diff --git a/tests/bootstrap-unit.php b/tests/bootstrap-unit.php
index c1939566..7001ac87 100644
--- a/tests/bootstrap-unit.php
+++ b/tests/bootstrap-unit.php
@@ -23,6 +23,31 @@
 // Include Composer's autoloader.
 require_once __DIR__ . '/../vendor/autoload.php';
 
+// THE OpenRegister CONTRACT INTERFACES, OPTED INTO RATHER THAN AUTOLOADED.
+//
+// conduction/hydra-gates claims `OCA\OpenRegister\Contract\` as a RUNTIME psr-4
+// prefix, so consumers get these interfaces implicitly. That prefix is LONGER
+// than openregister's own `OCA\OpenRegister\` -> `lib/`, and PSR-4 is
+// longest-prefix-wins, so whichever app's autoloader registers first defines
+// OpenRegister's contract for the whole process (ConductionNL/.github#531).
+//
+// Note the stub prefixes registered just below are `OCA\OpenRegister\Db\` and
+// `...\Service\` — neither covers `...\Contract\`, so once hydra-gates stops
+// declaring it nothing else in this app resolves it.
+//
+// interface_exists() is order-independent — it asks whether the interface is
+// RESOLVABLE, not who registered first. Appending a fallback autoloader does
+// NOT work: spl_autoload_register appends relative to registration order, and
+// that order across independently loaded apps is what nobody controls.
+foreach (['ObjectEntityInterface', 'ObjectServiceInterface'] as $contract) {
+	if (interface_exists('\\OCA\\OpenRegister\\Contract\\' . $contract) === false) {
+		$shipped = __DIR__ . '/../vendor/conduction/hydra-gates/hydra-gates/contracts/' . $contract . '.php';
+		if (file_exists($shipped) === true) {
+			require_once $shipped;
+		}
+	}
+}
+
 // Register OCP/NCU classes from nextcloud/ocp package.
 // nextcloud/ocp has no autoload section in its composer.json, so we register it manually.
 spl_autoload_register(function (string $class): void {
diff --git a/tests/bootstrap.php b/tests/bootstrap.php
index 4174546e..7783ea29 100644
--- a/tests/bootstrap.php
+++ b/tests/bootstrap.php
@@ -23,6 +23,32 @@
 // Include Composer's autoloader
 require_once __DIR__ . '/../vendor/autoload.php';
 
+// THE OpenRegister CONTRACT INTERFACES, OPTED INTO RATHER THAN AUTOLOADED.
+//
+// conduction/hydra-gates claims `OCA\OpenRegister\Contract\` as a RUNTIME psr-4
+// prefix, so consumers get these interfaces implicitly. That prefix is LONGER
+// than openregister's own `OCA\OpenRegister\` -> `lib/`, and PSR-4 is
+// longest-prefix-wins, so whichever app's autoloader registers first defines
+// OpenRegister's contract for the whole process (ConductionNL/.github#531).
+//
+// Loaded here, immediately after the autoloader and before the OpenRegister
+// stubs below, for the same reason those stubs are loaded early: what is
+// declared first wins, and the contract must exist before anything implementing
+// it is declared.
+//
+// interface_exists() is order-independent — it asks whether the interface is
+// RESOLVABLE, not who registered first. Appending a fallback autoloader does
+// NOT work: spl_autoload_register appends relative to registration order, and
+// that order across independently loaded apps is what nobody controls.
+foreach (['ObjectEntityInterface', 'ObjectServiceInterface'] as $contract) {
+	if (interface_exists('\\OCA\\OpenRegister\\Contract\\' . $contract) === false) {
+		$shipped = __DIR__ . '/../vendor/conduction/hydra-gates/hydra-gates/contracts/' . $contract . '.php';
+		if (file_exists($shipped) === true) {
+			require_once $shipped;
+		}
+	}
+}
+
 // OpenRegister test stubs. The real OCA\OpenRegister\Db\ObjectEntity has
 // __call magic getters that PHPUnit cannot configure on a mock, so the unit
 // tests use the explicit stub in tests/Stubs/. It is loaded HERE, BEFORE