(fix): normalize tenant types at boundary, restore strict comparison

- Add symmetric ctype_digit normalization to Adapter::getTenant() to
  match Document::getTenant(), ensuring both return int for numeric IDs
- Replace is_numeric with ctype_digit to avoid truncating float strings
- Revert all != back to !== now that types are normalized at the source
- Extract duplicated array-to-Document coercion into private helper
- Replace empty() with precise === '' check for ID validation

Co-Authored-By: Claude Opus 4.6 (1M context) <noreply@anthropic.com>

Author: abnegate

src/Database/Adapter.php

@@ -244,10 +244,16 @@ public function setTenant(int|string|null $tenant): bool
     /**
      * Get Tenant.
      *
-     * Get tenant to use for shared tables
+     * Get tenant to use for shared tables.
+     * Numeric values are normalized to int for consistent comparison
+     * across adapters that may return string representations.
      */
     public function getTenant(): int|string|null
     {
+        if (\is_string($this->tenant) && \ctype_digit($this->tenant)) {
+            return (int) $this->tenant;
+        }
+
         return $this->tenant;
     }
 

src/Database/Document.php

@@ -239,11 +239,15 @@ public function getUpdatedAt(): ?string
      *
      * @return int|string|null The tenant ID, or null if not set.
      */
+    /**
+     * Numeric string values are normalized to int for consistent comparison
+     * across adapters that may return string representations (e.g. PDO stringify).
+     */
     public function getTenant(): int|string|null
     {
         $tenant = $this->getAttribute('$tenant');
 
-        if (\is_numeric($tenant)) {
+        if (\is_string($tenant) && \ctype_digit($tenant)) {
             return (int) $tenant;
         }
 

src/Database/Hook/Relationships.php

@@ -53,6 +53,20 @@ public function __construct(
     ) {
     }
 
+    private function coerceToDocument(Document $document, string $key, mixed $value): mixed
+    {
+        if (\is_array($value) && ! \array_is_list($value)) {
+            try {
+                $value = new Document($value); // @phpstan-ignore argument.type
+            } catch (StructureException $e) {
+                throw new RelationshipException('Invalid relationship value. ' . $e->getMessage());
+            }
+            $document->setAttribute($key, $value);
+        }
+
+        return $value;
+    }
+
     /**
      * {@inheritDoc}
      */
@@ -148,14 +162,7 @@ public function afterDocumentCreate(Document $collection, Document $document): D
             $this->writeStack[] = $collection->getId();
 
             try {
-                if (\is_array($value) && ! \array_is_list($value)) {
-                    try {
-                        $value = new Document($value); // @phpstan-ignore argument.type
-                    } catch (StructureException $e) {
-                        throw new RelationshipException('Invalid relationship value. ' . $e->getMessage());
-                    }
-                    $document->setAttribute($key, $value);
-                }
+                $value = $this->coerceToDocument($document, $key, $value);
 
                 if (\is_array($value)) {
                     if (
@@ -290,14 +297,7 @@ public function afterDocumentUpdate(Document $collection, Document $old, Documen
             $key = $typedRelAttr->key;
             $value = $document->getAttribute($key);
 
-            if (\is_array($value) && ! \array_is_list($value)) {
-                try {
-                    $value = new Document($value); // @phpstan-ignore argument.type
-                } catch (StructureException $e) {
-                    throw new RelationshipException('Invalid relationship value. ' . $e->getMessage());
-                }
-                $document->setAttribute($key, $value);
-            }
+            $value = $this->coerceToDocument($document, $key, $value);
 
             $oldValue = $old->getAttribute($key);
             $rel = RelationshipVO::fromDocument($collection->getId(), $relationship);
@@ -543,7 +543,7 @@ public function afterDocumentUpdate(Document $collection, Document $old, Documen
                             }
                             $this->db->purgeCachedDocument($relatedCollection->getId(), $value);
                         } elseif ($value instanceof Document) {
-                            if (empty($value->getId())) {
+                            if ($value->getId() === '') {
                                 throw new RelationshipException('Invalid relationship value. Document must have a valid $id.');
                             }
 

src/Database/Traits/Collections.php

@@ -247,7 +247,7 @@ public function updateCollection(string $id, array $permissions, bool $documentS
 
         if (
             $this->adapter->getSharedTables()
-            && $collection->getTenant() != $this->adapter->getTenant()
+            && $collection->getTenant() !== $this->adapter->getTenant()
         ) {
             throw new NotFoundException('Collection not found');
         }
@@ -279,7 +279,7 @@ public function getCollection(string $id): Document
             $id !== self::METADATA
             && $this->adapter->getSharedTables()
             && $collection->getTenant() !== null
-            && $collection->getTenant() != $this->adapter->getTenant()
+            && $collection->getTenant() !== $this->adapter->getTenant()
         ) {
             return new Document();
         }
@@ -326,7 +326,7 @@ public function getSizeOfCollection(string $collection): int
             throw new NotFoundException('Collection not found');
         }
 
-        if ($this->adapter->getSharedTables() && $collection->getTenant() != $this->adapter->getTenant()) {
+        if ($this->adapter->getSharedTables() && $collection->getTenant() !== $this->adapter->getTenant()) {
             throw new NotFoundException('Collection not found');
         }
 
@@ -354,7 +354,7 @@ public function getSizeOfCollectionOnDisk(string $collection): int
             throw new NotFoundException('Collection not found');
         }
 
-        if ($this->adapter->getSharedTables() && $collection->getTenant() != $this->adapter->getTenant()) {
+        if ($this->adapter->getSharedTables() && $collection->getTenant() !== $this->adapter->getTenant()) {
             throw new NotFoundException('Collection not found');
         }
 
@@ -388,7 +388,7 @@ public function deleteCollection(string $id): bool
             throw new NotFoundException('Collection not found');
         }
 
-        if ($this->adapter->getSharedTables() && $collection->getTenant() != $this->adapter->getTenant()) {
+        if ($this->adapter->getSharedTables() && $collection->getTenant() !== $this->adapter->getTenant()) {
             throw new NotFoundException('Collection not found');
         }
 

src/Database/Traits/Documents.php

@@ -1405,7 +1405,7 @@ public function upsertDocumentsWithIncrease(
                     if ($document->getTenant() === null) {
                         throw new DatabaseException('Missing tenant. Tenant must be set when tenant per document is enabled.');
                     }
-                    if (! $old->isEmpty() && $old->getTenant() != $document->getTenant()) {
+                    if (! $old->isEmpty() && $old->getTenant() !== $document->getTenant()) {
                         throw new DatabaseException('Tenant cannot be changed.');
                     }
                 } else {