diff --git a/src/user_engine/adapters/tenant_management.py b/src/user_engine/adapters/tenant_management.py
index d06a9f7..19a4b54 100644
--- a/src/user_engine/adapters/tenant_management.py
+++ b/src/user_engine/adapters/tenant_management.py
@@ -22,11 +22,11 @@ class HTTPTenantManagementAdapter:
         correlation_id: str,
     ) -> TenantProvisioningResult:
         request = Request(
-            self.base_url + "/v1/tenants",
+            self.base_url + "/tenants",
             data=json.dumps({
-                "tenant": tenant, "display_name": display_name,
-                "idempotency_key": idempotency_key,
-                "correlation_id": correlation_id,
+                "tenant_id": tenant,
+                "identifier": tenant,
+                "actor": "tenant-engine",
             }).encode(),
             headers={
                 "Authorization": f"Bearer {self.bearer_token}",
@@ -41,12 +41,16 @@ class HTTPTenantManagementAdapter:
                 result = json.loads(response.read())
         except HTTPError as exc:
             exc.read(4096)
+            if exc.code == 409:
+                return TenantProvisioningResult(
+                    tenant=tenant, status="existing", resumed=True, external_ref=tenant,
+                )
             raise RuntimeError(f"tenant authority failed ({exc.code})") from exc
         except URLError as exc:
             raise RuntimeError("tenant authority unavailable") from exc
         return TenantProvisioningResult(
-            tenant=str(result.get("tenant") or tenant),
-            status=str(result["status"]),
-            resumed=bool(result.get("resumed", False)),
-            external_ref=str(result["external_ref"]) if result.get("external_ref") else None,
+            tenant=str(result.get("identifier") or tenant),
+            status="created",
+            resumed=False,
+            external_ref=str(result.get("tenant_id") or tenant),
         )
diff --git a/tests/test_tenant_management_adapter.py b/tests/test_tenant_management_adapter.py
new file mode 100644
index 0000000..d68085a
--- /dev/null
+++ b/tests/test_tenant_management_adapter.py
@@ -0,0 +1,44 @@
+import io
+import json
+import unittest
+from unittest.mock import patch
+
+from user_engine.adapters.tenant_management import HTTPTenantManagementAdapter
+
+
+class _Response(io.BytesIO):
+    def __enter__(self):
+        return self
+
+    def __exit__(self, *_args):
+        self.close()
+
+
+class TenantManagementAdapterTests(unittest.TestCase):
+    def test_uses_tenant_engine_contract(self):
+        body = _Response(json.dumps({
+            "tenant_id": "tenant:friendly:new",
+            "identifier": "tenant:friendly:new",
+            "grouping": "friendly",
+        }).encode())
+        adapter = HTTPTenantManagementAdapter(
+            base_url="http://tenant-engine", bearer_token="opaque"
+        )
+        with patch("user_engine.adapters.tenant_management.urlopen", return_value=body) as call:
+            result = adapter.create_tenant(
+                tenant="tenant:friendly:new", display_name="New",
+                idempotency_key="tenant-create-123", correlation_id="corr-1",
+            )
+        request = call.call_args.args[0]
+        self.assertEqual(request.full_url, "http://tenant-engine/tenants")
+        self.assertEqual(json.loads(request.data), {
+            "tenant_id": "tenant:friendly:new",
+            "identifier": "tenant:friendly:new",
+            "actor": "tenant-engine",
+        })
+        self.assertEqual(result.status, "created")
+        self.assertEqual(result.external_ref, "tenant:friendly:new")
+
+
+if __name__ == "__main__":
+    unittest.main()