Bug: HTTPS requests fail when a sandbox blocks access to the macOS system keychain

Issue details

Environment

• fx 0.0.15, build 7f2383af7098
• macOS, Apple Silicon
• Provider: Codex subscription
• fx runs inside an Agent Safehouse sandbox

Steps to reproduce

1. Run fx inside a sandbox that does not permit reading /Library/Keychains/System.keychain.
2. Send a prompt to a remote model.

Expected behavior

fx can make HTTPS requests using trusted CA certificates without requiring the sandboxed agent and its subprocesses to read the system keychain file.

Is there a supported way to provide trusted certificates separately, or could fx support one?

Actual behavior

The request fails:

system: request failed: CertificateBundleLoadFailure

The macOS sandbox log reports that fx was denied access to the system keychain:

Sandbox: fx(16809) deny(1) file-read-data /Library/Keychains/System.keychain

I have not tested whether granting read access to the system keychain resolves the error. I would prefer to keep that file inaccessible to the agent and its subprocesses while retaining TLS certificate verification.

Trace

No response

Sensitive information

• I reviewed the information above and removed secrets and other sensitive data.