Prefix MergeButler token environment variables

.github/skills/doc-writer/SKILL.md

@@ -90,7 +90,7 @@ MergeButler evaluate --config <path> --pr <url> --platform <GitHub|AzureDevOps>
 | `--config` | `-c` | Yes | Path to the YAML configuration file |
 | `--pr` | | Yes | URL of the pull request to evaluate |
 | `--platform` | `-p` | Yes | `GitHub` or `AzureDevOps` |
-| `--token` | `-t` | No | Auth token. Defaults to `GITHUB_TOKEN` or `AZURE_DEVOPS_TOKEN` env var |
+| `--token` | `-t` | No | Auth token. Defaults to `MERGEBUTLER__GITHUB_TOKEN` or `MERGEBUTLER__AZURE_DEVOPS_TOKEN` env var |
 | `--dry-run` | `-n` | No | Evaluate without submitting an approval |
 
 ### `config show`
@@ -240,8 +240,8 @@ Use GitHub Copilot to evaluate the PR diff against a natural-language prompt.
 
 | Platform | Library | Token env var |
 |----------|---------|---------------|
-| GitHub | [Octokit](https://github.com/octokit/octokit.net) | `GITHUB_TOKEN` |
-| Azure DevOps | REST API | `AZURE_DEVOPS_TOKEN` |
+| GitHub | [Octokit](https://github.com/octokit/octokit.net) | `MERGEBUTLER__GITHUB_TOKEN` |
+| Azure DevOps | REST API | `MERGEBUTLER__AZURE_DEVOPS_TOKEN` |
 
 ## Documentation Maintenance
 

Directory.Packages.props

@@ -19,7 +19,7 @@
   This would typically list all NuGet packages used within this solution.
   -->
   <ItemGroup>
-    <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="18.6.2" />
+    <PackageVersion Include="Microsoft.Testing.Extensions.CodeCoverage" Version="17.14.1" />
     <PackageVersion Include="GitHub.Copilot.SDK" Version="0.2.2" />
     <PackageVersion Include="Microsoft.Extensions.AI" Version="10.4.1" />
     <PackageVersion Include="Microsoft.Extensions.DependencyInjection" Version="10.0.5" />
@@ -43,4 +43,4 @@
     </PackageVersion>
     <PackageVersion Include="YamlDotNet" Version="16.3.0" />
   </ItemGroup>
-</Project>
+</Project>

MergeButler.Tests/Commands/PlatformServiceFactoryTests.cs

@@ -4,6 +4,16 @@ namespace MergeButler.Tests.Commands;
 
 public class PlatformServiceFactoryTests
 {
+    [Theory]
+    [InlineData(Platform.GitHub, PlatformServiceFactory.GitHubTokenEnvironmentVariable)]
+    [InlineData(Platform.AzureDevOps, PlatformServiceFactory.AzureDevOpsTokenEnvironmentVariable)]
+    public void GetTokenEnvironmentVariableName_ReturnsPrefixedName(Platform platform, string expected)
+    {
+        string result = PlatformServiceFactory.GetTokenEnvironmentVariableName(platform);
+
+        Assert.Equal(expected, result);
+    }
+
     [Theory]
     [InlineData("GitHub", Platform.GitHub)]
     [InlineData("github", Platform.GitHub)]
@@ -35,13 +45,52 @@ public void ResolveToken_ProvidedToken_ReturnsProvided()
         Assert.Equal("my-token", result);
     }
 
-    [Fact]
-    public void ResolveToken_NullToken_FallsBackToEnvVar()
+    [Theory]
+    [InlineData(Platform.GitHub, PlatformServiceFactory.GitHubTokenEnvironmentVariable, "GITHUB_TOKEN")]
+    [InlineData(Platform.AzureDevOps, PlatformServiceFactory.AzureDevOpsTokenEnvironmentVariable, "AZURE_DEVOPS_TOKEN")]
+    public void ResolveToken_NullToken_FallsBackToPrefixedEnvVar(Platform platform, string prefixedEnvVar, string legacyEnvVar)
+    {
+        string? savedPrefixedToken = Environment.GetEnvironmentVariable(prefixedEnvVar);
+        string? savedLegacyToken = Environment.GetEnvironmentVariable(legacyEnvVar);
+
+        try
+        {
+            Environment.SetEnvironmentVariable(prefixedEnvVar, "prefixed-token");
+            Environment.SetEnvironmentVariable(legacyEnvVar, "legacy-token");
+
+            string? result = PlatformServiceFactory.ResolveToken(platform, null);
+
+            Assert.Equal("prefixed-token", result);
+        }
+        finally
+        {
+            Environment.SetEnvironmentVariable(prefixedEnvVar, savedPrefixedToken);
+            Environment.SetEnvironmentVariable(legacyEnvVar, savedLegacyToken);
+        }
+    }
+
+    [Theory]
+    [InlineData(Platform.GitHub, PlatformServiceFactory.GitHubTokenEnvironmentVariable, "GITHUB_TOKEN")]
+    [InlineData(Platform.AzureDevOps, PlatformServiceFactory.AzureDevOpsTokenEnvironmentVariable, "AZURE_DEVOPS_TOKEN")]
+    public void ResolveToken_NullToken_DoesNotUseLegacyEnvVar(Platform platform, string prefixedEnvVar, string legacyEnvVar)
     {
-        // If env var is not set, returns null
-        string? result = PlatformServiceFactory.ResolveToken(Platform.GitHub, null);
-        // Can't assert specific value since it depends on env, but shouldn't throw
-        Assert.True(result is null || result.Length > 0);
+        string? savedPrefixedToken = Environment.GetEnvironmentVariable(prefixedEnvVar);
+        string? savedLegacyToken = Environment.GetEnvironmentVariable(legacyEnvVar);
+
+        try
+        {
+            Environment.SetEnvironmentVariable(prefixedEnvVar, null);
+            Environment.SetEnvironmentVariable(legacyEnvVar, "legacy-token");
+
+            string? result = PlatformServiceFactory.ResolveToken(platform, null);
+
+            Assert.Null(result);
+        }
+        finally
+        {
+            Environment.SetEnvironmentVariable(prefixedEnvVar, savedPrefixedToken);
+            Environment.SetEnvironmentVariable(legacyEnvVar, savedLegacyToken);
+        }
     }
 
     [Fact]

MergeButler.Tests/Mcp/PullRequestToolsTests.cs

@@ -1,3 +1,4 @@
+using MergeButler.Commands;
 using MergeButler.Mcp;
 
 namespace MergeButler.Tests.Mcp;
@@ -8,9 +9,11 @@ public class PullRequestToolsTests
     public async Task GradePullRequest_NoToken_ReturnsError()
     {
         // Ensure env var is not set for this test
-        string? savedToken = Environment.GetEnvironmentVariable("GITHUB_TOKEN");
+        string? savedToken = Environment.GetEnvironmentVariable(PlatformServiceFactory.GitHubTokenEnvironmentVariable);
+        string? savedLegacyToken = Environment.GetEnvironmentVariable("GITHUB_TOKEN");
         try
         {
+            Environment.SetEnvironmentVariable(PlatformServiceFactory.GitHubTokenEnvironmentVariable, null);
             Environment.SetEnvironmentVariable("GITHUB_TOKEN", null);
 
             string result = await PullRequestTools.GradePullRequest(
@@ -21,10 +24,12 @@ public async Task GradePullRequest_NoToken_ReturnsError()
 
             Assert.Contains("ERROR", result);
             Assert.Contains("token", result, StringComparison.OrdinalIgnoreCase);
+            Assert.Contains(PlatformServiceFactory.GitHubTokenEnvironmentVariable, result);
         }
         finally
         {
-            Environment.SetEnvironmentVariable("GITHUB_TOKEN", savedToken);
+            Environment.SetEnvironmentVariable(PlatformServiceFactory.GitHubTokenEnvironmentVariable, savedToken);
+            Environment.SetEnvironmentVariable("GITHUB_TOKEN", savedLegacyToken);
         }
     }
 
@@ -42,9 +47,11 @@ await Assert.ThrowsAsync<ArgumentException>(() =>
     [Fact]
     public async Task ApprovePullRequest_NoToken_ReturnsError()
     {
-        string? savedToken = Environment.GetEnvironmentVariable("GITHUB_TOKEN");
+        string? savedToken = Environment.GetEnvironmentVariable(PlatformServiceFactory.GitHubTokenEnvironmentVariable);
+        string? savedLegacyToken = Environment.GetEnvironmentVariable("GITHUB_TOKEN");
         try
         {
+            Environment.SetEnvironmentVariable(PlatformServiceFactory.GitHubTokenEnvironmentVariable, null);
             Environment.SetEnvironmentVariable("GITHUB_TOKEN", null);
 
             string result = await PullRequestTools.ApprovePullRequest(
@@ -55,10 +62,12 @@ public async Task ApprovePullRequest_NoToken_ReturnsError()
 
             Assert.Contains("ERROR", result);
             Assert.Contains("token", result, StringComparison.OrdinalIgnoreCase);
+            Assert.Contains(PlatformServiceFactory.GitHubTokenEnvironmentVariable, result);
         }
         finally
         {
-            Environment.SetEnvironmentVariable("GITHUB_TOKEN", savedToken);
+            Environment.SetEnvironmentVariable(PlatformServiceFactory.GitHubTokenEnvironmentVariable, savedToken);
+            Environment.SetEnvironmentVariable("GITHUB_TOKEN", savedLegacyToken);
         }
     }
 

MergeButler/Commands/EvaluateCommand.cs

@@ -28,7 +28,8 @@ public static Command Create()
 
         Option<string?> tokenOption = new("--token", ["-t"])
         {
-            Description = "Authentication token for the platform API. Defaults to GITHUB_TOKEN or AZURE_DEVOPS_TOKEN environment variable."
+            Description = "Authentication token for the platform API. Defaults to " +
+                          PlatformServiceFactory.TokenEnvironmentVariableNames + " environment variable."
         };
 
         Option<bool> dryRunOption = new("--dry-run", ["-n"])
@@ -110,7 +111,8 @@ internal static async Task ExecuteAsync(
 
         if (string.IsNullOrWhiteSpace(token))
         {
-            output.WriteLine("Error: No authentication token provided. Use --token or set the appropriate environment variable.");
+            output.WriteLine(
+                $"Error: No authentication token provided. Use --token or set the {PlatformServiceFactory.GetTokenEnvironmentVariableName(platform)} environment variable.");
             return;
         }
 

MergeButler/Commands/PlatformServiceFactory.cs

@@ -9,12 +9,21 @@ namespace MergeButler.Commands;
 /// </summary>
 public static class PlatformServiceFactory
 {
+    public const string EnvironmentVariablePrefix = "MERGEBUTLER__";
+    public const string GitHubTokenEnvironmentVariable = EnvironmentVariablePrefix + "GITHUB_TOKEN";
+    public const string AzureDevOpsTokenEnvironmentVariable = EnvironmentVariablePrefix + "AZURE_DEVOPS_TOKEN";
+    public const string TokenEnvironmentVariableNames =
+        GitHubTokenEnvironmentVariable + " or " + AzureDevOpsTokenEnvironmentVariable;
+
     public static string? ResolveToken(Platform platform, string? providedToken) =>
-        providedToken ?? platform switch
+        providedToken ?? Environment.GetEnvironmentVariable(GetTokenEnvironmentVariableName(platform));
+
+    public static string GetTokenEnvironmentVariableName(Platform platform) =>
+        platform switch
         {
-            Platform.GitHub => Environment.GetEnvironmentVariable("GITHUB_TOKEN"),
-            Platform.AzureDevOps => Environment.GetEnvironmentVariable("AZURE_DEVOPS_TOKEN"),
-            _ => null
+            Platform.GitHub => GitHubTokenEnvironmentVariable,
+            Platform.AzureDevOps => AzureDevOpsTokenEnvironmentVariable,
+            _ => throw new ArgumentOutOfRangeException(nameof(platform), platform, "Unsupported platform.")
         };
 
     public static IPullRequestService CreateService(Platform platform, string token)

MergeButler/Mcp/PullRequestTools.cs

@@ -13,12 +13,12 @@ public class PullRequestTools
 {
     [McpServerTool(Name = "grade_pull_request"),
      Description("Evaluate a pull request against MergeButler rules and return the grading result. " +
-                 "This does NOT approve the PR — use approve_pull_request for that.")]
+                  "This does NOT approve the PR — use approve_pull_request for that.")]
     public static async Task<string> GradePullRequest(
         [Description("Full URL of the pull request (e.g. https://github.com/owner/repo/pull/42)")] string prUrl,
         [Description("Platform hosting the PR: GitHub, AzureDevOps, or azdo. If not specified, inferred from git remotes.")] string? platform = null,
         [Description("Path to MergeButler YAML config file. When omitted, the effective config is built from the default user and repo locations.")] string? configPath = null,
-        [Description("Auth token for the platform API. If not provided, falls back to GITHUB_TOKEN or AZURE_DEVOPS_TOKEN environment variable.")] string? token = null,
+        [Description("Auth token for the platform API. If not provided, falls back to " + PlatformServiceFactory.TokenEnvironmentVariableNames + " environment variable.")] string? token = null,
         CancellationToken cancellationToken = default)
     {
         Platform platformEnum;
@@ -39,7 +39,7 @@ public static async Task<string> GradePullRequest(
         token = PlatformServiceFactory.ResolveToken(platformEnum, token);
         if (string.IsNullOrWhiteSpace(token))
         {
-            string envVar = platformEnum == Platform.GitHub ? "GITHUB_TOKEN" : "AZURE_DEVOPS_TOKEN";
+            string envVar = PlatformServiceFactory.GetTokenEnvironmentVariableName(platformEnum);
             return $"ERROR: No authentication token provided. Please provide a token parameter or set the {envVar} environment variable.";
         }
 
@@ -144,11 +144,11 @@ public static async Task<string> GradePullRequest(
 
     [McpServerTool(Name = "approve_pull_request"),
      Description("Submit an approval on a pull request. " +
-                 "Use grade_pull_request first to evaluate the PR before approving.")]
+                  "Use grade_pull_request first to evaluate the PR before approving.")]
     public static async Task<string> ApprovePullRequest(
         [Description("Full URL of the pull request (e.g. https://github.com/owner/repo/pull/42)")] string prUrl,
         [Description("Platform hosting the PR: GitHub, AzureDevOps, or azdo. If not specified, inferred from git remotes.")] string? platform = null,
-        [Description("Auth token for the platform API. If not provided, falls back to GITHUB_TOKEN or AZURE_DEVOPS_TOKEN environment variable.")] string? token = null,
+        [Description("Auth token for the platform API. If not provided, falls back to " + PlatformServiceFactory.TokenEnvironmentVariableNames + " environment variable.")] string? token = null,
         CancellationToken cancellationToken = default)
     {
         Platform platformEnum;
@@ -169,7 +169,7 @@ public static async Task<string> ApprovePullRequest(
         token = PlatformServiceFactory.ResolveToken(platformEnum, token);
         if (string.IsNullOrWhiteSpace(token))
         {
-            string envVar = platformEnum == Platform.GitHub ? "GITHUB_TOKEN" : "AZURE_DEVOPS_TOKEN";
+            string envVar = PlatformServiceFactory.GetTokenEnvironmentVariableName(platformEnum);
             return $"ERROR: No authentication token provided. Please provide a token parameter or set the {envVar} environment variable.";
         }
 

README.md

@@ -23,7 +23,7 @@ MergeButler evaluate --config .mergebutler.yml --pr <PR_URL> --platform <GitHub|
 | `--config` | `-c` | Yes | Path to the YAML configuration file |
 | `--pr` | | Yes | URL of the pull request to evaluate |
 | `--platform` | `-p` | Yes | `GitHub` or `AzureDevOps` |
-| `--token` | `-t` | No | Auth token. Defaults to `GITHUB_TOKEN` or `AZURE_DEVOPS_TOKEN` env var |
+| `--token` | `-t` | No | Auth token. Defaults to `MERGEBUTLER__GITHUB_TOKEN` or `MERGEBUTLER__AZURE_DEVOPS_TOKEN` env var |
 | `--dry-run` | `-n` | No | Evaluate without submitting an approval |
 
 #### Examples
@@ -32,8 +32,8 @@ MergeButler evaluate --config .mergebutler.yml --pr <PR_URL> --platform <GitHub|
 # GitHub PR
 MergeButler evaluate -c .mergebutler.yml --pr https://github.com/owner/repo/pull/42 -p GitHub
 
-# Azure DevOps PR
-MergeButler evaluate -c .mergebutler.yml --pr https://dev.azure.com/org/project/_git/repo/pullrequest/1 -p AzureDevOps -t $AZURE_DEVOPS_TOKEN
+# Azure DevOps PR using the default env var
+MERGEBUTLER__AZURE_DEVOPS_TOKEN=your-token MergeButler evaluate -c .mergebutler.yml --pr https://dev.azure.com/org/project/_git/repo/pullrequest/1 -p AzureDevOps
 
 # Dry run — see if a PR would be approved without actually approving it
 MergeButler evaluate -c .mergebutler.yml --pr https://github.com/owner/repo/pull/42 -p GitHub --dry-run
@@ -196,8 +196,8 @@ rules:
 
 | Platform | Library | Token env var |
 |----------|---------|---------------|
-| GitHub | [Octokit](https://github.com/octokit/octokit.net) | `GITHUB_TOKEN` |
-| Azure DevOps | REST API | `AZURE_DEVOPS_TOKEN` |
+| GitHub | [Octokit](https://github.com/octokit/octokit.net) | `MERGEBUTLER__GITHUB_TOKEN` |
+| Azure DevOps | REST API | `MERGEBUTLER__AZURE_DEVOPS_TOKEN` |
 
 ## MCP Server (Local Development)
 
@@ -232,7 +232,7 @@ Add to your `.vscode/mcp.json`:
 }
 ```
 
-PR tools accept `prUrl`, `platform`, and an optional `token` parameter. If no token is provided, the tools check environment variables (`GITHUB_TOKEN` / `AZURE_DEVOPS_TOKEN`) and return a descriptive error if none is found.
+PR tools accept `prUrl`, `platform`, and an optional `token` parameter. If no token is provided, the tools check environment variables (`MERGEBUTLER__GITHUB_TOKEN` / `MERGEBUTLER__AZURE_DEVOPS_TOKEN`) and return a descriptive error if none is found.
 
 ### `setup`
 
@@ -263,4 +263,4 @@ MergeButler setup
 
 # Non-interactive — perform all steps automatically
 MergeButler setup --yes
-```
+```