docker

Reviewed-on: #12

DOCKER_BUILD_FIX.md

@@ -1,167 +0,0 @@
-# Docker Build Fix - Simplified Dependency Installation
-
-## Issue
-Docker build was failing with:
-```
-npm error The `npm ci` command can only install with an existing package-lock.json
-```
-
-## Root Cause
-The original Dockerfile used `npm ci` which requires fully resolved `package-lock.json` files. These lockfiles were missing and stub lockfiles don't work because `npm ci` requires the complete dependency tree.
-
-## Solution Applied
-
-### Simplified Approach
-The Dockerfile now uses **`npm install`** instead of `npm ci`. This is simpler and more reliable:
-
-```dockerfile
-RUN npm install
-```
-
-**Why this works:**
-- ✅ No lockfile required
-- ✅ Automatically resolves and installs all dependencies
-- ✅ Works consistently across all environments
-- ✅ No manual lockfile maintenance needed
-- ✅ Simpler Dockerfile = easier to maintain
-
-### Trade-offs
-
-| Approach | Speed | Lockfile Required | Deterministic | Maintenance |
-|----------|-------|-------------------|---------------|-------------|
-| `npm ci` | Fastest | ✅ Yes | ✅ Yes | High |
-| **`npm install`** | Fast | ❌ No | ⚠️ By version ranges | **Low** |
-
-**Note:** While `npm install` resolves versions at build time (not 100% deterministic), your `package.json` uses caret ranges (e.g., `^4.19.0`) which only allow minor/patch updates, providing reasonable stability.
-
-### Files Modified
-
-1. **Dockerfile** - Simplified to use `npm install` in all three stages
-2. **.dockerignore** - Optimizes build context
-3. **backend/package.json** - Updated multer to v2.1.0 (v1.4.5 no longer exists)
-
-### Dependency Updates
-
-- **multer**: `^1.4.5` → `^2.1.0` (security fixes, v1.x removed from npm)
-- **@types/multer**: `^1.4.7` → `^2.1.0` (matching types)
-
-## How It Works
-
-### Build Flow
-
-1. **Copy package.json** into build stage
-2. **Run npm install** - automatically resolves and installs all dependencies
-3. **Build the application**
-
-No lockfile generation or validation needed!
-
-## Usage
-
-### Build Docker Image
-```bash
-docker build -t pnger:latest .
-```
-
-The build will:
-- Install dependencies from npm registry
-- Build frontend and backend
-- Create production image with only runtime dependencies
-- Complete successfully every time
-
-### Run Container
-```bash
-docker run -d \
-  -p 3000:3000 \
-  -e MAX_FILE_SIZE=10485760 \
-  --name pnger \
-  pnger:latest
-```
-
-### Unraid Deployment
-The Docker image builds cleanly in Unraid without any configuration needed.
-
-## Optional: Add Lockfiles for Deterministic Builds
-
-If you want 100% deterministic builds with locked dependency versions:
-
-```bash
-# Generate lockfiles locally
-cd frontend && npm install && cd ..
-cd backend && npm install && cd ..
-
-# Commit them
-git add frontend/package-lock.json backend/package-lock.json
-git commit -m "Add lockfiles for deterministic builds"
-
-# Update Dockerfile to use npm ci instead of npm install
-```
-
-**Benefits of lockfiles:**
-- Guaranteed exact dependency versions
-- Slightly faster builds
-- Better for production environments
-
-**Drawbacks:**
-- Must update lockfiles when changing dependencies
-- More complex maintenance
-
-## Build Optimization
-
-The `.dockerignore` file excludes:
-- `node_modules/` (prevents copying local dependencies)
-- Development files (`.env`, `.vscode/`, etc.)
-- Build artifacts
-- Documentation and test files
-
-This keeps build context small and fast.
-
-## Verification
-
-Test the complete build:
-```bash
-# Build image
-docker build -t pnger:test .
-
-# Run container
-docker run -d -p 3000:3000 --name pnger-test pnger:test
-
-# Check health
-curl http://localhost:3000
-
-# View logs
-docker logs pnger-test
-
-# Cleanup
-docker stop pnger-test && docker rm pnger-test
-```
-
-## Technical Details
-
-### Multi-Stage Build
-
-1. **frontend-builder**: Builds Svelte/Vite frontend with all dev dependencies
-2. **backend-builder**: Compiles TypeScript backend with all dev dependencies
-3. **production**: Combines compiled outputs with production dependencies only (`--omit=dev`)
-
-### Security Features
-
-- Runs as non-root user (`node`)
-- Health check endpoint configured
-- Minimal production dependencies
-- Alpine Linux base (smaller attack surface)
-- No unnecessary dev tools in production image
-
-### Multer v2.1.0 Upgrade
-
-Upgraded from v1.4.5 (no longer available) to v2.1.0:
-- ✅ Security fixes (CVE-2026-2359 and others)
-- ✅ Backward compatible API
-- ✅ Better performance
-- ✅ Active maintenance
-
----
-
-**Created**: 2026-03-08  
-**Branch**: `fix/add-package-lockfiles`  
-**Status**: Ready to merge  
-**Issue**: Docker build failing ✅ RESOLVED

Dockerfile

@@ -32,6 +32,11 @@ RUN npm run build
 # Stage 3: Production Runtime
 FROM node:20-alpine
 
+# Upgrade existing packages to fix base image vulnerabilities, 
+# then install su-exec and shadow (for usermod/groupmod)
+RUN apk upgrade --no-cache && \
+    apk add --no-cache su-exec shadow
+
 WORKDIR /app
 
 # Copy backend package files
@@ -48,17 +53,20 @@ COPY --from=backend-builder /app/backend/dist ./dist
 COPY --from=frontend-builder /app/frontend/dist ./dist/public
 
 # Create temp upload directory
-RUN mkdir -p /app/temp && \
+RUN mkdir -p /app/temp
-    chown -R node:node /app
 
-# Switch to non-root user
+# Copy entrypoint script
-USER node
+COPY docker-entrypoint.sh /usr/local/bin/
+RUN chmod +x /usr/local/bin/docker-entrypoint.sh
 
-# Environment variables (can be overridden via Unraid UI)
+# Environment variables (Unraid defaults and App defaults)
-ENV NODE_ENV=production
+ENV PUID=99 \
-ENV PORT=3000
+    PGID=100 \
-ENV MAX_FILE_SIZE=10485760
+    TZ=UTC \
-ENV TEMP_DIR=/app/temp
+    NODE_ENV=production \
+    PORT=3000 \
+    MAX_FILE_SIZE=10485760 \
+    TEMP_DIR=/app/temp
 
 # Expose port
 EXPOSE 3000
@@ -67,5 +75,7 @@ EXPOSE 3000
 HEALTHCHECK --interval=30s --timeout=3s --start-period=5s --retries=3 \
     CMD node -e "require('http').get('http://localhost:3000/', (r) => {process.exit(r.statusCode === 200 ? 0 : 1)})"
 
+ENTRYPOINT ["docker-entrypoint.sh"]
+
 # Start server
 CMD ["node", "dist/index.js"]

INSTRUCTIONS.md

@@ -1,70 +1,76 @@
-# PNGer Development Instructions
+# PNGer Development & Technical Instructions
 
 ## Project Overview
 
-PNGer is a single-container web application for PNG editing and resizing, designed for deployment on Unraid with Gitea version control.
+PNGer is a single-container web application for PNG editing and resizing, designed for deployment on Unraid with Gitea version control. It features a modern Svelte frontend and a high-performance Node.js/Sharp backend.
-
-## Development Roadmap
-
-### Phase 1: MVP Foundation (Current)
-- [x] Repository setup
-- [ ] Project structure initialization
-- [ ] Backend API scaffold
-- [ ] Frontend scaffold
-- [ ] Basic upload/download flow
-- [ ] Dockerfile configuration
-
-### Phase 2: Core Features
-- [ ] Image resize functionality
-- [ ] PNG compression
-- [ ] Real-time preview
-- [ ] Responsive UI design
-- [ ] Error handling
-
-### Phase 3: Polish & Deployment
-- [ ] Docker Compose for Unraid
-- [ ] Environment configuration
-- [ ] Documentation
-- [ ] Testing
-- [ ] Production build optimization
 
 ## Technical Architecture
 
+### Architecture Overview
+
+PNGer uses a multi-layered architecture designed for responsiveness and efficiency:
+
+```mermaid
+graph TD
+    A[User Browser] --> B[Svelte Frontend]
+    B --> C[Canvas API (Live Preview)]
+    B --> D[Express API (Backend)]
+    D --> E[Sharp Image Library]
+    D --> F[Runtime Environment (Docker)]
+```
+
 ### Backend (Express + Sharp)
 
-**Endpoints:**
+The backend is built with Node.js and TypeScript, using Express for the API and Sharp for high-performance image processing.
-- `POST /api/upload` - Accept PNG file
+
-- `POST /api/process` - Resize/compress image
+**Key Endpoints:**
+- `POST /api/transform` - Transform image (resize, crop, compress, convert)
 - `GET /api/health` - Health check
 
 **Key Dependencies:**
-- express: Web framework
+- `sharp`: High-performance image processing (handles resizing, cropping, and format conversion).
-- multer: File upload handling
+- `multer`: Middleware for handling `multipart/form-data`, used for file uploads.
-- sharp: Image processing
+- `express`: Web framework for the API.
-- cors: Cross-origin support
 
 ### Frontend (Svelte + Vite)
 
-**Components:**
+The frontend is a reactive Svelte application that prioritizes real-time feedback and UX.
-- `App.svelte` - Main container
-- `Uploader.svelte` - Drag & drop interface
-- `Editor.svelte` - Resize controls
-- `Preview.svelte` - Real-time image preview
-- `Download.svelte` - Download button
 
-**Key Dependencies:**
+**Core Components & Modules:**
-- svelte: Reactive framework
+- `App.svelte`: Main application container managing state and UI.
-- vite: Build tool
+- `lib/api.ts`: API client for backend communication.
-- axios: HTTP client
+- `lib/preview.ts`: Client-side preview logic using the Canvas API for instant feedback.
+- `lib/theme.ts`: Dark/light theme management with persistent storage.
+- `lib/presets.ts`: Configuration for smart image presets.
 
-### Docker Strategy
+### Design System (Dark/Light Modes)
 
-**Multi-stage Build:**
+The UI uses a modern design system with CSS custom properties for theming:
-1. Stage 1: Build frontend (Vite build)
+- **Light Mode**: Clean white background with dark gold (`#b8860b`) accents.
-2. Stage 2: Copy frontend + setup backend
+- **Dark Mode**: Deep black (`#0a0a0a`) background with light gold (`#daa520`) accents.
-3. Final image: Alpine-based Node.js
+- **Transparencies**: Dark/Light toggling allows users to inspect PNG transparency against different backgrounds.
 
-**Image Size Target:** < 150MB
+## Implementation Details
+
+### Live Preview System
+
+Live preview is implemented using a client-side Canvas-based approach to provide instant feedback (< 100ms) without server round-trips.
+
+**How it works:**
+1. User uploads an image.
+2. The browser loads the image into an HTML5 Canvas.
+3. On any parameter change (width, quality, etc.), a debounced (300ms) update applies transformations to the canvas.
+4. The canvas content is displayed side-by-side with the original for comparison.
+5. File sizes are estimated from the Canvas data URL to provide immediate feedback on optimization savings.
+
+### Docker Strategy & Fixes
+
+PNGer uses a multi-stage Docker build to minimize image size and maximize security.
+
+**Optimization Fixes applied:**
+- **Dependency Installation**: Uses `npm install` instead of `npm ci` to handle missing lockfiles gracefully while maintaining stability via caret ranges in `package.json`.
+- **Security**: Runs as a non-root `node` user in the final Alpine-based image.
+- **Multer Upgrade**: Upgraded to `v2.1.0` for improved security and performance.
 
 ## Local Development Setup
 
@@ -73,156 +79,56 @@ PNGer is a single-container web application for PNG editing and resizing, design
 - npm or pnpm
 - Docker (optional)
 
-### Initial Setup
+### Setup Steps
 
 ```bash
 # Clone repository
 git clone https://git.alwisp.com/jason/pnger.git
 cd pnger
 
-# Install root dependencies (if monorepo)
-npm install
-
 # Setup backend
 cd backend
 npm install
 npm run dev
 
-# Setup frontend (new terminal)
+# Setup frontend (separate terminal)
 cd frontend
 npm install
 npm run dev
 ```
 
-### Development Workflow
-
-1. **Feature Branch**: Create from `main`
-2. **Develop**: Make changes with hot-reload
-3. **Test**: Manual testing + health checks
-4. **Commit**: Descriptive commit messages
-5. **Push**: Push to Gitea
-6. **Review**: Self-review changes
-7. **Merge**: Merge to `main`
-
 ### Environment Variables
 
 **Backend (.env):**
-```
+- `PORT`: 3000 (internal)
-PORT=3000
+- `MAX_FILE_SIZE`: 10485760 (10MB default)
-NODE_ENV=development
+- `CORS_ORIGIN`: http://localhost:5173
-MAX_FILE_SIZE=10
-CORS_ORIGIN=http://localhost:5173
-```
 
 **Frontend (.env):**
-```
+- `VITE_API_URL`: http://localhost:3000/api
-VITE_API_URL=http://localhost:3000/api
-```
 
-## Docker Build & Test
+## Development Workflow & Standards
 
-```bash
+### Workflow
-# Build image
+1. **Feature Branch**: Create from `main`.
-docker build -t pnger:test .
+2. **Develop**: Use hot-reload (`npm run dev`).
+3. **Test**: Perform manual testing of image operations and presets.
+4. **Commit**: Use `type: description` format (e.g., `feat: add rotation`).
+5. **Merge**: Merge into `main` after review.
 
-# Run container
+### Code Standards
-docker run -p 8080:3000 --name pnger-test pnger:test
+- **TypeScript**: Use strict types where possible.
-
+- **Svelte**: Keep components modular and under 300 lines.
-# Test endpoints
+- **Async/Await**: Use for all asynchronous operations.
-curl http://localhost:8080/api/health
+- **Semantic HTML**: Ensure accessibility and proper structure.
-
-# View logs
-docker logs pnger-test
-
-# Stop and remove
-docker stop pnger-test && docker rm pnger-test
-```
-
-## Unraid Deployment
-
-### Setup Steps
-
-1. **SSH into Unraid**
-2. **Navigate to docker configs**: `/mnt/user/appdata/pnger`
-3. **Clone repository**:
-   ```bash
-   git clone https://git.alwisp.com/jason/pnger.git
-   cd pnger
-   ```
-4. **Build and run**:
-   ```bash
-   docker-compose up -d
-   ```
-5. **Access**: http://[unraid-ip]:8080
-
-### Update Process
-
-```bash
-cd /mnt/user/appdata/pnger
-git pull origin main
-docker-compose down
-docker-compose build
-docker-compose up -d
-```
-
-## Code Standards
-
-### JavaScript/Svelte
-- Use ES6+ features
-- Async/await for asynchronous operations
-- Descriptive variable names
-- Comments for complex logic only
-
-### File Organization
-- One component per file
-- Group related utilities
-- Keep components under 200 lines
-
-### Commit Messages
-- Format: `type: description`
-- Types: feat, fix, docs, style, refactor, test
-- Example: `feat: add drag and drop upload`
 
 ## Troubleshooting
 
-### Common Issues
+- **Port in use**: `lsof -ti:3000 | xargs kill -9`
+- **Sharp issues**: `npm rebuild sharp`
+- **Docker Cache**: `docker builder prune` if builds fail unexpectedly.
+- **Preview Glitches**: Check browser console for Canvas API errors.
 
-**Port already in use:**
+---
-```bash
-lsof -ti:3000 | xargs kill -9
-```
 
-**Sharp installation issues:**
+**Last Updated**: March 12, 2026
-```bash
-npm rebuild sharp
-```
-
-**Docker build fails:**
-- Check Docker daemon is running
-- Verify Dockerfile syntax
-- Clear Docker cache: `docker builder prune`
-
-## Performance Targets
-
-- Upload handling: < 100ms (for 5MB file)
-- Image processing: < 2s (for 10MP image)
-- Download generation: < 500ms
-- UI response time: < 100ms
-- Docker image size: < 150MB
-
-## Security Considerations
-
-- File type validation (PNG only)
-- File size limits (10MB default)
-- No persistent storage of user files
-- Memory cleanup after processing
-- CORS configuration
-
-## Next Steps
-
-1. Create backend folder structure
-2. Create frontend folder structure
-3. Initialize package.json files
-4. Create Dockerfile
-5. Create docker-compose.yml
-6. Begin MVP development

README.md

@@ -1,213 +1,49 @@
 # PNGer - Modern PNG Editor & Resizer
 
-A simple, reactive, modern PNG editor and resizer with direct upload and download features. Built with TypeScript and deployed as a single Docker container on Unraid.
+A sleek, modern PNG editor and resizer with **live preview**, **drag & drop**, **smart presets**, **keyboard shortcuts**, and **dark/light mode theming**. Built with TypeScript and optimized for deployment as a single Docker container.
 
-## Features
+## ✨ Features
 
-- **Drag & Drop Upload**: Intuitive file upload interface
+- **🎨 Modern UI**: Beautiful dark/light mode for inspecting transparency.
-- **Resize Operations**: Width, height, and aspect ratio controls
+- **⚡ Live Preview**: Instant side-by-side comparison with file size analysis.
-- **Crop to Fit**: Smart cropping with position control (center, top, bottom, etc.)
+- **🚀 Efficiency**: Drag & Drop upload, clipboard paste (`Ctrl+V`), and smart presets.
-- **Format Conversion**: PNG, WebP, and JPEG output
+- **🖼️ Precision**: Control width, height, quality, and crop positions (9 modes).
-- **Quality Control**: Adjustable compression settings
+- **📦 Reliable Deployment**: Multi-stage Docker build optimized for Unraid and Gitea.
-- **Direct Download**: No server-side storage, immediate download
-- **Modern UI**: Sleek, responsive TypeScript/Svelte design
 
-## Tech Stack
+## 🚀 Quick Start
 
-- **Frontend**: Svelte 4 + Vite + TypeScript
+### Docker/Unraid Deployment
-- **Backend**: Node.js + Express + TypeScript
+1. **Clone & Build**:
-- **Image Processing**: Sharp (high-performance image library)
-- **Container**: Docker (Alpine-based, multi-stage build)
-- **Deployment**: Unraid via Docker Compose
-
-## Quick Start
-
-### Unraid Deployment (Recommended)
-
-1. **Clone or pull this repository to your Unraid server:**
    ```bash
-   cd /mnt/user/appdata
    git clone https://git.alwisp.com/jason/pnger.git
    cd pnger
-   ```
-
-2. **Build the Docker image:**
-   ```bash
    docker build -t pnger:latest .
    ```
-
+2. **Run**:
-3. **Run via docker-compose:**
    ```bash
    docker compose up -d
    ```
+3. **Access**: `http://localhost:8080` (or your Unraid IP)
 
-4. **Access the application:**
+### Local Development
-   - Navigate to `http://[unraid-ip]:8080`
+1. **Install & Run Backend**: `cd backend && npm install && npm run dev`
+2. **Install & Run Frontend**: `cd frontend && npm install && npm run dev`
+3. **Access**: `http://localhost:5173`
 
-### Unraid Environment Variables (Configurable via UI)
+## 📚 Documentation
 
-When setting up in Unraid Docker UI, you can configure:
+For more detailed information, please refer to:
+- **[INSTRUCTIONS.md](./INSTRUCTIONS.md)**: Technical architecture, development setup, code standards, and troubleshooting.
+- **[ROADMAP.md](./ROADMAP.md)**: Project history, sprint updates, and future feature plans.
 
-| Variable | Default | Description |
+## ⌨️ Keyboard Shortcuts
-|----------|---------|-------------|
-| `HOST_PORT` | `8080` | External port to access the app |
-| `MAX_FILE_SIZE` | `10485760` | Max upload size in bytes (10MB default) |
-| `MEM_LIMIT` | `512m` | Memory limit for container |
-| `CPU_LIMIT` | `1.0` | CPU limit (1.0 = 1 full core) |
-| `NODE_ENV` | `production` | Node environment |
 
-### Unraid Docker Template Example
+- `Ctrl+V`: Paste image from clipboard
+- `Enter`: Download (when input not focused)
+- `?`: Show shortcuts help
+- `Esc`: Close dialogs
 
-```xml
+---
-<?xml version="1.0"?>
-<Container version="2">
-  <Name>pnger</Name>
-  <Repository>pnger:latest</Repository>
-  <Network>bridge</Network>
-  <Privileged>false</Privileged>
-  <WebUI>http://[IP]:[PORT:8080]</WebUI>
-  <Config Name="WebUI Port" Target="3000" Default="8080" Mode="tcp" Description="Port for web interface" Type="Port" Display="always" Required="true" Mask="false">8080</Config>
-  <Config Name="Max File Size" Target="MAX_FILE_SIZE" Default="10485760" Mode="" Description="Maximum upload file size in bytes" Type="Variable" Display="advanced" Required="false" Mask="false">10485760</Config>
-  <Config Name="Memory Limit" Target="" Default="512m" Mode="" Description="Container memory limit" Type="Variable" Display="advanced" Required="false" Mask="false">512m</Config>
-</Container>
-```
 
-## Local Development
+**License**: MIT  
-
+**Repository**: [https://git.alwisp.com/jason/pnger](https://git.alwisp.com/jason/pnger)
-### Prerequisites
-- Node.js 20+
-- npm or yarn
-
-### Setup
-
-1. **Install backend dependencies:**
-   ```bash
-   cd backend
-   npm install
-   ```
-
-2. **Install frontend dependencies:**
-   ```bash
-   cd frontend
-   npm install
-   ```
-
-3. **Run development servers:**
-   
-   Terminal 1 (Backend):
-   ```bash
-   cd backend
-   npm run dev
-   ```
-   
-   Terminal 2 (Frontend):
-   ```bash
-   cd frontend
-   npm run dev
-   ```
-
-4. **Access dev server:**
-   - Frontend: `http://localhost:5173`
-   - Backend API: `http://localhost:3000/api`
-
-### Building for Production
-
-```bash
-# Backend TypeScript compilation
-cd backend
-npm run build
-
-# Frontend build
-cd frontend
-npm run build
-```
-
-## Docker Deployment (Manual)
-
-```bash
-# Build the image (all dependencies and builds are handled internally)
-docker build -t pnger:latest .
-
-# Run the container
-docker run -d \
-  --name pnger \
-  -p 8080:3000 \
-  -e MAX_FILE_SIZE=10485760 \
-  --restart unless-stopped \
-  pnger:latest
-```
-
-## Project Structure
-
-```
-pnger/
-├── frontend/              # Svelte + TypeScript application
-│   ├── src/
-│   │   ├── App.svelte    # Main UI component
-│   │   ├── main.ts       # Entry point
-│   │   └── lib/
-│   │       └── api.ts    # API client
-│   ├── package.json
-│   ├── tsconfig.json
-│   └── vite.config.ts
-├── backend/               # Express + TypeScript API server
-│   ├── src/
-│   │   ├── index.ts      # Express server
-│   │   ├── routes/
-│   │   │   └── image.ts  # Image transform endpoint
-│   │   └── types/
-│   │       └── image.ts  # TypeScript types
-│   ├── package.json
-│   └── tsconfig.json
-├── Dockerfile             # Multi-stage build (frontend + backend)
-├── docker-compose.yml     # Unraid deployment config
-└── INSTRUCTIONS.md        # Development guide
-```
-
-## How It Works
-
-1. User uploads an image via the web interface
-2. Frontend sends image + transform parameters to backend API
-3. Backend processes image using Sharp (resize, crop, compress, convert format)
-4. Processed image is returned directly to browser
-5. Browser triggers automatic download
-6. No files stored on server (stateless operation)
-
-## API Endpoints
-
-### POST /api/transform
-
-Transform an image with resize, crop, and format conversion.
-
-**Request:**
-- Method: `POST`
-- Content-Type: `multipart/form-data`
-- Body:
-  - `file`: Image file (PNG/JPEG/WebP)
-  - `width`: Target width (optional)
-  - `height`: Target height (optional)
-  - `quality`: Quality 10-100 (optional, default: 80)
-  - `format`: Output format `png|webp|jpeg` (optional, default: `png`)
-  - `fit`: Resize mode `inside|cover` (optional, default: `inside`)
-  - `position`: Crop position when `fit=cover` (optional, default: `center`)
-
-**Response:**
-- Content-Type: `image/[format]`
-- Body: Transformed image binary
-
-## Configuration
-
-All configuration is handled via environment variables passed through Docker/Unraid:
-
-- `PORT`: Server port (default: `3000`, internal)
-- `MAX_FILE_SIZE`: Maximum upload size in bytes (default: `10485760` = 10MB)
-- `TEMP_DIR`: Temporary directory for uploads (default: `/app/temp`)
-- `NODE_ENV`: Node environment (default: `production`)
-
-## License
-
-MIT License - See LICENSE file for details
-
-## Repository
-
-https://git.alwisp.com/jason/pnger

ROADMAP.md

@@ -0,0 +1,62 @@
+# PNGer Feature Roadmap
+
+PNGer is evolved through intentional sprints focusing on user experience, performance, and professional-grade features.
+
+## Completed Features ✅
+
+### Sprint 0: Foundation (MVP)
+- ✅ **Core Repository Setup**: Project structure and build systems.
+- ✅ **Basic Image Operations**: Width/height resizing and quality adjustment.
+- ✅ **Format Support**: Conversion between PNG, WebP, and JPEG.
+- ✅ **Docker Deployment**: Multi-stage build for Unraid/Docker environments.
+- ✅ **Stateless Processing**: Direct download from memory; no server storage.
+
+### Sprint 1: Enhanced UX & Live Preview (March 2026)
+- ✅ **Live Preview**: Real-time side-by-side comparison with file size analysis.
+- ✅ **Modern Design System**: Dark/Light mode toggle with persistent storage.
+- ✅ **Drag & Drop Upload**: Intuitive drop zone with visual feedback.
+- ✅ **Clipboard Paste**: Paste images directly with `Ctrl+V`.
+- ✅ **Smart Presets**: 8 quick-access configurations for common use cases (Social Media, Web, Icons, etc.).
+- ✅ **Keyboard Shortcuts**: Fast workflow with `Enter`, `?`, and `Esc`.
+- ✅ **Performance Optimization**: Client-side Canvas rendering for instant feedback.
+
+---
+
+## Future Roadmap 🚀
+
+### Sprint 2: Batch Processing & Advanced Operations
+**Focus**: Efficiency and essential power-user tools.
+- [ ] **Batch Processing**: Upload multiple images and process as a single ZIP.
+- [ ] **Basic Transformations**: Rotate (90/180/Custom), Flip (H/V), and Grayscale.
+- [ ] **Content-Aware Resize**: Smart cropping and aspect ratio enforcement.
+- [ ] **Auto-Optimize**: One-click "best quality/size" ratio finder.
+
+### Sprint 3: Polish & Professional Tools
+**Focus**: Precision and customization.
+- [ ] **Custom Crop Tool**: Visual selector with aspect ratio lock.
+- [ ] **Watermarking**: Text and image-based branding.
+- [ ] **Image Filters**: Brightness, Contrast, Saturation, and Sharpen.
+- [ ] **Format Intelligence**: Suggestions based on image content (e.g., suggesting WebP for large images).
+
+### Sprint 4: Workflow & Automation
+**Focus**: Reusability and productivity.
+- [ ] **Custom Presets**: Save and export personal transformation pipelines.
+- [ ] **Processing History**: Recent files list (localStorage).
+- [ ] **Undo/Redo**: History for parameter adjustments.
+
+---
+
+## Priority Matrix
+
+| Feature | Impact | Effort | Priority |
+|---------|--------|--------|----------|
+| Batch Processing | Very High | Medium | 1 |
+| Auto-Optimize | High | Low | 1 |
+| Custom Crop | High | High | 2 |
+| Watermarking | Medium | Medium | 3 |
+
+---
+
+**Project Maintainer**: jason  
+**Repository**: [jason/pnger](https://git.alwisp.com/jason/pnger)  
+**Last Strategy Sync**: March 12, 2026

UNRAID.md

@@ -0,0 +1,66 @@
+# Unraid Installation Guide for PNGer
+
+This guide walks you through installing PNGer on Unraid using the Docker tab and "Add Container" feature.
+
+## Requirements
+- Unraid OS with Docker enabled.
+- Appdata path ready (optional, if you want persistent temp storage).
+
+## Step-by-Step Installation
+
+1. Log into your Unraid WebGUI and navigate to the **Docker** tab.
+2. Scroll to the bottom and click on **Add Container**.
+3. Fill in the following details:
+   - **Name**: `PNGer`
+   - **Repository**: `jason/pnger:latest` (or the repository you pushed the image to, e.g., `ghcr.io/yourusername/pnger:latest` if hosted, or `pnger:latest` if built locally).
+   - **Network Type**: `Bridge`
+
+4. Click on **+ Add another Path, Port, Variable, Label or Device** to add the required parameters.
+
+### Port Configuration
+- **Config Type**: `Port`
+- **Name**: `WebUI`
+- **Container Port**: `3000`
+- **Host Port**: `8080` (or whichever port is free on your Unraid system).
+- **Connection Protocol**: `TCP`
+
+### Environment Variables
+Add the following variables by clicking **+ Add another Path, Port, Variable...** and selecting **Variable** as the Config Type:
+
+1. **PUID**
+   - **Name**: `User ID (PUID)`
+   - **Key**: `PUID`
+   - **Value**: `99` (Unraid's nobody user).
+
+2. **PGID**
+   - **Name**: `Group ID (PGID)`
+   - **Key**: `PGID`
+   - **Value**: `100` (Unraid's users group).
+
+3. **TZ**
+   - **Name**: `Timezone`
+   - **Key**: `TZ`
+   - **Value**: `America/New_York` (Enter your specific Timezone here).
+
+4. **MAX_FILE_SIZE** (Optional)
+   - **Name**: `Max Upload Size (Bytes)`
+   - **Key**: `MAX_FILE_SIZE`
+   - **Value**: `10485760` (Default is 10MB; 10485760 bytes).
+
+### Volume Mapping (Optional)
+If you require persistence for the temporary directory processing uploads (usually not required):
+- **Config Type**: `Path`
+- **Name**: `Temp Processing Dir`
+- **Container Path**: `/app/temp`
+- **Host Path**: `/mnt/user/appdata/pnger/temp`
+
+5. **Apply Settings**:
+   - Scroll to the bottom and press **Apply**. Unraid will pull the image and create the container with the specified settings.
+
+## Accessing PNGer
+Once the container states "started", you can access the Web GUI by navigating to your Unraid IP and the port you assigned (e.g., `http://192.168.1.100:8080`).
+
+---
+
+**Troubleshooting:**
+If the container stops instantly, check the **Logs** in Unraid. Ensure that the port you selected on the host is not already in use by another container (like a web server or another app).

docker-compose.yml

@@ -10,10 +10,11 @@ services:
     ports:
       - "${HOST_PORT:-8080}:3000"
     environment:
+      - PUID=${PUID:-99}
+      - PGID=${PGID:-100}
+      - TZ=${TZ:-UTC}
       - NODE_ENV=${NODE_ENV:-production}
-      - PORT=3000
       - MAX_FILE_SIZE=${MAX_FILE_SIZE:-10485760}
-      - TEMP_DIR=/app/temp
     restart: unless-stopped
     healthcheck:
       test: ["CMD", "node", "-e", "require('http').get('http://localhost:3000/', (r) => {process.exit(r.statusCode === 200 ? 0 : 1)})"]

docker-entrypoint.sh

@@ -0,0 +1,23 @@
+#!/bin/sh
+set -e
+
+# Default to PUID 99 and PGID 100 if not specified
+PUID=${PUID:-99}
+PGID=${PGID:-100}
+
+echo "Starting with UID: $PUID, GID: $PGID"
+
+# Modify the 'node' user and group to match the provided PUID/PGID
+if [ "$(id -u node)" -ne "$PUID" ]; then
+    usermod -o -u "$PUID" node
+fi
+
+if [ "$(id -g node)" -ne "$PGID" ]; then
+    groupmod -o -g "$PGID" node
+fi
+
+# Ensure appropriate permissions on the application directory and temp dir
+chown -R node:node /app
+
+# Drop privileges to 'node' user and execute the command passed to the container
+exec su-exec node "$@"

frontend/src/App.svelte

@@ -1,28 +1,74 @@
 <script lang="ts">
+  import { onMount } from 'svelte';
   import { transformImage } from "./lib/api";
+  import {
+    generateClientPreview,
+    estimateSize,
+    formatFileSize,
+    calculateSavings,
+    debounce,
+    type TransformOptions
+  } from "./lib/preview";
+  import { theme } from "./lib/theme";
+  import { PRESETS, applyPreset, type Preset } from "./lib/presets";
 
   let file: File | null = null;
+  let filePreviewUrl: string | null = null;
   let width: number | null = null;
   let height: number | null = null;
   let quality = 80;
   let format: "png" | "webp" | "jpeg" = "png";
-
+  let fit: "inside" | "cover" = "inside";
-  // cropping / resizing
+  let position = "center";
-  let fit: "inside" | "cover" = "inside"; // inside = resize only, cover = crop
-  let position:
-    | "center"
-    | "top"
-    | "right"
-    | "bottom"
-    | "left"
-    | "top-left"
-    | "top-right"
-    | "bottom-left"
-    | "bottom-right" = "center";
 
   let processing = false;
   let error: string | null = null;
   
+  // Drag & drop state
+  let isDragging = false;
+  let showShortcuts = false;
+  
+  // Preview state
+  let previewUrl: string | null = null;
+  let previewSize = 0;
+  let originalSize = 0;
+  let showPreview = false;
+
+  // Generate preview with debounce
+  const updatePreview = debounce(async () => {
+    if (!file) {
+      previewUrl = null;
+      showPreview = false;
+      return;
+    }
+
+    try {
+      const options: TransformOptions = {
+        width: width || undefined,
+        height: height || undefined,
+        quality,
+        format,
+        fit,
+        position: fit === "cover" ? position : undefined
+      };
+
+      previewUrl = await generateClientPreview(file, options);
+      previewSize = estimateSize(previewUrl);
+      originalSize = file.size;
+      showPreview = true;
+    } catch (err) {
+      console.error("Preview generation failed:", err);
+    }
+  }, 300);
+
+  // Reactive preview updates
+  $: if (file) {
+    updatePreview();
+  }
+  $: if (width !== null || height !== null || quality || format || fit || position) {
+    if (file) updatePreview();
+  }
+
   async function onSubmit() {
     if (!file) {
       error = "Please select an image file";
@@ -37,7 +83,7 @@
         quality,
         format,
         fit,
-        position
+        position: fit === "cover" ? position : undefined
       });
       const url = URL.createObjectURL(blob);
       const a = document.createElement("a");
@@ -53,106 +99,566 @@
     }
   }
 
+  function handleFile(selectedFile: File) {
+    if (!selectedFile.type.startsWith('image/')) {
+      error = 'Please select an image file';
+      return;
+    }
+    file = selectedFile;
+    filePreviewUrl = URL.createObjectURL(selectedFile);
+    error = null;
+  }
+
   function onFileChange(e: Event) {
     const target = e.target as HTMLInputElement;
-    file = target.files?.[0] || null;
+    const selectedFile = target.files?.[0];
+    if (selectedFile) {
+      handleFile(selectedFile);
+    }
   }
+
+  // Drag & Drop handlers
+  function onDragOver(e: DragEvent) {
+    e.preventDefault();
+    isDragging = true;
+  }
+
+  function onDragLeave(e: DragEvent) {
+    e.preventDefault();
+    isDragging = false;
+  }
+
+  function onDrop(e: DragEvent) {
+    e.preventDefault();
+    isDragging = false;
+    
+    const droppedFile = e.dataTransfer?.files?.[0];
+    if (droppedFile) {
+      handleFile(droppedFile);
+    }
+  }
+
+  // Paste handler
+  function onPaste(e: ClipboardEvent) {
+    const items = e.clipboardData?.items;
+    if (!items) return;
+
+    for (let i = 0; i < items.length; i++) {
+      if (items[i].type.indexOf('image') !== -1) {
+        const pastedFile = items[i].getAsFile();
+        if (pastedFile) {
+          handleFile(pastedFile);
+        }
+        break;
+      }
+    }
+  }
+
+  // Keyboard shortcuts
+  function onKeyDown(e: KeyboardEvent) {
+    // Show shortcuts help
+    if (e.key === '?') {
+      e.preventDefault();
+      showShortcuts = !showShortcuts;
+      return;
+    }
+
+    // Close shortcuts dialog
+    if (e.key === 'Escape' && showShortcuts) {
+      showShortcuts = false;
+      return;
+    }
+
+    // Ctrl/Cmd + V - Paste (handled by paste event)
+    // Ctrl/Cmd + Enter - Transform & Download
+    if ((e.ctrlKey || e.metaKey) && e.key === 'Enter' && file && !processing) {
+      e.preventDefault();
+      onSubmit();
+      return;
+    }
+
+    // Enter alone - Transform & Download (if input not focused)
+    const activeElement = document.activeElement;
+    const isInputFocused = activeElement?.tagName === 'INPUT' || 
+                           activeElement?.tagName === 'SELECT' ||
+                           activeElement?.tagName === 'TEXTAREA';
+    
+    if (e.key === 'Enter' && !isInputFocused && file && !processing) {
+      e.preventDefault();
+      onSubmit();
+    }
+  }
+
+  function clearFile() {
+    file = null;
+    filePreviewUrl = null;
+    previewUrl = null;
+    showPreview = false;
+    originalSize = 0;
+    previewSize = 0;
+  }
+
+  // Apply preset
+  function selectPreset(preset: Preset) {
+    const settings = applyPreset(preset, width, height);
+    width = settings.width;
+    height = settings.height;
+    quality = settings.quality;
+    format = settings.format;
+    fit = settings.fit;
+  }
+
+  // Setup event listeners
+  onMount(() => {
+    document.addEventListener('paste', onPaste);
+    document.addEventListener('keydown', onKeyDown);
+    
+    return () => {
+      document.removeEventListener('paste', onPaste);
+      document.removeEventListener('keydown', onKeyDown);
+    };
+  });
+
+  const savings = showPreview ? calculateSavings(originalSize, previewSize) : null;
 </script>
 
-<main>
+<div class="container">
-  <h1>PNG Editor</h1>
+  <!-- Header -->
-
+  <header class="flex justify-between items-center" style="margin-bottom: var(--space-2xl);">
-  <input type="file" accept="image/*" on:change={onFileChange} />
-
-  <div>
-    <label>Width: <input type="number" bind:value={width} min="1" /></label>
-    <label>Height: <input type="number" bind:value={height} min="1" /></label>
-  </div>
-
-  <div>
-    <label>Fit mode:
-      <select bind:value={fit}>
-        <option value="inside">Resize only (no crop)</option>
-        <option value="cover">Crop to fit box</option>
-      </select>
-    </label>
-  </div>
-
-  {#if fit === "cover"}
     <div>
-      <label>Crop position:
+      <h1 class="mb-0">PNGer</h1>
-        <select bind:value={position}>
+      <p class="text-sm mb-0">Modern PNG Editor & Resizer</p>
-          <option value="center">Center</option>
+    </div>
-          <option value="top">Top</option>
+    <div class="flex gap-sm">
-          <option value="bottom">Bottom</option>
+      <button class="btn-outline" on:click={() => showShortcuts = !showShortcuts} title="Keyboard shortcuts (?)">
-          <option value="left">Left</option>
+        ⌨️
-          <option value="right">Right</option>
+      </button>
-          <option value="top-left">Top-left</option>
+      <button class="btn-outline" on:click={() => theme.toggle()}>
-          <option value="top-right">Top-right</option>
+        {#if $theme === 'dark'}
-          <option value="bottom-left">Bottom-left</option>
+          ☀️ Light
-          <option value="bottom-right">Bottom-right</option>
+        {:else}
-        </select>
+          🌙 Dark
-      </label>
+        {/if}
+      </button>
+    </div>
+  </header>
+
+  <!-- Shortcuts Modal -->
+  {#if showShortcuts}
+    <div class="modal-overlay" on:click={() => showShortcuts = false}>
+      <div class="modal-content" on:click|stopPropagation>
+        <h2>Keyboard Shortcuts</h2>
+        <div class="shortcuts-list">
+          <div class="shortcut-item">
+            <kbd>Ctrl</kbd> + <kbd>V</kbd>
+            <span>Paste image from clipboard</span>
+          </div>
+          <div class="shortcut-item">
+            <kbd>Enter</kbd>
+            <span>Transform & Download</span>
+          </div>
+          <div class="shortcut-item">
+            <kbd>Ctrl</kbd> + <kbd>Enter</kbd>
+            <span>Transform & Download (anywhere)</span>
+          </div>
+          <div class="shortcut-item">
+            <kbd>?</kbd>
+            <span>Show/hide this help</span>
+          </div>
+          <div class="shortcut-item">
+            <kbd>Esc</kbd>
+            <span>Close this dialog</span>
+          </div>
+        </div>
+        <button style="margin-top: var(--space-lg);" on:click={() => showShortcuts = false}>
+          Close
+        </button>
+      </div>
     </div>
   {/if}
 
-  <div>
+  <!-- Controls Section -->
-    <label>Quality:
+  <div class="card fade-in" style="margin-bottom: var(--space-xl);">
-      <input type="range" min="10" max="100" bind:value={quality} />
+    <div class="grid grid-cols-2 gap-lg">
-    </label>
+      <!-- Left Column: Upload & Dimensions -->
-    <span>{quality}</span>
+      <div>
+        <h2>Upload & Settings</h2>
+
+        <!-- Drag & Drop / File Upload -->
+        <div style="margin-bottom: var(--space-lg);">
+          <label style="display: block; margin-bottom: var(--space-sm); font-weight: 500;">
+            Select or Drop Image
+          </label>
+          
+          <!-- Drop Zone -->
+          <div 
+            class="drop-zone {isDragging ? 'dragging' : ''}"
+            on:dragover={onDragOver}
+            on:dragleave={onDragLeave}
+            on:drop={onDrop}
+          >
+            <input 
+              type="file" 
+              accept="image/*" 
+              on:change={onFileChange}
+              id="file-input"
+              style="display: none;"
+            />
+            <label for="file-input" class="drop-zone-label">
+              {#if file}
+                <div class="flex gap-sm items-center" style="flex-direction: column;">
+                  <span style="font-size: 2rem;">✅</span>
+                  <span class="text-sm">{file.name}</span>
+                  <span class="text-xs" style="color: var(--color-text-secondary);">
+                    ({formatFileSize(file.size)})
+                  </span>
+                </div>
+              {:else}
+                <div style="text-align: center;">
+                  <p style="font-size: 3rem; margin-bottom: var(--space-sm);">🖼️</p>
+                  <p style="margin-bottom: var(--space-xs);">Drag & drop image here</p>
+                  <p class="text-sm" style="color: var(--color-text-secondary); margin-bottom: var(--space-sm);">or click to browse</p>
+                  <p class="text-xs" style="color: var(--color-text-secondary);">Paste with Ctrl+V</p>
+                </div>
+              {/if}
+            </label>
+          </div>
+
+          {#if file}
+            <button class="btn-secondary" style="width: 100%; margin-top: var(--space-sm);" on:click={clearFile}>
+              Clear File
+            </button>
+          {/if}
+        </div>
+
+        <!-- Smart Presets -->
+        {#if file}
+          <div style="margin-bottom: var(--space-lg);" class="fade-in">
+            <label style="display: block; margin-bottom: var(--space-sm); font-weight: 500;">
+              Quick Presets
+            </label>
+            <div class="presets-grid">
+              {#each PRESETS as preset}
+                <button 
+                  class="preset-btn"
+                  on:click={() => selectPreset(preset)}
+                  title={preset.description}
+                >
+                  <span class="preset-icon">{preset.icon}</span>
+                  <span class="preset-name">{preset.name}</span>
+                </button>
+              {/each}
+            </div>
+          </div>
+        {/if}
+
+        <!-- Dimensions -->
+        <div style="margin-bottom: var(--space-lg);">
+          <h3>Dimensions</h3>
+          <div class="grid grid-cols-2 gap-md">
+            <div>
+              <label style="display: block; margin-bottom: var(--space-xs); font-size: 0.875rem;">
+                Width (px)
+              </label>
+              <input type="number" bind:value={width} min="1" placeholder="Auto" />
+            </div>
+            <div>
+              <label style="display: block; margin-bottom: var(--space-xs); font-size: 0.875rem;">
+                Height (px)
+              </label>
+              <input type="number" bind:value={height} min="1" placeholder="Auto" />
+            </div>
+          </div>
+        </div>
+
+        <!-- Fit Mode -->
+        <div style="margin-bottom: var(--space-lg);">
+          <label style="display: block; margin-bottom: var(--space-sm); font-weight: 500;">
+            Fit Mode
+          </label>
+          <select bind:value={fit}>
+            <option value="inside">Resize only (no crop)</option>
+            <option value="cover">Crop to fit box</option>
+          </select>
+        </div>
+
+        <!-- Crop Position (if cover) -->
+        {#if fit === "cover"}
+          <div style="margin-bottom: var(--space-lg);" class="fade-in">
+            <label style="display: block; margin-bottom: var(--space-sm); font-weight: 500;">
+              Crop Position
+            </label>
+            <select bind:value={position}>
+              <option value="center">Center</option>
+              <option value="top">Top</option>
+              <option value="bottom">Bottom</option>
+              <option value="left">Left</option>
+              <option value="right">Right</option>
+              <option value="top-left">Top-left</option>
+              <option value="top-right">Top-right</option>
+              <option value="bottom-left">Bottom-left</option>
+              <option value="bottom-right">Bottom-right</option>
+            </select>
+          </div>
+        {/if}
+      </div>
+
+      <!-- Right Column: Quality & Format -->
+      <div>
+        <h2>Quality & Format</h2>
+
+        <!-- Quality -->
+        <div style="margin-bottom: var(--space-lg);">
+          <div class="flex justify-between" style="margin-bottom: var(--space-sm);">
+            <label style="font-weight: 500;">Quality</label>
+            <span style="color: var(--color-accent); font-weight: 600;">{quality}%</span>
+          </div>
+          <input type="range" min="10" max="100" bind:value={quality} />
+        </div>
+
+        <!-- Format -->
+        <div style="margin-bottom: var(--space-xl);">
+          <label style="display: block; margin-bottom: var(--space-sm); font-weight: 500;">
+            Output Format
+          </label>
+          <select bind:value={format}>
+            <option value="png">PNG</option>
+            <option value="webp">WebP</option>
+            <option value="jpeg">JPEG</option>
+          </select>
+        </div>
+
+        <!-- Error Message -->
+        {#if error}
+          <p style="color: var(--color-error); padding: var(--space-md); background: var(--color-bg-tertiary); border-radius: var(--radius-md); margin-bottom: var(--space-lg);">
+            {error}
+          </p>
+        {/if}
+
+        <!-- Action Button -->
+        <button 
+          on:click|preventDefault={onSubmit} 
+          disabled={processing || !file}
+          style="width: 100%;"
+        >
+          {#if processing}
+            <span class="spinner" style="width: 16px; height: 16px; border: 2px solid currentColor; border-top-color: transparent; border-radius: 50%;"></span>
+            Processing...
+          {:else}
+            ⬇️ Transform & Download
+          {/if}
+        </button>
+        
+        {#if file}
+          <p class="text-xs" style="color: var(--color-text-secondary); text-align: center; margin-top: var(--space-sm); margin-bottom: 0;">
+            Press <kbd style="font-size: 0.75rem; padding: 2px 4px;">Enter</kbd> to download
+          </p>
+        {/if}
+      </div>
+    </div>
   </div>
 
-  <div>
+  <!-- Live Preview Section (Full Width Below) -->
-    <label>Format:
+  <div class="card fade-in">
-      <select bind:value={format}>
+    <h2>Live Preview</h2>
-        <option value="png">PNG</option>
+
-        <option value="webp">WebP</option>
+    {#if !file}
-        <option value="jpeg">JPEG</option>
+      <div style="display: flex; align-items: center; justify-content: center; color: var(--color-text-secondary); text-align: center; padding: var(--space-2xl); min-height: 400px;">
-      </select>
+        <div>
-    </label>
+          <p style="font-size: 3rem; margin-bottom: var(--space-md)">🖼️</p>
+          <p class="mb-0">Upload an image to see live preview</p>
+          <p class="text-sm" style="color: var(--color-text-secondary); margin-top: var(--space-sm);">Drag & drop, click to browse, or paste with Ctrl+V</p>
+        </div>
+      </div>
+    {:else if showPreview}
+      <div style="display: flex; flex-direction: column; gap: var(--space-lg);">
+        <!-- Image Comparison -->
+        <div class="grid grid-cols-2 gap-lg">
+          <!-- Original -->
+          <div style="display: flex; flex-direction: column;">
+            <h3 style="font-size: 1rem; margin-bottom: var(--space-sm);">Original</h3>
+            <div style="border: 2px solid var(--color-border); border-radius: var(--radius-md); overflow: hidden; display: flex; align-items: center; justify-content: center; background: var(--color-bg-tertiary); min-height: 500px;">
+              <img 
+                src={filePreviewUrl} 
+                alt="Original" 
+                style="max-width: 100%; max-height: 600px; object-fit: contain;"
+              />
+            </div>
+            <div style="margin-top: var(--space-sm); text-align: center;">
+              <p class="text-sm mb-0">
+                {formatFileSize(originalSize)}
+              </p>
+            </div>
+          </div>
+
+          <!-- Preview -->
+          <div style="display: flex; flex-direction: column;">
+            <h3 style="font-size: 1rem; margin-bottom: var(--space-sm);">Preview</h3>
+            <div style="border: 2px solid var(--color-accent); border-radius: var(--radius-md); overflow: hidden; display: flex; align-items: center; justify-content: center; background: var(--color-bg-tertiary); min-height: 500px;">
+              <img 
+                src={previewUrl} 
+                alt="Preview" 
+                style="max-width: 100%; max-height: 600px; object-fit: contain;"
+              />
+            </div>
+            <div style="margin-top: var(--space-sm); text-align: center;">
+              <p class="text-sm mb-0">
+                {formatFileSize(previewSize)}
+              </p>
+            </div>
+          </div>
+        </div>
+
+        <!-- Savings Info -->
+        {#if savings}
+          <div 
+            class="fade-in" 
+            style="
+              padding: var(--space-lg); 
+              background: {savings.isReduction ? 'var(--color-success)' : 'var(--color-warning)'}15; 
+              border: 2px solid {savings.isReduction ? 'var(--color-success)' : 'var(--color-warning)'};
+              border-radius: var(--radius-md);
+              text-align: center;
+            "
+          >
+            <p class="text-sm font-semibold mb-0" style="color: {savings.isReduction ? 'var(--color-success)' : 'var(--color-warning)'}; font-size: 1.125rem;">
+              {savings.formatted}
+            </p>
+          </div>
+        {/if}
+      </div>
+    {:else}
+      <div style="display: flex; align-items: center; justify-content: center; color: var(--color-text-secondary); min-height: 500px;">
+        <div class="spinner" style="width: 40px; height: 40px; border: 3px solid var(--color-border); border-top-color: var(--color-accent); border-radius: 50%;"></div>
+      </div>
+    {/if}
   </div>
-
+</div>
-  {#if error}
-    <p style="color: red">{error}</p>
-  {/if}
-
-  <button on:click|preventDefault={onSubmit} disabled={processing}>
-    {processing ? "Processing..." : "Transform & Download"}
-  </button>
-</main>
 
 <style>
-  main {
+  /* Drop zone styles */
-    max-width: 600px;
+  .drop-zone {
-    margin: 2rem auto;
+    border: 2px dashed var(--color-border);
-    padding: 1rem;
+    border-radius: var(--radius-md);
-    font-family: system-ui, -apple-system, sans-serif;
+    padding: var(--space-xl);
+    text-align: center;
+    cursor: pointer;
+    transition: all 0.2s ease;
+    background: var(--color-bg-secondary);
   }
 
-  h1 {
+  .drop-zone:hover {
-    margin-bottom: 2rem;
+    border-color: var(--color-accent);
+    background: var(--color-bg-tertiary);
   }
 
-  label {
+  .drop-zone.dragging {
+    border-color: var(--color-accent);
+    background: var(--color-accent)15;
+    border-style: solid;
+  }
+
+  .drop-zone-label {
     display: block;
-    margin: 1rem 0;
-  }
-
-  input[type="number"],
-  select {
-    margin-left: 0.5rem;
-  }
-
-  button {
-    margin-top: 1.5rem;
-    padding: 0.75rem 1.5rem;
-    font-size: 1rem;
     cursor: pointer;
   }
 
-  button:disabled {
+  /* Presets grid */
-    opacity: 0.5;
+  .presets-grid {
-    cursor: not-allowed;
+    display: grid;
+    grid-template-columns: repeat(4, 1fr);
+    gap: var(--space-sm);
+  }
+
+  .preset-btn {
+    display: flex;
+    flex-direction: column;
+    align-items: center;
+    gap: var(--space-xs);
+    padding: var(--space-sm);
+    border: 1px solid var(--color-border);
+    border-radius: var(--radius-sm);
+    background: var(--color-bg-secondary);
+    cursor: pointer;
+    transition: all 0.2s ease;
+    font-size: 0.75rem;
+  }
+
+  .preset-btn:hover {
+    border-color: var(--color-accent);
+    background: var(--color-bg-tertiary);
+    transform: translateY(-2px);
+  }
+
+  .preset-icon {
+    font-size: 1.5rem;
+  }
+
+  .preset-name {
+    font-size: 0.7rem;
+    text-align: center;
+    line-height: 1.2;
+    color: var(--color-text-primary);
+  }
+
+  /* Modal styles */
+  .modal-overlay {
+    position: fixed;
+    top: 0;
+    left: 0;
+    right: 0;
+    bottom: 0;
+    background: rgba(0, 0, 0, 0.5);
+    display: flex;
+    align-items: center;
+    justify-content: center;
+    z-index: 1000;
+    animation: fadeIn 0.2s ease;
+  }
+
+  .modal-content {
+    background: var(--color-bg-primary);
+    border-radius: var(--radius-lg);
+    padding: var(--space-2xl);
+    max-width: 500px;
+    width: 90%;
+    box-shadow: var(--shadow-2xl);
+  }
+
+  .shortcuts-list {
+    display: flex;
+    flex-direction: column;
+    gap: var(--space-md);
+    margin-top: var(--space-lg);
+  }
+
+  .shortcut-item {
+    display: flex;
+    align-items: center;
+    gap: var(--space-md);
+    padding: var(--space-sm);
+    background: var(--color-bg-secondary);
+    border-radius: var(--radius-sm);
+  }
+
+  .shortcut-item span {
+    flex: 1;
+    color: var(--color-text-secondary);
+  }
+
+  kbd {
+    display: inline-block;
+    padding: 4px 8px;
+    font-size: 0.875rem;
+    font-family: monospace;
+    background: var(--color-bg-tertiary);
+    border: 1px solid var(--color-border);
+    border-radius: var(--radius-sm);
+    box-shadow: 0 2px 0 var(--color-border);
+  }
+
+  @keyframes fadeIn {
+    from { opacity: 0; }
+    to { opacity: 1; }
   }
 </style>

frontend/src/app.css

@@ -0,0 +1,384 @@
+:root {
+  /* Light mode colors (white with dark gold) */
+  --color-bg-primary: #ffffff;
+  --color-bg-secondary: #f8f9fa;
+  --color-bg-tertiary: #e9ecef;
+  --color-text-primary: #1a1a1a;
+  --color-text-secondary: #6c757d;
+  --color-border: #dee2e6;
+  --color-accent: #b8860b; /* Dark gold */
+  --color-accent-hover: #8b6914;
+  --color-accent-light: #daa520;
+  --color-success: #28a745;
+  --color-error: #dc3545;
+  --color-warning: #ffc107;
+  
+  /* Shadows */
+  --shadow-sm: 0 1px 2px rgba(0, 0, 0, 0.05);
+  --shadow-md: 0 4px 6px rgba(0, 0, 0, 0.07);
+  --shadow-lg: 0 10px 15px rgba(0, 0, 0, 0.1);
+  --shadow-xl: 0 20px 25px rgba(0, 0, 0, 0.15);
+  
+  /* Spacing */
+  --space-xs: 0.25rem;
+  --space-sm: 0.5rem;
+  --space-md: 1rem;
+  --space-lg: 1.5rem;
+  --space-xl: 2rem;
+  --space-2xl: 3rem;
+  
+  /* Border radius */
+  --radius-sm: 0.25rem;
+  --radius-md: 0.5rem;
+  --radius-lg: 0.75rem;
+  --radius-xl: 1rem;
+  --radius-full: 9999px;
+  
+  /* Transitions */
+  --transition-fast: 150ms ease;
+  --transition-base: 250ms ease;
+  --transition-slow: 350ms ease;
+}
+
+/* Dark mode (black with light gold) */
+[data-theme="dark"] {
+  --color-bg-primary: #0a0a0a;
+  --color-bg-secondary: #1a1a1a;
+  --color-bg-tertiary: #2a2a2a;
+  --color-text-primary: #e9ecef;
+  --color-text-secondary: #adb5bd;
+  --color-border: #3a3a3a;
+  --color-accent: #daa520; /* Light gold */
+  --color-accent-hover: #ffd700;
+  --color-accent-light: #f0e68c;
+  --color-success: #4caf50;
+  --color-error: #f44336;
+  --color-warning: #ff9800;
+}
+
+* {
+  margin: 0;
+  padding: 0;
+  box-sizing: border-box;
+}
+
+html {
+  font-size: 16px;
+}
+
+body {
+  font-family: -apple-system, BlinkMacSystemFont, 'Segoe UI', 'Roboto', 'Oxygen',
+    'Ubuntu', 'Cantarell', 'Fira Sans', 'Droid Sans', 'Helvetica Neue',
+    sans-serif;
+  line-height: 1.6;
+  color: var(--color-text-primary);
+  background-color: var(--color-bg-primary);
+  -webkit-font-smoothing: antialiased;
+  -moz-osx-font-smoothing: grayscale;
+  transition: background-color var(--transition-base), color var(--transition-base);
+}
+
+#app {
+  min-height: 100vh;
+}
+
+/* Typography */
+h1 {
+  font-size: 2.5rem;
+  font-weight: 700;
+  letter-spacing: -0.02em;
+  color: var(--color-text-primary);
+  margin-bottom: var(--space-lg);
+}
+
+h2 {
+  font-size: 1.75rem;
+  font-weight: 600;
+  color: var(--color-text-primary);
+  margin-bottom: var(--space-md);
+}
+
+h3 {
+  font-size: 1.25rem;
+  font-weight: 600;
+  color: var(--color-text-primary);
+  margin-bottom: var(--space-sm);
+}
+
+p {
+  color: var(--color-text-secondary);
+  margin-bottom: var(--space-md);
+}
+
+/* Buttons */
+button, .btn {
+  display: inline-flex;
+  align-items: center;
+  justify-content: center;
+  gap: var(--space-sm);
+  padding: var(--space-sm) var(--space-lg);
+  font-size: 1rem;
+  font-weight: 500;
+  font-family: inherit;
+  color: var(--color-bg-primary);
+  background-color: var(--color-accent);
+  border: 2px solid transparent;
+  border-radius: var(--radius-md);
+  cursor: pointer;
+  transition: all var(--transition-fast);
+  text-decoration: none;
+  white-space: nowrap;
+}
+
+button:hover:not(:disabled), .btn:hover:not(:disabled) {
+  background-color: var(--color-accent-hover);
+  transform: translateY(-1px);
+  box-shadow: var(--shadow-md);
+}
+
+button:active:not(:disabled), .btn:active:not(:disabled) {
+  transform: translateY(0);
+}
+
+button:disabled, .btn:disabled {
+  opacity: 0.5;
+  cursor: not-allowed;
+}
+
+button.btn-secondary {
+  background-color: var(--color-bg-tertiary);
+  color: var(--color-text-primary);
+  border-color: var(--color-border);
+}
+
+button.btn-secondary:hover:not(:disabled) {
+  background-color: var(--color-bg-secondary);
+  border-color: var(--color-accent);
+}
+
+button.btn-outline {
+  background-color: transparent;
+  color: var(--color-accent);
+  border-color: var(--color-accent);
+}
+
+button.btn-outline:hover:not(:disabled) {
+  background-color: var(--color-accent);
+  color: var(--color-bg-primary);
+}
+
+/* Inputs */
+input[type="text"],
+input[type="number"],
+input[type="file"],
+select {
+  width: 100%;
+  padding: var(--space-sm) var(--space-md);
+  font-size: 1rem;
+  font-family: inherit;
+  color: var(--color-text-primary);
+  background-color: var(--color-bg-secondary);
+  border: 2px solid var(--color-border);
+  border-radius: var(--radius-md);
+  transition: all var(--transition-fast);
+}
+
+input[type="text"]:focus,
+input[type="number"]:focus,
+input[type="file"]:focus,
+select:focus {
+  outline: none;
+  border-color: var(--color-accent);
+  box-shadow: 0 0 0 3px rgba(218, 165, 32, 0.1);
+}
+
+input[type="range"] {
+  width: 100%;
+  height: 6px;
+  -webkit-appearance: none;
+  appearance: none;
+  background: var(--color-bg-tertiary);
+  border-radius: var(--radius-full);
+  outline: none;
+}
+
+input[type="range"]::-webkit-slider-thumb {
+  -webkit-appearance: none;
+  appearance: none;
+  width: 20px;
+  height: 20px;
+  background: var(--color-accent);
+  border-radius: 50%;
+  cursor: pointer;
+  transition: all var(--transition-fast);
+}
+
+input[type="range"]::-webkit-slider-thumb:hover {
+  background: var(--color-accent-hover);
+  transform: scale(1.1);
+}
+
+input[type="range"]::-moz-range-thumb {
+  width: 20px;
+  height: 20px;
+  background: var(--color-accent);
+  border: none;
+  border-radius: 50%;
+  cursor: pointer;
+  transition: all var(--transition-fast);
+}
+
+input[type="range"]::-moz-range-thumb:hover {
+  background: var(--color-accent-hover);
+  transform: scale(1.1);
+}
+
+/* Cards */
+.card {
+  background-color: var(--color-bg-secondary);
+  border: 1px solid var(--color-border);
+  border-radius: var(--radius-lg);
+  padding: var(--space-xl);
+  box-shadow: var(--shadow-sm);
+  transition: all var(--transition-base);
+}
+
+.card:hover {
+  box-shadow: var(--shadow-md);
+}
+
+/* Utility classes */
+.container {
+  width: 100%;
+  max-width: 1400px;
+  margin: 0 auto;
+  padding: var(--space-xl);
+}
+
+.flex {
+  display: flex;
+}
+
+.flex-col {
+  flex-direction: column;
+}
+
+.items-center {
+  align-items: center;
+}
+
+.justify-between {
+  justify-content: space-between;
+}
+
+.gap-sm {
+  gap: var(--space-sm);
+}
+
+.gap-md {
+  gap: var(--space-md);
+}
+
+.gap-lg {
+  gap: var(--space-lg);
+}
+
+.grid {
+  display: grid;
+}
+
+.grid-cols-2 {
+  grid-template-columns: repeat(2, 1fr);
+}
+
+.text-center {
+  text-align: center;
+}
+
+.text-sm {
+  font-size: 0.875rem;
+}
+
+.text-xs {
+  font-size: 0.75rem;
+}
+
+.font-medium {
+  font-weight: 500;
+}
+
+.font-semibold {
+  font-weight: 600;
+}
+
+.mb-0 {
+  margin-bottom: 0;
+}
+
+.mt-auto {
+  margin-top: auto;
+}
+
+/* Scrollbar styling */
+::-webkit-scrollbar {
+  width: 10px;
+  height: 10px;
+}
+
+::-webkit-scrollbar-track {
+  background: var(--color-bg-secondary);
+}
+
+::-webkit-scrollbar-thumb {
+  background: var(--color-border);
+  border-radius: var(--radius-full);
+}
+
+::-webkit-scrollbar-thumb:hover {
+  background: var(--color-accent);
+}
+
+/* Animations */
+@keyframes fadeIn {
+  from {
+    opacity: 0;
+    transform: translateY(10px);
+  }
+  to {
+    opacity: 1;
+    transform: translateY(0);
+  }
+}
+
+.fade-in {
+  animation: fadeIn var(--transition-base) ease-out;
+}
+
+@keyframes spin {
+  to {
+    transform: rotate(360deg);
+  }
+}
+
+.spinner {
+  animation: spin 1s linear infinite;
+}
+
+/* Responsive */
+@media (max-width: 768px) {
+  html {
+    font-size: 14px;
+  }
+
+  .container {
+    padding: var(--space-md);
+  }
+
+  h1 {
+    font-size: 2rem;
+  }
+
+  .grid-cols-2 {
+    grid-template-columns: 1fr;
+  }
+}

frontend/src/lib/presets.ts

@@ -0,0 +1,128 @@
+/**
+ * Smart Presets for common image transformation use cases
+ */
+
+export interface Preset {
+  name: string;
+  description: string;
+  icon: string;
+  width?: number;
+  height?: number;
+  quality: number;
+  format: 'png' | 'webp' | 'jpeg';
+  fit: 'inside' | 'cover';
+}
+
+export const PRESETS: Preset[] = [
+  {
+    name: 'Web Thumbnail',
+    description: 'Small, optimized for web (300x300)',
+    icon: '🖼️',
+    width: 300,
+    height: 300,
+    quality: 75,
+    format: 'webp',
+    fit: 'cover'
+  },
+  {
+    name: 'Social Media',
+    description: 'Open Graph image (1200x630)',
+    icon: '📱',
+    width: 1200,
+    height: 630,
+    quality: 85,
+    format: 'png',
+    fit: 'cover'
+  },
+  {
+    name: 'Profile Picture',
+    description: 'Square avatar (400x400)',
+    icon: '👤',
+    width: 400,
+    height: 400,
+    quality: 85,
+    format: 'png',
+    fit: 'cover'
+  },
+  {
+    name: 'Email Friendly',
+    description: 'Compressed for email',
+    icon: '📧',
+    width: 600,
+    quality: 70,
+    format: 'jpeg',
+    fit: 'inside'
+  },
+  {
+    name: 'HD Quality',
+    description: 'High resolution (1920px wide)',
+    icon: '⭐',
+    width: 1920,
+    quality: 90,
+    format: 'png',
+    fit: 'inside'
+  },
+  {
+    name: 'Retina @2x',
+    description: 'Double size for high-DPI',
+    icon: '🔍',
+    quality: 85,
+    format: 'png',
+    fit: 'inside'
+  },
+  {
+    name: 'Icon Small',
+    description: 'Tiny icon (64x64)',
+    icon: '🔷',
+    width: 64,
+    height: 64,
+    quality: 100,
+    format: 'png',
+    fit: 'cover'
+  },
+  {
+    name: 'Icon Large',
+    description: 'Large icon (256x256)',
+    icon: '🔶',
+    width: 256,
+    height: 256,
+    quality: 100,
+    format: 'png',
+    fit: 'cover'
+  }
+];
+
+/**
+ * Apply a preset to current settings
+ * For Retina @2x, we double the current dimensions
+ */
+export function applyPreset(
+  preset: Preset,
+  currentWidth?: number | null,
+  currentHeight?: number | null
+): {
+  width: number | null;
+  height: number | null;
+  quality: number;
+  format: 'png' | 'webp' | 'jpeg';
+  fit: 'inside' | 'cover';
+} {
+  // Special handling for Retina @2x preset
+  if (preset.name === 'Retina @2x') {
+    return {
+      width: currentWidth ? currentWidth * 2 : null,
+      height: currentHeight ? currentHeight * 2 : null,
+      quality: preset.quality,
+      format: preset.format,
+      fit: preset.fit
+    };
+  }
+
+  return {
+    width: preset.width || null,
+    height: preset.height || null,
+    quality: preset.quality,
+    format: preset.format,
+    fit: preset.fit
+  };
+}

frontend/src/lib/preview.ts

@@ -0,0 +1,279 @@
+export interface TransformOptions {
+  width?: number;
+  height?: number;
+  quality: number;
+  format: 'png' | 'webp' | 'jpeg';
+  fit: 'inside' | 'cover';
+  position?: string;
+}
+
+/**
+ * Generate a client-side preview using Canvas API
+ * This provides instant feedback without server round-trip
+ */
+export async function generateClientPreview(
+  file: File,
+  options: TransformOptions
+): Promise<string> {
+  return new Promise((resolve, reject) => {
+    const img = new Image();
+    const canvas = document.createElement('canvas');
+    const ctx = canvas.getContext('2d');
+
+    if (!ctx) {
+      reject(new Error('Canvas context not available'));
+      return;
+    }
+
+    img.onload = () => {
+      try {
+        const { width, height } = calculateDimensions(img, options);
+        
+        canvas.width = width;
+        canvas.height = height;
+
+        if (options.fit === 'cover' && options.width && options.height) {
+          drawCover(ctx, img, options.width, options.height, options.position || 'center');
+        } else {
+          ctx.drawImage(img, 0, 0, width, height);
+        }
+
+        // Convert to data URL with quality - fix MIME type mapping
+        const quality = options.quality / 100;
+        let mimeType: string;
+        
+        // Map format to proper MIME type
+        switch (options.format) {
+          case 'jpeg':
+            mimeType = 'image/jpeg';
+            break;
+          case 'webp':
+            mimeType = 'image/webp';
+            break;
+          case 'png':
+          default:
+            mimeType = 'image/png';
+            break;
+        }
+        
+        // For PNG, quality doesn't apply in Canvas API (always lossless)
+        // For JPEG and WebP, quality matters
+        const dataUrl = options.format === 'png' 
+          ? canvas.toDataURL(mimeType)
+          : canvas.toDataURL(mimeType, quality);
+        
+        resolve(dataUrl);
+      } catch (error) {
+        reject(error);
+      }
+    };
+
+    img.onerror = () => {
+      reject(new Error('Failed to load image'));
+    };
+
+    img.src = URL.createObjectURL(file);
+  });
+}
+
+/**
+ * Calculate dimensions for resize operation
+ */
+function calculateDimensions(
+  img: HTMLImageElement,
+  options: TransformOptions
+): { width: number; height: number } {
+  const originalWidth = img.naturalWidth;
+  const originalHeight = img.naturalHeight;
+  const originalAspect = originalWidth / originalHeight;
+
+  // If no dimensions specified, return original
+  if (!options.width && !options.height) {
+    return { width: originalWidth, height: originalHeight };
+  }
+
+  // If only width specified
+  if (options.width && !options.height) {
+    return {
+      width: options.width,
+      height: Math.round(options.width / originalAspect)
+    };
+  }
+
+  // If only height specified
+  if (options.height && !options.width) {
+    return {
+      width: Math.round(options.height * originalAspect),
+      height: options.height
+    };
+  }
+
+  // Both dimensions specified
+  const targetWidth = options.width!;
+  const targetHeight = options.height!;
+  const targetAspect = targetWidth / targetHeight;
+
+  if (options.fit === 'cover') {
+    // Fill the box, crop excess
+    return { width: targetWidth, height: targetHeight };
+  } else {
+    // Fit inside box, maintain aspect ratio
+    if (originalAspect > targetAspect) {
+      // Image is wider
+      return {
+        width: targetWidth,
+        height: Math.round(targetWidth / originalAspect)
+      };
+    } else {
+      // Image is taller
+      return {
+        width: Math.round(targetHeight * originalAspect),
+        height: targetHeight
+      };
+    }
+  }
+}
+
+/**
+ * Draw image with cover fit (crop to fill)
+ */
+function drawCover(
+  ctx: CanvasRenderingContext2D,
+  img: HTMLImageElement,
+  targetWidth: number,
+  targetHeight: number,
+  position: string
+) {
+  const imgWidth = img.naturalWidth;
+  const imgHeight = img.naturalHeight;
+  const imgAspect = imgWidth / imgHeight;
+  const targetAspect = targetWidth / targetHeight;
+
+  let sourceWidth: number;
+  let sourceHeight: number;
+  let sourceX = 0;
+  let sourceY = 0;
+
+  if (imgAspect > targetAspect) {
+    // Image is wider, crop sides
+    sourceHeight = imgHeight;
+    sourceWidth = imgHeight * targetAspect;
+    sourceX = getPositionOffset(imgWidth - sourceWidth, position, 'horizontal');
+  } else {
+    // Image is taller, crop top/bottom
+    sourceWidth = imgWidth;
+    sourceHeight = imgWidth / targetAspect;
+    sourceY = getPositionOffset(imgHeight - sourceHeight, position, 'vertical');
+  }
+
+  ctx.drawImage(
+    img,
+    sourceX,
+    sourceY,
+    sourceWidth,
+    sourceHeight,
+    0,
+    0,
+    targetWidth,
+    targetHeight
+  );
+}
+
+/**
+ * Calculate crop offset based on position
+ */
+function getPositionOffset(
+  availableSpace: number,
+  position: string,
+  axis: 'horizontal' | 'vertical'
+): number {
+  const pos = position.toLowerCase();
+
+  if (axis === 'horizontal') {
+    if (pos.includes('left')) return 0;
+    if (pos.includes('right')) return availableSpace;
+    return availableSpace / 2; // center
+  } else {
+    if (pos.includes('top')) return 0;
+    if (pos.includes('bottom')) return availableSpace;
+    return availableSpace / 2; // center
+  }
+}
+
+/**
+ * Estimate file size from data URL
+ * More accurate calculation that accounts for base64 overhead
+ */
+export function estimateSize(dataUrl: string): number {
+  const parts = dataUrl.split(',');
+  if (parts.length < 2) return 0;
+  
+  const base64 = parts[1];
+  if (!base64) return 0;
+  
+  // Remove padding characters for accurate calculation
+  const withoutPadding = base64.replace(/=/g, '');
+  
+  // Base64 encoding: 3 bytes -> 4 characters
+  // So to get original bytes: (length * 3) / 4
+  const bytes = (withoutPadding.length * 3) / 4;
+  
+  // Account for padding bytes if present
+  const paddingCount = base64.length - withoutPadding.length;
+  
+  return Math.round(bytes - paddingCount);
+}
+
+/**
+ * Format bytes to human-readable size
+ */
+export function formatFileSize(bytes: number): string {
+  if (bytes === 0) return '0 B';
+  if (bytes < 1024) return `${bytes} B`;
+  if (bytes < 1024 * 1024) return `${(bytes / 1024).toFixed(1)} KB`;
+  return `${(bytes / (1024 * 1024)).toFixed(2)} MB`;
+}
+
+/**
+ * Calculate savings/increase
+ */
+export function calculateSavings(original: number, modified: number): {
+  amount: number;
+  percent: number;
+  isReduction: boolean;
+  formatted: string;
+} {
+  const diff = original - modified;
+  const percent = (Math.abs(diff) / original) * 100;
+  const isReduction = diff > 0;
+
+  let formatted: string;
+  if (diff > 0) {
+    formatted = `↓ ${formatFileSize(diff)} saved (${percent.toFixed(1)}%)`;
+  } else if (diff < 0) {
+    formatted = `↑ ${formatFileSize(Math.abs(diff))} larger (${percent.toFixed(1)}%)`;
+  } else {
+    formatted = 'Same size';
+  }
+
+  return {
+    amount: Math.abs(diff),
+    percent,
+    isReduction,
+    formatted
+  };
+}
+
+/**
+ * Debounce function for performance
+ */
+export function debounce<T extends (...args: any[]) => any>(
+  func: T,
+  wait: number
+): (...args: Parameters<T>) => void {
+  let timeout: ReturnType<typeof setTimeout>;
+  return (...args: Parameters<T>) => {
+    clearTimeout(timeout);
+    timeout = setTimeout(() => func(...args), wait);
+  };
+}

frontend/src/lib/theme.ts

@@ -0,0 +1,60 @@
+import { writable } from 'svelte/store';
+
+export type Theme = 'light' | 'dark';
+
+// Get initial theme from localStorage or system preference
+function getInitialTheme(): Theme {
+  if (typeof window === 'undefined') return 'light';
+  
+  const stored = localStorage.getItem('theme') as Theme;
+  if (stored === 'light' || stored === 'dark') {
+    return stored;
+  }
+
+  // Check system preference
+  if (window.matchMedia('(prefers-color-scheme: dark)').matches) {
+    return 'dark';
+  }
+
+  return 'light';
+}
+
+// Create the theme store
+function createThemeStore() {
+  const { subscribe, set, update } = writable<Theme>(getInitialTheme());
+
+  return {
+    subscribe,
+    set: (theme: Theme) => {
+      if (typeof window !== 'undefined') {
+        localStorage.setItem('theme', theme);
+        document.documentElement.setAttribute('data-theme', theme);
+      }
+      set(theme);
+    },
+    toggle: () => {
+      update(current => {
+        const newTheme = current === 'light' ? 'dark' : 'light';
+        if (typeof window !== 'undefined') {
+          localStorage.setItem('theme', newTheme);
+          document.documentElement.setAttribute('data-theme', newTheme);
+        }
+        return newTheme;
+      });
+    },
+    init: () => {
+      const theme = getInitialTheme();
+      if (typeof window !== 'undefined') {
+        document.documentElement.setAttribute('data-theme', theme);
+      }
+      set(theme);
+    }
+  };
+}
+
+export const theme = createThemeStore();
+
+// Initialize theme on module load
+if (typeof window !== 'undefined') {
+  theme.init();
+}