Failing to login with OAuth in MCP HTTP server

What version of Codex is running?

codex-cli 0.46.0

Which model were you using?

gpt-5-codex medium

What platform is your computer?

Darwin 24.6.0 arm64 arm

What steps can reproduce the bug?

Configuring todoist mcp using the experimental RMCP client

experimental_use_rmcp_client = true

[mcp_servers.todoist]
url = "https://ai.todoist.net/mcp"

and then running

codex mcp login todoist

What is the expected behavior?

• Browser opens (I am using Arc browser)
• Login and authorize
• Close browser and get to terminal
• Login in mcp confirmed

What do you see instead?

• Browser opens (I am using Arc browser)
• Login and authorize
• Close browser and get to terminal

In terminal I see

Error: failed to handle OAuth callback

Caused by:
    OAuth token exchange failed: Server returned error response: Required argument is missing

Additional information

_No response_