fix: use OData V4 path for OpenAPI server URL if no protocol is set to match @sap/cds default behavior

CHANGELOG.md

@@ -11,6 +11,7 @@ The format is based on [Keep a Changelog](http://keepachangelog.com/).
 ### Deprecated
 ### Removed
 ### Fixed
+- set `odata` as the service protocol if no protocol is set to match the default behavior of `@sap/cds`
 ### Security
 
 ## [1.6.0] - 2026-08-04

lib/compile/index.js

@@ -156,7 +156,7 @@ function _getProtocols(csdl, csn, odataVersion) {
       protocols.push("odata");
     }
     else if (!service["@protocol"]) {
-      protocols.push("rest"); //taking rest as default in case no relevant protocol is there
+      protocols.push("odata"); // matches cds's default protocol when none is annotated
     } else if (service["@protocol"] === "none") {
       // if @protocol is 'none' then throw an error
       throw new Error(

test/lib/compile/openapi.test.js

@@ -262,6 +262,21 @@ service CatalogService {
     assert(openapi.servers[0].url.includes('odata'));
   });
 
+  test('default service without @protocol renders server URL with odata/v4', () => {
+    const csn = cds.compile.to.csn(`
+      @path: 'catalog'
+      service CatalogService {
+        entity Books {
+          key ID : Integer;
+          title   : String;
+        }
+      }`
+    );
+    const openapi = toOpenApi(csn);
+    assert(openapi.servers[0].url.includes('odata/v4'));
+    assert(!openapi.servers[0].url.includes('rest'));
+  });
+
   test('options: Multiple servers', () => {
     const csn = cds.compile.to.csn(`
       service A {entity E { key ID : UUID; };};`