PowerToys/AGENTS.md

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description	applyTo
Top-level AI contributor guidance for developing PowerToys - a collection of Windows productivity utilities	**

PowerToys – AI Contributor Guide

This is the top-level guidance for AI contributions to PowerToys. Keep changes atomic, follow existing patterns, and cite exact paths in PRs.

Overview

PowerToys is a set of utilities for power users to tune and streamline their Windows experience.

Area	Location	Description
Runner	src/runner/	Main executable, tray icon, module loader, hotkey management
Settings UI	src/settings-ui/	WinUI/WPF configuration app communicating via named pipes
Modules	src/modules/	Individual PowerToys utilities (each in its own subfolder)
Common Libraries	src/common/	Shared code: logging, IPC, settings, DPI, telemetry, utilities
Build Tools	tools/build/	Build scripts and automation
Documentation	doc/devdocs/	Developer documentation
Installer	installer/	WiX-based installer projects

For architecture details and module types, see Architecture Overview.

Conventions

For detailed coding conventions, see:

• Coding Guidelines – Dependencies, testing, PR management
• Coding Style – Formatting, C++/C#/XAML style rules
• Logging – C++ spdlog and C# Logger usage

Component-Specific Instructions

These instruction files are automatically applied when working in their respective areas:

• Runner & Settings UI – IPC contracts, schema migrations
• Common Libraries – ABI stability, shared code guidelines

Build

Prerequisites

• Visual Studio 2022 17.4+ or Visual Studio 2026
• Windows 10 1803+ (April 2018 Update or newer)
• Initialize submodules once: git submodule update --init --recursive

Build Commands

Task	Command
First build / NuGet restore	tools\build\build-essentials.cmd
Build current folder	tools\build\build.cmd
Build with options	build.ps1 -Platform x64 -Configuration Release

Build Discipline

1. One terminal per operation (build → test). Do not switch or open new ones mid-flow
2. After making changes, cd to the project folder that changed (.csproj/.vcxproj)
3. Use scripts to build: tools/build/build.ps1 or tools/build/build.cmd
4. For first build or missing NuGet packages, run build-essentials.cmd first
5. Exit code 0 = success; non-zero = failure – treat this as absolute
6. On failure, read the errors log: build.<config>.<platform>.errors.log
7. Do not start tests or launch Runner until the build succeeds

Build Logs

Located next to the solution/project being built:

• build.<configuration>.<platform>.errors.log – errors only (check this first)
• build.<configuration>.<platform>.all.log – full log
• build.<configuration>.<platform>.trace.binlog – for MSBuild Structured Log Viewer

For complete details, see Build Guidelines.

Tests

Test Discovery

• Find test projects by product code prefix (e.g., FancyZones, AdvancedPaste)
• Look for sibling folders or 1-2 levels up named <Product>*UnitTests or <Product>*UITests

Running Tests

1. Build the test project first, wait for exit code 0
2. Run via VS Test Explorer (Ctrl+E, T) or vstest.console.exe with filters
3. Avoid dotnet test in this repo – use VS Test Explorer or vstest.console.exe

Test Types

Type	Requirements	Setup
Unit Tests	Standard dev environment	None
UI Tests	WinAppDriver v1.2.1, Developer Mode	Install from WinAppDriver releases
Fuzz Tests	OneFuzz, .NET 8	See Fuzzing Tests

Test Discipline

1. Add or adjust tests when changing behavior
2. If tests skipped, state why (e.g., comment-only change, string rename)
3. New modules handling file I/O or user input must implement fuzzing tests

Special Requirements

• Mouse Without Borders: Requires 2+ physical computers (not VMs)
• Multi-monitor utilities: Test with 2+ monitors, different DPI settings

For UI test setup details, see UI Tests.

Boundaries

Ask for Clarification When

• Ambiguous spec after scanning relevant docs
• Cross-module impact (shared enum/struct) is unclear
• Security, elevation, or installer changes involved
• GPO or policy handling modifications needed

Areas Requiring Extra Care

Area	Concern	Reference
src/common/	ABI breaks	Common Libraries Instructions
src/runner/, src/settings-ui/	IPC contracts, schema	Runner & Settings UI Instructions
Installer files	Release impact	Careful review required
Elevation/GPO logic	Security	Confirm no regression in policy handling

What NOT to Do

• Don't merge incomplete features into main (use feature branches)
• Don't break IPC/JSON contracts without updating both runner and settings-ui
• Don't add noisy logs in hot paths
• Don't introduce third-party deps without PM approval and NOTICE.md update

Validation Checklist

Before finishing, verify:

• Build clean with exit code 0
• Tests updated and passing locally
• No unintended ABI breaks or schema changes
• IPC contracts consistent between runner and settings-ui
• New dependencies added to NOTICE.md
• PR is atomic (one logical change), with issue linked

Documentation Index

Core Architecture

• Architecture Overview
• Runner
• Settings System
• Module Interface

Development

• Coding Guidelines
• Coding Style
• Logging
• UI Tests
• Fuzzing Tests

Build & Tools

• Build Guidelines
• Tools Overview

Instructions (Auto-Applied)

• Runner & Settings UI
• Common Libraries