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doc/devdocs/modules/environmentvariables.md

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+# Environment Variables
+
+[Public overview - Microsoft Learn](https://learn.microsoft.com/en-us/windows/powertoys/environment-variables)
+
+## Quick Links
+
+[All Issues](https://github.com/microsoft/PowerToys/issues?q=is%3Aopen%20label%3A%22Product-Environment%20Variables%22)<br>
+[Bugs](https://github.com/microsoft/PowerToys/issues?q=is%3Aopen%20label%3AIssue-Bug%20label%3A%22Product-Environment%20Variables%22)<br>
+[Pull Requests](https://github.com/microsoft/PowerToys/pulls?q=is%3Apr+is%3Aopen+label%3A%22Product-Environment+Variables%22)
+[Checklist](https://github.com/microsoft/PowerToys/blob/releaseChecklist/doc/releases/tests-checklist-template.md?plain=1#L744)
+
+## Overview
+
+Environment Variables is a PowerToys module that provides an easy and convenient way to manage Windows environment variables. It offers a modern user interface for viewing, editing, and managing both user and system environment variables.
+
+## Features
+
+- View and edit user and system environment variables in a unified interface
+- Create profiles to group and manage sets of variables together
+- Profile-based variable management with on/off toggles
+- Automatic backup of existing variables when overridden by a profile
+- Restoration of original values when profiles are disabled
+
+## How It Works
+
+### Profiles
+
+Profiles are collections of environment variables that can be enabled or disabled together. When a profile is enabled:
+
+1. Variables in the profile override existing User variables with the same name
+2. Original values are automatically backed up for restoration when the profile is disabled
+3. Only one profile can be active at a time
+
+### Variable Precedence
+
+The module follows this precedence order for environment variables:
+1. Active profile variables (highest precedence)
+2. User variables
+3. System variables (lowest precedence)
+
+## Architecture
+
+The Environment Variables module is structured into three main components:
+
+### Project Structure
+
+```
+EnvironmentVariables/               # Contains assets, main windows, and telemetry
+EnvironmentVariablesModuleInterface # Interface definitions and package configurations
+EnvironmentVariableUILib            # Abstracted UI methods and implementations
+```
+
+### Key Components
+
+- **Main Window Framework**: Builds the modern Windows desktop UI, handles Windows messages, resource loading, and window closing operations
+- **Project Configuration**: Defines settings and configurations for the module
+- **UI Implementation**: Contains the user interface components and the backend logic
+
+## Implementation Details
+
+### Key Functions
+
+- **OpenEnvironmentKeyIfExists**: Accesses environment information through registry keys
+- **SetEnvironmentVariableFromRegistryWithoutNotify**: Sets variables directly to registry instead of using Environment API, avoiding the 1-second timeout for settings change notifications
+- **GetVariables**: Reads variables directly from registry instead of using Environment API to prevent automatic variable expansion
+
+### Technical Notes
+
+- The module reads and writes variables directly to the registry instead of using the Environment API
+- This direct registry access approach is used because the Environment API automatically expands variables and has a timeout for notifications
+- When a profile variable has the same name as an existing User variable, a backup is created with the naming pattern: `VARIABLE_NAME_powertoys_PROFILE_NAME`