refactor: WriteFailed named constructors, Rollback runner, Errors read-back helpers (H6)

- WriteFailed::rolledBack()/partial() replace the 11-parameter constructor (now
  private); the hint/state of either error are plain $hint/$state.
- Rollback::attempt(...steps) runs every undo step and collects failure messages;
  used by ContentCreate::discard, ContentUpdate::rollBack, MediaUpdate::rollBack and
  DiviSaver::restore.
- Errors::clientMessage/codeOf/fieldsOf replace DiviReplaceTextAbility::reason,
  the JSON digging in MediaUpdateAbility::failure and ContentCreateAbility::fields.
- Errors docblock documents the exception/WP_Error split.
- ContentCreateAbility::discard takes the client reason as a parameter (both callers
  still pass REASON_EXTRAS; changing the Divi text needs a ruling).

Error payloads unchanged.

Co-Authored-By: Claude Opus 5.5 (1M context) <noreply@anthropic.com>

src/Abilities/Errors.php

@@ -12,6 +12,14 @@ use WP_Error;
  * mcp-adapter 0.5 turns a WP_Error into a tool result with isError: true but
  * forwards only the message text. The message therefore carries the whole
  * structured error as JSON: {code, message, hint, fields?, usages?, …} (spec §8.2).
+ * clientMessage(), codeOf() and fieldsOf() read such an error back (batch results that list
+ * per-item errors, merged validation errors).
+ *
+ * How failures travel: pure helpers (e.g. the Divi Compose classes) throw
+ * InvalidArgumentException, which the caller collects into `fields`; abilities return a
+ * WP_Error from this factory; writes that may have left something behind throw WriteFailed
+ * (rolledBack()/partial()), which the AbilityRegistrar maps via toError(); internal steps
+ * throw RuntimeException, which is logged and becomes internal_error.
  */
 final class Errors
 {
@@ -190,6 +198,32 @@ final class Errors
         );
     }
 
+    /** The client message of an error (its JSON "message"), without the JSON around it. */
+    public static function clientMessage(WP_Error $error): string
+    {
+        $data = json_decode($error->get_error_message(), true);
+
+        return is_array($data) && is_string($data['message'] ?? null) ? $data['message'] : $error->get_error_message();
+    }
+
+    /** The error code as the client sees it (without the "lit_" prefix of the WP_Error code). */
+    public static function codeOf(WP_Error $error): string
+    {
+        return (string) preg_replace('/^lit_/', '', (string) $error->get_error_code());
+    }
+
+    /**
+     * The `fields` of a validation error (input path => problem); [] when it has none.
+     *
+     * @return array<string, string>
+     */
+    public static function fieldsOf(WP_Error $error): array
+    {
+        $data = $error->get_error_data();
+
+        return is_array($data) && is_array($data['fields'] ?? null) ? $data['fields'] : [];
+    }
+
     public static function internal(): WP_Error
     {
         return self::make(

src/Abilities/Rollback.php

@@ -0,0 +1,33 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Abilities;
+
+use Throwable;
+
+/**
+ * Runs the undo steps of a failed write. Every step runs, even after an earlier one failed;
+ * a step fails by throwing. The caller turns the collected messages into the log detail and
+ * picks WriteFailed::rolledBack() (no failures) or WriteFailed::partial().
+ */
+final class Rollback
+{
+    /**
+     * @param callable(): mixed ...$steps In the order they must run.
+     * @return list<string> The messages of the steps that threw, in step order. Never throws.
+     */
+    public static function attempt(callable ...$steps): array
+    {
+        $failures = [];
+        foreach ($steps as $step) {
+            try {
+                $step();
+            } catch (Throwable $e) {
+                $failures[] = $e->getMessage();
+            }
+        }
+
+        return $failures;
+    }
+}

src/Abilities/WriteFailed.php

@@ -12,27 +12,28 @@ use WP_Error;
  * Thrown by write paths when saving failed after something may already have been
  * written. getMessage() is the internal detail for the PHP error log; $reason is the
  * client-safe German text. The AbilityRegistrar logs the detail and returns toError():
- * lit_write_failed when everything was rolled back, lit_partial_write otherwise.
+ * lit_write_failed when everything was rolled back (rolledBack()), lit_partial_write
- * $state/$hint customise the partial-write error for writes that are not about a post (see
+ * otherwise (partial()).
- * Errors::partialWrite()); $details are added to either error. $rolledBackHint replaces the
+ *
- * default hint of the write_failed error, $rolledBackState its "Nichts wurde gespeichert."
+ * $detail is the log text (default: the cause's message, else the reason); $details are
- * (for rollbacks that deliberately keep a backup or revision).
+ * added to either error. For rolledBack(), $hint replaces the default hint and $state the
+ * "Nichts wurde gespeichert." (for rollbacks that deliberately keep a backup or revision,
+ * see Errors::notSavedKeeping()). For partial(), $state and $hint replace the post-oriented
+ * defaults for writes that are not about a post (see Errors::partialWrite()).
  */
 final class WriteFailed extends RuntimeException
 {
     /** @param array<string, mixed> $details Extra error details for the client. */
-    public function __construct(
+    private function __construct(
         public readonly string $reason,
         public readonly bool $rolledBack,
-        public readonly ?int $postId = null,
+        public readonly ?int $postId,
-        public readonly ?int $revisionId = null,
+        public readonly ?int $revisionId,
-        ?Throwable $previous = null,
+        ?Throwable $previous,
-        string $detail = '',
+        string $detail,
-        public readonly ?string $state = null,
+        public readonly ?string $state,
-        public readonly ?string $hint = null,
+        public readonly ?string $hint,
-        public readonly array $details = [],
+        public readonly array $details
-        public readonly ?string $rolledBackHint = null,
-        public readonly ?string $rolledBackState = null
     ) {
         $internal = $detail !== '' ? $detail : ($previous !== null ? $previous->getMessage() : $reason);
         parent::__construct(
@@ -42,10 +43,47 @@ final class WriteFailed extends RuntimeException
         );
     }
 
+    /**
+     * Everything was restored (lit_write_failed). $postId/$revisionId only name the entry for
+     * callers that log it; the client error does not carry them.
+     *
+     * @param array<string, mixed> $details
+     */
+    public static function rolledBack(
+        string $reason,
+        ?Throwable $cause = null,
+        string $detail = '',
+        ?string $hint = null,
+        ?string $state = null,
+        array $details = [],
+        ?int $postId = null,
+        ?int $revisionId = null
+    ): self {
+        return new self($reason, true, $postId, $revisionId, $cause, $detail, $state, $hint, $details);
+    }
+
+    /**
+     * The rollback was incomplete – something may have been saved (lit_partial_write).
+     *
+     * @param array<string, mixed> $details
+     */
+    public static function partial(
+        string $reason,
+        ?Throwable $cause = null,
+        string $detail = '',
+        ?int $postId = null,
+        ?int $revisionId = null,
+        ?string $state = null,
+        ?string $hint = null,
+        array $details = []
+    ): self {
+        return new self($reason, false, $postId, $revisionId, $cause, $detail, $state, $hint, $details);
+    }
+
     public function toError(): WP_Error
     {
         return $this->rolledBack
-            ? Errors::writeFailed($this->reason, $this->details, $this->rolledBackHint, $this->rolledBackState)
+            ? Errors::writeFailed($this->reason, $this->details, $this->hint, $this->state)
             : Errors::partialWrite(
                 $this->reason,
                 $this->postId,

src/Integrations/Divi/Pages/DiviReplaceTextAbility.php

@@ -186,7 +186,7 @@ final class DiviReplaceTextAbility implements Ability
             $divi = $this->loader->load($postId, true);
             $problem = $divi instanceof WP_Error ? $divi : $this->loader->writable($divi);
             if ($problem instanceof WP_Error) {
-                $skipped[] = ['post_id' => $postId, 'reason' => self::reason($problem)];
+                $skipped[] = ['post_id' => $postId, 'reason' => Errors::clientMessage($problem)];
                 continue;
             }
 
@@ -320,7 +320,7 @@ final class DiviReplaceTextAbility implements Ability
         } catch (WriteFailed $e) {
             self::log($postId, $e);
 
-            return ['post_id' => $postId, 'ok' => false, 'error' => self::reason($e->toError())];
+            return ['post_id' => $postId, 'ok' => false, 'error' => Errors::clientMessage($e->toError())];
         } catch (Throwable $e) {
             self::log($postId, $e);
 
@@ -343,7 +343,7 @@ final class DiviReplaceTextAbility implements Ability
         $postId = $input['post_id'];
         $page = $this->writer->page($input);
         if ($page instanceof WP_Error) {
-            return ['post_id' => $postId, 'ok' => false, 'error' => self::reason($page)];
+            return ['post_id' => $postId, 'ok' => false, 'error' => Errors::clientMessage($page)];
         }
 
         $post = $page->post;
@@ -475,14 +475,6 @@ final class DiviReplaceTextAbility implements Ability
             : 'Knoten nicht lesbar (Attribute kein JSON-Objekt) – im Divi-Builder bearbeiten';
     }
 
-    /** The client message of an error (its JSON "message"), without the JSON around it. */
-    private static function reason(WP_Error $error): string
-    {
-        $data = json_decode($error->get_error_message(), true);
-
-        return is_array($data) && is_string($data['message'] ?? null) ? $data['message'] : $error->get_error_message();
-    }
-
     private static function log(int $postId, Throwable $e): void
     {
         Log::failure(sprintf('lit/divi-replace-text on post %d', $postId), $e);

src/Integrations/Divi/Pages/DiviSaver.php

@@ -6,6 +6,7 @@ namespace LIT\MCP\Integrations\Divi\Pages;
 
 use LIT\MCP\Abilities\Errors;
 use LIT\MCP\Abilities\FollowUp;
+use LIT\MCP\Abilities\Rollback;
 use LIT\MCP\Abilities\WriteFailed;
 use LIT\MCP\Integrations\WordPress\PostGuard;
 use LIT\MCP\Integrations\WordPress\RevisionPoint;
@@ -78,14 +79,12 @@ class DiviSaver
 
         if ($result instanceof WP_Error || $result === 0) {
             $message = $result instanceof WP_Error ? $result->get_error_message() : 'returned 0';
-            throw new WriteFailed(
+            throw WriteFailed::rolledBack(
                 self::REASON,
-                true,
+                detail: sprintf('wp_update_post(%d) refused: %s', $postId, $message),
-                $postId,
+                state: self::keeping($revisionId),
-                $revisionId,
+                postId: $postId,
-                null,
+                revisionId: $revisionId
-                sprintf('wp_update_post(%d) refused: %s', $postId, $message),
-                rolledBackState: self::keeping($revisionId)
             );
         }
 
@@ -172,7 +171,7 @@ class DiviSaver
     private function restore(int $postId, string $before, ?int $revisionId, Throwable $cause): never
     {
         $detail = sprintf('Saving Divi content of post %d failed: %s', $postId, $cause->getMessage());
-        try {
+        $failures = Rollback::attempt(function () use ($postId, $before): void {
             $current = get_post($postId);
             if ($current instanceof WP_Post && PostGuard::missedSchedule($current)) {
                 throw new RuntimeException('restoring would publish a missed schedule');
@@ -185,19 +184,19 @@ class DiviSaver
             if ($restored instanceof WP_Error || $restored === 0) {
                 throw new RuntimeException('previous content could not be written back');
             }
-        } catch (Throwable $e) {
+        });
-            $detail .= '; rollback: ' . $e->getMessage();
+        if ($failures !== []) {
-            throw new WriteFailed(self::REASON, false, $postId, $revisionId, $cause, $detail);
+            $detail .= '; rollback: ' . $failures[0];
+            throw WriteFailed::partial(self::REASON, $cause, $detail, $postId, $revisionId);
         }
 
-        throw new WriteFailed(
+        throw WriteFailed::rolledBack(
             self::REASON,
-            true,
-            $postId,
-            $revisionId,
             $cause,
             $detail,
-            rolledBackState: self::keeping($revisionId)
+            state: self::keeping($revisionId),
+            postId: $postId,
+            revisionId: $revisionId
         );
     }
 

src/Integrations/Media/MediaImporter.php

@@ -261,20 +261,17 @@ class MediaImporter
         }
 
         if ($deleted) {
-            throw new WriteFailed($reason, true, null, null, null, $detail);
+            throw WriteFailed::rolledBack($reason, detail: $detail);
         }
 
-        throw new WriteFailed(
+        throw WriteFailed::partial(
             $reason,
-            false,
+            detail: $detail . '; attachment could not be deleted',
-            $attachmentId,
+            postId: $attachmentId,
-            null,
+            state: sprintf('Medium %d wurde trotzdem angelegt, aber ohne Alt-Text.', $attachmentId),
-            null,
+            hint: 'Den Aufruf nicht wiederholen (sonst liegt die Datei doppelt vor). Medium mit lit/media-get prüfen, '
-            $detail . '; attachment could not be deleted',
+                . 'den Alt-Text in der Mediathek nachtragen und dem Nutzer Bescheid geben.',
-            sprintf('Medium %d wurde trotzdem angelegt, aber ohne Alt-Text.', $attachmentId),
+            details: ['attachment_id' => $attachmentId]
-            'Den Aufruf nicht wiederholen (sonst liegt die Datei doppelt vor). Medium mit lit/media-get prüfen, den '
-                . 'Alt-Text in der Mediathek nachtragen und dem Nutzer Bescheid geben.',
-            ['attachment_id' => $attachmentId]
         );
     }
 

src/Integrations/Media/MediaUpdateAbility.php

@@ -7,6 +7,7 @@ namespace LIT\MCP\Integrations\Media;
 use LIT\MCP\Abilities\Ability;
 use LIT\MCP\Abilities\Errors;
 use LIT\MCP\Abilities\FollowUp;
+use LIT\MCP\Abilities\Rollback;
 use LIT\MCP\Abilities\ToolResult;
 use LIT\MCP\Abilities\WriteFailed;
 use LIT\MCP\ChangeLog\ChangeLog;
@@ -266,24 +267,20 @@ final class MediaUpdateAbility implements Ability
         $unrestored = [];
         $failures = [];
         foreach (array_reverse($written) as $entry) {
-            try {
+            $failed = Rollback::attempt(fn () => $this->writer->restore($entry['snapshot']));
-                $this->writer->restore($entry['snapshot']);
+            if ($failed !== []) {
-            } catch (Throwable $e) {
                 $unrestored[] = $entry['attachment'];
-                $failures[] = $e->getMessage();
+                $failures = array_merge($failures, $failed);
             }
         }
 
         $detail = 'Media update failed: ' . $cause->getMessage();
         if ($unrestored === []) {
-            throw new WriteFailed(
+            throw WriteFailed::rolledBack(
                 self::REASON,
-                true,
-                null,
-                null,
                 $cause,
                 $detail,
-                rolledBackHint: 'Das Zurücksetzen hat modified der Medien geändert: vor einem neuen Versuch die Medien '
+                hint: 'Das Zurücksetzen hat modified der Medien geändert: vor einem neuen Versuch die Medien '
                     . 'neu lesen (lit/media-get oder lit/media-search, direkt: lit-media-search) und den Stapel mit '
                     . 'dem aktuellen modified senden; tritt der Fehler wieder auf, den Administrator informieren '
                     . '(Details im PHP-Error-Log).'
@@ -301,17 +298,14 @@ final class MediaUpdateAbility implements Ability
             );
         }
 
-        throw new WriteFailed(
+        throw WriteFailed::partial(
             self::REASON,
-            false,
-            null,
-            null,
             $cause,
             $detail . '; rollback incomplete: ' . implode('; ', $failures),
-            sprintf('Möglicherweise geändert: Medien %s (siehe changed_ids).', implode(', ', $ids)),
+            state: sprintf('Möglicherweise geändert: Medien %s (siehe changed_ids).', implode(', ', $ids)),
-            'Den Aufruf nicht einfach wiederholen. Die unter changed_ids genannten Medien mit lit/media-get prüfen, '
+            hint: 'Den Aufruf nicht einfach wiederholen. Die unter changed_ids genannten Medien mit lit/media-get '
-                . 'die Metadaten ggf. korrigieren und dem Nutzer Bescheid geben.',
+                . 'prüfen, die Metadaten ggf. korrigieren und dem Nutzer Bescheid geben.',
-            ['changed_ids' => $ids]
+            details: ['changed_ids' => $ids]
         );
     }
 
@@ -374,12 +368,11 @@ final class MediaUpdateAbility implements Ability
      */
     private static function failure(int $index, array $item, WP_Error $error): array
     {
-        $payload = json_decode($error->get_error_message(), true);
         return [
             'index' => $index,
             'id' => PostGuard::id($item['id'] ?? null),
-            'code' => (string) preg_replace('/^lit_/', '', (string) $error->get_error_code()),
+            'code' => Errors::codeOf($error),
-            'error' => is_array($payload) ? (string) ($payload['message'] ?? '') : $error->get_error_message(),
+            'error' => Errors::clientMessage($error),
         ];
     }
 

src/Integrations/WordPress/Content/ContentCreateAbility.php

@@ -7,12 +7,14 @@ namespace LIT\MCP\Integrations\WordPress\Content;
 use LIT\MCP\Abilities\Ability;
 use LIT\MCP\Abilities\Errors;
 use LIT\MCP\Abilities\Rev;
+use LIT\MCP\Abilities\Rollback;
 use LIT\MCP\Abilities\ToolResult;
 use LIT\MCP\Abilities\WriteFailed;
 use LIT\MCP\ChangeLog\ChangeLog;
 use LIT\MCP\Integrations\WordPress\PostChangeResult;
 use LIT\MCP\Integrations\WordPress\PostGuard;
 use LIT\MCP\Integrations\WordPress\Schema\ContentSchema;
+use RuntimeException;
 use Throwable;
 use WP_Error;
 use WP_Post;
@@ -137,7 +139,7 @@ final class ContentCreateAbility implements Ability
             // A hook threw – the row may or may not exist and its ID is unknown; nothing is
             // searched or deleted, the client is told to check (lit_partial_write without id).
             $this->logPartial($postType, '', 'Anlegen abgebrochen; Entwurf möglicherweise vorhanden');
-            throw new WriteFailed(self::REASON_INSERT, false, null, null, $e);
+            throw WriteFailed::partial(self::REASON_INSERT, $e);
         }
         if ($postId instanceof WP_Error) {
             return Errors::invalidInput('WordPress hat den Eintrag abgelehnt: ' . $postId->get_error_message());
@@ -153,7 +155,7 @@ final class ContentCreateAbility implements Ability
         try {
             $layout = $withDivi ? $this->divi?->write($postId, $postType, self::sections($input)) : null;
         } catch (Throwable $e) {
-            $this->discard($postId, $postType, $e);
+            $this->discard($postId, $postType, $e, self::REASON_EXTRAS);
         }
         if ($layout instanceof WP_Error) {
             return $this->refuse($postId, $postType, $layout);
@@ -162,7 +164,7 @@ final class ContentCreateAbility implements Ability
         try {
             $this->writer->writeExtras($postId, $postType, $prepared, $input);
         } catch (Throwable $e) {
-            $this->discard($postId, $postType, $e);
+            $this->discard($postId, $postType, $e, self::REASON_EXTRAS);
         }
 
         $warnings = array_merge($prepared['warnings'], $layout['warnings'] ?? []);
@@ -207,7 +209,7 @@ final class ContentCreateAbility implements Ability
             return $prepared instanceof WP_Error ? $prepared : $divi;
         }
 
-        $fields = array_merge(self::fields($prepared), self::fields($divi));
+        $fields = array_merge(Errors::fieldsOf($prepared), Errors::fieldsOf($divi));
         if ($fields === []) {
             return $prepared;
         }
@@ -217,14 +219,6 @@ final class ContentCreateAbility implements Ability
             : Errors::invalidInput('Eingaben sind ungültig; nichts wurde angelegt.', $fields);
     }
 
-    /** @return array<string, string> */
-    private static function fields(WP_Error $error): array
-    {
-        $data = $error->get_error_data();
-
-        return is_array($data) && is_array($data['fields'] ?? null) ? $data['fields'] : [];
-    }
-
     /**
      * @param array<string, mixed> $input
      * @param list<string>         $warnings
@@ -254,42 +248,38 @@ final class ContentCreateAbility implements Ability
 
     /**
      * Rolls the brand-new draft back: terms it created, then the draft itself (force –
-     * it cannot have been used anywhere yet).
+     * it cannot have been used anywhere yet). $reason is the client text of the error.
      *
      * @throws WriteFailed Always.
      */
-    private function discard(int $postId, string $postType, Throwable $cause): never
+    private function discard(int $postId, string $postType, Throwable $cause, string $reason): never
     {
-        $problems = [];
+        $problems = Rollback::attempt(
-        try {
+            fn () => $this->writer->deleteCreatedTerms(),
-            $this->writer->deleteCreatedTerms();
+            static function () use ($postId): void {
-        } catch (Throwable $e) {
+                try {
-            $problems[] = $e->getMessage();
+                    $deleted = wp_delete_post($postId, true);
-        }
+                } catch (Throwable $e) {
-
+                    throw new RuntimeException(
-        try {
+                        sprintf('draft %d could not be deleted: %s', $postId, $e->getMessage()),
-            if (! wp_delete_post($postId, true)) {
+                        0,
-                $problems[] = sprintf('draft %d could not be deleted', $postId);
+                        $e
+                    );
+                }
+                if (! $deleted) {
+                    throw new RuntimeException(sprintf('draft %d could not be deleted', $postId));
+                }
             }
-        } catch (Throwable $e) {
+        );
-            $problems[] = sprintf('draft %d could not be deleted: %s', $postId, $e->getMessage());
-        }
 
         $detail = sprintf('Extras of new post %d could not be written: %s', $postId, $cause->getMessage());
         if ($problems === []) {
-            throw new WriteFailed(self::REASON_EXTRAS, true, null, null, $cause, $detail);
+            throw WriteFailed::rolledBack($reason, $cause, $detail);
         }
 
         $summary = sprintf('Entwurf %d: Anlegen nur teilweise zurückgenommen', $postId);
         $this->logPartial($postType, (string) $postId, $summary);
-        throw new WriteFailed(
+        throw WriteFailed::partial($reason, $cause, $detail . '; rollback: ' . implode('; ', $problems), $postId);
-            self::REASON_EXTRAS,
-            false,
-            $postId,
-            null,
-            $cause,
-            $detail . '; rollback: ' . implode('; ', $problems)
-        );
     }
 
     /**
@@ -311,15 +301,12 @@ final class ContentCreateAbility implements Ability
         if (! $deleted) {
             $summary = sprintf('Entwurf %d: Anlegen nicht zurückgenommen', $postId);
             $this->logPartial($postType, (string) $postId, $summary);
-            $fields = $denied instanceof WP_Error ? self::fields($denied) : $denied;
+            $fields = $denied instanceof WP_Error ? Errors::fieldsOf($denied) : $denied;
-            throw new WriteFailed(
+            throw WriteFailed::partial(
                 ($denied instanceof WP_Error ? 'Ungültiger Divi-Inhalt: ' : 'Keine Berechtigung für ')
                     . implode(', ', array_keys($fields)) . '.',
-                false,
+                detail: sprintf('New post %d refused after the insert; draft could not be deleted', $postId),
-                $postId,
+                postId: $postId
-                null,
-                null,
-                sprintf('New post %d refused after the insert; draft could not be deleted', $postId)
             );
         }
 

src/Integrations/WordPress/Content/ContentUpdateAbility.php

@@ -7,6 +7,7 @@ namespace LIT\MCP\Integrations\WordPress\Content;
 use LIT\MCP\Abilities\Ability;
 use LIT\MCP\Abilities\Errors;
 use LIT\MCP\Abilities\Rev;
+use LIT\MCP\Abilities\Rollback;
 use LIT\MCP\Abilities\ToolResult;
 use LIT\MCP\Abilities\WriteFailed;
 use LIT\MCP\ChangeLog\ChangeLog;
@@ -218,32 +219,21 @@ final class ContentUpdateAbility implements Ability
     private function rollBack(WP_Post $post, array $before, ?int $revisionId, array $snapshot, Throwable $cause): never
     {
         $postId = (int) $post->ID;
-        $steps = [
+        $failures = Rollback::attempt(
             fn () => $this->writer->deleteCreatedTerms(),
             fn () => $this->writer->restore($postId, (string) $post->post_type, $snapshot),
-            fn () => $this->restoreRow($post, $before, $revisionId),
+            fn () => $this->restoreRow($post, $before, $revisionId)
-        ];
+        );
-        $failures = [];
-        foreach ($steps as $step) {
-            try {
-                $step();
-            } catch (Throwable $e) {
-                $failures[] = $e->getMessage();
-            }
-        }
 
         $detail = sprintf('Update of post %d failed: %s', $postId, $cause->getMessage());
         if ($failures === []) {
-            throw new WriteFailed(
+            throw WriteFailed::rolledBack(
                 self::REASON,
-                true,
-                $postId,
-                $revisionId,
                 $cause,
                 $detail,
-                rolledBackState: $revisionId === null
+                state: $revisionId === null ? null : Errors::notSavedKeeping(sprintf('Revision %d', $revisionId)),
-                    ? null
+                postId: $postId,
-                    : Errors::notSavedKeeping(sprintf('Revision %d', $revisionId))
+                revisionId: $revisionId
             );
         }
 
@@ -254,13 +244,12 @@ final class ContentUpdateAbility implements Ability
             sprintf('"%s": Änderung nur teilweise zurückgenommen', $post->post_title),
             $revisionId
         );
-        throw new WriteFailed(
+        throw WriteFailed::partial(
             self::REASON,
-            false,
-            $postId,
-            $revisionId,
             $cause,
-            $detail . '; rollback incomplete: ' . implode('; ', $failures)
+            $detail . '; rollback incomplete: ' . implode('; ', $failures),
+            $postId,
+            $revisionId
         );
     }
 

src/Integrations/WordPress/Menus/MenuWriter.php

@@ -454,19 +454,22 @@ class MenuWriter
             . ($this->deleted !== [] ? '; already deleted: ' . implode(', ', $this->deleted) : '')
             . ($problems !== [] ? '; rollback: ' . implode('; ', $problems) : '');
 
-        throw new WriteFailed(
+        $reason = 'Das Menü konnte nicht gespeichert werden.';
-            'Das Menü konnte nicht gespeichert werden.',
+        $details = ['menu_id' => $menuId, 'previous_items' => MenuTree::build(array_values($current))];
-            $rolledBack,
+        if ($rolledBack) {
-            null,
+            throw WriteFailed::rolledBack($reason, $cause, $detail, details: $details);
-            null,
+        }
+
+        throw WriteFailed::partial(
+            $reason,
             $cause,
             $detail,
-            sprintf('Menü %d ist möglicherweise teilweise geändert worden.', $menuId),
+            state: sprintf('Menü %d ist möglicherweise teilweise geändert worden.', $menuId),
-            'Den Aufruf nicht einfach wiederholen. Zuerst den aktuellen Stand mit lit/menu-get prüfen und ihn ggf. '
+            hint: 'Den Aufruf nicht einfach wiederholen. Zuerst den aktuellen Stand mit lit/menu-get prüfen und ihn '
-                . 'mit lit/menu-set-items (beide über mcp-adapter-execute-ability) anhand von previous_items (Stand '
+                . 'ggf. mit lit/menu-set-items (beide über mcp-adapter-execute-ability) anhand von previous_items '
-                . 'vorher) wiederherstellen; entfernte Einträge müssen dabei neu angelegt werden. Dem Nutzer Bescheid '
+                . '(Stand vorher) wiederherstellen; entfernte Einträge müssen dabei neu angelegt werden. Dem Nutzer '
-                . 'geben.',
+                . 'Bescheid geben.',
-            ['menu_id' => $menuId, 'previous_items' => MenuTree::build(array_values($current))]
+            details: $details
         );
     }
 

src/Integrations/WordPress/Settings/WpSettingsUpdateAbility.php

@@ -238,7 +238,7 @@ final class WpSettingsUpdateAbility implements Ability
 
         $reason = 'Eine Einstellung konnte nicht gespeichert werden.';
         if ($stuck === []) {
-            throw new WriteFailed($reason, true, null, null, $cause);
+            throw WriteFailed::rolledBack($reason, $cause);
         }
 
         $this->log->recordPartial(
@@ -247,17 +247,14 @@ final class WpSettingsUpdateAbility implements Ability
             implode(',', $stuck),
             'Einstellungen nur teilweise zurückgenommen: ' . implode(', ', $stuck)
         );
-        throw new WriteFailed(
+        throw WriteFailed::partial(
             $reason,
-            false,
-            null,
-            null,
             $cause,
             $cause->getMessage() . '; not restored: ' . implode(', ', $stuck),
-            sprintf('Möglicherweise auf dem neuen, nicht vollständigen Stand: %s.', implode(', ', $stuck)),
+            state: sprintf('Möglicherweise auf dem neuen, nicht vollständigen Stand: %s.', implode(', ', $stuck)),
-            'Aktuelle Werte über lit/wp-settings-get (mcp-adapter-execute-ability) prüfen und ggf. erneut auf die '
+            hint: 'Aktuelle Werte über lit/wp-settings-get (mcp-adapter-execute-ability) prüfen und ggf. erneut auf '
-                . 'gewünschten Werte setzen.',
+                . 'die gewünschten Werte setzen.',
-            ['keys' => $stuck]
+            details: ['keys' => $stuck]
         );
     }
 

src/Integrations/WordPress/Status/PostCloner.php

@@ -182,13 +182,9 @@ class PostCloner
 
         if ($cloneId instanceof WP_Error || (int) $cloneId === 0) {
             $reason = $cloneId instanceof WP_Error ? $cloneId->get_error_message() : 'unknown error';
-            throw new WriteFailed(
+            throw WriteFailed::rolledBack(
                 $label . ' konnte nicht angelegt werden.',
-                true,
+                detail: sprintf('Clone (%s) of post %d could not be created: %s', $markerKey, $originalId, $reason)
-                null,
-                null,
-                null,
-                sprintf('Clone (%s) of post %d could not be created: %s', $markerKey, $originalId, $reason)
             );
         }
 
@@ -216,10 +212,10 @@ class PostCloner
         $deleted = wp_delete_post($cloneId, true);
         $detail = sprintf('Clone %d of post %d failed: %s', $cloneId, (int) $original->ID, $cause->getMessage());
         if ($deleted) {
-            throw new WriteFailed($reason, true, null, null, $cause, $detail . '; clone deleted');
+            throw WriteFailed::rolledBack($reason, $cause, $detail . '; clone deleted');
         }
 
-        throw new WriteFailed($reason, false, $cloneId, null, $cause, $detail . '; clone could not be deleted');
+        throw WriteFailed::partial($reason, $cause, $detail . '; clone could not be deleted', $cloneId);
     }
 
     /**

src/Integrations/WordPress/Status/PostReplaceWithCopyAbility.php

@@ -126,7 +126,7 @@ final class PostReplaceWithCopyAbility implements Ability
         try {
             $snapshot = $this->cloner->snapshot($original);
         } catch (Throwable $e) {
-            throw new WriteFailed(self::REASON, true, $originalId, null, $e);
+            throw WriteFailed::rolledBack(self::REASON, $e, postId: $originalId);
         }
 
         // Throws WriteFailed (backup deleted again) before anything touches the original.
@@ -275,13 +275,12 @@ final class PostReplaceWithCopyAbility implements Ability
                 sprintf('"%s": Austausch nur teilweise zurückgenommen', $original->post_title),
                 $revisionId
             );
-            throw new WriteFailed(
+            throw WriteFailed::partial(
                 self::REASON,
-                false,
-                $originalId,
-                $revisionId,
                 $cause,
                 $detail . '; rollback incomplete: ' . $e->getMessage(),
+                $originalId,
+                $revisionId,
                 sprintf(
                     'Eintrag %d ist möglicherweise teilweise geändert worden (Stand vorher: Revision %s); die '
                         . 'vollständige Sicherung des vorherigen Stands liegt als Eintrag %d im Papierkorb.',
@@ -297,17 +296,14 @@ final class PostReplaceWithCopyAbility implements Ability
             );
         }
 
-        throw new WriteFailed(
+        throw WriteFailed::rolledBack(
             self::REASON,
-            true,
-            $originalId,
-            $revisionId,
             $cause,
             $detail,
-            null,
+            state: Errors::notSavedKeeping(sprintf('Sicherung %d im Papierkorb', $backupId)),
-            null,
+            details: $details,
-            $details,
+            postId: $originalId,
-            rolledBackState: Errors::notSavedKeeping(sprintf('Sicherung %d im Papierkorb', $backupId))
+            revisionId: $revisionId
         );
     }
 

src/Integrations/WordPress/Status/StatusWrite.php

@@ -33,16 +33,13 @@ final class StatusWrite
                 sprintf('"%s": Statusänderung abgebrochen, Stand unklar', $post->post_title)
             );
 
-            throw new WriteFailed(
+            throw WriteFailed::partial(
                 $reason,
-                false,
-                $postId,
-                null,
                 $e,
-                '',
+                postId: $postId,
-                sprintf('Status von Eintrag %d ist möglicherweise schon geändert worden.', $postId),
+                state: sprintf('Status von Eintrag %d ist möglicherweise schon geändert worden.', $postId),
-                'Den Aufruf nicht einfach wiederholen. Zuerst mit lit/content-get (direkt: lit-content-get) Status '
+                hint: 'Den Aufruf nicht einfach wiederholen. Zuerst mit lit/content-get (direkt: lit-content-get) '
-                    . 'und Inhalt prüfen und dem Nutzer Bescheid geben.'
+                    . 'Status und Inhalt prüfen und dem Nutzer Bescheid geben.'
             );
         }
     }

tests/Unit/Abilities/AbilityRegistrarTest.php

@@ -182,7 +182,12 @@ final class AbilityRegistrarTest extends TestCase
         $previous = ini_set('error_log', $log);
         $ability = $this->ability();
         $ability->expects('execute')->andThrow(
-            new WriteFailed('Felder konnten nicht gespeichert werden.', false, 5, 811, new RuntimeException('meta /var/www'))
+            WriteFailed::partial(
+                'Felder konnten nicht gespeichert werden.',
+                new RuntimeException('meta /var/www'),
+                postId: 5,
+                revisionId: 811
+            )
         );
 
         try {

tests/Unit/Abilities/ErrorsTest.php

@@ -114,4 +114,24 @@ final class ErrorsTest extends TestCase
         self::assertStringContainsString('Entwurf', $payload['message']);
         self::assertArrayNotHasKey('post_id', $payload);
     }
+
+    public function testClientMessageReadsTheJsonMessageBack(): void
+    {
+        self::assertSame('Titel fehlt.', Errors::clientMessage(Errors::invalidInput('Titel fehlt.')));
+        self::assertSame('WordPress sagt nein', Errors::clientMessage(new \WP_Error('db', 'WordPress sagt nein')));
+        self::assertSame('{"code":"x"}', Errors::clientMessage(new \WP_Error('db', '{"code":"x"}')));
+    }
+
+    public function testCodeOfDropsTheLitPrefixOnly(): void
+    {
+        self::assertSame('validation_failed', Errors::codeOf(Errors::invalidInput('x')));
+        self::assertSame('db_error', Errors::codeOf(new \WP_Error('db_error', 'x')));
+    }
+
+    public function testFieldsOfReturnsTheFieldsOrNothing(): void
+    {
+        self::assertSame(['title' => 'Pflichtfeld'], Errors::fieldsOf(Errors::invalidInput('x', ['title' => 'Pflichtfeld'])));
+        self::assertSame([], Errors::fieldsOf(Errors::invalidInput('x')));
+        self::assertSame([], Errors::fieldsOf(new \WP_Error('db', 'x', 'kein Array')));
+    }
 }

tests/Unit/Abilities/RollbackTest.php

@@ -0,0 +1,54 @@
+<?php
+
+declare(strict_types=1);
+
+namespace LIT\MCP\Tests\Unit\Abilities;
+
+use LIT\MCP\Abilities\Rollback;
+use LIT\MCP\Tests\Unit\TestCase;
+use RuntimeException;
+
+final class RollbackTest extends TestCase
+{
+    public function testAllStepsRunInOrderAndNothingFailed(): void
+    {
+        $ran = [];
+
+        $failures = Rollback::attempt(
+            static function () use (&$ran): void {
+                $ran[] = 1;
+            },
+            static function () use (&$ran): void {
+                $ran[] = 2;
+            }
+        );
+
+        self::assertSame([], $failures);
+        self::assertSame([1, 2], $ran);
+    }
+
+    public function testAFailingStepDoesNotStopTheOthersAndItsMessageIsCollected(): void
+    {
+        $ran = [];
+
+        $failures = Rollback::attempt(
+            static function (): void {
+                throw new RuntimeException('Begriffe nicht gelöscht');
+            },
+            static function () use (&$ran): void {
+                $ran[] = 2;
+            },
+            static function (): void {
+                throw new \Error('Zeile nicht zurückgesetzt');
+            }
+        );
+
+        self::assertSame(['Begriffe nicht gelöscht', 'Zeile nicht zurückgesetzt'], $failures);
+        self::assertSame([2], $ran);
+    }
+
+    public function testAReturnValueIsNoFailure(): void
+    {
+        self::assertSame([], Rollback::attempt(static fn (): string => 'egal', static fn (): bool => false));
+    }
+}

tests/Unit/Abilities/WriteFailedTest.php

@@ -13,7 +13,7 @@ final class WriteFailedTest extends TestCase
     public function testCleanRollbackMapsToWriteFailed(): void
     {
         $cause = new RuntimeException('meta kaputt');
-        $failure = new WriteFailed('Felder konnten nicht gespeichert werden.', true, 5, null, $cause);
+        $failure = WriteFailed::rolledBack('Felder konnten nicht gespeichert werden.', $cause, postId: 5);
 
         self::assertTrue($failure->rolledBack);
         self::assertSame($cause, $failure->getPrevious());
@@ -23,16 +23,17 @@ final class WriteFailedTest extends TestCase
 
     public function testRolledBackHintReplacesTheDefaultHintOfWriteFailedOnly(): void
     {
-        $clean = new WriteFailed('x', true, rolledBackHint: 'Erst neu lesen.');
+        $clean = WriteFailed::rolledBack('x', hint: 'Erst neu lesen.');
-        $partial = new WriteFailed('x', false, rolledBackHint: 'Erst neu lesen.');
+        $partial = WriteFailed::partial('x');
 
         self::assertSame('Erst neu lesen.', $clean->toError()->get_error_data()['hint']);
         self::assertNotSame('Erst neu lesen.', $partial->toError()->get_error_data()['hint']);
+        self::assertStringStartsWith('Den Aufruf nicht einfach wiederholen.', $partial->toError()->get_error_data()['hint']);
     }
 
     public function testIncompleteRollbackMapsToPartialWriteWithTheIds(): void
     {
-        $error = (new WriteFailed('Felder konnten nicht gespeichert werden.', false, 5, 811))->toError();
+        $error = WriteFailed::partial('Felder konnten nicht gespeichert werden.', postId: 5, revisionId: 811)->toError();
 
         self::assertSame('lit_partial_write', $error->get_error_code());
         self::assertSame(5, $error->get_error_data()['post_id']);
@@ -41,13 +42,12 @@ final class WriteFailedTest extends TestCase
 
     public function testIncompleteRollbackCanDescribeItsOwnStateHintAndDetails(): void
     {
-        $error = (new WriteFailed(
+        $error = WriteFailed::partial(
             'Menü nicht gespeichert.',
-            false,
             state: 'Das Menü ist teilweise geändert.',
             hint: 'Mit lit/menu-get prüfen.',
             details: ['menu_id' => 3]
-        ))->toError();
+        )->toError();
 
         self::assertSame('lit_partial_write', $error->get_error_code());
         self::assertStringContainsString('Das Menü ist teilweise geändert.', $error->get_error_message());
@@ -59,8 +59,8 @@ final class WriteFailedTest extends TestCase
     public function testRolledBackStateReplacesNothingWasSavedOfWriteFailedOnly(): void
     {
         $state = 'Die Änderung wurde nicht gespeichert (Sicherung 88 bleibt erhalten).';
-        $clean = (new WriteFailed('x', true, rolledBackState: $state))->toError();
+        $clean = WriteFailed::rolledBack('x', state: $state)->toError();
-        $partial = (new WriteFailed('x', false, rolledBackState: $state))->toError();
+        $partial = WriteFailed::partial('x')->toError();
 
         self::assertStringContainsString($state, $clean->get_error_message());
         self::assertStringNotContainsString('Nichts wurde gespeichert', $clean->get_error_message());
@@ -69,10 +69,31 @@ final class WriteFailedTest extends TestCase
 
     public function testCleanRollbackKeepsItsDetails(): void
     {
-        $error = (new WriteFailed('Nicht übernommen.', true, details: ['backup_id' => 88]))->toError();
+        $error = WriteFailed::rolledBack('Nicht übernommen.', details: ['backup_id' => 88])->toError();
 
         self::assertSame('lit_write_failed', $error->get_error_code());
         self::assertSame(88, $error->get_error_data()['backup_id']);
         self::assertStringContainsString('"backup_id":88', $error->get_error_message());
     }
+
+    public function testTheLogMessageIsTheDetailOrTheCauseOrTheReasonWithTheRollbackOutcome(): void
+    {
+        $cause = new RuntimeException('meta kaputt');
+
+        self::assertSame('Detail [rolled back]', WriteFailed::rolledBack('x', $cause, 'Detail')->getMessage());
+        self::assertSame('meta kaputt [rollback incomplete]', WriteFailed::partial('x', $cause)->getMessage());
+        self::assertSame('Grund [rolled back]', WriteFailed::rolledBack('Grund')->getMessage());
+    }
+
+    public function testTheNamedConstructorsKeepTheIdsForCallersThatLogThem(): void
+    {
+        $clean = WriteFailed::rolledBack('x', postId: 7, revisionId: 811);
+        $partial = WriteFailed::partial('x', postId: 7, revisionId: 811);
+
+        self::assertTrue($clean->rolledBack);
+        self::assertSame([7, 811], [$clean->postId, $clean->revisionId]);
+        self::assertFalse($partial->rolledBack);
+        self::assertSame([7, 811], [$partial->postId, $partial->revisionId]);
+        self::assertArrayNotHasKey('post_id', $clean->toError()->get_error_data());
+    }
 }

tests/Unit/Integrations/Divi/Pages/DiviReplaceTextAbilityTest.php

@@ -561,7 +561,7 @@ final class DiviReplaceTextAbilityTest extends TestCase
     public function testWriteFailedKeepsItsOwnMessage(): void
     {
         $ability = $this->ability();
-        $this->failures = [new WriteFailed('Die Datenbank hat das Speichern abgelehnt.', true, 7)];
+        $this->failures = [WriteFailed::rolledBack('Die Datenbank hat das Speichern abgelehnt.', postId: 7)];
         $log = (string) tempnam(sys_get_temp_dir(), 'lit-log');
         $previous = ini_set('error_log', $log);
         try {

tests/Unit/Integrations/Divi/Pages/DiviWriterTest.php

@@ -171,7 +171,7 @@ final class DiviWriterTest extends TestCase
         $content = DiviPageLoaderTest::fixture('synthetic-basic.html');
         DiviPageLoaderTest::givenPost($content);
         $saver = Mockery::mock(DiviSaver::class);
-        $saver->allows('save')->andThrow(new WriteFailed(DiviSaver::REASON, false, 7, 811));
+        $saver->allows('save')->andThrow(WriteFailed::partial(DiviSaver::REASON, postId: 7, revisionId: 811));
         $log = Mockery::mock(ChangeLog::class);
         $log->expects('recordPartial')->with('lit/divi-delete', 'page', '7', 'Divi "Start": Änderung nur teilweise zurückgenommen', 811);
         $writer = $this->writer($saver, $log);
@@ -187,7 +187,7 @@ final class DiviWriterTest extends TestCase
         $content = DiviPageLoaderTest::fixture('synthetic-basic.html');
         DiviPageLoaderTest::givenPost($content);
         $saver = Mockery::mock(DiviSaver::class);
-        $saver->allows('save')->andThrow(new WriteFailed(DiviSaver::REASON, true, 7, 811));
+        $saver->allows('save')->andThrow(WriteFailed::rolledBack(DiviSaver::REASON, postId: 7, revisionId: 811));
         $log = Mockery::mock(ChangeLog::class);
         $log->expects('recordPartial')->never();
         $log->expects('record')->never();

tests/Unit/Integrations/Media/MediaUploadAbilitiesTest.php

@@ -108,7 +108,7 @@ final class MediaUploadAbilitiesTest extends TestCase
 
     public function testAPartialUploadIsLoggedAsPartialAndRethrown(): void
     {
-        $failure = new WriteFailed('Alt-Text fehlt.', false, 55);
+        $failure = WriteFailed::partial('Alt-Text fehlt.', postId: 55);
         $importer = Mockery::mock(MediaImporter::class);
         $importer->allows('fromUrl')->andThrow($failure);
         $log = Mockery::mock(ChangeLog::class);

tests/Unit/Integrations/WordPress/Menus/MenuSetItemsAbilityTest.php

@@ -242,7 +242,7 @@ final class MenuSetItemsAbilityTest extends TestCase
     {
         $writer = Mockery::mock(MenuWriter::class);
         $writer->allows('plan')->andReturn(['errors' => [], 'removals' => [], 'warnings' => []]);
-        $writer->expects('apply')->andThrow(new WriteFailed('Menü nicht gespeichert.', true));
+        $writer->expects('apply')->andThrow(WriteFailed::rolledBack('Menü nicht gespeichert.'));
         $log = Mockery::mock(ChangeLog::class);
         $log->shouldNotReceive('recordPartial');
         $ability = new MenuSetItemsAbility($writer, new MenuOperations(), $log);
@@ -255,7 +255,7 @@ final class MenuSetItemsAbilityTest extends TestCase
     {
         $writer = Mockery::mock(MenuWriter::class);
         $writer->allows('plan')->andReturn(['errors' => [], 'removals' => [], 'warnings' => []]);
-        $writer->expects('apply')->andThrow(new WriteFailed('Menü nicht gespeichert.', false));
+        $writer->expects('apply')->andThrow(WriteFailed::partial('Menü nicht gespeichert.'));
         $log = Mockery::mock(ChangeLog::class);
         $log->expects('recordPartial')->with('lit/menu-set-items', 'nav_menu', '3', Mockery::type('string'));
         $ability = new MenuSetItemsAbility($writer, new MenuOperations(), $log);

tests/Unit/Integrations/WordPress/Status/PostReplaceWithCopyAbilityTest.php

@@ -282,7 +282,7 @@ final class PostReplaceWithCopyAbilityTest extends TestCase
     {
         $cloner = Mockery::mock(PostCloner::class);
         $cloner->allows('snapshot')->andReturn(self::SNAPSHOT);
-        $cloner->expects('backup')->andThrow(new WriteFailed('Die Sicherung konnte nicht angelegt werden.', true));
+        $cloner->expects('backup')->andThrow(WriteFailed::rolledBack('Die Sicherung konnte nicht angelegt werden.'));
         $cloner->expects('replace')->never();
         $cloner->expects('restore')->never();
         Functions\expect('wp_save_post_revision')->never();