# Execution API - Complete Implementation Summary

## Overview

Successfully refactored the Execution API with:
- ✅ Unified request/response schema
- ✅ Service layer separation  
- ✅ Multiple catalog lookup strategies
- ✅ Full backward compatibility
- ✅ MCP-ready architecture

## Implementation Changes

### 1. Schema Unification (`schema.py`)

**ExecutionRequest** - Single unified input schema:
```python
{
    # Multiple lookup strategies (at least one required)
    "catalog_id": "cat_123",       # Direct catalog lookup
    "path": "examples/weather",    # Path-based lookup
    "playbook_id": "...",          # Legacy (normalized to path)
    "version": "v1.0.0",           # Version (default: "latest")
    
    # MCP-compatible execution type
    "type": "playbook",            # playbook, tool, model, workflow
    
    # Flexible parameter naming (aliases supported)
    "parameters": {...},           # Also accepts "input_payload"
    
    # Context (nested or flat)
    "context": {...}               # OR flat fields
}
```

**ExecutionResponse** - Backward compatible output:
```python
{
    # Dual field names for compatibility
    "execution_id": "exec_123",
    "id": "exec_123",              # ← Old name (same value)
    
    "type": "playbook",
    "execution_type": "playbook",  # ← Old name (same value)
    
    "timestamp": "2025-...",
    "start_time": "2025-...",      # ← Old name (same value)
    
    # Complete metadata
    "catalog_id": "cat_456",
    "path": "examples/weather",
    "playbook_id": "examples/weather",
    "playbook_name": "weather",
    "version": "v1.0.0",
    "status": "running",
    "progress": 0,
    "result": {...}
}
```

### 2. Service Layer (`service.py`)

**ExecutionService** class handles all business logic:

```python
class ExecutionService:
    @staticmethod
    async def resolve_catalog_entry(request):
        """
        Priority-based catalog lookup:
        1. catalog_id → Direct SELECT by ID
        2. path + version → SELECT by path and version
        3. path + "latest" → SELECT latest by path
        """
        
    @staticmethod
    async def execute(request):
        """
        Complete execution flow:
        1. Resolve catalog entry
        2. Execute via broker
        3. Persist workload
        4. Return response
        """
        
    @staticmethod
    async def persist_workload(execution_id, parameters):
        """Non-blocking workload persistence"""
```

### 3. Unified Endpoints (`endpoint.py`)

Both endpoints now use identical logic:

```python
@router.post("/executions/run")
async def execute_playbook(payload: ExecutionRequest):
    return await execute_request(payload)

@router.post("/execute")
async def execute_playbook_by_path_version(payload: ExecutionRequest):
    return await execute_request(payload)
```

## Catalog Lookup Strategies

### Strategy 1: catalog_id (Priority 1)

**Query:**
```sql
SELECT catalog_id, path, version, content
FROM noetl.catalog
WHERE catalog_id = %s
```

**Use Case:** Direct entry lookup when you know the exact catalog ID

### Strategy 2: path + version (Priority 2)

**Query:**
```sql
SELECT catalog_id, content
FROM noetl.catalog
WHERE path = %s AND version = %s
```

**Use Case:** Version-controlled execution with explicit version

### Strategy 3: path + "latest" (Priority 3)

**Query:**
```sql
SELECT catalog_id, version, content
FROM noetl.catalog
WHERE path = %s
ORDER BY created_at DESC
LIMIT 1
```

**Use Case:** Get latest version for a path

### Strategy 4: playbook_id (Legacy)

**Normalized to:** `path = playbook_id`, `version = "latest"`

**Use Case:** Backward compatibility with existing CLI and clients

## Backward Compatibility

### Response Field Mapping

| New Field | Old Field | Status |
|-----------|-----------|--------|
| `execution_id` | `id` | Both included |
| `type` | `execution_type` | Both included |
| `timestamp` | `start_time` | Both included |

### CLI Compatibility

**Old CLI code (unchanged):**
```python
exec_id = data.get("id") or data.get("execution_id")
```

**Result:** ✅ Works! Both fields present in response.

### Request Compatibility

All these formats work:

```python
# Legacy
{"playbook_id": "path", "parameters": {...}}

# Modern path-based
{"path": "path", "version": "v1.0.0", "parameters": {...}}

# Direct catalog
{"catalog_id": "cat_123", "parameters": {...}}
```

## MCP Compatibility

### Current: Playbook Execution

```json
{
    "path": "playbooks/pipeline",
    "version": "v2.0.0",
    "type": "playbook",
    "parameters": {...}
}
```

### Future: Tool Execution

```json
{
    "tool_name": "validator",
    "type": "tool",
    "arguments": {...}
}
```

Auto-normalized to:
```json
{
    "path": "tools/validator",
    "type": "tool",
    "parameters": {...}
}
```

### Future: Model Execution

```json
{
    "model_name": "sentiment",
    "type": "model",
    "inputs": {...},
    "inference_config": {...}
}
```

Auto-normalized to:
```json
{
    "path": "models/sentiment",
    "type": "model",
    "parameters": {...},
    "metadata": {"inference_config": {...}}
}
```

## Error Handling

### Validation Errors (400)

```json
{
    "detail": "At least one identifier must be provided: catalog_id, path, or playbook_id"
}
```

### Not Found Errors (404)

```json
{
    "detail": "Catalog entry 'path' with version 'v1.0.0' not found"
}
```

### Server Errors (500)

```json
{
    "detail": "Error fetching from catalog: <details>"
}
```

## File Structure

```
noetl/api/routers/execution/
├── __init__.py          # Exports router, schema, service
├── schema.py            # Pydantic models (unified request/response)
├── service.py           # Business logic (catalog lookup, execution)
└── endpoint.py          # FastAPI routes (thin routing layer)

docs/
├── execution_api_unified.md              # Architecture documentation
├── execution_api_backward_compatibility.md  # Compatibility guide
└── execution_api_schema.md               # Original schema docs

tests/api/
└── test_execution_backward_compatibility.py  # Compatibility tests
```

## Benefits

### ✅ Unified Interface
- Both endpoints use same schema and logic
- No code duplication
- Consistent behavior

### ✅ Multiple Lookup Strategies
- catalog_id for direct lookup
- path+version for version control
- playbook_id for legacy support
- Automatic fallback to "latest"

### ✅ Service Layer Separation
- Business logic isolated from routing
- Easy to test and maintain
- Reusable across endpoints

### ✅ Backward Compatible
- Old field names included in responses
- Legacy request formats supported
- Existing clients work without changes

### ✅ MCP Ready
- Generic `type` field for execution types
- Extensible for tools and models
- ToolExecutionRequest and ModelExecutionRequest included

### ✅ Discoverable
- catalog_id enables direct entry lookup
- Path-based browsing supported
- Version history accessible

## Testing

### Run Compatibility Test

```bash
python3 tests/api/test_execution_backward_compatibility.py
```

### Test Legacy CLI Format

```bash
noetl execute playbook "examples/weather" \
  --host localhost --port 8083 \
  --payload '{"city": "NYC"}' \
  --merge --json
```

### Test Modern Format

```bash
curl -X POST http://localhost:8083/api/executions/run \
  -H "Content-Type: application/json" \
  -d '{
    "path": "examples/weather",
    "version": "v1.0.0",
    "type": "playbook",
    "parameters": {"city": "NYC"}
  }'
```

### Test Catalog ID Format

```bash
curl -X POST http://localhost:8083/api/execute \
  -H "Content-Type: application/json" \
  -d '{
    "catalog_id": "cat_1234567890",
    "parameters": {"city": "NYC"}
  }'
```

## Migration Guide

### For Existing Clients

**No changes required!** Old format continues to work:

```python
# Old format still works
{
    "playbook_id": "examples/weather",
    "parameters": {"city": "NYC"}
}
```

### For New Clients

**Use modern format for better control:**

```python
# New format with explicit version
{
    "path": "examples/weather",
    "version": "v1.0.0",
    "type": "playbook",
    "parameters": {"city": "NYC"}
}
```

### For Direct Catalog Access

**When you know the catalog_id:**

```python
# Fastest lookup (no path resolution)
{
    "catalog_id": "cat_1234567890",
    "parameters": {"city": "NYC"}
}
```

## Next Steps

### Phase 1: Current ✅
- Unified schema implemented
- Service layer created
- Backward compatibility maintained
- Documentation complete

### Phase 2: Testing
- Integration tests with real server
- Load testing with multiple lookup strategies
- Performance comparison between strategies

### Phase 3: MCP Integration
- Implement tool execution
- Implement model execution
- Add MCP protocol support

### Phase 4: Optimization
- Cache catalog lookups
- Optimize version resolution
- Add batch execution support

## Conclusion

The Execution API has been successfully refactored with:
- **Unified architecture** for consistent behavior
- **Multiple lookup strategies** for flexibility
- **Service layer separation** for maintainability
- **Full backward compatibility** for existing clients
- **MCP readiness** for future extensibility

All changes maintain 100% backward compatibility while providing a modern, extensible foundation for future features. The CLI and existing clients continue to work without any modifications.
