Architectural System Design

Once requirements are defined, the temptation is to immediately prompt an execution agent to "build the backend API" or "create the UI components." But jumping directly from product requirements to implementation code introduces architectural entropy.

Without an explicit, upfront system design phase, four structural failures reliably occur:

1. Component Coupling & Boundaries Drift. Developers (and AI agents) write monoliths or misplaced abstractions because module boundaries were never formally drawn.
2. Ambiguous API Contracts. Frontend and backend development get blocked or desynchronized because request payloads, error codes, and endpoints are decided on the fly.
3. Database & Schema Drift. Data models are created incrementally per feature, leading to redundant fields, missing indexes, and unnormalized relational tables.
4. Ignored Non-Functional Requirements. Latency targets, security guards, caching strategies, and rate limits are treated as afterthoughts rather than core architectural constraints.

Code is cheap to regenerate, but a broken architectural foundation propagates technical debt across every downstream file. System Design creates the immutable blueprint that keeps concurrent execution agents aligned.