Add CLAUDE.md

Author: JayDoubleu

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
+
+This is an Azure AD MFA Report generator written in Python. It uses Azure CLI authentication to connect to Azure AD/Microsoft Graph API and generates an Excel report showing MFA registration status for all users in a tenant.
+
+## Development Commands
+
+### Setup and Dependencies
+```bash
+# Install dependencies (requires Poetry)
+poetry install --no-dev
+
+# Install development dependencies 
+poetry install
+
+# Select Python version if multiple installed
+poetry env use python3.9
+```
+
+### Running the Application
+```bash
+# Login to Azure CLI first
+az login
+
+# Run the MFA report generator
+poetry run mfa_report
+```
+
+### Code Quality Tools
+```bash
+# Format code with Black
+poetry run fmt
+
+# Run linting with flake8
+poetry run flake8
+
+# Type checking with mypy
+poetry run mypy .
+
+# Run tests
+poetry run pytest
+```
+
+## Architecture Overview
+
+### Core Components
+
+1. **main.py** - Entry point that orchestrates the entire MFA report generation:
+   - Handles SSL certificate configuration
+   - Authenticates using Azure CLI credentials
+   - Retrieves MFA registration details from graph.windows.net
+   - Fetches user account details from graph.microsoft.com
+   - Merges data and generates Excel report
+
+2. **helpers.py** - Contains all utility functions:
+   - `handle_custom_ssl()` - Injects custom CA certificates for SSL proxy environments
+   - `get_azure_credentials()` - Gets Azure CLI credentials
+   - `get_auth_user_details()` - Fetches MFA registration data
+   - `get_aad_users()` - Async parallel fetching of user details
+   - `xlsx_dict_prep()` - Prepares data for Excel export
+   - `generate_xlsx()` - Creates the Excel report file
+
+### Key Technical Details
+
+- Uses two different Microsoft Graph endpoints:
+  - `graph.windows.net` (beta API) for MFA registration details
+  - `graph.microsoft.com` (beta API) for user account details
+- Implements async/parallel requests using aiohttp for performance
+- Handles Windows AD vs Azure AD accounts differently
+- Supports custom SSL certificates via certificate.pem file
+- Generates timestamped Excel reports with formatted tables
+
+### Dependencies
+
+- Azure CLI authentication via `azure-cli-core`
+- Async HTTP requests with `aiohttp`
+- Excel generation using `openpyxl`
+- SSL certificate handling through `certifi`