Windows Desktop does not surface a healthy WSL stdio MCP server

Start by reproducing the sanitized MCP configuration and comparing the Desktop WSL launcher with the native docker.exe workaround. Trace how the Desktop task handles the stdio server after initialize and tools/list, including whether startup stderr is captured. Done means the WSL-launched server's tools are surfaced or a visible startup error is provided.

Windows Desktop does not surface a healthy WSL stdio MCP server

Summary

On Windows, Codex Desktop did not expose the tools of a healthy stdio MCP
server launched through wsl.exe, although the same configuration was enabled
in codex mcp list and the exact server command completed a full MCP protocol
probe. This resembles the existing WSL spawn-bridge reports, but the server in
this reproduction is Docker-backed and does not require Node or Python on the
Windows host.

Environment

• Codex Desktop Windows: 26.715.3651.0
• Codex CLI: 0.144.1
• WSL distribution: Ubuntu 24.04
• Docker Desktop engine: 29.6.1
• MemPalace container: 3.5.0

Sanitized configuration

[mcp_servers.mempalace]
command = "wsl.exe"
args = ["-d", "Ubuntu-24.04", "--", "docker", "run", "-i", "--rm",
        "-v", "theseus-mempalace-clean:/data", "theseus-mempalace:pilot"]
enabled = true
startup_timeout_sec = 60
tool_timeout_sec = 120

Evidence

1. codex mcp get mempalace reported the server as enabled using stdio.
2. Running the exact launcher independently completed MCP initialize, then
   notifications/initialized, then tools/list.
3. The response identified MemPalace 3.5.0 and returned 36 tools.
4. In the running Desktop task, no mempalace_* tools were surfaced, while
   other configured MCP tools were available.
5. A bounded Windows process/network snapshot found Codex Desktop, its
   code-mode host, Docker Desktop, and expected local service listeners alive;
   it did not indicate a Docker or WSL outage.

Candidate workaround

The same container and volume pass the identical full MCP probe when launched
with native docker.exe instead of wsl.exe:

[mcp_servers.mempalace]
command = "docker.exe"
args = ["run", "-i", "--rm", "-v", "theseus-mempalace-clean:/data",
        "theseus-mempalace:pilot"]

This removes only the Desktop-to-WSL process hop. It preserves the volume and
MCP server. Desktop reload verification is still pending after a full restart,
so this is a candidate workaround rather than a confirmed product fix.

Expected behavior

When codex mcp list reports an enabled stdio server and the exact command
successfully completes initialize and tools/list, Codex Desktop should
surface the server tools or provide a visible startup error with captured
stderr.

Related reports

• #21147: Windows Desktop WSL mode launches a Windows app-server path.
• Discussion #5471: MCP servers work from WSL CLI but are not detected in the
  Windows IDE/WSL bridge.