Implementation Checklist

Implementation Checklist

Create comprehensive, testable implementation plans that break complex features into manageable steps.

When to Use

• User asks to plan a feature implementation
• User wants to break down a large task
• User requests an implementation roadmap or checklist
• You identify a task that needs structured planning (3+ major components)

Structure

Overall Format

# [Feature Name] - Implementation Plan

## Overview
Brief description of the feature and its goals.

## Phases

### Phase 1: [Phase Name] (X steps)

#### Step X.Y: [Step Name]
Brief description of what this step accomplishes.

**Deliverables:**
- [ ] Specific file or component to create
- [ ] Another deliverable with concrete output
- [ ] Implementation details (specific functions, classes, etc.)

**Tests:**
- [ ] Specific test scenario to verify
- [ ] Another test scenario
- [ ] Edge cases to cover

**Success Criteria:** [Clear definition of done for this step]

---

Key Principles

1. Testable Steps

Every step should have:

• Concrete deliverables (files, classes, functions)
• Specific tests (not "add tests" but "test concurrent access", "test error handling for X")
• Clear success criteria (measurable, like "all tests pass" or "API returns expected response")

2. Small But Not Micro

• Too large: "Implement entire authentication system"
• Too small: "Add import statement for User class"
• Just right: "Implement JWT token validation with expiry checking"

Aim for steps that:

• Can be completed in one focused session
• Have clear input/output
• Can be tested independently when possible

3. Progressive Complexity

Order steps so that:

• Foundation pieces come first (data models, interfaces)
• Core logic comes next (business logic, algorithms)
• Integration comes after (platform-specific, UI)
• Polish comes last (documentation, samples, optimization)

4. Track Progress

As steps complete:

• Change [ ] to [x] for completed items
• Add implementation notes under completed steps
• Document test results (e.g., "✅ All 15 tests pass")
• Update success criteria with actual results

Template Sections

Deliverables Section

List specific, verifiable outputs:

**Deliverables:**
- [x] `UserRepository.kt` with CRUD operations
- [x] `UserRepositoryImpl.kt` implementing thread-safe storage
- [x] Error handling for network failures
- [x] Retry logic with exponential backoff
- [x] Connection pooling configuration

Tests Section

List specific test scenarios:

**Tests:**
- [x] Save user returns success for valid data
- [x] Save user returns error for duplicate email
- [x] Concurrent saves don't corrupt data
- [x] Network timeout triggers retry with backoff
- [x] Retry exhaustion returns final error
- [x] Connection pool limits concurrent requests

Success Criteria

Clear, measurable definition of done:

**Success Criteria:** ✅ Repository saves/loads users correctly, all 25 tests pass, thread-safe verified with 100 concurrent operations

Phases Organization

Organize into logical phases:

### Phase 1: Foundation (3 steps)
- Data models
- Storage interfaces
- Configuration

### Phase 2: Core Logic (4 steps)
- Business rules
- Validation
- State management
- Error handling

### Phase 3: Platform Integration (3 steps)
- Android implementation
- iOS implementation
- JVM implementation

### Phase 4: Polish (2 steps)
- Sample application
- Documentation

Example: Small Feature

# Email Validation - Implementation Plan

## Overview
Add comprehensive email validation with format checking and disposable email detection.

## Steps

### Step 1: Email Format Validator
Basic RFC-compliant email validation.

**Deliverables:**
- [ ] `EmailValidator.kt` with regex pattern matching
- [ ] Support for common TLDs and international characters
- [ ] Whitespace trimming and normalization

**Tests:**
- [ ] Valid emails pass (user@example.com)
- [ ] Invalid formats fail (no @, missing domain)
- [ ] Edge cases (unicode, subdomain, plus addressing)
- [ ] Performance (10000 validations < 100ms)

**Success Criteria:** Validates emails per RFC 5322, all tests pass

---

### Step 2: Disposable Email Detection
Block temporary/disposable email providers.

**Deliverables:**
- [ ] `DisposableEmailDetector.kt` with provider list
- [ ] 1000+ known disposable domains
- [ ] Efficient lookup (HashSet, O(1))

**Tests:**
- [ ] Known disposable domains detected (guerrillamail.com)
- [ ] Valid providers allowed (gmail.com, outlook.com)
- [ ] Case-insensitive matching
- [ ] Subdomain handling

**Success Criteria:** Detects disposable emails, lookup < 1ms

---

### Step 3: Integration
Combine validators into unified API.

**Deliverables:**
- [ ] `EmailValidationService` facade
- [ ] Combined validation (format + disposable)
- [ ] Clear error messages for each failure type

**Tests:**
- [ ] End-to-end validation flow
- [ ] Error message clarity
- [ ] Performance benchmarks

**Success Criteria:** Single validation API, all tests pass

Updating Plans

As you work:

1. Mark completed items: Change [ ] to [x]
2. Add implementation notes: Details about decisions made, gotchas encountered
3. Update success criteria: Add actual results (test counts, performance numbers)
4. Document deviations: Explain any changes from original plan

Example of completed step:

#### Step 1.1: Email Format Validator ✅ COMPLETE

**Deliverables:**
- [x] `EmailValidator.kt` with regex pattern matching
- [x] Support for common TLDs and international characters
- [x] Whitespace trimming and normalization
- [x] Implemented with Kotlin Regex (platform-agnostic)

**Implementation Notes:**
- Used RFC 5322 simplified pattern for KMP compatibility
- Added extension function `String.isValidEmail()` for convenience
- Normalization handles leading/trailing spaces and case

**Tests:**
- [x] 15 comprehensive tests in EmailValidatorTest
- [x] Valid email formats (50+ examples)
- [x] Invalid formats (30+ edge cases)
- [x] Unicode support verified
- [x] Performance: 10000 validations in 45ms

**Success Criteria:** ✅ Validates emails per RFC 5322, all 15 tests pass

Anti-Patterns

Vague Deliverables

❌ Bad: "Add authentication"
✅ Good: "Implement AuthService.kt with login(), logout(), and validateToken()"

Generic Tests

❌ Bad: "Add tests"
✅ Good: "Test login with valid credentials, invalid password, expired token"

Unclear Success

❌ Bad: "Authentication works"
✅ Good: "Users can login/logout, tokens expire after 1 hour, all 12 tests pass"

Tips

1. Start with overview: Brief feature description and goals
2. Break into phases: Group related steps (Foundation, Core, Integration, Polish)
3. Name phases clearly: Use descriptive names, not just "Phase 1"
4. Number steps: Use X.Y format (Phase.Step) for easy reference
5. Be specific: Concrete deliverables, not abstract concepts
6. Make testable: Every step should have verifiable tests
7. Update continuously: Mark progress, add notes, document deviations

Common Phase Patterns

Foundation Phase: Data models, interfaces, configuration
Core Logic Phase: Business rules, algorithms, state management
Platform Phase: Platform-specific implementations (Android, iOS, JVM)
Integration Phase: Wiring components together, orchestration
Sample Phase: Demo applications, examples
Documentation Phase: API docs, user guides, README
Polish Phase: Performance optimization, edge cases, final cleanup

Implementation Order Summary

At the end of the plan, include a summary section:

## Implementation Order Summary

**Total Steps: ~18-20**

1. **Phase 1 (Foundation)**: 3 steps - Core types, interfaces, storage
2. **Phase 2 (Business Logic)**: 5 steps - Throttling, sentiment, strategies
3. **Phase 3 (Platform)**: 3 steps - Android, iOS, JVM implementations
4. **Phase 4 (Manager)**: 2 steps - Manager, singleton factory
5. **Phase 5 (Sample App)**: 3 steps - Basic UI, advanced features, testing
6. **Phase 6 (Documentation)**: 2 steps - API docs, user guides
7. **Phase 7 (Integration)**: 1 step - Project setup, publishing

**Estimated Total:** ~20 well-defined, testable steps.

Each step is:
- ✅ Independently testable
- ✅ Builds on previous work
- ✅ Has clear deliverables and success criteria
- ✅ Small enough to complete in focused session
- ✅ Large enough to make meaningful progress

This summary provides:

• Quick overview of total scope
• Phase breakdown with step counts
• Phase descriptions (one-line summaries)
• Step characteristics (what makes them good steps)

Benefits:

• Helps stakeholders understand scope at a glance
• Shows logical progression through phases
• Demonstrates thoughtful step sizing
• Sets expectations for total effort

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