Sandbox blocks Go TLS on macOS: trustd Mach port inaccessible

Summary

All Go binaries fail TLS verification inside the Claude Code sandbox on macOS. This affects gh (GitHub CLI), and would affect any Go-based CLI tool.

Root cause

Go 1.18+ on macOS uses //go:cgo_import_dynamic to call Security.framework's SecTrustEvaluateWithError for TLS certificate verification. This is a direct dynamic symbol import — not cgo — so CGO_ENABLED=0 has no effect. The verification requires a Mach port connection to the trustd system daemon, which the sandbox blocks.

Error: tls: failed to verify certificate: x509: OSStatus -26276 (errSecNotAvailable)

What works vs. what doesn't

| Tool | TLS engine | In sandbox |
|------|-----------|------------|
| curl | LibreSSL (reads cert files) | Works |
| gh (Go) | Security.framework via trustd | Fails |
| Any Go binary | Security.framework via trustd | Fails |

Reproduction

# Inside Claude Code sandbox:
gh auth status
# => tls: failed to verify certificate: x509: OSStatus -26276

# Same command outside sandbox:
gh auth status
# => ✓ Logged in to github.com

What we tried (and why it doesn't work)

• CGO_ENABLED=0: Go 1.26 uses //go:cgo_import_dynamic, not cgo. Build flag is irrelevant.
• SSL_CERT_FILE: Go on macOS ignores this — always uses Security.framework.
• GODEBUG=x509usefallbackroots=1: Only activates if x509.SetFallbackRoots was called. macOS's loadSystemRoots() returns a systemPool: true marker, so Go never triggers the fallback path.

Suggested fix

Allow the Mach port to trustd (com.apple.trustd) in the sandbox profile. This is a read-only trust evaluation service — it doesn't modify system state. This would fix all Go-based CLI tools, not just gh.

Environment

• macOS Darwin 25.5.0 (arm64)
• Go 1.26.5 (nix)
• gh 2.97.0 (nix)
• Claude Code sandbox (default settings)