Add Copilot CLI detection (#5)

Author: chris-ware

README.md

@@ -57,6 +57,7 @@ $result = detectAgent();
 | AMP | `AMP_CURRENT_THREAD_ID` env var |
 | Opencode | `OPENCODE_CLIENT` or `OPENCODE` env var |
 | Claude | `CLAUDECODE` or `CLAUDE_CODE` env var |
+| Copilot | `COPILOT_CLI` env var |
 | Replit | `REPL_ID` env var |
 | Devin | `/opt/.devin` file exists |
 

src/AgentDetector.php

@@ -23,6 +23,7 @@ public static function detect(): AgentResult
             'amp' => ['AMP_CURRENT_THREAD_ID'],
             'claude' => ['CLAUDECODE', 'CLAUDE_CODE'],
             'replit' => ['REPL_ID'],
+            'copilot' => ['COPILOT_CLI'],
         ];
 
         foreach ($agentsWithEnvVars as $agent => $envVars) {

src/KnownAgent.php

@@ -15,4 +15,5 @@ enum KnownAgent: string
     case AugmentCli = 'augment-cli';
     case Opencode = 'opencode';
     case Amp = 'amp';
+    case Copilot = 'copilot';
 }

tests/AgentDetectorTest.php

@@ -20,6 +20,7 @@
         'AMP_CURRENT_THREAD_ID',
         'CLAUDECODE',
         'CLAUDE_CODE',
+        'COPILOT_CLI',
         'REPL_ID',
     ] as $var) {
         putenv($var);
@@ -41,6 +42,7 @@
         'AMP_CURRENT_THREAD_ID',
         'CLAUDECODE',
         'CLAUDE_CODE',
+        'COPILOT_CLI',
         'REPL_ID',
     ] as $var) {
         putenv($var);
@@ -168,6 +170,16 @@
         ->and($result->knownAgent())->toBe(KnownAgent::Claude);
 });
 
+it('detects copilot via COPILOT_CLI', function (): void {
+    putenv('COPILOT_CLI=1');
+
+    $result = AgentDetector::detect();
+
+    expect($result->isAgent)->toBeTrue()
+        ->and($result->name)->toBe('copilot')
+        ->and($result->knownAgent())->toBe(KnownAgent::Copilot);
+});
+
 it('detects replit via REPL_ID', function (): void {
     putenv('REPL_ID=some-repl-id');
 
@@ -289,6 +301,7 @@
     'augment-cli' => ['AUGMENT_AGENT', 'true', KnownAgent::AugmentCli],
     'opencode' => ['OPENCODE_CLIENT', 'true', KnownAgent::Opencode],
     'amp' => ['AMP_CURRENT_THREAD_ID', 'thread-id', KnownAgent::Amp],
+    'copilot' => ['COPILOT_CLI', '1', KnownAgent::Copilot],
     'claude' => ['CLAUDECODE', '1', KnownAgent::Claude],
     'replit' => ['REPL_ID', 'id', KnownAgent::Replit],
 ]);