diff --git a/src/config-utils.test.ts b/src/config-utils.test.ts
index 75461b90e..34f15ddc7 100644
--- a/src/config-utils.test.ts
+++ b/src/config-utils.test.ts
@@ -1023,6 +1023,8 @@ const getOverlayDatabaseModeMacro = test.macro({
     expected: {
       overlayDatabaseMode: OverlayDatabaseMode;
       useOverlayDatabaseCaching: boolean;
+      preliminaryOverlayDatabaseMode?: OverlayDatabaseMode;
+      preliminaryUseOverlayDatabaseCaching?: boolean;
     },
   ) => {
     return await withTmpDir(async (tempDir) => {
@@ -1091,7 +1093,44 @@ const getOverlayDatabaseModeMacro = test.macro({
           logger,
         );
 
-        t.deepEqual(result, expected);
+        const expectedResult = {
+          overlayDatabaseMode: expected.overlayDatabaseMode,
+          useOverlayDatabaseCaching: expected.useOverlayDatabaseCaching,
+        };
+        t.deepEqual(result, expectedResult);
+
+        let configFile: string | undefined;
+        if (Object.keys(setup.codeScanningConfig).length > 0) {
+          configFile = createConfigFile(
+            yaml.dump(setup.codeScanningConfig),
+            tempDir,
+          );
+        }
+
+        // Test getPreliminaryOverlayDatabaseMode as well
+        const preliminaryResult =
+          await configUtils.getPreliminaryOverlayDatabaseMode(
+            createTestInitConfigInputs({
+              languagesInput: setup.languages.join(","),
+              configFile,
+              features,
+              tempDir,
+              workspacePath: tempDir,
+              sourceRoot: tempDir,
+              repository,
+              logger,
+            }),
+          );
+
+        const expectedPreliminaryResult = {
+          overlayDatabaseMode:
+            expected.preliminaryOverlayDatabaseMode ??
+            expected.overlayDatabaseMode,
+          useOverlayDatabaseCaching:
+            expected.preliminaryUseOverlayDatabaseCaching ??
+            expected.useOverlayDatabaseCaching,
+        };
+        t.deepEqual(preliminaryResult, expectedPreliminaryResult);
       } finally {
         // Restore the original environment
         process.env = originalEnv;
@@ -1597,6 +1636,8 @@ test(
   {
     overlayDatabaseMode: OverlayDatabaseMode.None,
     useOverlayDatabaseCaching: false,
+    preliminaryOverlayDatabaseMode: OverlayDatabaseMode.Overlay,
+    preliminaryUseOverlayDatabaseCaching: false,
   },
 );
 
@@ -1611,6 +1652,8 @@ test(
   {
     overlayDatabaseMode: OverlayDatabaseMode.None,
     useOverlayDatabaseCaching: false,
+    preliminaryOverlayDatabaseMode: OverlayDatabaseMode.Overlay,
+    preliminaryUseOverlayDatabaseCaching: false,
   },
 );
 
@@ -1624,6 +1667,8 @@ test(
   {
     overlayDatabaseMode: OverlayDatabaseMode.None,
     useOverlayDatabaseCaching: false,
+    preliminaryOverlayDatabaseMode: OverlayDatabaseMode.Overlay,
+    preliminaryUseOverlayDatabaseCaching: false,
   },
 );
 
diff --git a/src/config-utils.ts b/src/config-utils.ts
index ff5cd81a7..0c5f36f22 100644
--- a/src/config-utils.ts
+++ b/src/config-utils.ts
@@ -839,6 +839,62 @@ export async function getOverlayDatabaseMode(
   };
 }
 
+/**
+ * Get preliminary overlay database mode using only the information available
+ * in InitConfigInputs, without depending on CodeQL.
+ *
+ * This is a simplified version of getOverlayDatabaseMode that can be called
+ * before the CodeQL CLI is available.
+ *
+ * @param inputs The initialization configuration inputs.
+ * @returns An object containing the overlay database mode and whether the
+ * action should perform overlay-base database caching.
+ */
+export async function getPreliminaryOverlayDatabaseMode(
+  inputs: InitConfigInputs,
+): Promise<{
+  overlayDatabaseMode: OverlayDatabaseMode;
+  useOverlayDatabaseCaching: boolean;
+}> {
+  const userConfig = await loadUserConfig(
+    inputs.configFile,
+    inputs.workspacePath,
+    inputs.apiDetails,
+    inputs.tempDir,
+    inputs.logger,
+  );
+
+  const languages = await getUnverifiedLanguagesForOverlay(
+    inputs.languagesInput,
+    inputs.repository,
+    inputs.sourceRoot,
+    inputs.logger,
+  );
+  const augmentationProperties = await calculateAugmentation(
+    inputs.packsInput,
+    inputs.queriesInput,
+    inputs.repositoryProperties,
+    languages,
+  );
+  const computedConfig = generateCodeScanningConfig(
+    inputs.logger,
+    userConfig,
+    augmentationProperties,
+  );
+
+  return getOverlayDatabaseMode(
+    undefined, // codeql
+    inputs.repository,
+    inputs.features,
+    undefined, // languages
+    inputs.languagesInput,
+    inputs.sourceRoot,
+    undefined, // buildMode
+    computedConfig,
+    inputs.logger,
+  );
+}
+
 function dbLocationOrDefault(
   dbLocation: string | undefined,
   tempDir: string,