refactor: AbilityRegistrar nimmt AbilityGuard-Liste und ToolRefusal statt DiviToolGate/DiviLocked; DiviToolGate implementiert AbilityGuard, DiviLocked ToolRefusal; Test mit Fake-Guard und Fake-Refusal ohne Divi

Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>

src/Abilities/AbilityGuard.php

@@ -0,0 +1,35 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Abilities;
+
+use WP_Error;
+
+defined('ABSPATH') || exit;
+
+/**
+ * A cross-cutting rule the AbilityRegistrar applies to every ability it registers: it may refuse a call before the
+ * ability runs, add notes to the result and extend the output schema accordingly (e.g. the Divi release lock).
+ * The registrar knows only this interface; which guards exist is decided in Plugin (composition root).
+ */
+interface AbilityGuard
+{
+    /**
+     * The refusal for this call before execute() runs, or null to let it through.
+     *
+     * @param array<string, mixed> $input
+     */
+    public function refusal(Ability $ability, array $input): ?WP_Error;
+
+    /** The result of a finished call, possibly with added warnings. */
+    public function annotate(Ability $ability, mixed $result): mixed;
+
+    /**
+     * The output schema, possibly extended (e.g. by a warnings property).
+     *
+     * @param array<string, mixed>|null $schema
+     * @return array<string, mixed>|null
+     */
+    public function outputSchema(Ability $ability, ?array $schema): ?array;
+}

src/Abilities/AbilityRegistrar.php

@@ -5,8 +5,6 @@ declare(strict_types=1);
 namespace LIT\MCP\Abilities;
 
 use LIT\MCP\Access;
-use LIT\MCP\Integrations\Divi\Release\DiviLocked;
-use LIT\MCP\Integrations\Divi\Release\DiviToolGate;
 use LIT\MCP\Integrations\IntegrationRegistry;
 use LIT\MCP\Log;
 use LIT\MCP\Server\RequestContext;
@@ -17,16 +15,20 @@ defined('ABSPATH') || exit;
 
 /**
  * Registers all abilities of available integrations with the Abilities API and wraps them
- * with the role gate, the Divi release lock (DiviToolGate) and neutral error handling.
+ * with the role gate, the AbilityGuards it is given (e.g. the Divi release lock) and neutral error handling.
+ * It knows no integration: guards and ToolRefusal exceptions are the only seams.
  */
 final class AbilityRegistrar
 {
     public const CATEGORY = 'lit-mcp';
 
+    /**
+     * @param list<AbilityGuard> $guards Applied in order: the first refusal wins, annotate() and outputSchema() chain.
+     */
     public function __construct(
         private IntegrationRegistry $registry,
         private ?ExposurePolicy $policy = null,
-        private ?DiviToolGate $divi = null
+        private array $guards = []
     ) {
     }
 
@@ -55,7 +57,7 @@ final class AbilityRegistrar
     /** @return array<string, mixed> */
     public function argsFor(Ability $ability): array
     {
-        $divi = $this->divi ?? new DiviToolGate($this->registry->groupMap(...));
+        $guards = $this->guards;
         $args = [
             'label' => $ability->label(),
             'description' => $ability->description(),
@@ -77,14 +79,22 @@ final class AbilityRegistrar
                     return Errors::internal();
                 }
             },
-            'execute_callback' => static function (mixed $input = null) use ($ability, $divi): mixed {
+            'execute_callback' => static function (mixed $input = null) use ($ability, $guards): mixed {
-                $refusal = $divi->refusal($ability);
+                $input = is_array($input) ? $input : [];
+                foreach ($guards as $guard) {
+                    $refusal = $guard->refusal($ability, $input);
                     if ($refusal !== null) {
                         return $refusal;
                     }
+                }
 
                 try {
-                    return $divi->annotate($ability, $ability->execute(is_array($input) ? $input : []));
+                    $result = $ability->execute($input);
+                    foreach ($guards as $guard) {
+                        $result = $guard->annotate($ability, $result);
+                    }
+
+                    return $result;
                 } catch (Throwable $e) {
                     Log::failure($ability->name(), $e);
 
@@ -104,7 +114,10 @@ final class AbilityRegistrar
             ],
         ];
 
-        $output = $divi->outputSchema($ability, $ability->outputSchema());
+        $output = $ability->outputSchema();
+        foreach ($guards as $guard) {
+            $output = $guard->outputSchema($ability, $output);
+        }
         if ($output !== null) {
             $args['output_schema'] = $output;
         }
@@ -113,19 +126,31 @@ final class AbilityRegistrar
     }
 
     /**
-     * A partial write stays partial_write; otherwise a Divi release lock anywhere in the cause chain is its refusal
+     * A partial write stays partial_write; otherwise the first ToolRefusal anywhere in the cause chain is the answer
-     * (spec §5.5); a rolled-back write is write_failed; anything else internal_error.
+     * (e.g. the Divi release lock, spec §5.5); a rolled-back write is write_failed; anything else internal_error.
      */
     private static function errorFor(Throwable $e): WP_Error
     {
         if ($e instanceof WriteFailed && ! $e->rolledBack) {
             return $e->toError();
         }
-        $locked = DiviLocked::in($e);
+        $refusal = self::refusalIn($e);
-        if ($locked !== null) {
+        if ($refusal !== null) {
-            return $locked->toError();
+            return $refusal->toError();
         }
 
         return $e instanceof WriteFailed ? $e->toError() : Errors::internal();
     }
+
+    /** The first ToolRefusal in $e's chain of previous exceptions (callers wrap failures in WriteFailed). */
+    private static function refusalIn(Throwable $e): ?ToolRefusal
+    {
+        for ($cause = $e; $cause !== null; $cause = $cause->getPrevious()) {
+            if ($cause instanceof ToolRefusal) {
+                return $cause;
+            }
+        }
+
+        return null;
+    }
 }

src/Abilities/ToolRefusal.php

@@ -0,0 +1,20 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Abilities;
+
+use WP_Error;
+
+defined('ABSPATH') || exit;
+
+/**
+ * Implemented by exceptions that stand for a deliberate refusal instead of a failure (e.g. DiviLocked): thrown
+ * anywhere below an ability's execute(), also wrapped as the cause of a WriteFailed, the AbilityRegistrar answers
+ * with toError() instead of internal_error.
+ */
+interface ToolRefusal
+{
+    /** The error the client gets for this refusal. */
+    public function toError(): WP_Error;
+}

src/Integrations/Divi/Release/DiviLocked.php

@@ -4,6 +4,7 @@ declare(strict_types=1);
 
 namespace LIT\MCP\Integrations\Divi\Release;
 
+use LIT\MCP\Abilities\ToolRefusal;
 use RuntimeException;
 use Throwable;
 use WP_Error;
@@ -11,7 +12,7 @@ use WP_Error;
 defined('ABSPATH') || exit;
 
 /** A write refused because the installed Divi is not released (spec §5.5); AbilityRegistrar returns toError(). */
-final class DiviLocked extends RuntimeException
+final class DiviLocked extends RuntimeException implements ToolRefusal
 {
     public function __construct(public readonly ReleaseStatus $status)
     {

src/Integrations/Divi/Release/DiviToolGate.php

@@ -6,6 +6,7 @@ namespace LIT\MCP\Integrations\Divi\Release;
 
 use Closure;
 use LIT\MCP\Abilities\Ability;
+use LIT\MCP\Abilities\AbilityGuard;
 use LIT\MCP\ChangeLog\ChangeLog;
 use LIT\MCP\Integrations\Divi\Library\LibraryAccess;
 use LIT\MCP\Integrations\Divi\ThemeBuilder\ThemeBuilderAccess;
@@ -17,9 +18,9 @@ defined('ABSPATH') || exit;
  * The central release lock of the Divi tools (spec §5.5): a writing tool of the groups Divi, Divi-Bibliothek or Divi
  * Theme Builder is refused before it runs while Divi is not released (logged with result "refused"); a reading tool
  * runs and gets the notice in warnings. Other tools that reach Divi (lit/content-create with divi) meet the adapter
- * lock (ReleaseGate::assertWritable()).
+ * lock (ReleaseGate::assertWritable()). The AbilityRegistrar receives it as an AbilityGuard from Plugin.
  */
-final class DiviToolGate
+final class DiviToolGate implements AbilityGuard
 {
     public const GROUPS = ['divi', LibraryAccess::GROUP, ThemeBuilderAccess::GROUP];
 
@@ -39,7 +40,7 @@ final class DiviToolGate
         return in_array(($this->groups)()[$ability->name()] ?? '', self::GROUPS, true);
     }
 
-    public function refusal(Ability $ability): ?WP_Error
+    public function refusal(Ability $ability, array $input): ?WP_Error
     {
         if (! $this->covers($ability) || self::readsOnly($ability)) {
             return null;

src/Plugin.php

@@ -144,7 +144,11 @@ final class Plugin
         DiviCheckCommand::register($diviCheck);
 
         $policy = ExposurePolicy::fromOption()->withGroups($registry->groupMap(...));
-        (new AbilityRegistrar($registry, $policy, new DiviToolGate($registry->groupMap(...), $changeLog)))->register();
+        (new AbilityRegistrar(
+            $registry,
+            $policy,
+            [new DiviToolGate($registry->groupMap(...), $changeLog)]
+        ))->register();
         (new ServerRegistrar(
             $registry,
             new InstructionsBuilder($registry, static fn (): array => $schema->postTypeNames(), $policy),

tests/Unit/Abilities/AbilityRegistrarTest.php

@@ -6,8 +6,11 @@ namespace LIT\MCP\Tests\Unit\Abilities;
 
 use Brain\Monkey\Functions;
 use LIT\MCP\Abilities\Ability;
+use LIT\MCP\Abilities\AbilityGuard;
 use LIT\MCP\Abilities\AbilityRegistrar;
+use LIT\MCP\Abilities\Errors;
 use LIT\MCP\Abilities\ExposurePolicy;
+use LIT\MCP\Abilities\ToolRefusal;
 use LIT\MCP\Abilities\WriteFailed;
 use LIT\MCP\Integrations\Divi\Release\DiviLocked;
 use LIT\MCP\Integrations\Divi\Release\DiviToolGate;
@@ -20,6 +23,7 @@ use LIT\MCP\Server\RequestContext;
 use LIT\MCP\Tests\Unit\TestCase;
 use Mockery;
 use RuntimeException;
+use Throwable;
 use WP_Error;
 
 final class AbilityRegistrarTest extends TestCase
@@ -56,7 +60,7 @@ final class AbilityRegistrarTest extends TestCase
         $integration->allows('abilities')->andReturn([$ability]);
         $registry = new IntegrationRegistry($integration);
 
-        return new AbilityRegistrar($registry, null, new DiviToolGate($registry->groupMap(...)));
+        return new AbilityRegistrar($registry, null, [new DiviToolGate($registry->groupMap(...))]);
     }
 
     private function ability(bool $readonly = true): Mockery\MockInterface
@@ -247,6 +251,147 @@ final class AbilityRegistrarTest extends TestCase
         self::assertToolError($this->executeLogged($ability), 'partial_write');
     }
 
+    /** @param list<AbilityGuard> $guards */
+    private function guardedRegistrar(Ability $ability, array $guards): AbilityRegistrar
+    {
+        $integration = Mockery::mock(Integration::class);
+        $integration->allows('id')->andReturn('core');
+        $integration->allows('isAvailable')->andReturn(true);
+        $integration->allows('abilities')->andReturn([$ability]);
+
+        return new AbilityRegistrar(new IntegrationRegistry($integration), null, $guards);
+    }
+
+    /**
+     * A guard without any Divi knowledge: refuses with $refusal (or lets through), appends $tag to the result's
+     * "trail" and to the schema's "trail" property; $seen collects the inputs it was asked about.
+     */
+    private function guard(string $tag, ?WP_Error $refusal = null, array &$seen = []): AbilityGuard
+    {
+        return new class ($tag, $refusal, $seen) implements AbilityGuard {
+            public function __construct(private string $tag, private ?WP_Error $refusal, private array &$seen)
+            {
+            }
+
+            public function refusal(Ability $ability, array $input): ?WP_Error
+            {
+                $this->seen[] = $input;
+
+                return $this->refusal;
+            }
+
+            public function annotate(Ability $ability, mixed $result): mixed
+            {
+                $result['trail'] = [...($result['trail'] ?? []), $this->tag];
+
+                return $result;
+            }
+
+            public function outputSchema(Ability $ability, ?array $schema): ?array
+            {
+                $schema['properties']['trail'][] = $this->tag;
+
+                return $schema;
+            }
+        };
+    }
+
+    private function refusalException(WP_Error $error, ?Throwable $previous = null): RuntimeException
+    {
+        return new class ($error, $previous) extends RuntimeException implements ToolRefusal {
+            public function __construct(private WP_Error $error, ?Throwable $previous)
+            {
+                parent::__construct('refused', 0, $previous);
+            }
+
+            public function toError(): WP_Error
+            {
+                return $this->error;
+            }
+        };
+    }
+
+    public function testWithoutGuardsNothingIsCheckedOrAdded(): void
+    {
+        $ability = $this->ability(false);
+        $ability->expects('execute')->with(['a' => 1])->andReturn(['ok' => true]);
+
+        $args = $this->registrarFor($ability)->argsFor($ability);
+
+        self::assertSame(['ok' => true], ($args['execute_callback'])(['a' => 1]));
+        self::assertSame(['type' => 'object'], $args['output_schema']);
+    }
+
+    public function testAGuardRefusesBeforeTheAbilityRuns(): void
+    {
+        $seen = [];
+        $ability = $this->ability(false);
+        $ability->expects('execute')->never();
+        $registrar = $this->guardedRegistrar($ability, [$this->guard('a', Errors::forbidden('Nein.'), $seen)]);
+
+        $result = ($registrar->argsFor($ability)['execute_callback'])(['x' => 1]);
+
+        self::assertToolError($result, 'forbidden');
+        self::assertSame([['x' => 1]], $seen);
+    }
+
+    public function testTheFirstRefusalWinsAndLaterGuardsAreNotAsked(): void
+    {
+        $seenSecond = [];
+        $ability = $this->ability(false);
+        $ability->expects('execute')->never();
+        $registrar = $this->guardedRegistrar($ability, [
+            $this->guard('a'),
+            $this->guard('b', Errors::notFound('Weg.')),
+            $this->guard('c', Errors::forbidden('Nein.'), $seenSecond),
+        ]);
+
+        self::assertToolError(($registrar->argsFor($ability)['execute_callback'])([]), 'not_found');
+        self::assertSame([], $seenSecond);
+    }
+
+    public function testGuardsAnnotateTheResultAndExtendTheSchemaInOrder(): void
+    {
+        $ability = $this->ability(false);
+        $ability->allows('execute')->andReturn(['ok' => true]);
+        $registrar = $this->guardedRegistrar($ability, [$this->guard('a'), $this->guard('b')]);
+
+        $args = $registrar->argsFor($ability);
+
+        self::assertSame(['ok' => true, 'trail' => ['a', 'b']], ($args['execute_callback'])([]));
+        self::assertSame(['a', 'b'], $args['output_schema']['properties']['trail']);
+    }
+
+    public function testAToolRefusalThrownByAnAbilityIsItsErrorWithoutDivi(): void
+    {
+        $ability = $this->ability();
+        $ability->allows('execute')->andThrow($this->refusalException(Errors::forbidden('Gesperrt.')));
+
+        self::assertToolError($this->executeLogged($ability), 'forbidden');
+    }
+
+    public function testAToolRefusalInsideARolledBackWriteIsItsErrorButPartialStaysPartial(): void
+    {
+        $refusal = $this->refusalException(Errors::notFound('Weg.'));
+        $rolledBack = $this->ability();
+        $rolledBack->allows('execute')->andThrow(WriteFailed::rolledBack('Nicht gespeichert.', $refusal));
+        $partial = $this->ability();
+        $partial->allows('execute')->andThrow(WriteFailed::partial('Teilweise gespeichert.', $refusal));
+
+        self::assertToolError($this->executeLogged($rolledBack), 'not_found');
+        self::assertToolError($this->executeLogged($partial), 'partial_write');
+    }
+
+    public function testTheFirstRefusalInTheCauseChainWins(): void
+    {
+        $inner = $this->refusalException(Errors::notFound('Innen.'));
+        $outer = $this->refusalException(Errors::forbidden('Außen.'), $inner);
+        $ability = $this->ability();
+        $ability->allows('execute')->andThrow(WriteFailed::rolledBack('Nicht gespeichert.', $outer));
+
+        self::assertToolError($this->executeLogged($ability), 'forbidden');
+    }
+
     /**
      * Runs the execute callback with error_log() redirected (a PHP internal, not stubbable – like the tests above).
      */

tests/Unit/Integrations/Divi/Release/DiviToolGateTest.php

@@ -47,7 +47,7 @@ final class DiviToolGateTest extends TestCase
     {
         $gate = $this->gate(FakeChangeLog::forbidden());
 
-        self::assertNull($gate->refusal($this->ability('lit/divi-insert', false)));
+        self::assertNull($gate->refusal($this->ability('lit/divi-insert', false), []));
         self::assertSame(['ok' => true], $gate->annotate($this->ability('lit/divi-outline', true), ['ok' => true]));
     }
 
@@ -58,10 +58,10 @@ final class DiviToolGateTest extends TestCase
         $gate = $this->gate($log);
 
         foreach (['lit/divi-insert', 'lit/library-save', 'lit/tb-create-template'] as $name) {
-            self::assertToolError($gate->refusal($this->ability($name, false)), 'divi_untested', $name);
+            self::assertToolError($gate->refusal($this->ability($name, false), []), 'divi_untested', $name);
         }
-        self::assertNull($gate->refusal($this->ability('lit/content-create', false)), 'not a Divi tool (adapter lock)');
+        self::assertNull($gate->refusal($this->ability('lit/content-create', false), []), 'not a Divi tool (adapter lock)');
-        self::assertNull($gate->refusal($this->ability('lit/divi-outline', true)), 'reading stays allowed');
+        self::assertNull($gate->refusal($this->ability('lit/divi-outline', true), []), 'reading stays allowed');
         self::assertSame(['refused', 'refused', 'refused'], array_column($log->records, 'result'));
         self::assertSame('Abgelehnt: Divi 5.3.0 ist nicht freigegeben.', $log->records[0]['summary']);
     }