# Story 6.4: Create Prompt Engineering System

## Story Information
- **Epic/Task**: Task 6 - Develop AI Integration Layer
- **Story Number**: 6.4
- **Title**: Create Prompt Engineering System
- **Status**: Ready
- **Complexity**: Medium
- **Priority**: Medium
- **Dependencies**: Tasks 6.1, 6.3 (6.1 completed, 6.3 draft)

## Story Statement
As the Directus Task Management system, I need a sophisticated prompt engineering system that manages prompt templates, optimizes prompts for different AI models, enables dynamic prompt composition, and provides A/B testing capabilities so that AI interactions are consistent, effective, and continuously improving.

## Acceptance Criteria
1. [ ] Prompt template system supports variables and conditional logic
2. [ ] Template versioning tracks changes and performance metrics
3. [ ] Dynamic prompt composition handles complex multi-part prompts
4. [ ] Model-specific optimization for GPT-4, Claude, and other models
5. [ ] A/B testing framework measures prompt effectiveness
6. [ ] Prompt library includes 20+ pre-built templates for common tasks
7. [ ] Template validation ensures proper structure and syntax
8. [ ] Performance metrics track token usage and response quality
9. [ ] Template inheritance enables prompt composition and reuse
10. [ ] Unit tests achieve 80% coverage for prompt components

## Dev Notes

### Architecture Context References
- **[Source: Story 6.1]** - OpenAI and LangChain integration established
- **[Source: Story 6.3]** - Context management provides dynamic data
- **[Source: architecture.md#AI Integration]** - Prompt requirements

### Previous Story Insights
- GPT-4-turbo configuration in place
- LangChain prompt templates partially implemented
- Token tracking helps optimize prompt length
- Caching can store successful prompt patterns

### Prompt Engineering Architecture

**System Components**:
```typescript
interface PromptEngineeringSystem {
  // Template management
  templateRegistry: TemplateRegistryService;
  templateEngine: TemplateEngineService;
  
  // Optimization
  promptOptimizer: PromptOptimizationService;
  modelAdapter: ModelSpecificAdapterService;
  
  // Testing and metrics
  abTestingEngine: ABTestingService;
  metricsCollector: PromptMetricsService;
  
  // Composition
  promptComposer: DynamicComposerService;
  chainBuilder: PromptChainBuilderService;
}
```

**Template Categories**:
- Task Creation Templates
- Query Resolution Templates
- Summarization Templates
- Classification Templates
- Extraction Templates
- Conversation Templates

### File Locations
- **Prompt Services**: `src/services/prompts/` - Prompt engineering services
- **Templates**: `src/services/prompts/templates/` - Template definitions
- **Optimizers**: `src/services/prompts/optimizers/` - Optimization logic
- **Tests**: `tests/services/prompts/` - Prompt service tests

## Tasks / Subtasks

### Task 1: Set up Prompt Engineering Infrastructure (AC: 1)
- [ ] Create `src/services/prompts/prompt-engineering.service.ts`
- [ ] Define prompt interfaces and types
- [ ] Set up template configuration system
- [ ] Implement base template parser
- [ ] Add prompt validation utilities

### Task 2: Build Template Registry System (AC: 1, 6, 9)
- [ ] Create `src/services/prompts/template-registry.service.ts`
- [ ] Implement template storage and retrieval
- [ ] Add template categorization
- [ ] Create template inheritance system
- [ ] Build template search functionality

### Task 3: Implement Template Engine (AC: 1, 3, 7)
- [ ] Create `src/services/prompts/template-engine.service.ts`
- [ ] Add variable substitution system
- [ ] Implement conditional logic processing
- [ ] Create template composition functions
- [ ] Add template validation and sanitization

### Task 4: Develop Model-Specific Optimizers (AC: 4)
- [ ] Create `src/services/prompts/optimizers/gpt-optimizer.service.ts`
- [ ] Create `src/services/prompts/optimizers/claude-optimizer.service.ts`
- [ ] Implement token optimization strategies
- [ ] Add model-specific formatting
- [ ] Create fallback mechanisms

### Task 5: Build Dynamic Prompt Composer (AC: 3)
- [ ] Create `src/services/prompts/composers/dynamic-composer.service.ts`
- [ ] Implement multi-part prompt assembly
- [ ] Add context injection system
- [ ] Create prompt chaining logic
- [ ] Implement priority-based composition

### Task 6: Create Pre-built Template Library (AC: 6)
- [ ] Create task creation templates
- [ ] Add summarization templates
- [ ] Build classification templates
- [ ] Create extraction templates
- [ ] Implement conversation templates

### Task 7: Implement Template Versioning (AC: 2)
- [ ] Create `src/services/prompts/versioning/template-version.service.ts`
- [ ] Add version tracking system
- [ ] Implement rollback functionality
- [ ] Create performance tracking per version
- [ ] Add migration utilities

### Task 8: Build A/B Testing Framework (AC: 5)
- [ ] Create `src/services/prompts/testing/ab-testing.service.ts`
- [ ] Implement test configuration system
- [ ] Add result collection and analysis
- [ ] Create statistical significance testing
- [ ] Build automated winner selection

### Task 9: Implement Metrics Collection (AC: 8)
- [ ] Create `src/services/prompts/metrics/prompt-metrics.service.ts`
- [ ] Track token usage per template
- [ ] Measure response quality scores
- [ ] Add latency tracking
- [ ] Create cost analysis tools

### Task 10: Create API Endpoints
- [ ] Add GET `/api/prompts/templates`
- [ ] Add POST `/api/prompts/generate`
- [ ] Add PUT `/api/prompts/templates/:id`
- [ ] Add POST `/api/prompts/test`
- [ ] Implement proper validation

### Task 11: Write Tests (AC: 10)
- [ ] Create unit tests for template engine
- [ ] Add tests for prompt optimizers
- [ ] Test A/B testing framework
- [ ] Validate template library
- [ ] Achieve 80% coverage

### Task 12: Documentation
- [ ] Create prompt engineering guide
- [ ] Document template syntax
- [ ] Add optimization best practices
- [ ] Create template examples
- [ ] Write troubleshooting guide

## Dev Agent Record
*To be filled by implementing agent*

### File List
**Created:**
- 

**Modified:**
- 

---
*Story created by: Bob (Scrum Master)
Date: 2025-08-12*