Decisions require interfaces

Software systems communicate through interfaces.

Organisations frequently expect teams to coordinate without them.

When coordination depends entirely on conversation each interaction must be renegotiated. Responsibility becomes ambiguous and decisions slow down.

Decision interfaces formalise the interaction between domains.

Product may request feasibility from engineering. Engineering may request capacity from infrastructure. Governance may request assurance from delivery.

These requests become predictable.

Interfaces define the questions one domain may ask another and the information required for an answer.

Teams no longer renegotiate their responsibilities repeatedly.

Instead decisions travel across defined surfaces within the organisation.

The system begins to resemble a distributed architecture rather than a collection of teams negotiating continuously.

Coordination improves when decisions move through defined interfaces rather than conversation.