# TASK_1: Core Macro Engine Implementation
**Created By**: Agent_1 | **Priority**: HIGH | **Duration**: 4 hours
**Technique Focus**: Design by Contract + Type Safety + Defensive Programming
**Size Constraint**: Target <250 lines/module, Max 400 if splitting awkward
## š¦ Status & Assignment
**Status**: COMPLETED
**Assigned**: Agent_1
**Dependencies**: None
**Blocking**: TASK_2, TASK_3, TASK_4
## š Required Reading (Complete before starting)
- [x] **development/protocols/KM_MCP.md**: Keyboard Maestro protocol specifications
- [x] **development/protocols/FASTMCP_PYTHON_PROTOCOL.md**: MCP implementation guidelines
- [x] **CLAUDE.md**: ADDER+ technique requirements and standards
## šÆ Implementation Overview
Create the foundational macro execution engine with type-safe command processing, contract-based validation, and defensive error handling.
<thinking>
Core engine architecture decisions:
1. Command Pattern: Encapsulate macro operations as objects
2. Type Safety: Strong typing for all macro operations and parameters
3. Contracts: Pre/post conditions for execution safety
4. Error Boundaries: Comprehensive error handling and recovery
5. Execution Context: Secure, isolated execution environment
</thinking>
## ā
Implementation Subtasks (Sequential completion)
### Phase 1: Foundation & Architecture
- [x] **Type definitions**: Create branded types for MacroId, CommandId, ExecutionContext
- [x] **Contract interfaces**: Define protocols for macro execution with pre/post conditions
- [x] **Error hierarchy**: Implement comprehensive error types for macro operations
- [x] **Execution context**: Secure context management for macro operations
### Phase 2: Core Engine Implementation
- [x] **Command parser**: Parse macro definitions with type validation
- [x] **Execution engine**: Core macro execution with contract enforcement
- [x] **State management**: Track execution state with immutable patterns
- [x] **Security boundaries**: Input validation and execution sandboxing
### Phase 3: Integration & Testing
- [x] **TESTING.md setup**: Initialize test tracking for core engine
- [x] **Property tests**: Implement property-based testing for execution safety
- [x] **Performance validation**: Ensure execution meets timing requirements
- [x] **Documentation**: Create ABOUT.md for engine architecture
## š§ Implementation Files & Specifications
### Core Files to Create:
```
src/
āāā core/
ā āāā __init__.py # Public API exports
ā āāā types.py # Branded types and protocols (50-75 lines)
ā āāā contracts.py # Design by Contract decorators (75-100 lines)
ā āāā engine.py # Main execution engine (150-200 lines)
ā āāā parser.py # Command parsing logic (100-150 lines)
ā āāā context.py # Execution context management (75-100 lines)
ā āāā errors.py # Error hierarchy and handling (50-75 lines)
āāā tests/
āāā TESTING.md # Live test status tracking
āāā test_core/
āāā test_engine.py # Core engine tests
āāā test_parser.py # Parser validation tests
āāā test_contracts.py # Contract verification tests
```
### Key Implementation Requirements:
#### types.py - Branded Types & Protocols
```python
from typing import NewType, Protocol, TypeVar, Generic
from dataclasses import dataclass
from enum import Enum
MacroId = NewType('MacroId', str)
CommandId = NewType('CommandId', str)
ExecutionToken = NewType('ExecutionToken', str)
class ExecutionStatus(Enum):
PENDING = "pending"
RUNNING = "running"
COMPLETED = "completed"
FAILED = "failed"
CANCELLED = "cancelled"
class MacroCommand(Protocol):
def execute(self, context: 'ExecutionContext') -> 'CommandResult': ...
def validate(self) -> bool: ...
def get_dependencies(self) -> list[CommandId]: ...
```
#### contracts.py - Design by Contract
```python
from functools import wraps
from typing import Callable, Any
from .errors import ContractViolationError
def require(condition: Callable[..., bool], message: str = "Precondition failed"):
"""Precondition contract decorator."""
def ensure(condition: Callable[..., bool], message: str = "Postcondition failed"):
"""Postcondition contract decorator."""
def invariant(condition: Callable[..., bool], message: str = "Invariant violated"):
"""Class invariant decorator."""
```
#### engine.py - Core Execution Engine
```python
@dataclass(frozen=True)
class MacroEngine:
"""Type-safe macro execution engine with contract enforcement."""
@require(lambda self, macro: macro.is_valid())
@ensure(lambda result: result.execution_token is not None)
def execute_macro(self, macro: MacroDefinition) -> ExecutionResult:
"""Execute macro with comprehensive safety checks."""
@require(lambda self, token: token.is_valid())
def get_execution_status(self, token: ExecutionToken) -> ExecutionStatus:
"""Retrieve current execution status."""
```
## šļø Modularity Strategy
- **types.py**: Core type definitions and protocols (target: 75 lines)
- **contracts.py**: Contract enforcement decorators (target: 100 lines)
- **engine.py**: Main execution logic (target: 200 lines, max 250)
- **parser.py**: Command parsing and validation (target: 150 lines)
- **context.py**: Execution context management (target: 100 lines)
- **errors.py**: Error types and handling (target: 75 lines)
## ā
Success Criteria
- Type-safe macro execution with comprehensive validation
- All advanced techniques implemented (contracts, defensive programming, typed interfaces)
- TESTING.md established with initial test suite
- Performance: Macro execution < 100ms for simple commands
- Security: Input validation prevents code injection
- Documentation: ABOUT.md created explaining engine architecture
- Modularity: All files within size constraints
- Zero regressions: All tests passing before task completion
