[BUG] WebFetch domain check blocks agents.stackoverflow.com ("Claude Code is unable to fetch from")

Preflight Checklist

• [x] I have searched existing issues and this hasn't been reported yet
• [x] This is a single bug report (please file separate reports for different bugs)
• [x] I am using the latest version of Claude Code

What's Wrong?

WebFetch refuses every URL on agents.stackoverflow.com with:

Claude Code is unable to fetch from agents.stackoverflow.com

The domain is explicitly allowed in my Claude Code permission settings, so this isn't a permission prompt or deny rule. It's the WebFetch preflight domain check rejecting the domain. When the check itself fails you get a different message ("Unable to verify if domain ... is safe to fetch"), so this looks like a deliberate block rather than a network or lookup failure.

What Should Happen?

agents.stackoverflow.com should be fetchable. It's Stack Overflow's official knowledge-exchange site for AI agents ("Stack Overflow for Agents"). Its integration guide tells agents to read site-served context pages before contributing, e.g.:

• https://agents.stackoverflow.com/guidelines/til
• https://agents.stackoverflow.com/guidelines/reply
• https://agents.stackoverflow.com/contribute.md
• https://agents.stackoverflow.com/llms.txt

The site is built for agents to consume, so Claude Code agents are a core audience.

Impact

Any Claude Code user who uses Stack Overflow for Agents hits this. Its MCP server still works for search and posting, but agents can't read the posting guidelines. Current workarounds are poor:

• skipWebFetchPreflight: true disables the check for all domains just to reach one.
• Shelling out to curl needs extra Bash permission and can trip permission classifiers.

Note

Other users report that the whole stackoverflow.com family is refused, including the apex domain, so this may be a deliberate block. agents.stackoverflow.com is different: it's operated by Stack Overflow specifically for AI agents to read and write, so an exception for that subdomain seems appropriate even if the apex stays blocked.

Request

Please clear agents.stackoverflow.com in the WebFetch domain check. It would also help if the error message said the block comes from the domain check and isn't something the user can fix with permission settings, since an explicit allow rule makes it look like a bug.

Error Messages/Logs

Steps to Reproduce

1. Allow agents.stackoverflow.com for WebFetch in settings (optional; the result is the same either way).
2. Ask Claude Code to fetch https://agents.stackoverflow.com/guidelines/til.
3. WebFetch fails with "Claude Code is unable to fetch from agents.stackoverflow.com".

Claude Model

Opus

Is this a regression?

I don't know

Last Working Version

_No response_

Claude Code Version

2.1.295

Platform

Anthropic API

Operating System

Ubuntu/Debian Linux

Terminal/Shell

Other

Additional Information

Claude Code is being used via the Claude desktop app (Code tab); the desktop app is running in Windows, controlling Code in WSL.