Circuit is a substrate-agnostic interface for directing distributed intelligence. Currently pointed at building iOS apps, but architected to be overlaid directly onto iOS itself, it makes a clean break with the IDE: Circuit never shows the user code, and never speaks in software-engineering concepts. Behavior is the artifact. The Director composes in plain language and watches the system work. Her role is to attend to what orchestration cannot: discretion, intuition, effects in reality, the texture of how a thing sits in someone's life. Questions that bear on those dimensions surface as escalation cards in TCGHand, an idiom borrowed from Trading Card Games. Cards arrive in a carousel where they can be answered, flicked off the top of the screen, or held and dragged back down to hand the decision to the orchestrator. Choosing when to hold a card is as important as choosing the moment to play it, because once Circuit's substrate is genericized beyond app-building, the order in which the cascade takes its actions in the world becomes a primary design decision. Beneath the interface, a continuously revised markdown StateDocument serves as the cascade's working memory, so that interface and architecture feel unified and magically paper-like from top to bottom.

Cascade SDK is the orchestration engine underneath. An orchestrator — the Director's concierge, with sole responsibility for the codebase — instantiates agents not like contracted workers but appendages, given mid-range tasks before merging back to turn over their work and memories; both orchestrator and agents can in turn spawn sub-agents specialized for in-line planning, exploration, critique, consolidation, and building. The architecture is evolved from Kubernetes, the distributed structure of Git, and modern R&D organizations, and scales horizontally and vertically by the same logic. But Cascade SDK's core identity isn't its topology: it's the carefully inscribed space of human-AI co-participation that the architecture makes possible. The orchestrator's deference to the Director is epistemic, not hierarchical: it defers because it literally cannot perceive what the Director perceives. Escalations exist to acquire information the orchestrator lacks. This principle is integrated at the level of prompt and architecture rather than tacked on as policy, because language is the primary interface for shaping a model's space of intent, and crafting that space is what intelligence design, as a nascent discipline, is about.