CLI Conventions

This document describes the conventions for implementing command-line interfaces (CLI) in PowerToys modules.

Library

Use the System.CommandLine library for CLI argument parsing. This is already defined in Directory.Packages.props:

<PackageReference Include="System.CommandLine" Version="2.0.0-beta4.22272.1" />

Add the reference to your project:

<PackageReference Include="System.CommandLine" />

Option Naming and Definition

• Use --kebab-case for long form (e.g., --shrink-only).
• Use single -x for short form (e.g., -s, -w).
• Define aliases as static readonly arrays: ["--silent", "-s"].
• Create options using Option<T> with descriptive help text.
• Add validators for options that require range or format checking.

RootCommand Setup

• Create a RootCommand with a brief description.
• Add all options and arguments to the command.

Parsing

• Use Parser(rootCommand).Parse(args) to parse CLI arguments.
• Extract option values using parseResult.GetValueForOption().
• Note: Use Parser directly; RootCommand.Parse() may not be available with the pinned System.CommandLine version.

Parse/Validation Errors

• On parse/validation errors, print error messages and usage, then exit with non-zero code.

Examples

Reference implementations:

• Awake: src/modules/Awake/Awake/Program.cs
• ImageResizer: src/modules/imageresizer/ui/Cli/

Help Output

• Provide a PrintUsage() method for custom help formatting if needed.

Best Practices

1. Consistency: Follow existing module patterns.
2. Documentation: Always provide help text for each option.
3. Validation: Validate input and provide clear error messages.
4. Atomicity: Make one logical change per PR; avoid drive-by refactors.
5. Build/Test Discipline: Build and test synchronously, one terminal per operation.
6. Style: Follow repo analyzers (.editorconfig, StyleCop) and formatting rules.

Logging Requirements

• Use ManagedCommon.Logger for consistent logging.
• Initialize logging early in Main().
• Use dual output (console + log file) for errors and warnings to ensure visibility.
• Reference: src/modules/imageresizer/ui/Cli/CliLogger.cs

Error Handling

Exit Codes

• 0: Success
• 1: General error (parsing, validation, runtime)
• 2: Invalid arguments (optional)

Exception Handling

• Always wrap Main() in try-catch for unhandled exceptions.
• Log exceptions before exiting with non-zero code.
• Display user-friendly error messages to stderr.
• Preserve detailed stack traces in log files only.

Testing Requirements

• Include tests for argument parsing, validation, and edge cases.
• Place CLI tests in module-specific test projects (e.g., src/modules/[module]/tests/*CliTests.cs).

Signing and Deployment

• CLI executables are signed automatically in CI/CD.
• New CLI tools: Add your executable and dll to .pipelines/ESRPSigning_core.json in the signing list.
• CLI executables are deployed alongside their parent module (e.g., C:\Program Files\PowerToys\modules\[ModuleName]\).
• Use self-contained deployment (import Common.SelfContained.props).