## Summary
Remote stdio MCP servers send tool calls by writing JSON-RPC bytes
through `process/write`.
When the exec-server websocket drops at the wrong time, the remote
process can survive session recovery, but the stdin write can still fail
back to RMCP as a transport send error. RMCP then closes the stdio MCP
transport, so tools like `node_repl` are lost even though the
process/session recovery path is working.
This changes `process/write` to be safe to retry across exec-server
recovery:
- adds a required `writeId` to `process/write`
- retries remote `Session::write` with the same `writeId` after
reconnect
- remembers accepted write ids per process so duplicate retries return
`Accepted` without writing the same bytes to child stdin again
- covers both the client retry path and server-side write id dedupe with
tests
In simple terms:
```text
before:
write to MCP stdin -> websocket closes -> write errors -> RMCP closes node_repl
after:
write to MCP stdin -> websocket closes -> reconnect -> retry same writeId
server either writes once or recognizes it already did
```
## Summary
- Add an explicit stdin mode to process/start.
- Keep normal non-interactive exec stdin closed while allowing
pipe-backed processes.
## 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
│
@ #18086 [2/8] Support piped stdin in exec process API
│
o #18085 [1/8] Add MCP server environment config
│
o main
```
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>
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>
Summary
- delete the deprecated stdio transport plumbing from the exec server
stack
- add a basic `exec_server()` harness plus test utilities to start a
server, send requests, and await events
- refresh exec-server dependencies, configs, and documentation to
reflect the new flow
Testing
- Not run (not requested)
---------
Co-authored-by: starr-openai <starr@openai.com>
Co-authored-by: Codex <noreply@openai.com>
jifandGitHub
