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When to Use

Decision Framework

Spec-driven development is most effective when applied strategically. Use this decision framework to determine whether the methodology is appropriate for your specific situation.

Primary Decision Criteria

Complexity Assessment

Use spec-driven development when:

  • The feature involves multiple components or systems
  • Integration with external APIs or services is required
  • Complex business logic or data transformations are involved
  • Multiple user roles or permission levels need to be handled
  • The feature affects existing system architecture

Consider alternatives when:

  • The change is a simple bug fix or minor adjustment
  • The implementation is well-understood and follows established patterns
  • The feature is purely cosmetic (UI-only changes with no logic)

Risk and Impact Evaluation

Use spec-driven development when:

  • The feature is customer-facing or affects user experience significantly
  • Failure could impact system stability or data integrity
  • The feature involves sensitive data or security considerations
  • Multiple teams or stakeholders depend on the outcome
  • The implementation will be difficult to change once deployed

Consider alternatives when:

  • The feature is internal tooling with limited impact
  • The change is easily reversible
  • You're building a throwaway prototype or proof of concept

Team and Collaboration Factors

Use spec-driven development when:

  • Multiple developers will work on the feature
  • Cross-functional collaboration is required (design, product, engineering)
  • Knowledge transfer and documentation are important
  • The team is distributed or works asynchronously
  • New team members need to understand the feature

Consider alternatives when:

  • You're working solo on a well-understood problem
  • The team has extensive shared context about the feature
  • Immediate implementation is more valuable than documentation

Timeline and Resource Considerations

Use spec-driven development when: - You have sufficient time for planning (typically 20-30% of total development time) - The cost of rework would be significant - Accurate estimation is important for project planning - The feature will be maintained and extended over time

Consider alternatives when: - You're under extreme time pressure for a critical fix - The feature is experimental and may be discarded - Resources for documentation and planning are severely limited

Project Type Recommendations

New Feature Development

  • User-facing features: Authentication systems, data dashboards, workflow tools
  • API development: REST endpoints, GraphQL schemas, webhook systems
  • Data processing: ETL pipelines, reporting systems, analytics features
  • Integration projects: Third-party service integrations, system migrations

System Architecture Changes

  • Database schema modifications: Adding new entities, changing relationships
  • Performance optimizations: Caching strategies, query optimization
  • Security enhancements: Access control, audit logging, encryption
  • Scalability improvements: Load balancing, distributed processing

Cross-Team Initiatives

  • Platform features: Shared libraries, common utilities, infrastructure
  • Compliance projects: GDPR, accessibility, security standards
  • Migration projects: Technology upgrades, system consolidation

Enhancement Projects

  • Feature extensions: Adding functionality to existing features
  • User experience improvements: Workflow optimization, interface redesign
  • Configuration and settings: Admin panels, user preferences
  • Reporting and analytics: New metrics, dashboard improvements

Maintenance and Refactoring

  • Code modernization: Updating deprecated APIs, framework upgrades
  • Technical debt reduction: Refactoring complex modules, improving test coverage
  • Documentation projects: API documentation, user guides

Simple Changes

  • Bug fixes: Single-line changes, configuration updates
  • Content updates: Text changes, image replacements
  • Style adjustments: CSS modifications, minor UI tweaks
  • Dependency updates: Library version bumps, security patches

Experimental Work

  • Proof of concepts: Technology evaluation, feasibility studies
  • Rapid prototypes: Quick mockups, throwaway implementations
  • A/B test variations: Simple feature toggles, minor variations

Emergency Situations

  • Critical hotfixes: Production outages, security vulnerabilities
  • Time-sensitive patches: Urgent customer requests, compliance deadlines
  • Rollback procedures: Reverting problematic deployments

Practical Examples

Scenario: Building a new user authentication system with OAuth integration, role-based permissions, and session management.

Why spec-driven development fits: - High complexity with multiple components (auth service, user management, permissions) - Security-critical functionality requiring careful design - Multiple stakeholders (security team, product, engineering) - Long-term maintenance and extension expected - Integration with external OAuth providers

Spec approach: - Requirements phase: Define user stories for different auth flows, security requirements - Design phase: Architecture for auth service, database schema, API design - Tasks phase: Step-by-step implementation of auth components, testing strategy

Scenario: Fixing a typo in a validation error message.

Why spec-driven development doesn't fit: - Extremely low complexity - No risk to system stability - Single developer can handle independently - Change is easily reversible - No architectural implications

Better approach: - Direct fix with code review - Simple test to verify the change - Update any relevant documentation

Scenario: Building a system to process customer data uploads, validate content, transform formats, and generate reports.

Why spec-driven development fits: - Complex data transformations and business logic - Multiple failure modes requiring error handling - Performance and scalability considerations - Integration with existing reporting systems - Regulatory compliance requirements

Spec approach: - Requirements phase: Data validation rules, transformation requirements, error handling - Design phase: Pipeline architecture, data flow, monitoring and alerting - Tasks phase: Incremental implementation of processing stages

Scenario: Updating the application's color palette to match new brand guidelines.

Why spec-driven development doesn't fit: - Primarily cosmetic changes - Well-understood implementation (CSS updates) - Low risk of system impact - Easy to iterate and adjust - No complex business logic

Better approach: - Design system documentation - Direct implementation with visual review - Automated testing for accessibility compliance

Decision Tree

Is the change complex or involve multiple components?
├─ Yes → Continue evaluation
└─ No → Consider direct implementation

Is the risk/impact of failure significant?
├─ Yes → Continue evaluation  
└─ No → Consider direct implementation

Do multiple people need to collaborate on this?
├─ Yes → Continue evaluation
└─ No → Consider direct implementation

Do you have time for proper planning (20-30% of dev time)?
├─ Yes → Use spec-driven development
└─ No → Consider direct implementation with minimal documentation

Adapting the Process

Spec-First vs. Spec-Alongside

Spec-First (Recommended): - Complete spec before any implementation - Full review and approval process - Best for complex, high-risk features

Spec-Alongside: - Develop spec and implementation in parallel - Use spec to guide implementation decisions - Good for exploratory development with documentation needs

Integration with Development Workflows

Agile/Scrum Integration

  • Use specs for larger user stories or epics
  • Create specs during sprint planning
  • Reference specs during daily standups and reviews
  • Update specs based on sprint retrospective feedback

Continuous Integration

  • Include spec validation in CI pipeline
  • Ensure implementation matches spec requirements
  • Use specs for automated testing guidance
  • Update specs as part of the development process

Code Review Process

  • Include spec review as part of code review
  • Verify implementation follows spec design
  • Update specs when implementation reveals better approaches
  • Use specs to provide context for reviewers

Measuring Success

Indicators That Spec-Driven Development Is Working

  • Reduced rework and bug fixes after initial implementation
  • Faster onboarding of new team members to features
  • Better estimation accuracy for similar features
  • Improved stakeholder satisfaction with delivered features
  • Easier maintenance and extension of existing features

Warning Signs to Adjust Approach

  • Specs taking longer to write than implementation
  • Specs becoming outdated immediately after creation
  • Team resistance to following the process
  • Specs not being referenced during implementation
  • Over-documentation of simple features