Chapter 1: Spec-First Development

In legacy software engineering, developers jumped straight into code editors to write syntax. In AI-assisted software development, starting without a technical specification is the fastest way to corrupt your project's context window.

---

1. The Premature Prompting Anti-Pattern

When you open an AI chat or coding copilot and type a raw prompt like "build a booking app for a salon", the model is forced to make hundreds of unguided assumptions:

• What are the CSS color variables?
• What are the database collection names?
• Which API routes handle authentication?
• What is the shape of the user object?

Because these details were omitted, the AI invents temporary names. By prompt #5, different components use conflicting database key names (userId vs. customerId), breaking your data flow.

---

2. The Solution: PRD Spec Lock

Spec-First Development requires locking a Product Requirement Document (PRD) before generating code.

A locked spec defines:

• Brand Identity & Tokens: Primary hex colors, typography, dark mode CSS variables.
• Database Schemas: Table column names, primary keys, and data types.
• Route & Navigation Map: User-facing pages, admin control panels, and server API route endpoints.
• Security Boundaries: Role-based access rules and validation gates.

---

3. Step-by-Step Implementation

• Write your PRD in markdown format (PRD.md).
• Store architectural guidelines in AGENTS.md or CLAUDE.md at your project root.
• Pass the locked PRD to your AI agent as the foundational context for all prompt loops.

Explore the next chapter: Prompt Loop Design.