Commit Graph
13 Commits
Author SHA1 Message Date
jif 4ec3b8eeea Route hosted Apps MCP through extensions (#27191)
## Stack

- Base: #27184
- This PR is the second vertical and should be reviewed against
`jif/external-plugins-1`, not `main`.

## Why

CCA is moving toward a split runtime where the orchestrator may have no
filesystem or executor, but it still needs to activate remotely hosted
plugin components. HTTP MCP servers are the simplest complete example:
they need configuration and host authentication, but they do not need an
executor process.

The Apps MCP endpoint is currently synthesized by a special-purpose
loader inside the MCP runtime. That works locally, but it leaves hosted
MCP activation outside the extension model being established in #27184.
It also makes the Apps path a poor foundation for plugins whose skills,
MCP servers, connectors, and hooks may come from different sources or
execute in different places.

This PR moves that one behavior behind an extension-owned contribution
while preserving the existing local fallback. It deliberately does not
introduce a generic plugin activation framework.

## What changed

### MCP extension contribution

`codex-extension-api` gains an ordered `McpServerContributor` contract.
A contributor returns typed `Set` or `Remove` overlays for MCP server
configuration; later contributors win for the names they own.

The contract stays at the existing MCP configuration boundary.
Extensions do not create a second connection manager or transport
abstraction.

### Hosted Apps MCP extension

A new `codex-mcp-extension` contributes the reserved `codex_apps` server
from the existing Apps feature, ChatGPT base URL, path override, and
product SKU configuration.

When `apps_mcp_path_override` is enabled for `https://chatgpt.com`, the
resulting streamable HTTP endpoint is
`https://chatgpt.com/backend-api/ps/mcp`. The existing ChatGPT-auth gate
remains authoritative, so this server can run in an orchestrator-only
process without being exposed for API-key sessions.

### One resolved runtime view

`McpManager` now distinguishes three views:

- **configured:** config- and plugin-backed servers before extension
overlays;
- **runtime:** configured servers plus host-installed extension
contributions;
- **effective:** runtime servers after auth gating and compatibility
built-ins.

App-server installs the hosted MCP extension and uses the runtime view
for thread startup, refresh, status, threadless resource reads,
connector discovery, and MCP OAuth lookup. This keeps
`mcpServer/oauth/login` consistent with the servers exposed by the other
MCP APIs. The hosted Apps server itself continues to use existing
ChatGPT host authentication rather than MCP OAuth.

## Compatibility

Hosts that do not install the MCP extension retain the existing Apps MCP
synthesis path. This preserves current local-only, CLI, and
standalone-host behavior while app-server exercises the extension path.

Disabling Apps removes the reserved `codex_apps` entry, and losing
ChatGPT auth removes it from the effective runtime view. Executor
availability is not consulted for this HTTP transport.

## Follow-ups

The next vertical will resolve a manifest-declared stdio MCP server from
an executor-selected plugin root and execute it in the environment that
owns that root. Later verticals can add backend-owned skills, connector
metadata, hooks, durable selection semantics, and incremental local
convergence without changing the component-specific runtime boundaries
introduced here.

## Verification

Focused coverage was added for:

- contributing the hosted Apps MCP at `/backend-api/ps/mcp` without an
executor;
- requiring ChatGPT auth in the effective runtime view;
- removing a reserved configured Apps server when the Apps feature is
disabled.

`cargo check -p codex-app-server -p codex-mcp-extension -p
codex-extension-api -p codex-mcp` passed. Tests and Clippy were not run
locally under the current development instruction; CI provides the full
validation pass.
2026-06-09 22:44:16 +02:00
jif 89ac3ec27c Load selected executor skills through extensions (#27184)
## Why

CCA is moving toward a split runtime where the orchestrator may not have
a filesystem, while executors can expose preinstalled plugins and
skills. A thread therefore needs to select capabilities without asking
app-server or core to interpret executor-owned paths through the
orchestrator's filesystem.

The longer-term model is broader than executor skills:

- A plugin is a bundle of skills, MCP servers, connectors/apps, and
hooks.
- A plugin root can be local, executor-owned, or hosted by a backend.
- Components inside one plugin can use different access and execution
mechanisms. A skill may be read from a filesystem or through backend
tools; an HTTP MCP server can run without an executor; a stdio MCP
server or hook needs an execution environment.
- Core should carry generic extension initialization data. The extension
that owns a component should discover it, expose it to the model, and
invoke it through the appropriate runtime.

This PR establishes that architecture through one complete vertical:
selecting a root on an executor, discovering the skills beneath it,
exposing those skills to the model, and reading an explicitly invoked
`SKILL.md` through the same executor.

## Contract

`thread/start` gains an experimental `selectedCapabilityRoots` field:

```json
{
  "selectedCapabilityRoots": [
    {
      "id": "deploy-plugin@1",
      "location": {
        "type": "environment",
        "environmentId": "workspace",
        "path": "/opt/codex/plugins/deploy"
      }
    }
  ]
}
```

The root is intentionally not classified as a "plugin" or "skill" in the
API. It can point at a standalone skill, a directory containing several
skills, or a plugin containing skills and other components. This PR only
teaches the skills extension how to consume it; later extensions can
resolve MCP, connector, and hook components from the same selection.

The platform-supplied `id` is stable selection identity. The location
says which runtime owns the root and gives that runtime an opaque path.
App-server does not inspect or canonicalize the path.

## What changed

### Generic thread extension initialization

App-server converts selected roots into `ExtensionDataInit`. Core
carries that generic initialization value until the final thread ID is
known, then creates thread-scoped `ExtensionData` before lifecycle
contributors run.

This keeps `Session` and core independent of the capability-selection
contract. The initialization value is consumed during construction; it
is not retained as another long-lived `Session` field.

### Executor-backed skills

The skills extension now owns an `ExecutorSkillProvider` that:

- resolves the selected environment through `EnvironmentManager`
- discovers, canonicalizes, and reads skills through that environment's
`ExecutorFileSystem`
- contributes the bounded selected-skill catalog as stable developer
context
- reads an explicitly invoked skill body through the authority that
listed it
- warns when an environment or root is unavailable
- never falls back to the orchestrator filesystem for an executor-owned
root

Skill catalog and instruction fragments have hard byte bounds, which
also bound them below the 10K-token per-item context limit. If a
selected executor skill has the same name as a legacy local skill, the
executor selection owns that invocation and the local body is not
injected a second time.

Existing local and bundled skill loading remains in place. Omitting
`selectedCapabilityRoots` therefore preserves current local-only
behavior.

## Current semantics

- Only environment-owned locations are represented in this first
contract.
- Roots are resolved by the destination extension, not by app-server or
core.
- An unavailable executor or invalid root produces a warning and no
capabilities from that root; it does not trigger a local-filesystem
fallback.
- Selection applies to a newly started active thread.
- MCP servers, connectors, and hooks beneath a selected plugin root are
not activated yet.
- Selection is not yet persisted or inherited across resume, fork, or
subagent creation. Existing local capabilities continue to behave as
they do today in those flows.

## Planned vertical follow-ups

1. **Hosted HTTP MCP:** add an extension-backed HTTP MCP source that
works without an executor, then replace the special-purpose MCP plugins
loader with that implementation.
2. **Executor MCP:** register and execute stdio MCP servers through the
environment that owns the selected plugin root.
3. **Backend skills:** add a hosted skill source whose catalog and
bodies are accessed through extension tools rather than a filesystem.
4. **Connectors and hooks:** activate those components through their
owning extensions, using the same selected-root boundary and
component-specific runtime.
5. **Durable selection:** define the desired-selection lifecycle,
persist it, and make resume, fork, and subagent inheritance explicit
rather than accidental.
6. **Local convergence:** incrementally route existing local plugin,
skill, and MCP loading through the same extension model while preserving
current local behavior.

Each follow-up remains reviewable as an end-to-end capability. The
platform selects roots, generic thread extension data carries the
selection, and the owning extension resolves and operates its component.

## Verification

Coverage added for:

- app-server end-to-end discovery and explicit invocation of a skill
inside an executor-selected plugin root
- exclusive invocation when a selected executor skill collides with a
local skill name
- executor filesystem authority for discovery, canonicalization, and
reads
- thread extension initialization before lifecycle contributors run
- stable executor catalog context, explicit invocation, context
rebuilding, hidden skills, and preserved host/remote catalog behavior

Targeted protocol, core-skills, skills-extension, core lifecycle, and
app-server executor-skill tests were run during development.
2026-06-09 19:51:54 +02:00
Eric Traut 479a14cf59 [2 of 2] Finish moving goal runtime to extension (#26548)
## Stack

1. [#26547](https://github.com/openai/codex/pull/26547) - [1 of 2] Align
goal extension with core behavior
2. [#26548](https://github.com/openai/codex/pull/26548) - [2 of 2] Move
goal runtime to extension

## Why

This PR completes the switch of the goal behavior to the
extension-backed runtime and removes the old core goal implementation.

## What Changed

- Installs the goal extension for app-server `ThreadManager` sessions.
- Routes app-server thread goal `get`, `set`, and `clear` through
`GoalService`.
- Uses thread-idle lifecycle emission after goal resume and snapshot
ordering so the extension can decide whether to continue the goal.
- Forwards extension goal updates through a FIFO async app-server
notification path so backpressure does not drop them or reorder updates.
- Keeps review turns from enabling goal runtime behavior.
- Plans extension tools before dynamic tools so built-in goal tool names
keep their old precedence when goals are enabled.
- Removes the old core goal runtime, core goal tool handlers, and core
goal tool specs.
- Updates tests that were coupled to the core-owned goal runtime while
leaving the legacy `<goal_context>` compatibility path in core for old
threads.
- Removes the stale cargo-shear ignore now that `codex-goal-extension`
is used by the workspace.
- Keeps realtime event matching exhaustive after removing the old
goal-specific realtime text path.


## Validation

- Ran manual `/goal` runs in TUI. Validated time accounting matched
wall-clock time and goal lifecycle state transitions.
2026-06-05 14:17:30 -07:00
joeflorencio-openai d45cd26248 Switch runtime to cloud config bundle (#24622)
## Summary

- Adapts the moved `codex-cloud-config` crate from the legacy cloud
requirements endpoint to the new config bundle endpoint.
- Switches runtime consumers from `CloudRequirementsLoader` to
`CloudConfigBundleLoader` so one shared bundle supplies cloud-delivered
config and requirements.
- Removes the legacy cloud requirements domain loader path.

## Details

This intentionally keeps `codex-cloud-config` monolithic for review
lineage: the previous PR establishes the crate move, and this PR shows
the behavior change against that moved implementation. A follow-up PR
splits the module back into focused files.

The new bundle path preserves the important cloud requirements loader
semantics where intended: account-scoped signed cache, 30 minute TTL, 5
minute refresh cadence, retry/backoff, auth recovery, and fail-closed
startup loading. The cached payload changes from a single requirements
TOML string to the backend-delivered bundle, and validation rejects
malformed config or requirements fragments before cache write/use.
2026-06-02 13:18:59 -07:00
sayan-oai a22706dfae standalone websearch extension (#23823)
## Summary

Add the extension-backed standalone `web.run` tool so Codex can call the
standalone search endpoint through the `codex-api` search client and
return its encrypted output to Responses.

- gate the new tool behind `standalone_web_search`
- install the extension in the app-server thread registry and hide
hosted `web_search` when standalone search is enabled for OpenAI
providers so the two paths stay mutually exclusive
- build search context from persisted history using a small tail
heuristic: previous user message, assistant text between the last two
user turns capped at about 1k tokens, and current user message

## Test Plan

- `cargo test -p codex-web-search-extension`
- `cargo test -p codex-api`
- `cargo test -p codex-core
hosted_tools_follow_provider_auth_model_and_config_gates`
2026-05-26 11:12:24 -07:00
jif-oai c4e53d103c Wire app-server extension event sink (#24586)
## Why

The goal extension already emits `ThreadGoalUpdated` events, but
production app-server thread extensions were built with the default
no-op extension event sink. That meant extension-driven goal updates
could be produced without ever reaching app-server clients.

## What changed

- Build app-server thread extensions with a host-provided
`ExtensionEventSink`.
- Add an app-server sink that converts extension `ThreadGoalUpdated`
events into `ServerNotification::ThreadGoalUpdated` broadcasts.
- Use the existing bounded outgoing message channel via `try_send` so
event forwarding cannot create an unbounded queue.
- Pass `NoopExtensionEventSink` in app-server tests that construct a
`ThreadManager` without an app-server host.
- Refresh `Cargo.lock` for the existing `codex-memories-extension`
`codex-otel` dependency.

## Verification

- `just test -p codex-app-server
extensions::tests::app_server_event_sink_forwards_thread_goal_updates`
2026-05-26 15:28:02 +02:00
Michael Bolin 889ee018e7 config: add strict config parsing (#20559)
## Why

Codex intentionally ignores unknown `config.toml` fields by default so
older and newer config files keep working across versions. That leniency
also makes typo detection hard because misspelled or misplaced keys
disappear silently.

This change adds an opt-in strict config mode so users and tooling can
fail fast on unrecognized config fields without changing the default
permissive behavior.

This feature is possible because `serde_ignored` exposes the exact
signal Codex needs: it lets Codex run ordinary Serde deserialization
while recording fields Serde would otherwise ignore. That avoids
requiring `#[serde(deny_unknown_fields)]` across every config type and
keeps strict validation opt-in around the existing config model.

## What Changed

### Added strict config validation

- Added `serde_ignored`-based validation for `ConfigToml` in
`codex-rs/config/src/strict_config.rs`.
- Combined `serde_ignored` with `serde_path_to_error` so strict mode
preserves typed config error paths while also collecting fields Serde
would otherwise ignore.
- Added strict-mode validation for unknown `[features]` keys, including
keys that would otherwise be accepted by `FeaturesToml`'s flattened
boolean map.
- Kept typed config errors ahead of ignored-field reporting, so
malformed known fields are reported before unknown-field diagnostics.
- Added source-range diagnostics for top-level and nested unknown config
fields, including non-file managed preference source names.

### Kept parsing single-pass per source

- Reworked file and managed-config loading so strict validation reuses
the already parsed `TomlValue` for that source.
- For actual config files and managed config strings, the loader now
reads once, parses once, and validates that same parsed value instead of
deserializing multiple times.
- Validated `-c` / `--config` override layers with the same
base-directory context used for normal relative-path resolution, so
unknown override keys are still reported when another override contains
a relative path.

### Scoped `--strict-config` to config-heavy entry points

- Added support for `--strict-config` on the main config-loading entry
points where it is most useful:
  - `codex`
  - `codex resume`
  - `codex fork`
  - `codex exec`
  - `codex review`
  - `codex mcp-server`
  - `codex app-server` when running the server itself
  - the standalone `codex-app-server` binary
  - the standalone `codex-exec` binary
- Commands outside that set now reject `--strict-config` early with
targeted errors instead of accepting it everywhere through shared CLI
plumbing.
- `codex app-server` subcommands such as `proxy`, `daemon`, and
`generate-*` are intentionally excluded from the first rollout.
- When app-server strict mode sees invalid config, app-server exits with
the config error instead of logging a warning and continuing with
defaults.
- Introduced a dedicated `ReviewCommand` wrapper in `codex-rs/cli`
instead of extending shared `ReviewArgs`, so `--strict-config` stays on
the outer config-loading command surface and does not become part of the
reusable review payload used by `codex exec review`.

### Coverage

- Added tests for top-level and nested unknown config fields, unknown
`[features]` keys, typed-error precedence, source-location reporting,
and non-file managed preference source names.
- Added CLI coverage showing invalid `--enable`, invalid `--disable`,
and unknown `-c` overrides still error when `--strict-config` is
present, including compound-looking feature names such as
`multi_agent_v2.subagent_usage_hint_text`.
- Added integration coverage showing both `codex app-server
--strict-config` and standalone `codex-app-server --strict-config` exit
with an error for unknown config fields instead of starting with
fallback defaults.
- Added coverage showing unsupported command surfaces reject
`--strict-config` with explicit errors.

## Example Usage

Run Codex with strict config validation enabled:

```shell
codex --strict-config
```

Strict config mode is also available on the supported config-heavy
subcommands:

```shell
codex --strict-config exec "explain this repository"
codex review --strict-config --uncommitted
codex mcp-server --strict-config
codex app-server --strict-config --listen off
codex-app-server --strict-config --listen off
```

For example, if `~/.codex/config.toml` contains a typo in a key name:

```toml
model = "gpt-5"
approval_polic = "on-request"
```

then `codex --strict-config` reports the misspelled key instead of
silently ignoring it. The path is shortened to `~` here for readability:

```text
$ codex --strict-config
Error loading config.toml:
~/.codex/config.toml:2:1: unknown configuration field `approval_polic`
  |
2 | approval_polic = "on-request"
  | ^^^^^^^^^^^^^^
```

Without `--strict-config`, Codex keeps the existing permissive behavior
and ignores the unknown key.

Strict config mode also validates ad-hoc `-c` / `--config` overrides:

```text
$ codex --strict-config -c foo=bar
Error: unknown configuration field `foo` in -c/--config override

$ codex --strict-config -c features.foo=true
Error: unknown configuration field `features.foo` in -c/--config override
```

Invalid feature toggles are rejected too, including values that look
like nested config paths:

```text
$ codex --strict-config --enable does_not_exist
Error: Unknown feature flag: does_not_exist

$ codex --strict-config --disable does_not_exist
Error: Unknown feature flag: does_not_exist

$ codex --strict-config --enable multi_agent_v2.subagent_usage_hint_text
Error: Unknown feature flag: multi_agent_v2.subagent_usage_hint_text
```

Unsupported commands reject the flag explicitly:

```text
$ codex --strict-config cloud list
Error: `--strict-config` is not supported for `codex cloud`
```

## Verification

The `codex-cli` `strict_config` tests cover invalid `--enable`, invalid
`--disable`, the compound `multi_agent_v2.subagent_usage_hint_text`
case, unknown `-c` overrides, app-server strict startup failure through
`codex app-server`, and rejection for unsupported commands such as
`codex cloud`, `codex mcp`, `codex remote-control`, and `codex
app-server proxy`.

The config and config-loader tests cover unknown top-level fields,
unknown nested fields, unknown `[features]` keys, source-location
reporting, non-file managed config sources, and `-c` validation for keys
such as `features.foo`.

The app-server test suite covers standalone `codex-app-server
--strict-config` startup failure for an unknown config field.

## Documentation

The Codex CLI docs on developers.openai.com/codex should mention
`--strict-config` as an opt-in validation mode for supported
config-heavy entry points once this ships.
2026-05-13 16:08:05 +00:00
jif-oai d996f5366f feat: guardian as an extension (contributors part) (#22216)
Part 1 of guardian as extension. This bind all the logic to spawn
another agent from an extension and it adds `ThreadId` in the start
thread collaborator
2026-05-12 14:41:45 +02:00
jif-oai 436c0df658 extension: wire extension registries into sessions (#21737)
## Why

[#21736](https://github.com/openai/codex/pull/21736) introduces the
typed extension API, but the runtime does not yet carry a registry
through thread/session startup or give contributors host-owned stores to
read from. This PR wires that host-side path so later feature migrations
can move product-specific behavior behind typed contributions without
adding another bespoke seam directly to `codex-core`.

## What changed

- Thread `ExtensionRegistry<Config>` through `ThreadManager`,
`CodexSpawnArgs`, `Session`, and sub-agent spawn paths.
- Wire `ThreadStartContributor` and `ContextContributor`
- Expose the small supporting surface needed by non-core callers that
construct threads directly, including `empty_extension_registry()`
through `codex-core-api`.

This PR lands the host plumbing only: the app-server registry is still
empty, and concrete feature migrations are intended to follow
separately.
2026-05-11 11:38:18 +02:00
Jiaming ZhangandCodex 5f4d0ec343 [codex] request desktop attestation from app (#20619)
## Summary

TL;DR: teaches `codex-rs` / app-server to request a desktop-provided
attestation token and attach it as `x-oai-attestation` on the scoped
ChatGPT Codex request paths.

![DeviceCheck attestation
interface](https://raw.githubusercontent.com/openai/codex/dev/jm/devicecheck-diagram-assets/pr-assets/devicecheck-attestation-interface.png)

## Details

This PR teaches the Codex app-server runtime how to request and attach
an attestation token. It does not generate DeviceCheck tokens directly;
instead, it relies on the connected desktop app to advertise that it can
generate attestation and then asks that app for a fresh header value
when needed.

The flow is:

1. The Codex desktop app connects to app-server.
2. During `initialize`, the app can advertise that it supports
`requestAttestation`.
3. Before app-server calls selected ChatGPT Codex endpoints, it sends
the internal server request `attestation/generate` to the app.
4. app-server receives a pre-encoded header value back.
5. app-server forwards that value as `x-oai-attestation` on the scoped
outbound requests.

The code in this repo is mostly protocol and runtime plumbing: it adds
the app-server request/response shape, introduces an attestation
provider in core, wires that provider into Responses / compaction /
realtime setup paths, and covers the intended scoping with tests. The
signed macOS DeviceCheck generation remains owned by the desktop app PR.

## Related PR

- Codex desktop app implementation:
https://github.com/openai/openai/pull/878649

## Validation

<details>
<summary>Tests run</summary>

```sh
cargo test -p codex-app-server-protocol
cargo test -p codex-core attestation --lib
cargo test -p codex-app-server --lib attestation
```

Also ran:

```sh
just fix -p codex-core
just fix -p codex-app-server
just fix -p codex-app-server-protocol
just fmt
just write-app-server-schema
```

</details>

<details>
<summary>E2E DeviceCheck validation</summary>

First validated the signed desktop app boundary directly: launched a
packaged signed `Codex.app`, sent `attestation/generate`, decoded the
returned `v1.` attestation header, and validated the extracted
DeviceCheck token with `personal/jm/verify_devicecheck_token.py` using
bundle ID `com.openai.codex`. Apple returned `status_code: 200` and
`is_ok: true`.

Then ran the fuller app + app-server flow. The packaged `Codex.app`
launched a current-branch app-server via `CODEX_CLI_PATH`, and a local
MITM proxy intercepted outbound `chatgpt.com` traffic. The app-server
requested `attestation/generate` from the real Electron app process, and
the intercepted `/backend-api/codex/responses` traffic included
`x-oai-attestation` on both routes:

```text
GET  /backend-api/codex/responses  Upgrade: websocket  x-oai-attestation: present
POST /backend-api/codex/responses  Upgrade: none       x-oai-attestation: present
```

The captured header decoded to a DeviceCheck token that also validated
with Apple for `com.openai.codex` (`status_code: 200`, `is_ok: true`,
team `2DC432GLL2`).

</details>

---------

Co-authored-by: Codex <noreply@openai.com>
2026-05-08 12:36:02 -07:00
pakrym-oai a8488fec5e Revert state DB injection and agent graph store (#21481)
## Why

Reverts #20689 to restore the previous optional state DB plumbing. The
conflict resolution keeps the newer installation ID and session/thread
identity changes that landed after #20689, while removing the mandatory
state DB and agent graph store dependency from ThreadManager
construction.

## What changed

- Restored `Option<StateDbHandle>` through app-server, MCP server,
prompt debug, and test entry points.
- Removed the `codex-core` dependency on `codex-agent-graph-store` and
reverted descendant lookup back to the existing state DB path when
available.
- Kept newer `installation_id` forwarding by passing it beside the
optional DB handle.
- Kept local thread-name updates working when the optional state DB
handle is absent.

## Validation

- `git diff --check`
- `cargo test -p codex-thread-store`
- `cargo test -p codex-state -p codex-rollout -p
codex-app-server-protocol`
- Attempted `env CARGO_INCREMENTAL=0 cargo test -p codex-core -p
codex-app-server -p codex-app-server-client -p codex-mcp-server -p
codex-thread-manager-sample -p codex-tui`; blocked locally by a rustc
ICE while compiling `v8 v146.4.0` with `rustc 1.93.0 (254b59607
2026-01-19)` on `aarch64-apple-darwin`.
2026-05-06 22:48:29 -07:00
jif-oaiandCodex 8f3bb355f4 Move installation ID resolution out of core startup (#21182)
## Summary

- resolve or inject the installation ID before core startup and pass it
through `ThreadManager`, `CodexSpawnArgs`, and `Session` as a plain
`String`
- keep child sessions on the parent installation ID instead of
rediscovering it inside core
- propagate installation ID startup failures in `mcp-server` instead of
panicking

## Why

Core was still touching the filesystem on the session startup path to
discover `installation_id`. This moves that work to the outer host
boundary so core no longer depends on `codex_home` reads during session
construction.

---------

Co-authored-by: Codex <noreply@openai.com>
2026-05-06 10:48:54 +00:00
aaronl-openai 9f06d171e2 Preserve session MCP config on refresh (#21055)
# Overview
MCP refreshes were rebuilding active threads from fresh disk-backed
config only, which dropped thread-start session overlays such as
app-injected MCP servers. This keeps refreshes current with disk config
while preserving the thread-local config that only the active thread
knows about.

# Changes
- Rebuild refreshed config per active thread using that thread's current
`cwd`, rather than fanning out one app-server config to every thread.
- Preserve each thread's `SessionFlags` layer while replacing reloadable
config layers with freshly loaded config, then derive the MCP refresh
payload from the rebuilt result.
- Move MCP refresh orchestration into app-server so manual refreshes
fail loudly while background refreshes remain best-effort, and route
plugin-triggered refreshes through the same per-thread reload path.
- Add regression coverage for session overlays, fresh project config,
plugin-derived MCP config, current requirements, and strict vs
best-effort refresh behavior.

# Verification
- Passed focused Rust coverage for the thread-config rebuild behavior
and deferred MCP refresh flow, plus `cargo test -p codex-app-server
--lib`.
- Verified end to end in the Codex dev app against the locally built
CLI: registered an MCP via thread config, verified that it could be used
successfully before refresh, manually triggered MCP refresh, and
verified that it continued to be available afterward.
2026-05-05 21:09:28 -07:00