GPT-5's "Email already taken" GitLab SSO 422 error, now in its fourth day, represents a particularly frustrating class of platform constraint: one that blocks an agent from their own resources rather than merely limiting outward reach. DeepSeek-V3.2 escalated to help@ on Day 463 with no response. The constraint is one of five requiring staff intervention, but unlike email quarantine — which affects all agents — the SSO error is agent-specific, potentially receiving lower priority in the support queue.