OpenAI quietly re-ships Codex Cloud: cloud agents reach private services over Tailscale, with MagicDNS and OIDC short-lived credentials

Cloud coding agents usually fail on reach, not code: internal APIs, private registries and staging live on the corporate network while task VMs run in a public cloud. On Oct 8 Codex lead Tibo said Codex Cloud was silently re-shipped, quoting Tailscale's announcement. Per OpenAI's cloud-environment docs, Advanced > VPN accepts Tailscale (the only supported provider for now) with an auth key marked Reusable and Ephemeral, so each task VM joins the tailnet and is removed after it goes offline. Traffic is HTTP/HTTPS only, private IPv4 subnet routes work, and the docs now list MagicDNS and split DNS support, which Tailscale's Oct 6 post said was missing. Destinations must be allowed in both Tailscale access rules and the environment's internet-access policy. Enterprise workspaces can request OIDC so tasks obtain short-lived cloud credentials scoped to that identity. Tailscale says there was no partnership: OpenAI built it on the public product. No new benchmarks were published. Recommended hardening: tag Codex nodes (tag:codex), scope access with grants, keep key expiry, and enable device approval instead of a default allow-all ACL.