diff --git a/lib/Service/OrganizationSyncService.php b/lib/Service/OrganizationSyncService.php
index 87c3228d..c063c4c4 100644
--- a/lib/Service/OrganizationSyncService.php
+++ b/lib/Service/OrganizationSyncService.php
@@ -21,7 +21,6 @@
 namespace OCA\SoftwareCatalog\Service;
 
 use OCA\OpenRegister\Contract\ObjectServiceInterface;
-use OCA\OpenRegister\Service\ObjectService;
 use OCA\SoftwareCatalog\Service\SoftwareCatalogue\ContactPersonHandler;
 use OCP\IAppConfig;
 use OCP\IDBConnection;
@@ -384,10 +383,13 @@ public function performOrganizationsSync(int $batchSize = 50, int $maxExecutionS
 
 		$rows = $qb->executeQuery()->fetchAll();
 
-		if ($this->objectService instanceof ObjectService === false) {
-			$this->logger->error('OrganizationSync: could not resolve ObjectService');
-			return $stats;
-		}
+		// No resolution guard here any more. $objectService is a promoted,
+		// readonly, non-nullable ObjectServiceInterface, so it cannot be
+		// unresolved by the time this runs. The old check asked
+		// `instanceof ObjectService` — the CONCRETE class — against a property
+		// typed as the interface, so any implementation other than that one
+		// class made it return $stats and log "could not resolve", silently
+		// skipping the whole batch rather than syncing it.
 
 		foreach ($rows as $row) {
 			if ((time() - $startTime) >= $maxExecutionSeconds) {
@@ -508,10 +510,9 @@ public function performContactSync(int $batchSize = 100, int $maxExecutionSecond
 
 		$this->logger->info('ContactSync: processing ' . count($contacts) . ' contacts with existing NC accounts');
 
-		if ($this->objectService instanceof ObjectService === false) {
-			$this->logger->error('ContactSync: could not resolve ObjectService');
-			return $stats;
-		}
+		// Same as above: the promoted readonly ObjectServiceInterface cannot be
+		// unresolved, and the old `instanceof ObjectService` check against the
+		// concrete class made this skip every contact instead.
 
 		foreach ($contacts as $contact) {
 			if ((time() - $startTime) >= $maxExecutionSeconds) {
diff --git a/lib/Service/ViewService.php b/lib/Service/ViewService.php
index 2ce681b3..5766e624 100644
--- a/lib/Service/ViewService.php
+++ b/lib/Service/ViewService.php
@@ -22,7 +22,6 @@
 namespace OCA\SoftwareCatalog\Service;
 
 use OCA\OpenRegister\Contract\ObjectServiceInterface;
-use OCA\OpenRegister\Service\ObjectService;
 use OCP\App\IAppManager;
 use OCP\IAppConfig;
 use OCP\ICache;
@@ -1407,7 +1406,13 @@ private function getObjectService(): ?ObjectServiceInterface {
 		}
 
 		try {
-			return $this->container->get(ObjectService::class);
+			// Ask for the CONTRACT, not the concrete class. This method
+			// declares `?ObjectServiceInterface`, and resolving the concrete
+			// ObjectService returns something that only satisfies it by
+			// coincidence — under test it is a double of the concrete class,
+			// which does not implement the interface, so the declared return
+			// type rejected it.
+			return $this->container->get(ObjectServiceInterface::class);
 		} catch (\Exception $e) {
 			$this->logger->warning(
 				'Failed to get ObjectService',
diff --git a/tests/Stubs/Db/ObjectEntity.php b/tests/Stubs/Db/ObjectEntity.php
index 34311c7b..f336f7d6 100644
--- a/tests/Stubs/Db/ObjectEntity.php
+++ b/tests/Stubs/Db/ObjectEntity.php
@@ -147,17 +147,27 @@ protected function setter(string $name, array $args): void {
 	/** @return int */
 	abstract public function getId();
 
-	/** @return string */
-	abstract public function getUuid();
+	// These four carry the CONTRACT's return types, not looser ones. A
+	// return type may be narrowed by an implementor but never widened, and
+	// an omitted type is the widest there is — so declaring these untyped
+	// against ObjectEntityInterface's `?string` / `array` is a fatal at
+	// class load, which is what it was:
+	//   Declaration of ...\Db\ObjectEntity::getUuid() must be compatible
+	//   with ...\Contract\ObjectEntityInterface::getUuid(): ?string
+	// That kills the whole suite before a single test runs, which is why
+	// all six PHPUnit cells and all four quality tools went red together.
+
+	/** @return string|null */
+	abstract public function getUuid(): ?string;
 
 	/** @return array<string,mixed> */
-	abstract public function getObject();
+	abstract public function getObject(): array;
 
-	/** @return mixed */
-	abstract public function getRegister();
+	/** @return string|null */
+	abstract public function getRegister(): ?string;
 
-	/** @return mixed */
-	abstract public function getSchema();
+	/** @return string|null */
+	abstract public function getSchema(): ?string;
 
 	/**
 	 * @param array<string,mixed>|null $object
diff --git a/tests/Unit/Controller/OrganisationMembersControllerTest.php b/tests/Unit/Controller/OrganisationMembersControllerTest.php
index fca13f43..44dd3bfe 100644
--- a/tests/Unit/Controller/OrganisationMembersControllerTest.php
+++ b/tests/Unit/Controller/OrganisationMembersControllerTest.php
@@ -121,8 +121,8 @@ function (string $uuid): Organisation {
 			$this->userSession,
 			$this->groupManager,
 			$this->userManager,
-			$this->container,
-			$this->createMock(LoggerInterface::class)
+			$this->createMock(LoggerInterface::class),
+			$this->organisationService
 		);
 	}//end makeController()
 
diff --git a/tests/Unit/Service/FacetServiceTest.php b/tests/Unit/Service/FacetServiceTest.php
index c6af92fd..033725ea 100644
--- a/tests/Unit/Service/FacetServiceTest.php
+++ b/tests/Unit/Service/FacetServiceTest.php
@@ -182,7 +182,7 @@ function (string $id) use ($objectService, $organisationService) {
 	 *
 	 * @return ObjectServiceInterface
 	 */
-	private function makePaginatedObjectService(array $results, array &$capturedRef): ObjectService {
+	private function makePaginatedObjectService(array $results, array &$capturedRef): ObjectServiceInterface {
 		$objectService = $this->createMock(ObjectServiceInterface::class);
 		$objectService->method('searchObjectsPaginated')->willReturnCallback(
 			function (array $query) use ($results, &$capturedRef): array {
diff --git a/tests/Unit/Service/IntakeModerationTest.php b/tests/Unit/Service/IntakeModerationTest.php
index 88356e28..e2011ac2 100644
--- a/tests/Unit/Service/IntakeModerationTest.php
+++ b/tests/Unit/Service/IntakeModerationTest.php
@@ -363,7 +363,7 @@ public function testBeoordeelingNonPendingCannotBeApproved(): void {
 	 *
 	 * @return ObjectServiceInterface The mock.
 	 */
-	private function objectService(array $found): ObjectService {
+	private function objectService(array $found): ObjectServiceInterface {
 		$objectService = $this->createMock(ObjectServiceInterface::class);
 		$objectService->method('searchObjects')->willReturn($found);
 		$objectService->method('saveObject')->willReturnCallback(
@@ -383,7 +383,7 @@ function (array $object) {
 	 *
 	 * @return ObjectServiceInterface The mock.
 	 */
-	private function objectServiceWithFind(ObjectEntity $entity): ObjectService {
+	private function objectServiceWithFind(ObjectEntity $entity): ObjectServiceInterface {
 		$objectService = $this->createMock(ObjectServiceInterface::class);
 		$objectService->method('find')->willReturn($entity);
 		$objectService->method('saveObject')->willReturnCallback(
diff --git a/tests/Unit/Service/MergeOrganisatieServiceTest.php b/tests/Unit/Service/MergeOrganisatieServiceTest.php
index 7cba96a5..9bcf0ed3 100644
--- a/tests/Unit/Service/MergeOrganisatieServiceTest.php
+++ b/tests/Unit/Service/MergeOrganisatieServiceTest.php
@@ -794,9 +794,9 @@ public function getId() {
 			/**
 			 * The object uuid.
 			 *
-			 * @return string
+			 * @return string|null
 			 */
-			public function getUuid() {
+			public function getUuid(): ?string {
 				return (string)$this->uuid;
 			}//end getUuid()
 
@@ -806,25 +806,25 @@ public function getUuid() {
 			 *
 			 * @return array<string, mixed>
 			 */
-			public function getObject() {
+			public function getObject(): array {
 				return array_merge(['id' => $this->uuid], ($this->object ?? []));
 			}//end getObject()
 
 			/**
 			 * The register id — unused by these tests.
 			 *
-			 * @return mixed
+			 * @return string|null
 			 */
-			public function getRegister() {
+			public function getRegister(): ?string {
 				return null;
 			}//end getRegister()
 
 			/**
 			 * The schema id — unused by these tests.
 			 *
-			 * @return mixed
+			 * @return string|null
 			 */
-			public function getSchema() {
+			public function getSchema(): ?string {
 				return null;
 			}//end getSchema()
 
diff --git a/tests/Unit/Service/ReviewAggregateServiceTest.php b/tests/Unit/Service/ReviewAggregateServiceTest.php
index 9a5af9f5..c2fa5789 100644
--- a/tests/Unit/Service/ReviewAggregateServiceTest.php
+++ b/tests/Unit/Service/ReviewAggregateServiceTest.php
@@ -147,7 +147,7 @@ public function testInvalidSubjectTypeRejected(): void {
 	 *
 	 * @return ObjectServiceInterface The mock.
 	 */
-	private function objectService(array $found): ObjectService {
+	private function objectService(array $found): ObjectServiceInterface {
 		$objectService = $this->createMock(ObjectServiceInterface::class);
 		$objectService->method('searchObjects')->willReturn($found);
 		return $objectService;
diff --git a/tests/Unit/Service/ReviewServiceTest.php b/tests/Unit/Service/ReviewServiceTest.php
index 462b6e27..a351c75c 100644
--- a/tests/Unit/Service/ReviewServiceTest.php
+++ b/tests/Unit/Service/ReviewServiceTest.php
@@ -280,7 +280,7 @@ public function testEntityUuidReadsAMagicAccessorUuid(): void {
 	 *
 	 * @return ObjectServiceInterface The mock.
 	 */
-	private function objectService(array $found): ObjectService {
+	private function objectService(array $found): ObjectServiceInterface {
 		$objectService = $this->createMock(ObjectServiceInterface::class);
 		$objectService->method('searchObjects')->willReturn($found);
 		$objectService->method('saveObject')->willReturnCallback(