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Phase 4: Spec

Document detailed requirements for what to build.

Purpose​

Create clear, unambiguous specifications that:

  1. Define exactly what to build
  2. Establish acceptance criteria
  3. Enable accurate estimation

Activities​

Requirements Documentation​

  • Write Product Requirements Document (PRD)
  • Create feature specifications
  • Define acceptance criteria

Prioritization​

  • Rank features by importance
  • Define MVP scope
  • Identify dependencies

Estimation​

  • Break down into tasks
  • Estimate effort
  • Identify risks

Outputs​

OutputDescription
PRDProduct Requirements Document
Feature SpecsDetailed feature documentation
Acceptance CriteriaDefinition of done for each feature
BacklogPrioritized list of work items

PRD Structure​

# Product Requirements Document

## Overview
[Brief description of the product/feature]

## Goals
[What success looks like]

## Non-Goals
[What we're explicitly NOT doing]

## User Stories
[As a X, I want Y, so that Z]

## Requirements
### Functional Requirements
[What the system must do]

### Non-Functional Requirements
[Performance, security, etc.]

## Success Metrics
[How we measure success]

## Timeline
[Key milestones]

Writing Good Specs​

Be Specific​

  • Bad: "Fast page load"
  • Good: "Page loads in < 2 seconds on 3G"

Include Acceptance Criteria​

Every feature needs clear "done" criteria:

  • Given [context]
  • When [action]
  • Then [expected result]

Avoid Ambiguity​

  • Define terms
  • Include examples
  • Use diagrams where helpful

Exit Criteria​

Ready to move to Architect when:

  • PRD is complete
  • Features are specified
  • Acceptance criteria defined
  • Scope is agreed upon

Templates​

Next Phase​

Phase 5: Architect - Design the technical solution.