# After Effects MCP Batch Command Improvements
## Overview
This document describes the improvements made to the After Effects MCP batch command system, error handling, and testing infrastructure.
## Key Improvements
### 1. Enhanced Batch Execution System
The `batch_execute` command has been improved with:
- **Better validation**: Pre-execution validation of all commands
- **Detailed error reporting**: Each command failure includes context, parameters, and timing
- **Performance metrics**: Execution duration tracking for each command
- **Flexible execution modes**: Sequential or parallel execution
Example response:
```json
{
"total": 10,
"successful": 8,
"failed": 2,
"totalDuration": 1234,
"averageDuration": 123.4,
"executionMode": "parallel",
"results": [
{
"id": "set_keyframe_0",
"tool": "set_keyframe",
"success": true,
"result": { ... },
"duration": 120,
"index": 0
},
{
"id": "apply_easy_ease_1",
"tool": "apply_easy_ease",
"success": false,
"error": {
"message": "Property has no keyframes",
"code": "PROPERTY_ERROR",
"details": { ... }
},
"duration": 150,
"index": 1,
"params": { ... } // Included for debugging
}
]
}
```
### 2. Comprehensive Error Handling
#### Error Handler Module (`errorHandler.ts`)
- **AE Error Code Mapping**: Maps After Effects numeric error codes to meaningful strings
- **Context-Aware Errors**: Errors include command, parameters, and script context
- **Parameter Validation**: Pre-execution validation with clear error messages
- **Intelligent Error Classification**: Automatically categorizes errors based on message content
#### Error Codes
```typescript
AE_GENERAL_ERROR
AE_OUT_OF_MEMORY
AE_FILE_NOT_FOUND
AE_PROPERTY_NOT_FOUND
AE_KEYFRAME_INDEX_OUT_OF_RANGE
AE_NO_KEYFRAMES
// ... and many more
```
### 3. Fixed apply_easy_ease Implementation
The `apply_easy_ease` command now includes:
- **Better error messages**: Includes layer name, property path, and keyframe counts
- **Property validation**: Checks if property can be animated before attempting
- **Detailed failure info**: Reports exactly which keyframe failed and why
- **Success validation**: Ensures at least one keyframe was modified
### 4. ES3 Compatibility
All generated ExtendScript code is now ES3-compatible:
- ✅ No template literals (`${expression}`)
- ✅ No arrow functions
- ✅ No const/let declarations
- ✅ No destructuring
- ✅ Proper error handling with try-catch
### 5. Test Suite
Created comprehensive test suite (`ae-commands.test.ts`) that validates:
- **Parameter validation**: Tests required/optional parameters for all commands
- **ES3 compatibility**: Ensures generated scripts are ES3-compliant
- **Error formatting**: Validates error messages are properly formatted
- **Command coverage**: Tests key commands across all categories
Run tests with:
```bash
./test-commands.sh
```
## Usage Examples
### Batch Execution with Error Handling
```javascript
// Execute multiple commands with detailed error reporting
const result = await mcp.batch_execute({
commands: [
{
tool: "set_keyframe",
params: { compId: 1, layerIndex: 1, property: "Position", time: 0, value: [100, 100] }
},
{
tool: "apply_easy_ease",
params: { compId: 1, layerIndex: 1, propertyPath: "Transform.Position" }
}
],
sequential: false // Run in parallel for better performance
});
```
### Error Context Example
When an error occurs, you get detailed context:
```json
{
"message": "Property \"Transform.Scale\" has no keyframes. Layer: Background (1)",
"code": "PROPERTY_ERROR",
"context": {
"command": "apply_easy_ease",
"params": {
"compId": 1,
"layerIndex": 1,
"propertyPath": "Transform.Scale"
}
}
}
```
## Benefits
1. **Faster Debugging**: Detailed error messages pinpoint exact issues
2. **Better Performance**: Parallel batch execution for independent commands
3. **Improved Reliability**: Pre-execution validation catches errors early
4. **ES3 Compliance**: All scripts work with After Effects' ExtendScript engine
5. **Comprehensive Testing**: Automated tests ensure command reliability
## Migration Guide
The batch system is backward compatible, but to get the enhanced features:
1. Use `batch_execute` instead of command-specific batch endpoints
2. Check the `success` field in each result
3. Use the `error.code` field for programmatic error handling
4. Include command IDs for easier result tracking
## Future Improvements
Potential areas for further enhancement:
- Command dependency resolution for optimal execution order
- Automatic retry logic for transient failures
- Progress callbacks for long-running batch operations
- Command result caching for repeated operations
