Architecture diagrams often start with boxes because systems and organisational units are easy to name. But many of the hardest problems live in the lines: who exchanges information, who waits for whom, where decisions are made, how errors propagate and what happens when responsibilities cross boundaries. The interactions deserve first-class architectural attention.
A line is a commitment
An integration implies ownership, data meaning, timing, failure handling and change coordination.
Human interactions matter too
Manual approvals, emails, spreadsheets and informal escalation paths are part of the system even if they are absent from the official architecture.
Design for the behaviour you want
If a target architecture only rearranges boxes without changing the interactions that produce current problems, the outcome may remain the same.
Why this matters to soapplied
These ideas influence how I frame technology decisions: understand purpose and perspective, see the interactions, imagine a better whole, and then choose a feasible intervention. The method should remain practical enough to produce a decision, not become an academic exercise.