diff --git a/docs/architecture/ADMIN_QUERY_DELIVERY_OPERATIONS_BLUEPRINT.md b/docs/architecture/ADMIN_QUERY_DELIVERY_OPERATIONS_BLUEPRINT.md
index 07d557a..36af7e8 100644
--- a/docs/architecture/ADMIN_QUERY_DELIVERY_OPERATIONS_BLUEPRINT.md
+++ b/docs/architecture/ADMIN_QUERY_DELIVERY_OPERATIONS_BLUEPRINT.md
@@ -392,7 +392,7 @@ final class DeliveryOperationsAdminQueryRequestDTO implements \JsonSerializable
 - **Retry Bounds**: `attemptNoMin` and `attemptNoMax` must be unsigned (>= 0). If both are set, `attemptNoMin <= attemptNoMax`.
 - **Text Search**: `errorMessageLike` uses safe exact contains search with escaping (`LIKE :error_message_like ESCAPE '\\'`). Escaping must natively escape `\`, `%`, and `_`. Case insensitivity depends on the table's collation.
 - **Null-State Tri-State**: `nullStateFilters` accepts an associative array mapping exactly to these allowed property names: `actorType`, `actorId`, `targetType`, `targetId`, `scheduledAt`, `completedAt`, `correlationId`, `requestId`, `provider`, `providerMessageId`, `errorCode`, `errorMessage`. Values must be strictly `bool` (`true` -> `IS NULL`, `false` -> `IS NOT NULL`). An exception is thrown for invalid properties or non-bool values. Duplicate semantic conditions (e.g., both equality and null-state) naturally translate into SQL `WHERE column = X AND column IS NULL`, producing 0 rows as intended.
-- **Metadata JSON Search**: `metadataFilters` must be an exact associative array mapping `['stringPath' => scalarValue]`. No arbitrary JSON path evaluation. Maximum 5 filters per request. The path format must strictly enforce leading `$.`, exactly 1 to 5 non-empty ASCII `[A-Za-z0-9_]+` segments, dot separators only, no repeated dots, and maximum total length 64 bytes/characters. Allowed scalar value types: `string|int|float|bool|null`. Values must be successfully encoded via `json_encode(..., JSON_THROW_ON_ERROR)`. A JSON `null` filter explicitly searches for `CAST(NULL AS JSON)` value stored in the document, whereas missing a path returns NULL which requires `JSON_CONTAINS_PATH(metadata, 'one', :path) = 1` checks to differentiate. Null vs missing must be handled correctly in SQL.
+- **Metadata JSON Search**: `metadataFilters` must be an exact associative array mapping `['stringPath' => scalarValue]`. No arbitrary JSON path evaluation. Maximum 5 filters per request. The path format must strictly enforce leading `$.`, exactly 1 to 5 non-empty ASCII `[A-Za-z0-9_]+` segments, dot separators only, no repeated dots, and maximum total length 64 bytes/characters. Allowed scalar value types: `string|int|float|bool|null`. Values must be successfully encoded via `json_encode(..., JSON_THROW_ON_ERROR)`. A JSON `null` filter explicitly searches for `'null' JSON literal` value stored in the document, whereas missing a path returns NULL which requires `JSON_CONTAINS_PATH(metadata, 'one', :path) = 1` checks to differentiate. Null vs missing must be handled correctly in SQL.
 
 ### 3.5 Result DTO
 `DeliveryOperationsAdminPageResultDTO`
@@ -500,7 +500,7 @@ For `errorMessageLike`, the parameter value must be escaped using:
 This matches the explicit `ESCAPE '\\'` SQL clause.
 
 ### Metadata Paths
-Path format strictly matches `/^\$\.[A-Za-z0-9_]+(\.[A-Za-z0-9_]+){0,4}$/`. Callers must supply the leading `$.`. Maximum 5 keys. Maximum path length 64 bytes/characters. Deterministic placeholders (e.g., `meta_path_0`, `meta_val_0`). Parameter values encoded via `json_encode(..., JSON_THROW_ON_ERROR)`. JSON-null searches natively match `CAST('null' AS JSON)` if the path exists, enforced via `JSON_CONTAINS_PATH`.
+Path format strictly matches `/^\$\.[A-Za-z0-9_]+(\.[A-Za-z0-9_]+){0,4}$/`. Callers must supply the leading `$.`. Maximum 5 keys. Maximum path length 64 bytes/characters. Deterministic placeholders (e.g., `meta_path_exists_N`, `meta_value_N`). Parameter values encoded via `json_encode(..., JSON_THROW_ON_ERROR)`. JSON-null searches natively match `the 'null' JSON literal` if the path exists, enforced via `JSON_CONTAINS_PATH`.
 
 ### SQL Semantics
 - **Empty filters:** generates empty `whereSql` (no `WHERE` string added to data/count SQL).
diff --git a/docs/roadmap/ADMIN_QUERY_API_ROADMAP.md b/docs/roadmap/ADMIN_QUERY_API_ROADMAP.md
index 60f152c..9a5b51d 100644
--- a/docs/roadmap/ADMIN_QUERY_API_ROADMAP.md
+++ b/docs/roadmap/ADMIN_QUERY_API_ROADMAP.md
@@ -1,6 +1,6 @@
 # Admin Query API Roadmap
 
-**Status:** Phase 4 Complete / DeliveryOperations Runtime Implemented / Pending Release
+**Status:** Phase 4 Active / DeliveryOperations Runtime Implemented / Pending Release
 
 ## 1. Scope Boundary
 
@@ -93,9 +93,9 @@ Implement the Admin Query API for domains that never received the incorrect post
 
 These are new post-v1.0 features, not corrections to the first-release Runtime.
 
-- **Status:** Phase 4 is active. DiagnosticsTelemetry Runtime is complete and merged.
+- **Status:** Phase 4 is active. DiagnosticsTelemetry Runtime is complete and merged. DeliveryOperations Runtime Implemented.
   - `DiagnosticsTelemetry`: [Owner Approved / Runtime Implemented / Complete](../architecture/ADMIN_QUERY_DIAGNOSTICS_TELEMETRY_BLUEPRINT.md)
-  - `DeliveryOperations`: Owner Approved / Runtime Implemented / Complete
+  - `DeliveryOperations`: Owner Approved / Runtime Implemented / Pending Merge
 
 ### Phase 5 — Reporting and Dashboard Summary Contracts
 
@@ -140,7 +140,7 @@ Every implementation phase must prove all of the following:
 
 ## 6. Current Gate
 
-- Phase 4 is complete;
-- DeliveryOperations Runtime is complete;
+- Phase 4 is active;
+- DeliveryOperations Runtime is complete / Pending Merge;
 - reporting/dashboard does not start until Admin pagination is released and verified for all six domains;
 - no release/tag authorized.
diff --git a/src/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsRowMapper.php b/src/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsRowMapper.php
index 8d5d42a..0b47971 100644
--- a/src/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsRowMapper.php
+++ b/src/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsRowMapper.php
@@ -62,9 +62,18 @@ public function map(array $row): DeliveryOperationsViewDTO
         if (isset($row['metadata']) && is_string($row['metadata']) && $row['metadata'] !== '') {
             try {
                 $decoded = json_decode($row['metadata'], true, 512, JSON_THROW_ON_ERROR);
-                if (is_array($decoded) && array_is_list($decoded) === false || $decoded === []) {
-                    /** @var array<string, mixed> $decoded */
-                    $metadata = $decoded;
+                if (is_array($decoded)) {
+                    $allKeysStrings = true;
+                    foreach (array_keys($decoded) as $decodedKey) {
+                        if (!is_string($decodedKey)) {
+                            $allKeysStrings = false;
+                            break;
+                        }
+                    }
+                    if ($allKeysStrings) {
+                        /** @var array<string, mixed> $decoded */
+                        $metadata = $decoded;
+                    }
                 }
             } catch (JsonException) {
                 // Mapping failure or corruption -> fallback to null.
diff --git a/tests/Integration/DeliveryOperations/DeliveryOperationsAdminQueryMysqlRepositoryTest.php b/tests/Integration/DeliveryOperations/DeliveryOperationsAdminQueryMysqlRepositoryTest.php
index a1654ab..a725937 100644
--- a/tests/Integration/DeliveryOperations/DeliveryOperationsAdminQueryMysqlRepositoryTest.php
+++ b/tests/Integration/DeliveryOperations/DeliveryOperationsAdminQueryMysqlRepositoryTest.php
@@ -308,18 +308,43 @@ public function testItPreservesCallerOwnedTransaction(): void
         $this->assertSame(0, $res2->filtered);
     }
 
-    public function testItTranslatesRealPdoExceptionToStorageException(): void
+    public function testItTranslatesRealMappingFailureToStorageException(): void
     {
-        $this->pdo->exec('DROP TABLE maa_event_logging_delivery_operations');
+        $this->insertLog(eventId: 'e1');
+
+        $this->pdo->exec("RENAME TABLE maa_event_logging_delivery_operations TO maa_event_logging_delivery_operations_real");
+        $this->pdo->exec("CREATE VIEW maa_event_logging_delivery_operations AS SELECT id, event_id, channel, operation_type, actor_type, actor_id, target_type, target_id, status, attempt_no, scheduled_at, completed_at, correlation_id, request_id, provider, provider_message_id, error_code, error_message, metadata, 'invalid-date' as occurred_at FROM maa_event_logging_delivery_operations_real");
+
+        try {
+            $this->repository->paginate(new DeliveryOperationsAdminQueryRequestDTO());
+            $this->fail('Expected DeliveryOperationsStorageException');
+        } catch (DeliveryOperationsStorageException $e) {
+            $this->assertStringContainsString('Failed to map DeliveryOperations row', $e->getMessage());
+        } finally {
+            $this->pdo->exec("DROP VIEW IF EXISTS maa_event_logging_delivery_operations");
+            $this->pdo->exec("RENAME TABLE maa_event_logging_delivery_operations_real TO maa_event_logging_delivery_operations");
+        }
+    }
+
+    public function testItTranslatesRealPdoExceptionToStorageExceptionAndPreservesTransaction(): void
+    {
+        $this->pdo->beginTransaction();
+
+        $this->pdo->exec('SET @@session.max_join_size=1');
+
+        $this->insertLog(eventId: 'e1');
+        $this->insertLog(eventId: 'e2');
 
         try {
             $this->repository->paginate(new DeliveryOperationsAdminQueryRequestDTO());
             $this->fail('Expected DeliveryOperationsStorageException');
         } catch (DeliveryOperationsStorageException $e) {
-            $this->assertStringContainsString('Failed to query DeliveryOperations records:', $e->getMessage());
-            $this->assertInstanceOf(\PDOException::class, $e->getPrevious());
+            $this->assertStringContainsString('Failed to query DeliveryOperations records', $e->getMessage());
         } finally {
-            $this->setUp(); // Re-create schema for subsequent tests if necessary
+            $this->pdo->exec('SET @@session.max_join_size=DEFAULT');
         }
+
+        $this->assertTrue($this->pdo->inTransaction());
+        $this->pdo->rollBack();
     }
 }
diff --git a/tests/Regression/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsQueryMysqlRepositoryRegressionTest.php b/tests/Regression/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsQueryMysqlRepositoryRegressionTest.php
index 348dcc3..4b6f028 100644
--- a/tests/Regression/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsQueryMysqlRepositoryRegressionTest.php
+++ b/tests/Regression/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsQueryMysqlRepositoryRegressionTest.php
@@ -239,15 +239,112 @@ public function testDtoPreservesPrimitiveSignatureAndDefaults(): void
 
         // Assert all but limit are nullable
         foreach ($params as $param) {
+            $type = $param->getType();
+            $this->assertInstanceOf(\ReflectionNamedType::class, $type);
             if ($param->getName() === 'limit') {
-                $this->assertFalse($param->getType()->allowsNull());
+                $this->assertFalse($type->allowsNull());
+                $this->assertSame('int', $type->getName());
                 $this->assertTrue($param->isDefaultValueAvailable());
                 $this->assertSame(50, $param->getDefaultValue());
             } else {
-                $this->assertTrue($param->getType()->allowsNull());
+                $this->assertTrue($type->allowsNull());
                 $this->assertTrue($param->isDefaultValueAvailable());
                 $this->assertNull($param->getDefaultValue());
+
+                if (str_ends_with($param->getName(), 'At') || in_array($param->getName(), ['after', 'before'])) {
+                    $this->assertSame(DateTimeImmutable::class, $type->getName());
+                } elseif (in_array($param->getName(), ['actorId', 'targetId', 'cursorId'])) {
+                    $this->assertSame('int', $type->getName());
+                } else {
+                    $this->assertSame('string', $type->getName());
+                }
             }
         }
     }
+
+    public function testPrimitiveRepositoryNeverCallsTransactionMethods(): void
+    {
+        $this->pdo->expects($this->never())->method('beginTransaction');
+        $this->pdo->expects($this->never())->method('commit');
+        $this->pdo->expects($this->never())->method('rollBack');
+
+        $this->pdo->expects($this->once())
+            ->method('prepare')
+            ->willReturn($this->statement);
+
+        $this->statement->expects($this->once())
+            ->method('execute');
+
+        $this->statement->expects($this->once())
+            ->method('fetchAll')
+            ->willReturn([]);
+
+        $this->repository->find(new DeliveryOperationsQueryDTO());
+    }
+
+    public function testPrimitiveRepositoryNeverCallsTransactionMethodsOnFailure(): void
+    {
+        $this->pdo->expects($this->never())->method('beginTransaction');
+        $this->pdo->expects($this->never())->method('commit');
+        $this->pdo->expects($this->never())->method('rollBack');
+
+        $this->pdo->expects($this->once())
+            ->method('prepare')
+            ->willThrowException(new PDOException('PDO failure'));
+
+        $this->expectException(DeliveryOperationsStorageException::class);
+        $this->repository->find(new DeliveryOperationsQueryDTO());
+    }
+
+    public function testPrimitiveRepositoryContractBoundariesArePreserved(): void
+    {
+        $interfaces = class_implements(DeliveryOperationsQueryMysqlRepository::class);
+        $this->assertContains(\Maatify\EventLogging\DeliveryOperations\Contract\DeliveryOperationsQueryInterface::class, $interfaces);
+        $this->assertTrue((new \ReflectionClass(DeliveryOperationsQueryMysqlRepository::class))->isFinal());
+
+        $constructor = (new \ReflectionClass(DeliveryOperationsQueryMysqlRepository::class))->getConstructor();
+        $this->assertNotNull($constructor);
+        $this->assertCount(1, $constructor->getParameters());
+        $param = $constructor->getParameters()[0];
+        $this->assertSame('pdo', $param->getName());
+        $type = $param->getType();
+        $this->assertInstanceOf(\ReflectionNamedType::class, $type);
+        $this->assertSame(PDO::class, $type->getName());
+
+        $findMethod = (new \ReflectionClass(DeliveryOperationsQueryMysqlRepository::class))->getMethod('find');
+        $this->assertTrue($findMethod->isPublic());
+        $this->assertCount(1, $findMethod->getParameters());
+        $queryParam = $findMethod->getParameters()[0];
+        $this->assertSame('query', $queryParam->getName());
+        $queryType = $queryParam->getType();
+        $this->assertInstanceOf(\ReflectionNamedType::class, $queryType);
+        $this->assertSame(DeliveryOperationsQueryDTO::class, $queryType->getName());
+
+        $returnType = $findMethod->getReturnType();
+        $this->assertInstanceOf(\ReflectionNamedType::class, $returnType);
+        $this->assertSame('array', $returnType->getName());
+    }
+
+    public function testPrimitiveRepositoryBoundariesAndSchemaArePreservedUnchanged(): void
+    {
+        // Prove primitive read API is strictly separated from writer boundaries
+        $this->assertTrue(interface_exists(\Maatify\EventLogging\DeliveryOperations\Contract\DeliveryOperationsLoggerInterface::class));
+        $this->assertTrue(class_exists(\Maatify\EventLogging\DeliveryOperations\Infrastructure\Mysql\DeliveryOperationsLoggerMysqlRepository::class));
+        $this->assertTrue(class_exists(\Maatify\EventLogging\DeliveryOperations\Recorder\DeliveryOperationsRecorder::class));
+        $this->assertTrue(class_exists(\Maatify\EventLogging\DeliveryOperations\Recorder\DeliveryOperationsDefaultPolicy::class));
+
+        // Schema verification
+        $schemaPath = __DIR__ . '/../../../../../src/DeliveryOperations/Database/schema.maa_event_logging_delivery_operations.sql';
+        $this->assertFileExists($schemaPath);
+        $schema = file_get_contents($schemaPath);
+        $this->assertIsString($schema);
+        $this->assertStringContainsString('maa_event_logging_delivery_operations', $schema);
+        $this->assertStringContainsString('INDEX idx_delivery_ops_actor_time (actor_type, actor_id, occurred_at)', $schema);
+
+        // Fail-open boundary verification (Recorder does not throw StorageException)
+        $recorderClass = new \ReflectionClass(\Maatify\EventLogging\DeliveryOperations\Recorder\DeliveryOperationsRecorder::class);
+        $docComment = $recorderClass->getMethod('record')->getDocComment();
+        $docString = is_string($docComment) ? $docComment : '';
+        $this->assertFalse(str_contains($docString, '@throws ' . DeliveryOperationsStorageException::class));
+    }
 }
\ No newline at end of file
diff --git a/tests/Unit/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsAdminQueryMysqlRepositoryTest.php b/tests/Unit/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsAdminQueryMysqlRepositoryTest.php
index e089d9a..d6c5ed2 100644
--- a/tests/Unit/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsAdminQueryMysqlRepositoryTest.php
+++ b/tests/Unit/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsAdminQueryMysqlRepositoryTest.php
@@ -31,9 +31,9 @@ protected function setUp(): void
         $this->repository = new DeliveryOperationsAdminQueryMysqlRepository($this->pdo);
     }
 
-    public function testItAdaptsResultCorrectly(): void
+    public function testItAdaptsResultCorrectlyWithLimitsMaxAndMinPaginationGates(): void
     {
-        $this->pdo->expects($this->exactly(3))
+        $this->pdo->expects($this->exactly(9)) // 3 requests * 3 prepares (1 data + 2 count)
             ->method('prepare')
             ->willReturnCallback(function (string $sql) {
                 if (!str_contains($sql, 'COUNT(*)')) {
@@ -51,20 +51,70 @@ public function testItAdaptsResultCorrectly(): void
         $this->statement->method('execute')->willReturn(true);
         $this->statement->method('bindValue')->willReturn(true);
 
-        $this->countStatement->expects($this->exactly(2))
+        $this->countStatement->expects($this->exactly(6))
             ->method('columnCount')
             ->willReturn(1);
 
-        $this->countStatement->expects($this->exactly(4))
+        $this->countStatement->expects($this->exactly(12))
             ->method('fetch')
-            ->willReturnOnConsecutiveCalls(['COUNT(*)' => 1], false, ['COUNT(*)' => 1], false);
+            ->willReturnOnConsecutiveCalls(
+                ['COUNT(*)' => 1], false, ['COUNT(*)' => 1], false,
+                ['COUNT(*)' => 1], false, ['COUNT(*)' => 1], false,
+                ['COUNT(*)' => 1], false, ['COUNT(*)' => 1], false
+            );
 
         $this->countStatement->method('errorCode')->willReturn('00000');
         $this->statement->method('errorCode')->willReturn('00000');
 
-        $this->statement->expects($this->exactly(2))
+        $this->statement->expects($this->exactly(6))
             ->method('fetch')
             ->willReturnOnConsecutiveCalls(
+                [
+                    'id' => '1',
+                    'event_id' => 'evt-1',
+                    'channel' => 'chan-1',
+                    'operation_type' => 'op-1',
+                    'actor_type' => 'act-1',
+                    'actor_id' => '42',
+                    'target_type' => 'tar-1',
+                    'target_id' => '43',
+                    'status' => 'stat-1',
+                    'attempt_no' => '0',
+                    'scheduled_at' => null,
+                    'completed_at' => null,
+                    'correlation_id' => null,
+                    'request_id' => null,
+                    'provider' => null,
+                    'provider_message_id' => null,
+                    'error_code' => null,
+                    'error_message' => null,
+                    'metadata' => null,
+                    'occurred_at' => '2023-01-01 00:00:00.000000',
+                ],
+                false,
+                [
+                    'id' => '1',
+                    'event_id' => 'evt-1',
+                    'channel' => 'chan-1',
+                    'operation_type' => 'op-1',
+                    'actor_type' => 'act-1',
+                    'actor_id' => '42',
+                    'target_type' => 'tar-1',
+                    'target_id' => '43',
+                    'status' => 'stat-1',
+                    'attempt_no' => '0',
+                    'scheduled_at' => null,
+                    'completed_at' => null,
+                    'correlation_id' => null,
+                    'request_id' => null,
+                    'provider' => null,
+                    'provider_message_id' => null,
+                    'error_code' => null,
+                    'error_message' => null,
+                    'metadata' => null,
+                    'occurred_at' => '2023-01-01 00:00:00.000000',
+                ],
+                false,
                 [
                     'id' => '1',
                     'event_id' => 'evt-1',
@@ -90,21 +140,23 @@ public function testItAdaptsResultCorrectly(): void
                 false
             );
 
-        $request = new DeliveryOperationsAdminQueryRequestDTO(page: 1, perPage: 20);
-        $result = $this->repository->paginate($request);
+        // First request to verify min clamp to page=1, perPage=1
+        $requestMin = new DeliveryOperationsAdminQueryRequestDTO(page: 0, perPage: 0);
+        $resultMin = $this->repository->paginate($requestMin);
+        $this->assertEquals(1, $resultMin->page);
+        $this->assertEquals(1, $resultMin->perPage);
 
-        $this->assertEquals(1, $result->page);
-        $this->assertEquals(20, $result->perPage);
-        $this->assertEquals(1, $result->total);
-        $this->assertEquals(1, $result->filtered);
-        $this->assertEquals(1, $result->totalPages);
-        $this->assertFalse($result->hasNext);
-        $this->assertFalse($result->hasPrevious);
-        $this->assertEquals('occurred_at', $result->sortBy);
-        $this->assertEquals('DESC', $result->sortDirection);
-
-        $this->assertCount(1, $result->items);
-        $this->assertEquals(1, $result->items[0]->id);
+        // Second request to verify max clamp to perPage=200
+        $requestMax = new DeliveryOperationsAdminQueryRequestDTO(page: 1, perPage: 500);
+        $resultMax = $this->repository->paginate($requestMax);
+        $this->assertEquals(1, $resultMax->page);
+        $this->assertEquals(200, $resultMax->perPage);
+
+        // Third request to verify defaults
+        $requestDefault = new DeliveryOperationsAdminQueryRequestDTO();
+        $resultDefault = $this->repository->paginate($requestDefault);
+        $this->assertEquals(1, $resultDefault->page);
+        $this->assertEquals(20, $resultDefault->perPage);
     }
 
     public function testItTranslatesPDOExceptionToStorageException(): void
@@ -188,4 +240,53 @@ public function testItWrapsMapperFailure(): void
 
         $this->repository->paginate($request);
     }
+
+    public function testItNeverCallsTransactionMethods(): void
+    {
+        $this->pdo->expects($this->never())->method('beginTransaction');
+        $this->pdo->expects($this->never())->method('commit');
+        $this->pdo->expects($this->never())->method('rollBack');
+
+        $this->pdo->expects($this->exactly(3))
+            ->method('prepare')
+            ->willReturnCallback(function (string $sql) {
+                if (str_contains($sql, 'COUNT(*)')) {
+                    return $this->countStatement;
+                }
+                return $this->statement;
+            });
+
+        $this->countStatement->method('execute')->willReturn(true);
+        $this->countStatement->method('bindValue')->willReturn(true);
+        $this->statement->method('execute')->willReturn(true);
+        $this->statement->method('bindValue')->willReturn(true);
+        $this->countStatement->method('columnCount')->willReturn(1);
+        $this->countStatement->method('errorCode')->willReturn('00000');
+        $this->statement->method('errorCode')->willReturn('00000');
+        $this->countStatement->method('fetch')->willReturnOnConsecutiveCalls(['COUNT(*)' => 1], false, ['COUNT(*)' => 1], false);
+        $this->statement->method('fetch')->willReturn(false); // return 0 items
+
+        $request = new DeliveryOperationsAdminQueryRequestDTO(page: 1, perPage: 20);
+        $result = $this->repository->paginate($request);
+        $this->assertCount(0, $result->items);
+    }
+
+    public function testItNeverCallsTransactionMethodsOnFailure(): void
+    {
+        $this->pdo->expects($this->never())->method('beginTransaction');
+        $this->pdo->expects($this->never())->method('commit');
+        $this->pdo->expects($this->never())->method('rollBack');
+
+        $this->pdo->expects($this->once())
+            ->method('prepare')
+            ->willThrowException(new \PDOException('Failure'));
+
+        $request = new DeliveryOperationsAdminQueryRequestDTO(page: 1, perPage: 20);
+        try {
+            $this->repository->paginate($request);
+            $this->fail('Expected Exception');
+        } catch (DeliveryOperationsStorageException) {
+            // expected
+        }
+    }
 }
diff --git a/tests/Unit/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsRowMapperTest.php b/tests/Unit/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsRowMapperTest.php
index fecc25a..ec9cec5 100644
--- a/tests/Unit/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsRowMapperTest.php
+++ b/tests/Unit/DeliveryOperations/Infrastructure/Mysql/DeliveryOperationsRowMapperTest.php
@@ -99,6 +99,22 @@ public function testItMapsInvalidJsonToNull(): void
         $this->assertNull($dto->metadata);
     }
 
+    public function testItMapsNumericKeyJsonToNull(): void
+    {
+        $dto = $this->mapper->map([
+            'metadata' => '{"1": "x"}'
+        ]);
+        $this->assertNull($dto->metadata);
+    }
+
+    public function testItMapsMixedKeyJsonToNull(): void
+    {
+        $dto = $this->mapper->map([
+            'metadata' => '{"a": "x", "1": "y"}'
+        ]);
+        $this->assertNull($dto->metadata);
+    }
+
     public function testItMapsEmptyJsonToNull(): void
     {
         $dto = $this->mapper->map([