature is
disabled or the model is truly unknown, and can lead to bad performance
and issues in the harness.
Add a user-facing warning when this happens so they are aware when their
setup is broken.
### Tests
Added tests, tested locally.
`SandboxPolicy::ReadOnly` previously implied broad read access and could
not express a narrower read surface.
This change introduces an explicit read-access model so we can support
user-configurable read restrictions in follow-up work, while preserving
current behavior today.
It also ensures unsupported backends fail closed for restricted-read
policies instead of silently granting broader access than intended.
## What
- Added `ReadOnlyAccess` in protocol with:
- `Restricted { include_platform_defaults, readable_roots }`
- `FullAccess`
- Updated `SandboxPolicy` to carry read-access configuration:
- `ReadOnly { access: ReadOnlyAccess }`
- `WorkspaceWrite { ..., read_only_access: ReadOnlyAccess }`
- Preserved existing behavior by defaulting current construction paths
to `ReadOnlyAccess::FullAccess`.
- Threaded the new fields through sandbox policy consumers and call
sites across `core`, `tui`, `linux-sandbox`, `windows-sandbox`, and
related tests.
- Updated Seatbelt policy generation to honor restricted read roots by
emitting scoped read rules when full read access is not granted.
- Added fail-closed behavior on Linux and Windows backends when
restricted read access is requested but not yet implemented there
(`UnsupportedOperation`).
- Regenerated app-server protocol schema and TypeScript artifacts,
including `ReadOnlyAccess`.
## Compatibility / rollout
- Runtime behavior remains unchanged by default (`FullAccess`).
- API/schema changes are in place so future config wiring can enable
restricted read access without another policy-shape migration.
Summary
- add a `prefer_websockets` field to `ModelInfo`, defaulting to `false`
in all fixtures and constructors
- wire the new flag into websocket selection so models that opt in
always use websocket transport even when the feature gate is off
Testing
- Not run (not requested)
- Replace image blocks in MCP tool results with a text placeholder when
the active model does not accept image input.
- Add an e2e rmcp test to verify sanitized tool output is what gets sent
back to the model.
## Summary
- keep wiremock MockServer handles alive through async assertions in
remote model suite tests
- assert /models request count in remote_models_hide_picker_only_models
- use a slightly higher parallel timing threshold on aarch64 while
keeping existing x86 threshold
## Validation
- just fmt
- targeted tests:
- cargo test -p codex-core --test all
suite::remote_models::remote_models_merge_replaces_overlapping_model --
--exact
- cargo test -p codex-core --test all
suite::remote_models::remote_models_hide_picker_only_models -- --exact
- cargo test -p codex-core --test all
suite::tool_parallelism::shell_tools_run_in_parallel -- --exact
- soak loop: 40 iterations of all three targeted tests
## Notes
- cargo test -p codex-core has one unrelated local-env failure in
shell_snapshot::tests::try_new_creates_and_deletes_snapshot_file from
exported certificate env content in this workspace.
- local bazel test //codex-rs/core:core-all-test failed to build due
missing rust-objcopy in this host toolchain.
Summary
- add a `required` flag for MCP servers everywhere config/CLI data is
touched so mandatory helpers can be round-tripped
- have `codex exec` and `codex app-server` thread start/resume fail fast
when required MCPs fail to initialize
We started working with MCP in Codex before
https://crates.io/crates/rmcp was mature, so we had our own crate for
MCP types that was generated from the MCP schema:
8b95d3e082/codex-rs/mcp-types/README.md
Now that `rmcp` is more mature, it makes more sense to use their MCP
types in Rust, as they handle details (like the `_meta` field) that our
custom version ignored. Though one advantage that our custom types had
is that our generated types implemented `JsonSchema` and `ts_rs::TS`,
whereas the types in `rmcp` do not. As such, part of the work of this PR
is leveraging the adapters between `rmcp` types and the serializable
types that are API for us (app server and MCP) introduced in #10356.
Note this PR results in a number of changes to
`codex-rs/app-server-protocol/schema`, which merit special attention
during review. We must ensure that these changes are still
backwards-compatible, which is possible because we have:
```diff
- export type CallToolResult = { content: Array<ContentBlock>, isError?: boolean, structuredContent?: JsonValue, };
+ export type CallToolResult = { content: Array<JsonValue>, structuredContent?: JsonValue, isError?: boolean, _meta?: JsonValue, };
```
so `ContentBlock` has been replaced with the more general `JsonValue`.
Note that `ContentBlock` was defined as:
```typescript
export type ContentBlock = TextContent | ImageContent | AudioContent | ResourceLink | EmbeddedResource;
```
so the deletion of those individual variants should not be a cause of
great concern.
Similarly, we have the following change in
`codex-rs/app-server-protocol/schema/typescript/Tool.ts`:
```
- export type Tool = { annotations?: ToolAnnotations, description?: string, inputSchema: ToolInputSchema, name: string, outputSchema?: ToolOutputSchema, title?: string, };
+ export type Tool = { name: string, title?: string, description?: string, inputSchema: JsonValue, outputSchema?: JsonValue, annotations?: JsonValue, icons?: Array<JsonValue>, _meta?: JsonValue, };
```
so:
- `annotations?: ToolAnnotations` ➡️ `JsonValue`
- `inputSchema: ToolInputSchema` ➡️ `JsonValue`
- `outputSchema?: ToolOutputSchema` ➡️ `JsonValue`
and two new fields: `icons?: Array<JsonValue>, _meta?: JsonValue`
---
[//]: # (BEGIN SAPLING FOOTER)
Stack created with [Sapling](https://sapling-scm.com). Best reviewed
with [ReviewStack](https://reviewstack.dev/openai/codex/pull/10349).
* #10357
* __->__ #10349
* #10356
### Motivation
- Allow MCP OAuth flows to request scopes defined in `config.toml`
instead of requiring users to always pass `--scopes` on the CLI.
CLI/remote parameters should still override config values.
### Description
- Add optional `scopes: Option<Vec<String>>` to `McpServerConfig` and
`RawMcpServerConfig`, and propagate it through deserialization and the
built config types.
- Serialize `scopes` into the MCP server TOML via
`serialize_mcp_server_table` in `core/src/config/edit.rs` and include
`scopes` in the generated config schema (`core/config.schema.json`).
- CLI: update `codex-rs/cli/src/mcp_cmd.rs` `run_login` to fall back to
`server.scopes` when the `--scopes` flag is empty, with explicit CLI
scopes still taking precedence.
- App server: update
`codex-rs/app-server/src/codex_message_processor.rs`
`mcp_server_oauth_login` to use `params.scopes.or_else(||
server.scopes.clone())` so the RPC path also respects configured scopes.
- Update many test fixtures to initialize the new `scopes` field (set to
`None`) so test code builds with the new struct field.
### Testing
- Ran config tooling and formatters: `just write-config-schema`
(succeeded), `just fmt` (succeeded), and `just fix -p codex-core`, `just
fix -p codex-cli`, `just fix -p codex-app-server` (succeeded where
applicable).
- Ran unit tests for the CLI: `cargo test -p codex-cli` (passed).
- Ran unit tests for core: `cargo test -p codex-core` (ran; many tests
passed but several failed, including model refresh/403-related tests,
shell snapshot/timeouts, and several `unified_exec` expectations).
- Ran app-server tests: `cargo test -p codex-app-server` (ran; many
integration-suite tests failed due to mocked/remote HTTP 401/403
responses and wiremock expectations).
If you want, I can split the tests into smaller focused runs or help
debug the failing integration tests (they appear to be unrelated to the
config change and stem from external HTTP/mocking behaviors encountered
during the test runs).
------
[Codex
Task](https://chatgpt.com/codex/tasks/task_i_69718f505914832ea1f334b3ba064553)
## Summary
Support updating Personality mid-Thread via UserTurn/OverwriteTurn. This
is explicitly unused by the clients so far, to simplify PRs - app-server
and tui implementations will be follow-ups.
## Testing
- [x] added integration tests
Enterprises want to restrict the MCP servers their users can use.
Admins can now specify an allowlist of MCPs in `requirements.toml`. The
MCP servers are matched on both Name and Transport (local path or HTTP
URL) -- both must match to allow the MCP server. This prevents
circumventing the allowlist by renaming MCP servers in user config. (It
is still possible to replace the local path e.g. rewrite say
`/usr/local/github-mcp` with a nefarious MCP. We could allow hash
pinning in the future, but that would break updates. I also think this
represents a broader, out-of-scope problem.)
We introduce a new field to Constrained: "normalizer". In general, it is
a fn(T) -> T and applies when `Constrained<T>.set()` is called. In this
particular case, it disables MCP servers which do not match the
allowlist. An alternative solution would remove this and instead throw a
ConstraintError. That would stop Codex launching if any MCP server was
configured which didn't match. I think this is bad.
We currently reuse the enabled flag on MCP servers to disable them, but
don't propagate any information about why they are disabled. I'd like to
add that in a follow up PR, possibly by switching out enabled with an
enum.
In action:
```
# MCP server config has two MCPs. We are going to allowlist one of them.
➜ codex git:(gt/restrict-mcps) ✗ cat ~/.codex/config.toml | grep mcp_servers -A1
[mcp_servers.hello_world]
command = "hello-world-mcp"
--
[mcp_servers.docs]
command = "docs-mcp"
# Restrict the MCPs to the hello_world MCP.
➜ codex git:(gt/restrict-mcps) ✗ defaults read com.openai.codex requirements_toml_base64 | base64 -d
[mcp_server_allowlist.hello_world]
command = "hello-world-mcp"
# List the MCPs, observe hello_world is enabled and docs is disabled.
➜ codex git:(gt/restrict-mcps) ✗ just codex mcp list
cargo run --bin codex -- "$@"
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.25s
Running `target/debug/codex mcp list`
Name Command Args Env Cwd Status Auth
docs docs-mcp - - - disabled Unsupported
hello_world hello-world-mcp - - - enabled Unsupported
# Remove the restrictions.
➜ codex git:(gt/restrict-mcps) ✗ defaults delete com.openai.codex requirements_toml_base64
# Observe both MCPs are enabled.
➜ codex git:(gt/restrict-mcps) ✗ just codex mcp list
cargo run --bin codex -- "$@"
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.25s
Running `target/debug/codex mcp list`
Name Command Args Env Cwd Status Auth
docs docs-mcp - - - enabled Unsupported
hello_world hello-world-mcp - - - enabled Unsupported
# A new requirements that updates the command to one that does not match.
➜ codex git:(gt/restrict-mcps) ✗ cat ~/requirements.toml
[mcp_server_allowlist.hello_world]
command = "hello-world-mcp-v2"
# Use those requirements.
➜ codex git:(gt/restrict-mcps) ✗ defaults write com.openai.codex requirements_toml_base64 "$(base64 -i /Users/gt/requirements.toml)"
# Observe both MCPs are disabled.
➜ codex git:(gt/restrict-mcps) ✗ just codex mcp list
cargo run --bin codex -- "$@"
Finished `dev` profile [unoptimized + debuginfo] target(s) in 0.75s
Running `target/debug/codex mcp list`
Name Command Args Env Cwd Status Auth
docs docs-mcp - - - disabled Unsupported
hello_world hello-world-mcp - - - disabled Unsupported
```
### Summary
With codesigning on Mac, Windows and Linux, we should be able to safely
remove `features.rmcp_client` and `use_experimental_use_rmcp_client`
check from the codebase now.
- Make Config.model optional and centralize default-selection logic in
ModelsManager, including a default_model helper (with
codex-auto-balanced when available) so sessions now carry an explicit
chosen model separate from the base config.
- Resolve `model` once in `core` and `tui` from config. Then store the
state of it on other structs.
- Move refreshing models to be before resolving the default model
