PowerShell-master/.github/instructions/instruction-file-format.instructions.md

metadata

applyTo:
  - .github/instructions/**/*.instructions.md

Instruction File Format Guide

This document describes the format and guidelines for creating custom instruction files for GitHub Copilot in the PowerShell repository.

File Naming Convention

All instruction files must use the .instructions.md suffix:

• ✅ Correct: build-checkout-prerequisites.instructions.md
• ✅ Correct: start-psbuild-basics.instructions.md
• ❌ Incorrect: build-guide.md
• ❌ Incorrect: instructions.md

Required Frontmatter

Every instruction file must start with YAML frontmatter containing an applyTo section:

---
applyTo:
  - "path/to/files/**/*.ext"
  - "specific-file.ext"
---

applyTo Patterns

Specify which files or directories these instructions apply to:

For workflow files:

applyTo:
  - ".github/**/*.yml"
  - ".github/**/*.yaml"

For build scripts:

applyTo:
  - "build.psm1"
  - "tools/ci.psm1"

For multiple contexts:

applyTo:
  - "build.psm1"
  - "tools/**/*.psm1"
  - ".github/**/*.yml"

Content Structure

1. Clear Title

Use a descriptive H1 heading after the frontmatter:

# Build Configuration Guide

2. Purpose or Overview

Start with a brief explanation of what the instructions cover:

## Purpose

This guide explains how to configure PowerShell builds for different scenarios.

3. Actionable Content

Provide clear, actionable guidance:

✅ Good - Specific and actionable:

## Default Usage

Use `Start-PSBuild` with no parameters for testing:

```powershell
Import-Module ./tools/ci.psm1
Start-PSBuild

**❌ Bad - Vague and unclear:**
```markdown
## Usage

You can use Start-PSBuild to build stuff.

4. Code Examples

Include working code examples with proper syntax highlighting:

```yaml
- name: Build PowerShell
  shell: pwsh
  run: |
    Import-Module ./tools/ci.psm1
    Start-PSBuild

### 5. Context and Rationale

Explain why things are done a certain way:

```markdown
**Why fetch-depth: 1000?**
- The build system needs Git history for version calculation
- Shallow clones would break versioning logic

Best Practices

Be Concise

• Focus on essential information
• Remove redundant explanations
• Use bullet points for lists

Be Specific

• Provide exact commands and parameters
• Include file paths and line numbers when relevant
• Show concrete examples, not abstract concepts

Avoid Duplication

• Don't repeat information from other instruction files
• Reference other files when appropriate
• Keep each file focused on one topic

Use Proper Formatting

Headers:

• Use H1 (#) for the main title
• Use H2 (##) for major sections
• Use H3 (###) for subsections

Code blocks:

• Always specify the language: ```yaml, ```powershell, ```bash
• Keep examples short and focused
• Test examples before including them

Lists:

• Use - for unordered lists
• Use 1. for ordered lists
• Keep list items concise

Example Structure

---
applyTo:
  - "relevant/files/**/*.ext"
---

# Title of Instructions

Brief description of what these instructions cover.

## Section 1

Content with examples.

```language
code example

Section 2

More specific guidance.

Subsection

Detailed information when needed.

Best Practices

• Actionable tip 1
• Actionable tip 2

## Maintaining Instructions

### When to Create a New File

Create a new instruction file when:
- Covering a distinct topic not addressed elsewhere
- The content is substantial enough to warrant its own file
- The `applyTo` scope is different from existing files

### When to Update an Existing File

Update an existing file when:
- Information is outdated
- New best practices emerge
- Examples need correction

### When to Merge or Delete

Merge or delete files when:
- Content is duplicated across multiple files
- A file is too small to be useful standalone
- Information is no longer relevant

## Reference

For more details, see:
- [GitHub Copilot Custom Instructions Documentation](https://docs.github.com/en/copilot/how-tos/configure-custom-instructions/add-repository-instructions)