Project Constitution Management

Overview

Create and maintain a project constitution that defines project-wide principles, standards, and patterns.

A constitution provides:

• Architectural decisions
• Coding standards
• Error handling patterns
• Quality gates
• Common practices

All specs are validated against the constitution for consistency.

Prerequisites

Ensure spec-kit is initialized:

{Skill: spec-kit}

If spec-kit prompts for restart, pause this workflow and resume after restart.

What is a Constitution?

Purpose: Document project-wide rules that ensure consistency across features.

Contains:

• Architectural principles
• Coding standards
• API design patterns
• Error handling approaches
• Security requirements
• Testing standards
• Performance requirements
• Accessibility standards

Benefits:

• Consistency across features
• Onboarding documentation
• Design decision record
• Spec validation reference

When to Create

Good times:

• New project starting
• After second or third feature (patterns emerging)
• Team wants consistency
• Before major expansion

Bad times:

• First feature (too early, no patterns yet)
• During active implementation
• As reaction to single issue

Rule of thumb: Create after you see patterns repeating.

The Process

1. Decide if Constitution Needed

Ask:

• Are there repeated patterns in specs?
• Do you want consistency enforced?
• Is this a team project?
• Is this a long-term project?

If solo + small project: Constitution might be overkill

If team OR large OR long-term: Constitution recommended

2. Gather Existing Patterns

Review existing specs:

ls specs/features/
cat specs/features/*.md

Identify patterns:

• How do we handle errors?
• What API patterns do we follow?
• What security requirements are common?
• What coding standards do we use?

Extract commonalities: Make implicit standards explicit.

3. Use Spec-Kit or Manual Creation

With spec-kit:

speckit constitution

Manual creation: Create specs/constitution.md with template below.

4. Create Constitution Content

Template:

# Project Constitution

**Project:** [Project Name]
**Created:** YYYY-MM-DD
**Last Updated:** YYYY-MM-DD

## Purpose

This constitution defines project-wide principles, patterns, and standards.
All features and implementations must align with these principles.

## Architectural Principles

### [Principle Name]
**Description:** [What this principle means]
**Rationale:** [Why we follow this]
**Examples:**
- ✓ [Good example]
- ✗ [Bad example]

[Repeat for each principle]

## API Design Standards

### RESTful Conventions
- Use standard HTTP methods (GET, POST, PUT, DELETE)
- Plural resource names (/users, not /user)
- Return appropriate status codes
- Use JSON for request/response bodies

### Error Responses
**Format:**
```json
{
  "error": "Human-readable error message",
  "code": "ERROR_CODE",
  "details": { ... }
}

Status Codes:

• 400: Bad Request (client error)
• 401: Unauthorized (auth required)
• 403: Forbidden (auth insufficient)
• 404: Not Found
• 422: Unprocessable Entity (validation failed)
• 500: Internal Server Error

Error Handling

Approach

• All errors must be handled explicitly
• Use try-catch for I/O operations
• Log errors with context
• Return user-friendly messages

Retry Logic

• Database operations: 3 retries with exponential backoff
• External APIs: 2 retries with fixed delay
• Timeout: 30 seconds for external calls

Security Requirements

Authentication

• All API endpoints require JWT authentication (except public endpoints)
• JWTs expire after 30 minutes
• Refresh tokens expire after 7 days

Input Validation

• Validate all user input
• Sanitize before database operations
• Reject unexpected fields

Secrets Management

• Never commit secrets to git
• Use environment variables
• Rotate secrets quarterly

Testing Standards

Coverage Requirements

• Minimum 80% code coverage
• 100% coverage for critical paths

Test Types

• Unit tests for all functions
• Integration tests for API endpoints
• E2E tests for critical user flows

Test Organization

• Tests in tests/ directory
• Mirror source structure
• Use descriptive test names

Performance Requirements

Response Times

• API responses: < 200ms (p95)
• Database queries: < 50ms (p95)
• Page loads: < 2 seconds

Scalability

• Design for 10,000 concurrent users
• Horizontal scaling preferred
• Stateless where possible

Code Quality Standards

Code Style

• Follow [ESLint/Prettier/etc.] configuration
• Consistent naming conventions
• Comments for complex logic only

Code Review

• All code must be reviewed
• Spec compliance verified
• Tests required before merge

Accessibility Standards

WCAG Compliance

• Meet WCAG 2.1 Level AA
• Keyboard navigation required
• Screen reader compatible

Documentation Standards

Code Documentation

• JSDoc for public functions
• README in each module
• Architecture diagrams for complex systems

Spec Documentation

• All features must have specs
• Specs updated with changes
• Specs validated before implementation

Change Management

Updating This Constitution

• Requires team discussion (if team)
• Document rationale for changes
• Update all affected specs
• Communicate changes

Exceptions

• Exceptions must be documented in spec
• Requires justification
• Reviewed during code review

Glossary

[Term 1]: [Definition] [Term 2]: [Definition]

Decision Log

[Decision Date]: [Decision Title]

Context: [Why decision needed] Decision: [What was decided] Rationale: [Why this decision] Implications: [What this affects]

[Add new decisions here]

### 5. Review and Refine

**Questions to ask:**
- Is this too restrictive?
- Is this clear enough?
- Can we realistically follow this?
- Does this reflect our actual practices?

**Adjust as needed.**

### 6. Validate Against Existing Specs

**Check existing specs:**
```bash
# For each existing spec
cat specs/features/[feature].md

# Does it align with constitution?
# Any violations?

If violations found:

• Update spec, OR
• Update constitution (if spec is right), OR
• Note as exception

7. Commit Constitution

git add specs/constitution.md
git commit -m "Add project constitution

Defines project-wide principles and standards:
- Architectural principles
- API design standards
- Error handling patterns
- Security requirements
- Testing standards
- Code quality standards

All future specs will be validated against this constitution.

🤖 Generated with [Claude Code](https://claude.com/claude-code)

Co-Authored-By: Claude <noreply@anthropic.com>"

8. Communicate and Adopt

For team projects:

• Share with team
• Get consensus
• Document exceptions
• Reference in onboarding

For solo projects:

• Keep visible
• Reference when creating specs
• Update as you learn

Constitution Checklist

Use TodoWrite to track:

• Decide if constitution needed
• Gather existing patterns from specs/code
• Create constitution file (spec-kit or manual)
• Fill in all relevant sections
• Review for clarity and feasibility
• Validate against existing specs
• Handle any violations found
• Commit constitution to git
• Communicate to team (if applicable)

Example Constitution

# Todo App Project Constitution

**Created:** 2025-11-10

## Purpose

Define standards for the todo app project to ensure consistency.

## Architectural Principles

### RESTful API Design
All endpoints follow REST conventions:
- `GET /api/todos` - List todos
- `POST /api/todos` - Create todo
- `PUT /api/todos/:id` - Update todo
- `DELETE /api/todos/:id` - Delete todo

### Data Validation
- Validate on server (never trust client)
- Return 422 for validation failures
- Provide specific error messages

## Error Handling

### Error Response Format
```json
{
  "error": "Human-readable message",
  "field": "field_name",  // for validation errors
  "code": "ERROR_CODE"
}

Common Errors

• 400: Malformed request
• 401: Not authenticated
• 404: Todo not found
• 422: Validation failed (e.g., title too long)

Testing Standards

Requirements

• All endpoints have integration tests
• All validation rules have tests
• Edge cases tested

Coverage

• Minimum 80% coverage
• 100% coverage for API endpoints

Code Quality

Naming

• camelCase for variables and functions
• PascalCase for classes
• UPPER_CASE for constants

Comments

• JSDoc for public functions
• Inline comments for complex logic only

Security

Authentication

• JWT tokens required for all /api/* endpoints
• Tokens expire after 1 hour
• Refresh on activity

Input Sanitization

• Escape HTML in todo titles/descriptions
• Limit field lengths (title: 200 chars, description: 2000 chars)

Decision Log

2025-11-10: Use JWT for Auth

Context: Need authentication for multi-user support Decision: Use JWT tokens stored in httpOnly cookies Rationale: Secure, stateless, industry standard Implications: Need token refresh mechanism, logout handling

## Maintaining the Constitution

**Update when:**
- New patterns emerge
- Decisions change
- Standards evolve
- Exceptions become rules

**Don't update when:**
- Single feature needs exception
- Trying to justify shortcut
- Reacting to single issue

**Update process:**
1. Propose change
2. Update constitution
3. Update affected specs
4. Communicate change
5. Add to decision log

## Common Sections

### Minimal Constitution
- Architectural principles
- Error handling
- Testing standards

### Standard Constitution
- Above, plus:
- API design
- Security requirements
- Code quality

### Comprehensive Constitution
- Above, plus:
- Performance requirements
- Accessibility standards
- Deployment practices
- Monitoring/observability

**Start minimal, expand as needed.**

## Anti-Patterns

**Avoid:**
- Creating constitution too early (no patterns yet)
- Making it too restrictive (can't follow it)
- Copying from other projects (doesn't fit yours)
- Never updating it (becomes outdated)
- Not following it (then why have it?)

**Instead:**
- Wait for patterns to emerge
- Make it realistic and followable
- Extract from your own project
- Update as project evolves
- Enforce during spec validation

## Remember

**Constitution is living document.**

- Starts small, grows with project
- Reflects actual practices
- Updated as standards evolve
- Referenced regularly

**Constitution enables consistency.**

- Specs validated against it
- Reduces decision fatigue
- Onboards new developers
- Documents architectural decisions

**Constitution serves the project.**

- Not rigid rules set in stone
- Pragmatic guidelines
- Updated when they don't serve
- Exceptions documented

**Good constitution helps. Bad constitution hinders.**

Make yours helpful.