fix: prevent mcp-oauth's duplicate server registration instead of tolerating it

Proactively unhook wp-media/mcp-oauth's own mcp_adapter_init callback before
creating our server, rather than letting it collide and rely on WP_DEBUG=true
being harmless. The collision previously surfaced as a fatal-looking
_doing_it_wrong notice under WP-CLI (breaking every wp command while the
plugin is active) and could leak debug notices into HTTP responses on
customer sites that run WP_DEBUG.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01At3V6SjwbMe6eMzVGW3Hs7

tests/Unit/Server/ServerRegistrarTest.php

@@ -12,9 +12,16 @@ use LIT\MCP\Integrations\IntegrationRegistry;
 use LIT\MCP\Server\ServerRegistrar;
 use LIT\MCP\Tests\Unit\TestCase;
 use Mockery;
+use WPMedia\MCP\OAuth\Transport\ServerRegistrar as OAuthServerRegistrar;
 
 final class ServerRegistrarTest extends TestCase
 {
+    protected function tearDown(): void
+    {
+        unset($GLOBALS['wp_filter']);
+        parent::tearDown();
+    }
+
     private function registry(): IntegrationRegistry
     {
         $direct = Mockery::mock(Ability::class);
@@ -77,4 +84,37 @@ final class ServerRegistrarTest extends TestCase
 
         self::assertFalse($oauthChecked, 'createServer must bail out before touching the adapter');
     }
+
+    public function testUnhookOAuthDefaultServerRemovesOnlyTheMcpOauthCallback(): void
+    {
+        $oauthRegistrar = Mockery::mock(OAuthServerRegistrar::class);
+        $oauthCallback = [$oauthRegistrar, 'register_server'];
+        $unrelatedCallback = static function (): void {
+        };
+
+        $hook = new class {
+            /** @var array<int, array<string, array{function: mixed, accepted_args: int}>> */
+            public array $callbacks = [];
+        };
+        $hook->callbacks = [
+            5 => ['unrelated-id' => ['function' => $unrelatedCallback, 'accepted_args' => 0]],
+            10 => ['oauth-id' => ['function' => $oauthCallback, 'accepted_args' => 0]],
+        ];
+        $GLOBALS['wp_filter']['mcp_adapter_init'] = $hook;
+
+        Functions\expect('remove_action')
+            ->once()
+            ->with('mcp_adapter_init', $oauthCallback, 10);
+
+        (new ServerRegistrar($this->registry(), $this->instructions()))->unhookOAuthDefaultServer();
+    }
+
+    public function testUnhookOAuthDefaultServerIsNoOpWhenHookIsMissing(): void
+    {
+        unset($GLOBALS['wp_filter']['mcp_adapter_init']);
+
+        Functions\expect('remove_action')->never();
+
+        (new ServerRegistrar($this->registry(), $this->instructions()))->unhookOAuthDefaultServer();
+    }
 }