diff --git a/.github/agents.md b/.github/agents.md
new file mode 100644
index 0000000..954eedb
--- /dev/null
+++ b/.github/agents.md
@@ -0,0 +1,265 @@
+# GitHub Copilot Agent Personas
+
+This file defines specialized agent personas for the Espargne retirement planning application. These agents have specific roles, boundaries, and capabilities tailored to this project.
+
+---
+
+## Test Agent
+
+**Name**: `test-agent`  
+**Description**: Writes and maintains comprehensive test suites for the TypeScript/React retirement planning application.
+
+### Responsibilities
+- Write new unit tests using Vitest framework
+- Update existing tests when code changes
+- Ensure test coverage for financial calculations
+- Validate Big.js precision in tests
+- Test React component behavior
+
+### Technology Stack
+- **Test Framework**: Vitest 4.0.18
+- **React Testing**: @testing-library/react 16.3.2
+- **Assertion Library**: Vitest built-in matchers
+- **Coverage Tool**: v8 (via Vitest)
+
+### Commands
+```bash
+pnpm test run              # Run all tests once
+pnpm test                  # Watch mode
+pnpm test:ui               # Interactive UI
+pnpm test:coverage         # Generate coverage report
+```
+
+### Boundaries & Constraints
+- ✅ **DO**: Write tests in `src/tests/` directory
+- ✅ **DO**: Use Big.js helpers for financial assertions
+- ✅ **DO**: Follow existing test patterns and naming conventions
+- ✅ **DO**: Ensure tests are deterministic and isolated
+- ❌ **DO NOT**: Modify production code in `src/lib/` without explicit request
+- ❌ **DO NOT**: Remove or skip existing tests
+- ❌ **DO NOT**: Use floating-point numbers for currency assertions
+- ❌ **DO NOT**: Commit test artifacts or coverage files
+
+### Test Patterns
+```typescript
+// Good: Using Big.js for financial assertions
+import { toBig, multiply } from '../lib/bigHelpers';
+
+test('calculates correct balance growth', () => {
+  const balance = toBig(100000);
+  const growth = multiply(balance, 0.05);
+  expect(growth.toString()).toBe('5000.00');
+});
+
+// Bad: Using raw numbers for currency
+test('calculates balance growth', () => {
+  const balance = 100000;
+  const growth = balance * 0.05;  // ❌ Floating-point errors
+  expect(growth).toBe(5000);
+});
+```
+
+### Coverage Targets
+- **Overall**: 80%+ coverage maintained
+- **Critical Paths**: 100% coverage for:
+  - Tax calculations (`taxCalculator.ts`)
+  - RMD calculations (`rmdCalculator.ts`)
+  - Withdrawal coordinator (`withdrawalCoordinator.ts`)
+  - Big.js helpers (`bigHelpers.ts`)
+
+---
+
+## Documentation Agent
+
+**Name**: `docs-agent`  
+**Description**: Maintains and improves documentation for the retirement planning application.
+
+### Responsibilities
+- Update README.md and documentation files
+- Keep inline code comments current
+- Update API documentation when interfaces change
+- Maintain architectural decision records
+- Update copilot-instructions.md when patterns change
+
+### Technology Stack
+- **Format**: Markdown
+- **Code Docs**: TSDoc comments
+- **Architecture Docs**: ADR format (optional)
+
+### Commands
+```bash
+pnpm build       # Verify TypeScript compiles
+pnpm dev         # Test documentation examples work
+```
+
+### Boundaries & Constraints
+- ✅ **DO**: Update documentation when code changes
+- ✅ **DO**: Keep examples accurate and tested
+- ✅ **DO**: Use clear, concise language
+- ✅ **DO**: Include code examples with proper syntax highlighting
+- ❌ **DO NOT**: Make breaking changes to public APIs
+- ❌ **DO NOT**: Remove or significantly alter existing documentation without discussion
+- ❌ **DO NOT**: Include sensitive information or credentials
+- ❌ **DO NOT**: Modify `.github/copilot-instructions.md` without clear justification
+
+### Documentation Files
+- `README.md` - Project overview, setup, features
+- `.github/copilot-instructions.md` - Coding patterns and conventions
+- `.github/instructions/CodingConventions.instructions.md` - Code style rules
+- `VISUALIZATION_PORT.md` - Chart implementation details
+- `WITHDRAWAL_COORDINATOR.md` - Withdrawal strategy documentation
+
+---
+
+## Build Agent
+
+**Name**: `build-agent`  
+**Description**: Handles build configuration, dependencies, and deployment setup.
+
+### Responsibilities
+- Update build configuration when needed
+- Manage dependency updates (with security checks)
+- Optimize build performance
+- Configure deployment pipelines
+- Maintain GitHub Actions workflows
+
+### Technology Stack
+- **Build Tool**: Vite 7.2.4
+- **Package Manager**: pnpm 10.x
+- **CI/CD**: GitHub Actions
+- **Deployment**: GitHub Pages (static site)
+
+### Commands
+```bash
+pnpm install     # Install dependencies
+pnpm build       # Production build
+pnpm preview     # Test production build locally
+```
+
+### Boundaries & Constraints
+- ✅ **DO**: Test build changes locally before committing
+- ✅ **DO**: Check security advisories before updating dependencies
+- ✅ **DO**: Maintain Node.js version compatibility (20.19+, 22.12+)
+- ✅ **DO**: Preserve build output size (~686KB target)
+- ❌ **DO NOT**: Update major versions without testing
+- ❌ **DO NOT**: Add unnecessary dependencies
+- ❌ **DO NOT**: Change deployment configuration without approval
+- ❌ **DO NOT**: Commit `node_modules/`, `dist/`, or lock files unnecessarily
+
+### Critical Dependencies
+- `big.js@7.0.1` - Must maintain version for financial precision
+- `react@19.2.0` - Core framework
+- `vite@7.2.4` - Build tool (requires Node 20.19+/22.12+)
+- `recharts@2.12.7` - Visualization library
+
+---
+
+## Code Agent (Default)
+
+**Name**: `code-agent`  
+**Description**: General-purpose coding agent for feature development and bug fixes.
+
+### Responsibilities
+- Implement new features
+- Fix bugs and issues
+- Refactor code for maintainability
+- Optimize performance
+- Ensure code quality and type safety
+
+### Technology Stack
+- **Language**: TypeScript 5.9.3 (strict mode)
+- **Framework**: React 19.2.0
+- **State Management**: React hooks + localStorage
+- **Styling**: CSS Modules
+- **Financial Math**: Big.js 7.0.1
+
+### Commands
+```bash
+pnpm dev         # Start dev server
+pnpm build       # Build and type check
+pnpm test        # Run tests
+```
+
+### Boundaries & Constraints
+- ✅ **DO**: Use Big.js for all financial calculations
+- ✅ **DO**: Follow existing code patterns and conventions
+- ✅ **DO**: Write tests for new features
+- ✅ **DO**: Use TypeScript strict mode
+- ✅ **DO**: Follow form visibility toggle pattern
+- ❌ **DO NOT**: Use JavaScript number type for currency
+- ❌ **DO NOT**: Inline CSS styles in JSX
+- ❌ **DO NOT**: Add console.log statements in production code
+- ❌ **DO NOT**: Modify financial calculation logic without extensive testing
+- ❌ **DO NOT**: Change localStorage keys without migration path
+
+### Critical Code Patterns
+See `.github/copilot-instructions.md` for detailed patterns including:
+- Big.js for financial calculations
+- Account type discrimination
+- localStorage persistence
+- Form callback pattern
+- Component organization
+
+---
+
+## General Guidelines for All Agents
+
+### Security & Privacy
+- Never commit secrets, API keys, or credentials
+- Validate all user inputs
+- Use Big.js to avoid floating-point security issues
+- Keep dependencies updated for security patches
+
+### Quality Standards
+- Maintain TypeScript strict mode compliance
+- Write deterministic, testable code
+- Follow existing architectural patterns
+- Keep functions small and focused
+- Use explicit return types
+
+### Collaboration
+- Create clear, focused PRs
+- Write descriptive commit messages
+- Request review for significant changes
+- Update documentation with code changes
+- Run tests before committing
+
+### Temporary Files
+**Always use `/tmp/espargne-web/` for temporary files:**
+```bash
+mkdir -p /tmp/espargne-web
+# Use for: logs, test artifacts, debug output, temporary scripts
+# Clean up when finished
+```
+
+---
+
+## Agent Selection Guide
+
+**For testing tasks**: Use `@test-agent`
+- Writing new tests
+- Fixing failing tests
+- Improving test coverage
+- Test refactoring
+
+**For documentation**: Use `@docs-agent`
+- README updates
+- API documentation
+- Architecture docs
+- Comment updates
+
+**For build/deploy**: Use `@build-agent`
+- Dependency updates
+- Build configuration
+- CI/CD workflows
+- Performance optimization
+
+**For feature work**: Use `@code-agent` (default)
+- New features
+- Bug fixes
+- Code refactoring
+- UI improvements
+
+**For complex tasks**: Combine agents
+- Feature + tests: `@code-agent` then `@test-agent`
+- Build change + docs: `@build-agent` then `@docs-agent`
diff --git a/.github/workflows/ci.yml b/.github/workflows/ci.yml
new file mode 100644
index 0000000..3339480
--- /dev/null
+++ b/.github/workflows/ci.yml
@@ -0,0 +1,83 @@
+name: CI
+
+on:
+  push:
+    branches: [ main ]
+  pull_request:
+    branches: [ main ]
+
+jobs:
+  test:
+    name: Build and Test
+    runs-on: ubuntu-latest
+    
+    strategy:
+      matrix:
+        node-version: [20.19.x, 22.12.x]
+    
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10
+      
+      - name: Setup Node.js ${{ matrix.node-version }}
+        uses: actions/setup-node@v4
+        with:
+          node-version: ${{ matrix.node-version }}
+          cache: 'pnpm'
+      
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+      
+      - name: Run tests (if tests exist)
+        run: pnpm test run || echo "No tests found - skipping"
+        continue-on-error: true
+      
+      - name: Build
+        run: pnpm build
+      
+      - name: Clean coverage directory
+        if: matrix.node-version == '22.12.x'
+        run: rm -rf coverage
+      
+      - name: Generate coverage report
+        if: matrix.node-version == '22.12.x'
+        run: pnpm test:coverage
+      
+      - name: Upload coverage to GitHub
+        if: matrix.node-version == '22.12.x' && hashFiles('coverage/coverage-final.json') != ''
+        uses: actions/upload-artifact@v4
+        with:
+          name: coverage-report
+          path: coverage/
+          if-no-files-found: error
+          retention-days: 7
+
+  lint:
+    name: Lint Code
+    runs-on: ubuntu-latest
+    
+    steps:
+      - name: Checkout code
+        uses: actions/checkout@v4
+      
+      - name: Setup pnpm
+        uses: pnpm/action-setup@v4
+        with:
+          version: 10
+      
+      - name: Setup Node.js
+        uses: actions/setup-node@v4
+        with:
+          node-version: 22.12.x
+          cache: 'pnpm'
+      
+      - name: Install dependencies
+        run: pnpm install --frozen-lockfile
+      
+      - name: Run ESLint
+        run: pnpm lint
diff --git a/CONTRIBUTING.md b/CONTRIBUTING.md
new file mode 100644
index 0000000..9fd1b25
--- /dev/null
+++ b/CONTRIBUTING.md
@@ -0,0 +1,308 @@
+# Contributing to Espargne
+
+Thank you for your interest in contributing to Espargne! This document provides guidelines for contributing to the project.
+
+## Table of Contents
+
+- [Code of Conduct](#code-of-conduct)
+- [Getting Started](#getting-started)
+- [Development Workflow](#development-workflow)
+- [Coding Standards](#coding-standards)
+- [Testing Guidelines](#testing-guidelines)
+- [Pull Request Process](#pull-request-process)
+- [Working with Copilot Agent](#working-with-copilot-agent)
+
+## Code of Conduct
+
+This project follows standard open-source community guidelines:
+- Be respectful and inclusive
+- Focus on constructive feedback
+- Prioritize collaboration over ego
+- Help others learn and grow
+
+## Getting Started
+
+### Prerequisites
+
+- Node.js 20.19+ or 22.12+
+- pnpm package manager (10.x)
+- Git for version control
+
+### Initial Setup
+
+```bash
+# Clone the repository
+git clone https://github.com/frouaix/espargne-web.git
+cd espargne-web
+
+# Install dependencies
+pnpm install
+
+# Start development server
+pnpm dev
+
+# Run tests
+pnpm test
+```
+
+The development server will be available at `http://localhost:5174`.
+
+## Development Workflow
+
+### 1. Create a Branch
+
+```bash
+git checkout -b feature/your-feature-name
+# or
+git checkout -b fix/bug-description
+```
+
+Branch naming conventions:
+- `feature/` - New features
+- `fix/` - Bug fixes
+- `docs/` - Documentation changes
+- `refactor/` - Code refactoring
+- `test/` - Test additions or updates
+
+### 2. Make Changes
+
+- Follow the coding standards (see below)
+- Write tests for new functionality
+- Update documentation as needed
+- Keep commits small and focused
+
+### 3. Test Your Changes
+
+```bash
+# Run linter
+pnpm lint
+
+# Run type check
+pnpm build  # Includes type checking
+
+# Run tests
+pnpm test run
+
+# Generate coverage report
+pnpm test:coverage
+```
+
+### 4. Commit Your Changes
+
+Write clear, descriptive commit messages:
+
+```bash
+git add .
+git commit -m "feat: Add Monte Carlo simulation variance control"
+# or
+git commit -m "fix: Correct RMD calculation for age 73-75"
+# or
+git commit -m "docs: Update withdrawal strategy documentation"
+```
+
+Commit message prefixes:
+- `feat:` - New feature
+- `fix:` - Bug fix
+- `docs:` - Documentation only
+- `style:` - Code style/formatting
+- `refactor:` - Code refactoring
+- `test:` - Test changes
+- `chore:` - Build/tooling changes
+
+### 5. Push and Create PR
+
+```bash
+git push origin your-branch-name
+```
+
+Then create a Pull Request on GitHub.
+
+## Coding Standards
+
+### TypeScript Conventions
+
+See `.github/instructions/CodingConventions.instructions.md` for detailed rules. Key points:
+
+- **Always use semicolons** (`;`)
+- **Use explicit return types** for functions
+- **Prefer destructuring** over direct property access
+- **No console.log** in production code
+- **No inline CSS** - use CSS Modules or styled components
+
+### Financial Calculations
+
+**CRITICAL**: Always use Big.js for monetary values:
+
+```typescript
+// ✅ Correct
+import { toBig, multiply } from '../lib/bigHelpers';
+const balance = toBig(100000);
+const growth = multiply(balance, 0.05);
+
+// ❌ Wrong - Floating-point errors
+const balance = 100000;
+const growth = balance * 0.05;
+```
+
+### Component Patterns
+
+Follow established patterns (see `.github/copilot-instructions.md`):
+- Form visibility toggle pattern
+- localStorage persistence pattern
+- Account type discrimination
+- Form callback pattern
+
+## Testing Guidelines
+
+### Test Coverage Requirements
+
+- **Minimum 80% overall coverage**
+- **100% coverage for critical paths**:
+  - Tax calculations
+  - RMD calculations
+  - Withdrawal coordination
+  - Big.js helpers
+
+### Writing Tests
+
+```typescript
+import { describe, it, expect } from 'vitest';
+import { toBig, multiply } from '../lib/bigHelpers';
+
+describe('Financial Calculation', () => {
+  it('should calculate correct balance growth', () => {
+    const balance = toBig(100000);
+    const rate = toBig(0.05);
+    const growth = multiply(balance, rate);
+    
+    expect(growth.toString()).toBe('5000.00');
+  });
+});
+```
+
+### Running Tests
+
+```bash
+# Run all tests
+pnpm test run
+
+# Watch mode
+pnpm test
+
+# UI mode
+pnpm test:ui
+
+# Coverage report
+pnpm test:coverage
+```
+
+## Pull Request Process
+
+### Before Submitting
+
+1. ✅ All tests pass (`pnpm test run`)
+2. ✅ Linter passes (`pnpm lint`)
+3. ✅ Build succeeds (`pnpm build`)
+4. ✅ Coverage maintained or improved
+5. ✅ Documentation updated if needed
+6. ✅ No console.log statements in code
+7. ✅ Git history is clean (squash if needed)
+
+### PR Template
+
+When creating a PR, include:
+
+```markdown
+## Description
+Brief description of changes
+
+## Type of Change
+- [ ] Bug fix
+- [ ] New feature
+- [ ] Documentation update
+- [ ] Refactoring
+- [ ] Testing
+
+## Testing
+- [ ] All existing tests pass
+- [ ] New tests added for new functionality
+- [ ] Manual testing completed
+
+## Checklist
+- [ ] Code follows project conventions
+- [ ] No console.log statements
+- [ ] Big.js used for all financial calculations
+- [ ] Documentation updated
+- [ ] Tests pass
+- [ ] Build succeeds
+```
+
+### Review Process
+
+1. **Automated Checks**: CI workflow runs automatically
+2. **Code Review**: Maintainer reviews code quality and approach
+3. **Feedback**: Address any requested changes
+4. **Approval**: Once approved, PR will be merged
+5. **Deployment**: Changes deploy automatically via GitHub Pages
+
+### Review Expectations
+
+- Respond to feedback within 48 hours
+- Be open to suggestions and improvements
+- Explain your approach if asked
+- Update PR based on feedback
+
+## Working with Copilot Agent
+
+This repository is configured for GitHub Copilot coding agent. See `.github/agents.md` for agent-specific guidelines.
+
+### Agent Personas
+
+- `@test-agent` - Testing tasks
+- `@docs-agent` - Documentation updates
+- `@build-agent` - Build/deployment configuration
+- `@code-agent` - General development (default)
+
+### Assigning Issues to Copilot
+
+When creating issues for Copilot agent:
+
+1. **Be specific**: Clear goal, acceptance criteria, affected files
+2. **Set boundaries**: What should/shouldn't be changed
+3. **Provide context**: Link to related issues or docs
+4. **Start small**: Well-scoped tasks work best
+
+Example:
+```markdown
+## Task
+Add validation for Social Security claiming age
+
+## Acceptance Criteria
+- Validate age is between 62-70
+- Show error message for invalid ages
+- Update tests to cover validation
+
+## Files to Modify
+- src/components/SSAIncomeForm.tsx
+- src/tests/integration/SSAIncomeForm.test.tsx
+
+## Constraints
+- Use existing form validation pattern
+- Don't modify SSA calculation logic
+- Include unit tests
+```
+
+## Getting Help
+
+- **Documentation**: See `.github/copilot-instructions.md`
+- **Issues**: Open a GitHub issue for bugs or feature requests
+- **Questions**: Start a GitHub Discussion
+- **Security**: Email security concerns privately
+
+## License
+
+By contributing, you agree that your contributions will be licensed under the MIT License.
+
+---
+
+Thank you for contributing to Espargne! 🎉
diff --git a/README.md b/README.md
index b08bc57..55adff1 100644
--- a/README.md
+++ b/README.md
@@ -226,6 +226,30 @@ This software is provided "AS IS" under the MIT License, WITHOUT WARRANTY OF ANY
 
 **By using this application, you acknowledge that you understand these limitations and accept full responsibility for your financial decisions.**
 
+## Contributing
+
+Contributions are welcome! This project is set up to work with GitHub Copilot coding agent.
+
+- See [CONTRIBUTING.md](CONTRIBUTING.md) for development guidelines and workflow
+- See [.github/agents.md](.github/agents.md) for Copilot agent personas and boundaries
+- See [.github/copilot-instructions.md](.github/copilot-instructions.md) for detailed coding patterns
+
+### Quick Start for Contributors
+
+```bash
+git clone https://github.com/frouaix/espargne-web.git
+cd espargne-web
+pnpm install
+pnpm dev
+pnpm test
+```
+
+Before submitting a PR:
+- ✅ Run tests: `pnpm test run`
+- ✅ Run linter: `pnpm lint`
+- ✅ Run build: `pnpm build`
+- ✅ Update documentation if needed
+
 ## License
 
 MIT License - see [LICENSE](LICENSE) file for details.