# Quality Criteria and Acceptance Standards

## Overview

This document defines the quality gates and acceptance criteria that must be met before code can be merged and released.

---

## 1. Code Quality Metrics

### 1.1 Code Coverage

**Minimum Thresholds**:
```json
{
  "statements": 85,
  "branches": 80,
  "functions": 85,
  "lines": 85
}
```

**Coverage by Component**:
| Component | Minimum Coverage |
|-----------|------------------|
| Chess Engine (rules) | 95% |
| Game State Manager | 90% |
| UI Components | 80% |
| Utilities | 85% |
| Event Handlers | 80% |

**Exclusions**:
- Configuration files
- Type definitions
- Constants files
- Third-party integrations

---

### 1.2 Code Complexity

**Cyclomatic Complexity**:
- Maximum per function: 10
- Maximum per file: 50
- Warning threshold: 7

**Cognitive Complexity**:
- Maximum per function: 15
- Recommend refactoring above: 10

**File Size Limits**:
- Maximum lines per file: 500
- Warning threshold: 300
- Test files: 1000 (allowed for comprehensive test suites)

---

### 1.3 Code Style

**Linting**:
- ESLint: Zero errors
- Warnings: Max 5 per 1000 lines
- Disabled rules: None (all rules enforced)

**Formatting**:
- Prettier: 100% formatted
- Line length: 100 characters
- Indentation: 2 spaces
- Trailing commas: Required
- Semicolons: Required

**TypeScript** (if applicable):
- Strict mode: Enabled
- No implicit any: Enforced
- Type coverage: >90%

---

## 2. Performance Criteria

### 2.1 Load Time Performance

**Initial Page Load**:
- Time to First Byte (TTFB): <300ms
- First Contentful Paint (FCP): <1.5s
- Largest Contentful Paint (LCP): <2.5s
- Time to Interactive (TTI): <3.5s
- Cumulative Layout Shift (CLS): <0.1

**Bundle Size**:
- Main bundle (gzipped): <150KB
- JavaScript total: <250KB
- CSS total: <30KB
- Images: WebP format, <500KB total

---

### 2.2 Runtime Performance

**Move Calculation**:
- Legal move generation: <100ms
- Check detection: <50ms
- Checkmate detection: <200ms
- Complex positions (30+ pieces): <150ms

**UI Rendering**:
- Frame rate during animations: 60 FPS (16.67ms per frame)
- UI update after move: <16ms
- Board rotation animation: <500ms
- Piece drag responsiveness: <10ms

**Memory Usage**:
- Initial memory: <20MB
- Peak during gameplay: <50MB
- Memory leak tolerance: 0 (no leaks allowed)
- Garbage collection frequency: <1 per minute

---

### 2.3 Network Performance

**Offline Functionality**:
- Full game playable offline: Required
- Service Worker: Implemented
- Cache strategy: Cache-first for static assets

**Data Transfer** (if applicable):
- API response time: <200ms
- WebSocket latency: <50ms
- Compressed responses: Required

---

## 3. Functional Criteria

### 3.1 Chess Rules Compliance

**Core Rules**:
- All piece movements: 100% accurate
- Castling rules: Fully compliant
- En passant: Correctly implemented
- Pawn promotion: All pieces supported
- Check/Checkmate: Correctly detected
- Stalemate: Correctly detected

**Advanced Rules**:
- Fifty-move rule: Implemented
- Threefold repetition: Detected
- Insufficient material: Detected
- Dead position: Detected

**FIDE Compliance**:
- Laws of Chess conformance: 100%
- Standard algebraic notation (SAN): Supported
- Portable Game Notation (PGN): Import/export

---

### 3.2 User Experience

**Interaction**:
- Drag-and-drop: Smooth, no lag
- Click-to-move: Responsive
- Move validation feedback: Immediate (<100ms)
- Error messages: Clear, actionable

**Visual Feedback**:
- Valid moves highlighted: Required
- Check indication: Visual + auditory
- Last move highlight: Required
- Captured pieces display: Recommended

**Responsive Design**:
- Mobile (320px-767px): Fully functional
- Tablet (768px-1023px): Optimized layout
- Desktop (1024px+): Enhanced features
- Touch targets: Minimum 44x44px

---

## 4. Accessibility Standards

### 4.1 WCAG 2.1 Level AA Compliance

**Perceivable**:
- Color contrast: Minimum 4.5:1 (normal text), 3:1 (large text)
- Non-color indicators: Required for all states
- Alt text: All images and icons
- Captions: For any video/audio content

**Operable**:
- Keyboard navigation: 100% functionality
- No keyboard traps: Required
- Focus visible: Clear indicators
- Time limits: Adjustable or disabled

**Understandable**:
- Language attribute: Set correctly
- Consistent navigation: Required
- Error identification: Clear messages
- Labels/instructions: All inputs

**Robust**:
- Valid HTML: W3C compliant
- ARIA attributes: Correctly used
- Compatible assistive tech: Screen readers, voice control

---

### 4.2 Keyboard Accessibility

**Required Controls**:
- Tab: Navigate between elements
- Arrow keys: Navigate board
- Enter/Space: Select and move pieces
- Escape: Cancel selection
- Numbers: Quick piece selection (optional)

**Focus Management**:
- Visible focus indicator: Required
- Logical tab order: Enforced
- Skip links: Provided
- Focus trapping in modals: Implemented

---

### 4.3 Screen Reader Support

**Announcements**:
- Move notifications: "White pawn e2 to e4"
- Game state: "White in check"
- Captured pieces: "Black knight captured"
- Game end: "Checkmate. Black wins."

**Labels**:
- All interactive elements: Labeled
- Board squares: Descriptive (e.g., "e4, white square, empty")
- Pieces: "White pawn on e2"

---

## 5. Browser Compatibility

### 5.1 Desktop Browsers

**Fully Supported**:
- Chrome 100+ (latest, -1, -2 versions)
- Firefox 100+ (latest, -1)
- Safari 15+ (latest, -1)
- Edge 100+ (latest)

**Graceful Degradation**:
- Chrome 90-99: Core features
- Firefox 90-99: Core features
- Safari 14: Core features

**Not Supported**:
- Internet Explorer: Not supported
- Opera Mini: Not supported

---

### 5.2 Mobile Browsers

**Fully Supported**:
- iOS Safari 15+ (iPhone, iPad)
- Chrome Android 100+
- Samsung Internet 15+

**Touch Optimization**:
- Touch targets: Minimum 44x44px
- Gestures: Intuitive and documented
- Orientation: Both portrait and landscape

---

## 6. Security Criteria

### 6.1 Input Validation

**Client-Side**:
- All user input: Sanitized
- Move validation: Server-side (if multiplayer)
- XSS prevention: Required
- CSRF protection: Implemented (if applicable)

**Data Storage**:
- LocalStorage: Only non-sensitive data
- No credentials in localStorage: Enforced
- Encrypted storage: For sensitive data (if any)

---

### 6.2 Dependency Security

**Vulnerability Scanning**:
- npm audit: Zero high/critical vulnerabilities
- Snyk/Dependabot: Enabled
- Automated updates: Security patches

**Allowed Severity**:
- Critical: 0
- High: 0
- Medium: <3
- Low: <10

---

## 7. Testing Criteria

### 7.1 Test Coverage

**Test Types Distribution**:
- Unit tests: 70% of test suite
- Integration tests: 20% of test suite
- E2E tests: 10% of test suite

**Test Quality**:
- Flaky tests: 0 (must be fixed immediately)
- Test execution time: <2 minutes (all tests)
- Test isolation: 100% (no dependencies)

---

### 7.2 Test Execution

**Pre-Commit**:
- Unit tests: 100% pass rate
- Linting: Zero errors
- Type checking: Zero errors

**Pre-Merge**:
- All tests: 100% pass rate
- Coverage check: Pass
- E2E smoke tests: Pass

**Pre-Release**:
- Full E2E suite: 100% pass
- Cross-browser tests: Pass
- Accessibility audit: Pass
- Performance audit: Pass

---

## 8. Documentation Criteria

### 8.1 Code Documentation

**Comments**:
- Complex logic: Explained
- Public APIs: JSDoc documented
- Algorithms: Referenced (e.g., "Using minimax algorithm")

**README**:
- Setup instructions: Complete
- Running tests: Documented
- Build process: Clear
- Deployment: Detailed

---

### 8.2 User Documentation

**In-App Help**:
- Rules of chess: Accessible
- How to play: Interactive tutorial
- Keyboard shortcuts: Listed

**External Docs**:
- User guide: Provided
- FAQ: Maintained
- Changelog: Updated

---

## 9. Deployment Criteria

### 9.1 Pre-Deployment Checklist

- [ ] All tests pass (unit, integration, E2E)
- [ ] Code coverage meets thresholds
- [ ] Performance budgets met
- [ ] Accessibility audit passed
- [ ] Security scan clean
- [ ] Browser compatibility verified
- [ ] Documentation updated
- [ ] Changelog updated
- [ ] Release notes prepared

---

### 9.2 Deployment Process

**Staging Environment**:
- Deploy to staging first
- Manual QA testing
- Stakeholder approval
- Soak test: 24 hours minimum

**Production Deployment**:
- Blue-green deployment
- Canary release: 5% traffic initially
- Monitor error rates
- Rollback plan: Ready

---

## 10. Monitoring and Alerts

### 10.1 Production Metrics

**Error Tracking**:
- JavaScript errors: <0.1% of sessions
- Failed API calls: <1%
- Browser compatibility issues: <0.5%

**Performance Monitoring**:
- LCP degradation: Alert if >2.5s
- CLS increase: Alert if >0.1
- TTI slowdown: Alert if >4s

**User Experience**:
- Average game duration: Tracked
- Move frequency: Monitored
- Abandonment rate: <10%

---

## 11. Success Metrics

### 11.1 Quality Score

**Weighted Quality Score** (0-100):
- Code coverage: 20 points
- Performance: 20 points
- Accessibility: 15 points
- Browser compatibility: 15 points
- Security: 15 points
- Test quality: 15 points

**Minimum Acceptable Score**: 85/100

---

### 11.2 Release Readiness

**Definition of Done**:
1. Quality score ≥85
2. All critical bugs fixed
3. All acceptance tests passed
4. Documentation complete
5. Security scan passed
6. Performance benchmarks met
7. Accessibility audit passed
8. Stakeholder sign-off obtained

**Go/No-Go Decision**:
- Any criterion failed: No-go
- All criteria met: Approved for release
- Exceptions: Require VP approval

---

## 12. Continuous Improvement

### 12.1 Retrospective Metrics

**Track Over Time**:
- Test coverage trends
- Performance trends
- Bug escape rate
- Time to fix defects

**Quality Improvement**:
- Quarterly review of thresholds
- Adjust based on team capability
- Benchmark against industry standards

---

## Appendix: Calculation Examples

### Code Coverage Score
```
Coverage = (Statements + Branches + Functions + Lines) / 4
Example: (88 + 82 + 90 + 87) / 4 = 86.75%
```

### Performance Score
```
Score = 100 - (LCP_penalty + CLS_penalty + TTI_penalty)
LCP_penalty = max(0, (LCP - 2.5) * 20)
Example: LCP=2.2s, CLS=0.05, TTI=3.0s → Score = 95
```

### Quality Gate Pass/Fail
```python
def quality_gate_passed(metrics):
    return (
        metrics.coverage >= 85 and
        metrics.performance_score >= 80 and
        metrics.accessibility_score >= 90 and
        metrics.security_vulnerabilities == 0 and
        metrics.critical_bugs == 0
    )
```