In their seminal essay, Ink & Switch laid out a vision for "Local-First Software": applications that respond instantly, work offline seamlessly, and allow for real-time collaboration. As an industry, we are rushing to adopt this paradigm to build Figma-like or Linear-like experiences.

But there is a massive architectural collision happening. Traditional Domain-Driven Design assumes the Cloud is the undisputed Single Source of Truth. We keep our clients "thin," relying on backend Aggregate Roots to enforce invariants and validate commands.

Local-first software shatters this model. If the app must work instantly offline and merge collaborative edits later, the local device is no longer just a View—it is a primary node in a distributed system.

How do we design domains where the Source of Truth is concurrent and distributed? In this talk, we’ll map the Local-First ideals to strategic DDD patterns. We will explore how to treat the local device as a fully autonomous Bounded Context, why syncing "Domain Events" is safer than syncing database rows for collaborative features, and how to embrace eventual consistency in the UI without losing data integrity. You'll leave with a framework for building local-first apps that respect both the user's network and your core business rules.