docs: update plans

plans/core-features-plan.md

@@ -31,13 +31,18 @@ interface ImageUploadProps {
 - URL fetch with CORS handling
 ```
 
-#### **2. Image Cropping Interface**
+#### **2. Image Cropping Interface** ✅ **COMPLETED**
 
 **Priority: HIGH**
 
-- **Cropper Integration**: Fixed 320px width constraint
-- **Crop Confirmation**: Accept/Cancel options
-- **Error Handling**: Invalid crop areas
+- **Cropper Integration**: Fixed 320px width constraint ✅
+- **Crop Confirmation**: Accept/Cancel options ✅
+- **Error Handling**: Invalid crop areas ✅
+
+**Implementation Details:**
+- Integrated cropperjs v2.1.0 with Web Components
+- Used `$toCanvas()` method to get HTMLCanvasElement
+- Implemented proper error handling with user-friendly messages
 
 **Key Components:**
 
@@ -180,10 +185,10 @@ Week 1: Foundation
 └── Basic project structure
 
 Week 2: Image System
-├── Image upload component
-├── Image cropping component
-├── Image validation utilities
-└── Image service layer
+├── Image upload component ✅
+├── Image cropping component ✅
+├── Image validation utilities ✅
+└── Image service layer ✅
 
 Week 3: Text System
 ├── Text management component
@@ -209,9 +214,11 @@ Week 5: UI & Polish
 ### **Dependencies to Install**
 
 ```bash
-npm install cropperjs file-saver @types/cropperjs
+npm install cropperjs@^2.1.0 file-saver @types/cropperjs@^1.1.5
 ```
 
+**Note:** Using cropperjs v2.1.0 with Web Components API. The `$toCanvas()` method is used to obtain HTMLCanvasElement from `<cropper-canvas>` component.
+
 ### **TypeScript Interfaces**
 
 ```typescript
@@ -341,3 +348,30 @@ export const handleImageError = (error: unknown): string => {
 _Created: 2026-02-03_
 _Focus: Core Features Implementation_
 _Estimated Duration: 5 weeks_
+
+## 📝 **Implementation Notes**
+
+### **Image Cropping Implementation (Completed)**
+
+**Challenge:** cropperjs v2.x uses Web Components API which differs significantly from v1.x
+
+**Solution:**
+1. Used `getCropperCanvas()` to get `<cropper-canvas>` Web Component
+2. Called `$toCanvas()` method to convert to HTMLCanvasElement
+3. Applied `toDataURL()` on the resulting canvas to get base64 image
+
+**Code Example:**
+```typescript
+const cropperCanvasElement = cropper.getCropperCanvas();
+const canvas = await cropperCanvasElement.$toCanvas({
+  width: 320,
+  imageSmoothingEnabled: true,
+  imageSmoothingQuality: "high",
+});
+const croppedImage = canvas.toDataURL("image/png");
+```
+
+**Key Points:**
+- cropperjs v2.x methods return Web Components, not standard DOM elements
+- `$toCanvas()` is an async method that returns HTMLCanvasElement
+- Proper error handling is essential for user experience