fix: resolve boundary condition bug for exact-fit parts

CLAUDE.md

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+# CLAUDE.md
+
+This file provides guidance to Claude Code (claude.ai/code) when working with code in this repository.
+
+## Project Overview
+
+**deepnest** is an Electron-based desktop application for nesting parts for CNC tools, laser cutters, and plotters. It's a fork of the original SVGNest and deepnest projects with performance improvements and new features.
+
+Key technologies:
+- **Electron** with Node.js backend
+- **TypeScript** for type safety (compiled to JavaScript)
+- **Custom nesting engine** with C/C++ components via native modules
+- **Web-based UI** with SVG rendering
+- **Genetic algorithm** for optimization
+- **Clipper library** for polygon operations
+
+## Common Development Commands
+
+### Building and Running
+```bash
+# Install dependencies
+npm install
+
+# Build TypeScript to JavaScript
+npm run build
+
+# Start the application
+npm run start
+
+# Clean build artifacts
+npm run clean
+
+# Full clean including node_modules
+npm run clean-all
+```
+
+### Testing
+```bash
+# Run Playwright tests (requires one-time setup)
+npx playwright install chromium
+npm run test
+
+# Generate new tests interactively
+npm run pw:codegen
+```
+
+### Code Quality
+```bash
+# Lint and format code (runs automatically via pre-commit hooks)
+prettier --write **/*.{ts,html,css,scss,less,json}
+eslint --fix **/*.{ts,html,css,scss,less,json}
+```
+
+### Distribution
+```bash
+# Create distribution package
+npm run dist
+
+# Build everything and create distribution
+npm run dist-all
+```
+
+## Architecture
+
+### Application Structure
+- **main.js** - Electron main process entry point
+- **main/** - Core application code
+  - **deepnest.js** - Main nesting algorithm and genetic optimization
+  - **background.js** - Background worker for intensive calculations
+  - **index.html** - Main UI
+  - **util/** - Utility modules (geometry, matrix operations, etc.)
+
+### Key Components
+
+1. **Main Process (main.js)**
+   - Creates Electron windows
+   - Handles IPC communication
+   - Manages background workers
+   - Handles file operations and settings
+
+2. **Nesting Engine (deepnest.js)**
+   - `DeepNest` class - Main nesting logic
+   - `GeneticAlgorithm` class - Optimization algorithm
+   - SVG parsing and polygon processing
+   - Clipper library integration for geometry operations
+
+3. **Background Workers**
+   - Separate renderer processes for CPU-intensive tasks
+   - Communicates via IPC with main process
+   - Prevents UI blocking during calculations
+
+4. **TypeScript Utilities (main/util/)**
+   - Geometry operations
+   - Point, Vector, Matrix classes
+   - Polygon hull calculations
+   - SVG parsing utilities
+
+### Key Algorithms
+- **Genetic Algorithm** for part placement optimization
+- **No-Fit Polygon (NFP)** calculation for collision detection
+- **Polygon offsetting** using Clipper library
+- **Curve simplification** with Douglas-Peucker algorithm
+
+## Development Notes
+
+### TypeScript Configuration
+- Strict mode enabled with comprehensive type checking
+- Outputs to `./build` directory
+- Targets ES2023 with DOM and Node.js types
+
+### Electron Configuration
+- Uses `@electron/remote` for renderer process access
+- Context isolation disabled for legacy compatibility
+- Node integration enabled in renderers
+
+### Testing
+- Uses Playwright for end-to-end testing
+- Headless mode disabled by default for debugging
+- Screenshots and videos captured on test failure
+
+### Native Dependencies
+- Requires C++ build tools (Visual Studio on Windows)
+- Uses `@deepnest/calculate-nfp` for performance-critical calculations
+- Electron rebuild required after native module changes
+
+### Environment Variables
+- `deepnest_debug=1` - Opens dev tools
+- `SAVE_PLACEMENTS_PATH` - Custom export directory
+- `DEEPNEST_LONGLIST` - Keep more nesting results
+
+## Important File Locations
+
+- **Entry point**: `main.js`
+- **Main UI**: `main/index.html`
+- **Core logic**: `main/deepnest.js`
+- **Background worker**: `main/background.js`
+- **TypeScript source**: `main/util/*.ts`
+- **Tests**: `tests/`
+- **Build output**: `build/`
+
+## Performance Considerations
+
+- Nesting calculations run in background processes to prevent UI freezing
+- Polygon simplification reduces complexity for better performance
+- Genetic algorithm parameters can be tuned via configuration
+- Native modules handle computationally intensive operations
+
+## Debugging
+
+Set `deepnest_debug=1` environment variable to enable Chrome DevTools in all Electron windows.
+
+## Known Issues and Recent Fixes
+
+### Boundary Condition Bug (Fixed)
+- **Issue**: A 100mm x 100mm part could not be placed in a 100mm x 100mm bin
+- **Root Cause**: The `noFitPolygonRectangle` function was never called from `noFitPolygon`, and exact-fit cases created degenerate polygons
+- **Fix**: 
+  - Added rectangle detection check in `noFitPolygon` function (`main/util/geometryutil.js:1594-1599`)
+  - Added special handling for exact-fit cases in `noFitPolygonRectangle` (`main/util/geometryutil.js:1581-1592`)
+- **Files Modified**: `main/util/geometryutil.js`