feat: Add ability to sync copilot instructions across repositories

[Copilot]

Overview

This PR adds support for syncing .github/copilot-instructions.md files across multiple repositories via pull requests, following the same pattern as the existing dependabot.yml sync feature.

Changes

New Action Inputs

Added two new inputs to action.yml:

• copilot-instructions-md: Path to a copilot-instructions.md file to sync to target repositories
• copilot-instructions-pr-title: Customizable PR title (defaults to chore: update copilot-instructions.md)

Implementation

Implemented syncCopilotInstructions() function that:

• Reads the source copilot-instructions.md file from the specified path
• Compares content with existing files in target repositories
• Creates or updates .github/copilot-instructions.md via pull requests
• Uses the GitHub API to ensure verified commits
• Checks for existing open PRs to avoid duplicates
• Supports dry-run mode for previewing changes

Usage Examples

Basic usage:

- name: Sync Copilot Instructions
  uses: joshjohanning/bulk-github-repo-settings-sync-action@v1
  with:
    github-token: ${{ steps.app-token.outputs.token }}
    repositories: 'owner/repo1,owner/repo2'
    copilot-instructions-md: './.github/copilot-instructions.md'

With per-repository overrides:

repos:
  - repo: owner/repo1
    copilot-instructions-md: './config/copilot/javascript-instructions.md'
  - repo: owner/repo2
    copilot-instructions-md: './config/copilot/python-instructions.md'
  - repo: owner/repo3  # Uses global default

Behavior

• If .github/copilot-instructions.md doesn't exist in the target repo, it creates it and opens a PR
• If it exists but content differs, it updates it via PR
• If content is identical, no PR is created
• Updates existing open PRs instead of creating duplicates
• Supports per-repository overrides via YAML configuration

Testing

• Added 8 comprehensive tests covering all scenarios (create, update, unchanged, PR exists, dry-run, error handling)
• All 50 tests passing (42 existing + 8 new)
• Code coverage maintained at 80%
• Linting and formatting checks passed
• Security scan completed with 0 vulnerabilities

Documentation

• Updated README with complete usage examples
• Added new section demonstrating copilot instructions syncing
• Updated action inputs table with new parameters
• Included per-repository override examples

Version

Bumped version from 1.1.1 to 1.2.0 (minor version increment for new feature)

Closes #[issue-number]

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• img.shields.io
  • Triggering command: node /home/REDACTED/work/bulk-github-repo-settings-sync-action/bulk-github-repo-settings-sync-action/node_modules/.bin/make-coverage-badge-better --label-color #333 --output-path ./badges/coverage.svg (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

Original prompt

---

This section details on the original issue you should resolve

<issue_title>Add ability to sync copilot instructions</issue_title>
<issue_description>Just like we are doing with the ability to sync a dependent.yml file. (.github/copilot-instructions.yml)</issue_description>

Comments on the Issue (you are @copilot in this section)

Fixes #17

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