Disruption often tests the places where systems meet, the edges. The interface between emergency services and local councils, or between health providers and community groups for example can become the ‘zone’ where tensions and differences emerge. When ‘handovers’ between sub systems are weak, confusion spreads and frustration emerges. Resilient systems design for cross boundary interactions. Clear protocols, shared language, and trusted relationships ensure responsibilities transfer and flow smoothly. Boundaries become points of strength, not weakness. Resilience grows when cross boundary flows are designed as carefully as the work itself.