architecture-design

Architecture Design

Overview

System requirements say what the system must do. Architecture design says how the system will be built to do it. This skill bridges the gap between requirements and implementation — decomposing the system into modules, defining every interface, analyzing cross-cutting constraints, and documenting the trade-offs behind every non-trivial decision.

A good architecture document is the answer key for every downstream question: "which module owns this feature?", "what does module A promise to module B?", "why did we choose this protocol over that one?". Without it, every implementer answers these differently, and integration becomes a discovery process instead of an execution plan.

Architecture design is to SE what task-breakdown planning is to software development — but for hardware-software system architecture rather than implementation tasks.

When to Use

• Structured system requirements exist (output of requirements-decompose) and are confirmed
• Starting a new chip application design from scratch
• Adding a major subsystem (new power domain, new communication interface, new safety feature) to an existing design
• Evaluating architecture alternatives against a set of quantified requirements
• A downstream skill (spec-authoring) detects an architecture decision that was assumed but never documented
• A design review surfaces interface or module-boundary issues that require architectural resolution

When NOT to use:

• Requirements are not yet decomposed and confirmed (run requirements-decompose first)
• The change is limited to a single module's internal implementation with no interface impact
• Pure implementation task ("write the driver for this already-specified interface")
• The architecture document already exists and only needs a small clarification (edit the document directly)

The Process

DECOMPOSE ──→ INTERFACE ──→ CONSTRAINT ──→ TRADE-OFF ──→ DOCUMENT
    │             │             │              │              │
    ▼             ▼             ▼              ▼              ▼
  Module       Define        Analyze        Evaluate       Produce
  breakdown    every IF     cross-cutting   alternatives   architecture
               precisely    constraints     & decide        document