# ComfyUI Frontend V3 Compatibility - Implementation Summary

## Core Concept
**Import-based API versioning** with proxy-synchronized data layers. Extensions choose their API version through imports, getting typed interfaces and guaranteed backward compatibility.

## Architecture Overview

### 1. Version-Specific Imports
```typescript
// Legacy (unchanged)
import { app } from '@/scripts/app'

// Version-specific
import { app } from '@/scripts/app/v1'       // v1.x API
import { app } from '@/scripts/app/v1_2'     // v1.2 API
import { app } from '@/scripts/app/v3'       // v3.x API
import { app } from '@/scripts/app/latest'   // Latest

// Typed interfaces per version
app.registerExtension({
  beforeRegisterNodeDef(nodeType, nodeData: ComfyNodeDefV1_2, app: ComfyAppV1_2) {
    // nodeData guaranteed to be v1.2 format
  }
})
```

### 2. Dual Endpoint Data Fetching
```typescript
// Simultaneous fetching from multiple endpoints
const [currentData, v3Data] = await Promise.allSettled([
  api.get('/object_info'),      // Current format
  api.get('/v3/object_info')    // V3 format
])

// All versions stored and transformed
nodeDefinitions.value = {
  canonical: mergeToCanonical(currentData, v3Data),
  v1: transformToV1(currentData),
  v1_2: transformToV1_2(currentData),
  v3: v3Data || transformToV3(currentData)
}
```

### 3. Proxy-Based Synchronization
```typescript
// Bidirectional data sync through proxies
const createV1_2Proxy = (canonical: ComfyNodeDefLatest) => {
  return new Proxy({}, {
    get(target, prop) {
      return transformCanonicalToV1_2(canonical, prop)
    },
    set(target, prop, value) {
      transformV1_2ToCanonical(canonical, prop, value)
      notifyChange(canonical.name, prop, value)
      return true
    }
  })
}
```

## Implementation Structure

### Phase 1: API Infrastructure (3-4 days)
- **Entry Points**: `src/scripts/app/v1.ts`, `src/scripts/app/v1_2.ts`, etc.
- **Type Definitions**: `src/types/versions/` with version-specific interfaces
- **Adapters**: `src/scripts/app/adapters/` for API compatibility layers

### Phase 2: Data Layer (2-3 days)
- **Multi-Version Store**: Single store with all format versions
- **Transform Pipeline**: `src/utils/versionTransforms.ts` for format conversion
- **Reactive Getters**: Version-specific computed properties

### Phase 3: Proxy System (2-3 days)
- **Bidirectional Proxies**: `src/utils/versionProxies.ts`
- **Change Notification**: Event system for data sync
- **Type Safety**: Proper typing for proxy objects

### Phase 4: Extension Integration (2-3 days)
- **Version-Aware Service**: Extensions grouped by API version
- **Hook Invocation**: Transform args per version before calling
- **App Adapters**: Version-specific app instances

## Key Benefits

- **Type Safety**: Compile-time checking for each API version
- **Zero Breaking Changes**: Existing extensions work unchanged
- **Bidirectional Sync**: Changes through any API stay synchronized
- **Performance**: No runtime version detection overhead
- **Future Proof**: Easy to add new API versions
- **Developer Experience**: Clear, typed interfaces

## Migration Path

```typescript
// Step 1: No changes (works with latest)
import { app } from '@/scripts/app'

// Step 2: Explicit version (better compatibility)  
import { app } from '@/scripts/app/v1_2'

// Step 3: Use newer APIs when ready
import { app } from '@/scripts/app/latest'
```

## Example Usage

```typescript
// v1.2 Extension
import { app } from '@/scripts/app/v1_2'

app.registerExtension({
  name: 'MyExtension',
  beforeRegisterNodeDef(nodeType, nodeData: ComfyNodeDefV1_2, app) {
    // nodeData.input.required - v1 format
    // nodeData.inputs - v1.2 format
    if (nodeData.inputs) {
      // Use v1.2 features
    } else {
      // Fallback to v1 format
    }
  }
})
```

## Implementation Timeline
- **Phase 1**: API Version Infrastructure (3-4 days)
- **Phase 2**: Multi-Version Data Layer (2-3 days)  
- **Phase 3**: Proxy-Based Synchronization (2-3 days)
- **Phase 4**: Extension System Integration (2-3 days)
- **Phase 5**: Migration Tools & Documentation (1-2 days)

**Total**: 10-15 days

This approach provides type-safe API versioning that scales with ComfyUI's growth while maintaining complete backward compatibility and smooth migration paths for extension developers.