stdio MCP server stops working after updating 0.48.0

What version of Codex is running?

codex-cli 0.48.0 | codex-cli 0.49.0

What subscription do you have?

Pro

Which model were you using?

gpt-5 codex

What platform is your computer?

Linux 6.6.87.2-microsoft-standard-WSL2 x86_64 unknown

What issue are you seeing?

Goland SSE MCP Server connected via supergateway not working.

2025-10-25T16:54:00.504780Z  INFO MCP server stderr (supergateway): [supergateway] Starting...
2025-10-25T16:54:00.504962Z  INFO MCP server stderr (supergateway): [supergateway] Supergateway is supported by Supermachine (hosted MCPs) - https://supermachine.ai
2025-10-25T16:54:00.504992Z  INFO MCP server stderr (supergateway): [supergateway]   - outputTransport: stdio
2025-10-25T16:54:00.505192Z  INFO MCP server stderr (supergateway): [supergateway]   - sse: http://localhost:64342/sse
2025-10-25T16:54:00.505289Z  INFO MCP server stderr (supergateway): [supergateway]   - Headers: (none)
2025-10-25T16:54:00.505318Z  INFO MCP server stderr (supergateway): [supergateway] Connecting to SSE...
2025-10-25T16:54:00.506031Z  INFO MCP server stderr (supergateway): [supergateway] Stdio server listening
2025-10-25T16:54:00.508621Z  INFO MCP server stderr (supergateway): [supergateway] Stdio → SSE: {
2025-10-25T16:54:00.508647Z  INFO MCP server stderr (supergateway):   jsonrpc: '2.0',
2025-10-25T16:54:00.508650Z  INFO MCP server stderr (supergateway):   id: 0,
2025-10-25T16:54:00.508652Z  INFO MCP server stderr (supergateway):   method: 'initialize',
2025-10-25T16:54:00.508653Z  INFO MCP server stderr (supergateway):   params: {
2025-10-25T16:54:00.508655Z  INFO MCP server stderr (supergateway):     protocolVersion: '2025-06-18',
2025-10-25T16:54:00.508657Z  INFO MCP server stderr (supergateway):     capabilities: { elicitation: {} },
2025-10-25T16:54:00.508659Z  INFO MCP server stderr (supergateway):     clientInfo: { name: 'codex-mcp-client', title: 'Codex', version: '0.48.0' }
2025-10-25T16:54:00.508661Z  INFO MCP server stderr (supergateway):   }
2025-10-25T16:54:00.508662Z  INFO MCP server stderr (supergateway): }
2025-10-25T16:54:00.563301Z  INFO MCP server stderr (supergateway): [supergateway] SSE connected
2025-10-25T16:54:00.563754Z  INFO MCP server stderr (supergateway): [supergateway] Response: {
2025-10-25T16:54:00.563777Z  INFO MCP server stderr (supergateway):   jsonrpc: '2.0',
2025-10-25T16:54:00.563781Z  INFO MCP server stderr (supergateway):   id: 0,
2025-10-25T16:54:00.563782Z  INFO MCP server stderr (supergateway):   result: {
2025-10-25T16:54:00.563784Z  INFO MCP server stderr (supergateway):     _meta: {},
2025-10-25T16:54:00.563785Z  INFO MCP server stderr (supergateway):     protocolVersion: '2024-11-05',
2025-10-25T16:54:00.563791Z  INFO MCP server stderr (supergateway):     capabilities: { experimental: {}, logging: {}, tools: [Object], sampling: {} },
2025-10-25T16:54:00.563794Z  INFO MCP server stderr (supergateway):     serverInfo: { name: 'GoLand MCP Server', version: '2025.2.4' }
2025-10-25T16:54:00.563796Z  INFO MCP server stderr (supergateway):   }
2025-10-25T16:54:00.563798Z  INFO MCP server stderr (supergateway): }
2025-10-25T16:54:00.564481Z  INFO MCP server stderr (supergateway): [supergateway] SSE → Stdio: { jsonrpc: '2.0', method: 'notifications/initialized' }
2025-10-25T16:54:00.564872Z  INFO MCP server stderr (supergateway): [supergateway] Stdio → SSE: {
2025-10-25T16:54:00.564904Z  INFO MCP server stderr (supergateway):   jsonrpc: '2.0',
2025-10-25T16:54:00.564907Z  INFO MCP server stderr (supergateway):   id: 1,
2025-10-25T16:54:00.564908Z  INFO MCP server stderr (supergateway):   method: 'tools/list',
2025-10-25T16:54:00.564910Z  INFO MCP server stderr (supergateway):   params: { _meta: { progressToken: 0 } }
2025-10-25T16:54:00.564911Z  INFO MCP server stderr (supergateway): }
2025-10-25T16:54:00.566309Z  INFO MCP server stderr (supergateway): [supergateway] stdin closed. Exiting...
2025-10-25T16:54:00.575887Z  WARN Failed to list tools for MCP server 'goland': Err(
    "tools/list failed: Transport closed",
)

What steps can reproduce the bug?

Install any JetBrains IDE, and use following config to try connecting MCP server.

[mcp_servers.goland]
command = "supergateway"
args = [ "--sse", "http://localhost:64342/sse" ]
disabled_tools = [ "execute_terminal_command"]

What is the expected behavior?

"goland" tool visible in MCP Tools.

2025-10-25T16:48:36.693479Z  INFO aggregated 20 tools from 1 servers

Additional information

It worked in release 0.47.0.
It is working with MCP inspector, so seems not a server bug.
<img width="3570" height="1876" alt="Image" src="https://github.com/user-attachments/assets/bf0eb65f-177a-403a-98a7-5b4b27fd8bc8" />

PRs touched MCP client between 0.47.0 to 0.48.0 are following:
https://github.com/openai/codex/pull/5298
https://github.com/openai/codex/pull/5300
https://github.com/openai/codex/pull/5309
https://github.com/openai/codex/pull/5367
https://github.com/openai/codex/pull/5393
https://github.com/openai/codex/pull/5423
https://github.com/openai/codex/pull/5487
https://github.com/openai/codex/pull/5529

But only https://github.com/openai/codex/pull/5529 seems related to this issue.