### Why
The RMCP layer needs a Streamable HTTP client that can talk either
directly over `reqwest` or through the executor HTTP runner without
duplicating MCP session logic higher in the stack. This PR adds that
client-side transport boundary so remote Streamable HTTP MCP can reuse
the same RMCP flow as the local path.
### What
- Add a shared `rmcp-client/src/streamable_http/` module with:
- `transport_client.rs` for the local-or-remote transport enum
- `local_client.rs` for the direct `reqwest` implementation
- `remote_client.rs` for the executor-backed implementation
- `common.rs` for the small shared Streamable HTTP helpers
- Teach `RmcpClient` to build Streamable HTTP transports in either local
or remote mode while keeping the existing OAuth ownership in RMCP.
- Translate remote POST, GET, and DELETE session operations into
executor `http/request` calls.
- Preserve RMCP session expiry handling and reconnect behavior for the
remote transport.
- Add remote transport coverage in
`rmcp-client/tests/streamable_http_remote.rs` and keep the shared test
support in `rmcp-client/tests/streamable_http_test_support.rs`.
### Verification
- `cargo check -p codex-rmcp-client`
- online CI
### Stack
1. #18581 protocol
2. #18582 runner
3. #18583 RMCP client
4. #18584 manager wiring and local/remote coverage
---------
Co-authored-by: Codex <noreply@openai.com>
### Why
Remote streamable HTTP MCP needs the executor to perform ordinary HTTP
requests on the executor side. This keeps network placement aligned with
`experimental_environment = "remote"` without adding MCP-specific
executor APIs.
### What
- Add an executor-side `http/request` runner backed by `reqwest`.
- Validate request method and URL scheme, preserving the transport
boundary at plain HTTP.
- Return buffered responses for ordinary calls and emit ordered
`http/request/bodyDelta` notifications for streaming responses.
- Register the request handler in the exec-server router.
- Document the runner entrypoint, conversion helpers, body-stream
bridge, notification sender, timeout behavior, and new integration-test
helpers.
- Add exec-server integration tests with the existing websocket harness
and a local TCP HTTP peer for buffered and streamed responses, with
comments spelling out what each test proves and its
setup/exercise/assert phases.
### Stack
1. #18581 protocol
2. #18582 runner
3. #18583 RMCP client
4. #18584 manager wiring and local/remote coverage
### Verification
- `just fmt`
- `cargo check -p codex-exec-server -p codex-rmcp-client --tests`
- `cargo check -p codex-core --test all` compile-only
- `git diff --check`
- Online full CI is running from the `full-ci` branch, including the
remote Rust test job.
Co-authored-by: Codex <noreply@openai.com>
---------
Co-authored-by: Codex <noreply@openai.com>
This introduces session-scoped ownership for exec-server so ws
disconnects no longer immediately kill running remote exec processes,
and it prepares the protocol for reconnect-based resume.
- add session_id / resume_session_id to the exec-server initialize
handshake
- move process ownership under a shared session registry
- detach sessions on websocket disconnect and expire them after a TTL
instead of killing processes immediately (we will resume based on this)
- allow a new connection to resume an existing session and take over
notifications/ownership
- I use UUID to make them not predictable as we don't have auth for now
- make detached-session expiry authoritative at resume time so teardown
wins at the TTL boundary
- reject long-poll process/read calls that get resumed out from under an
older attachment
---------
Co-authored-by: Codex <noreply@openai.com>
## Summary
- add optional `sandboxPolicy` support to the app-server filesystem
request surface
- thread sandbox-aware filesystem options through app-server and
exec-server adapters
- enforce sandboxed read/write access in the filesystem abstraction with
focused local and remote coverage
## Validation
- `cargo test -p codex-app-server-protocol`
- `cargo test -p codex-exec-server file_system`
- `cargo test -p codex-app-server suite::v2::fs`
---------
Co-authored-by: Codex <noreply@openai.com>
## Summary
- match the exec-process structure to filesystem PR #15232
- expose `ExecProcess` on `Environment`
- make `LocalProcess` the real implementation and `RemoteProcess` a thin
network proxy over `ExecServerClient`
- make `ProcessHandler` a thin RPC adapter delegating to `LocalProcess`
- add a shared local/remote process test
## Validation
- `just fmt`
- `CARGO_TARGET_DIR=~/.cache/cargo-target/codex cargo test -p
codex-exec-server`
- `just fix -p codex-exec-server`
---------
Co-authored-by: Codex <noreply@openai.com>
For each feature we have:
1. Trait exposed on environment
2. **Local Implementation** of the trait
3. Remote implementation that uses the client to proxy via network
4. Handler implementation that handles PRC requests and calls into
**Local Implementation**
Stacked PR 2/3, based on the stub PR.
Adds the exec RPC implementation and process/event flow in exec-server
only.
---------
Co-authored-by: Codex <noreply@openai.com>
Stacked PR 1/3.
This is the initialize-only exec-server stub slice: binary/client
scaffolding and protocol docs, without exec/filesystem implementation.
---------
Co-authored-by: Codex <noreply@openai.com>
