Generating PR Age Charts

Build an interactive CLI tool that visualizes pull request age distribution for a GitHub repository using Copilot's built-in capabilities.

Runnable example: recipe/pr-visualization.cs

# Auto-detect from current git repo
dotnet run recipe/pr-visualization.cs

# Specify a repo explicitly
dotnet run recipe/pr-visualization.cs -- --repo github/copilot-sdk

Example scenario

You want to understand how long PRs have been open in a repository. This tool detects the current Git repo or accepts a repo as input, then lets Copilot fetch PR data via the GitHub MCP Server and generate a chart image.

Prerequisites

dotnet add package GitHub.Copilot.SDK

Usage

# Auto-detect from current git repo
dotnet run

# Specify a repo explicitly
dotnet run -- --repo github/copilot-sdk

Full example: Program.cs

using System.Diagnostics;
using GitHub.Copilot.SDK;

// ============================================================================
// Git & GitHub Detection
// ============================================================================

bool IsGitRepo()
{
    try
    {
        Process.Start(new ProcessStartInfo
        {
            FileName = "git",
            Arguments = "rev-parse --git-dir",
            RedirectStandardOutput = true,
            RedirectStandardError = true,
            UseShellExecute = false,
            CreateNoWindow = true
        })?.WaitForExit();
        return true;
    }
    catch
    {
        return false;
    }
}

string? GetGitHubRemote()
{
    try
    {
        var proc = Process.Start(new ProcessStartInfo
        {
            FileName = "git",
            Arguments = "remote get-url origin",
            RedirectStandardOutput = true,
            UseShellExecute = false,
            CreateNoWindow = true
        });

        var remoteUrl = proc?.StandardOutput.ReadToEnd().Trim();
        proc?.WaitForExit();

        if (string.IsNullOrEmpty(remoteUrl)) return null;

        // Handle SSH: git@github.com:owner/repo.git
        var sshMatch = System.Text.RegularExpressions.Regex.Match(
            remoteUrl, @"git@github\.com:(.+/.+?)(?:\.git)?$");
        if (sshMatch.Success) return sshMatch.Groups[1].Value;

        // Handle HTTPS: https://github.com/owner/repo.git
        var httpsMatch = System.Text.RegularExpressions.Regex.Match(
            remoteUrl, @"https://github\.com/(.+/.+?)(?:\.git)?$");
        if (httpsMatch.Success) return httpsMatch.Groups[1].Value;

        return null;
    }
    catch
    {
        return null;
    }
}

string? ParseRepoArg(string[] args)
{
    var repoIndex = Array.IndexOf(args, "--repo");
    if (repoIndex != -1 && repoIndex + 1 < args.Length)
    {
        return args[repoIndex + 1];
    }
    return null;
}

string PromptForRepo()
{
    Console.Write("Enter GitHub repo (owner/repo): ");
    return Console.ReadLine()?.Trim() ?? "";
}

// ============================================================================
// Main Application
// ============================================================================

Console.WriteLine("🔍 PR Age Chart Generator\n");

// Determine the repository
var repo = ParseRepoArg(args);

if (!string.IsNullOrEmpty(repo))
{
    Console.WriteLine($"📦 Using specified repo: {repo}");
}
else if (IsGitRepo())
{
    var detected = GetGitHubRemote();
    if (detected != null)
    {
        repo = detected;
        Console.WriteLine($"📦 Detected GitHub repo: {repo}");
    }
    else
    {
        Console.WriteLine("⚠️  Git repo found but no GitHub remote detected.");
        repo = PromptForRepo();
    }
}
else
{
    Console.WriteLine("📁 Not in a git repository.");
    repo = PromptForRepo();
}

if (string.IsNullOrEmpty(repo) || !repo.Contains('/'))
{
    Console.WriteLine("❌ Invalid repo format. Expected: owner/repo");
    return;
}

var parts = repo.Split('/');
var owner = parts[0];
var repoName = parts[1];

// Create Copilot client - no custom tools needed!
await using var client = new CopilotClient(new CopilotClientOptions { LogLevel = "error" });
await client.StartAsync();

var session = await client.CreateSessionAsync(new SessionConfig
{
    Model = "gpt-5",
    SystemMessage = new SystemMessageConfig
    {
        Content = $"""
<context>
You are analyzing pull requests for the GitHub repository: {owner}/{repoName}
The current working directory is: {Environment.CurrentDirectory}
</context>

<instructions>
- Use the GitHub MCP Server tools to fetch PR data
- Use your file and code execution tools to generate charts
- Save any generated images to the current working directory
- Be concise in your responses
</instructions>
"""
    }
});

// Set up event handling
session.On(evt =>
{
    switch (evt)
    {
        case AssistantMessageEvent msg:
            Console.WriteLine($"\n🤖 {msg.Data.Content}\n");
            break;
        case ToolExecutionStartEvent toolStart:
            Console.WriteLine($"  ⚙️  {toolStart.Data.ToolName}");
            break;
    }
});

// Initial prompt - let Copilot figure out the details
Console.WriteLine("\n📊 Starting analysis...\n");

await session.SendAsync(new MessageOptions
{
    Prompt = $"""
      Fetch the open pull requests for {owner}/{repoName} from the last week.
      Calculate the age of each PR in days.
      Then generate a bar chart image showing the distribution of PR ages
      (group them into sensible buckets like <1 day, 1-3 days, etc.).
      Save the chart as "pr-age-chart.png" in the current directory.
      Finally, summarize the PR health - average age, oldest PR, and how many might be considered stale.
    """
});

// Interactive loop
Console.WriteLine("\n💡 Ask follow-up questions or type \"exit\" to quit.\n");
Console.WriteLine("Examples:");
Console.WriteLine("  - \"Expand to the last month\"");
Console.WriteLine("  - \"Show me the 5 oldest PRs\"");
Console.WriteLine("  - \"Generate a pie chart instead\"");
Console.WriteLine("  - \"Group by author instead of age\"");
Console.WriteLine();

while (true)
{
    Console.Write("You: ");
    var input = Console.ReadLine()?.Trim();

    if (string.IsNullOrEmpty(input)) continue;
    if (input.ToLower() is "exit" or "quit")
    {
        Console.WriteLine("👋 Goodbye!");
        break;
    }

    await session.SendAsync(new MessageOptions { Prompt = input });
}

How it works

Repository detection: Checks --repo flag → git remote → prompts user
No custom tools: Relies entirely on Copilot CLI's built-in capabilities:
- GitHub MCP Server - Fetches PR data from GitHub
- File tools - Saves generated chart images
- Code execution - Generates charts using Python/matplotlib or other methods
Interactive session: After initial analysis, user can ask for adjustments

Why this approach?

Aspect	Custom Tools	Built-in Copilot
Code complexity	High	Minimal
Maintenance	You maintain	Copilot maintains
Flexibility	Fixed logic	AI decides best approach
Chart types	What you coded	Any type Copilot can generate
Data grouping	Hardcoded buckets	Intelligent grouping

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