Modern systems rely on services, vendors, and integrations that teams do not control. Reliability issues usually appear at these boundaries, where visibility is limited, ownership is shared, and assumptions fail.

This talk is based on real experience with fintech systems handling compliance workflows and third-party integrations. Failures rarely stay within a single component. They cross systems, teams, and responsibilities.

We will look at how to design safer boundaries, operate with incomplete information, and handle incidents when parts of the system behave like black boxes. It also touches on the coordination required between teams and vendors to keep systems running.

The focus is practical: how to keep systems reliable when control is partial and constraints are not negotiable.