fix: verify option writes before treating update_option() false as failure

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

src/Integrations/WordPress/Settings/WpSettingsUpdateAbility.php

@@ -138,7 +138,7 @@ final class WpSettingsUpdateAbility implements Ability
         try {
             foreach ($settings as $key => $value) {
                 $key = (string) $key;
-                if ($previous[$key] === $value) {
+                if ($this->isStored($key, $this->whitelist->normalize($key, $value))) {
                     continue;
                 }
 
@@ -168,17 +168,34 @@ final class WpSettingsUpdateAbility implements Ability
 
     private function writeOne(string $key, mixed $value): void
     {
+        $normalized = $this->whitelist->normalize($key, $value);
+
         if ($key === 'permalink_structure') {
-            $this->setPermalinkStructure((string) $value);
+            $this->setPermalinkStructure((string) $normalized);
 
             return;
         }
 
-        if (update_option($key, $this->whitelist->normalize($key, $value)) === false) {
-            throw new RuntimeException(sprintf('update_option(%s) returned false', $key));
+        // update_option() returns false both for a genuine failure and for a value
+        // that already matches the stored option (WordPress core short-circuits the
+        // write in that case, see wp-includes/option.php) – get_option() afterwards
+        // tells the two apart, the same way MetaFieldSource::holds() does for meta.
+        if (update_option($key, $normalized) === false && ! $this->isStored($key, $normalized)) {
+            throw new RuntimeException(sprintf('update_option(%s) failed', $key));
         }
     }
 
+    /** Whether option $key already holds $normalized, compared like WordPress compares scalars. */
+    private function isStored(string $key, mixed $normalized): bool
+    {
+        $stored = get_option($key);
+        if (is_scalar($stored) && is_scalar($normalized)) {
+            return (string) $stored === (string) $normalized;
+        }
+
+        return $stored == $normalized; // phpcs:ignore Universal.Operators.StrictComparisons.LooseEqual
+    }
+
     /**
      * A write failed; restores the keys already written to their previous values and
      * reports write_failed (fully restored) or partial_write (some keys could not be
@@ -223,5 +240,11 @@ final class WpSettingsUpdateAbility implements Ability
         global $wp_rewrite;
         $wp_rewrite->set_permalink_structure($structure);
         flush_rewrite_rules();
+
+        // set_permalink_structure() has no return value to check; verify the option
+        // itself so a failure here is caught and rolled back like any other setting.
+        if (! $this->isStored('permalink_structure', $structure)) {
+            throw new RuntimeException('set_permalink_structure() did not update the stored value.');
+        }
     }
 }