Pick Gradle distribution based on client JVM version

The Tooling API daemon defaults to the same JVM as the client, so the
hardcoded 8.12 fallback fails on Java 24+ and Java 25+. Map the running
Java version to the lowest Gradle distribution that can host its daemon
(8.12 for <=23, 8.14.3 for 24, 9.1.0 for 25+) instead.

Author: timtebeek

rewrite-gradle-tooling-model/model/src/main/java/org/openrewrite/gradle/toolingapi/OpenRewriteModelBuilder.java

@@ -82,7 +82,7 @@ public static OpenRewriteModel forProjectDirectory(File projectDir, @Nullable Fi
         } else if (Files.exists(projectDir.toPath().resolve("gradle/wrapper/gradle-wrapper.properties"))) {
             connector.useBuildDistribution();
         } else {
-            connector.useGradleVersion("8.12");
+            connector.useGradleVersion(defaultGradleVersion());
         }
         connector
                 // Uncomment to hit breakpoints inside OpenRewriteModelBuilder in unit tests
@@ -132,6 +132,37 @@ public static OpenRewriteModel forProjectDirectory(File projectDir, @Nullable Fi
         }
     }
 
+    /**
+     * Pick a Gradle distribution compatible with the JVM running the Tooling API client.
+     * The daemon defaults to the same JVM as the client, so the chosen distribution must support that Java version.
+     * See <a href="https://docs.gradle.org/current/userguide/compatibility.html">Gradle compatibility matrix</a>.
+     */
+    static String defaultGradleVersion() {
+        return defaultGradleVersion(javaSpecificationVersion());
+    }
+
+    static String defaultGradleVersion(int javaFeatureVersion) {
+        if (javaFeatureVersion >= 25) {
+            return "9.1.0";
+        }
+        if (javaFeatureVersion >= 24) {
+            return "8.14.3";
+        }
+        return "8.12";
+    }
+
+    private static int javaSpecificationVersion() {
+        String version = System.getProperty("java.specification.version", "8");
+        if (version.startsWith("1.")) {
+            version = version.substring(2);
+        }
+        try {
+            return Integer.parseInt(version);
+        } catch (NumberFormatException e) {
+            return 8;
+        }
+    }
+
     /**
      * Everywhere except within openrewrite/rewrite itself the plugin will be resolved from some artifact repository
      * But within openrewrite/rewrite it comes from a build directory.

rewrite-gradle-tooling-model/model/src/test/java/org/openrewrite/gradle/toolingapi/OpenRewriteModelBuilderTest.java

@@ -0,0 +1,48 @@
+/*
+ * Copyright 2026 the original author or authors.
+ * <p>
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ * <p>
+ * https://www.apache.org/licenses/LICENSE-2.0
+ * <p>
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.openrewrite.gradle.toolingapi;
+
+import org.junit.jupiter.api.Test;
+
+import static org.assertj.core.api.Assertions.assertThat;
+
+class OpenRewriteModelBuilderTest {
+
+    @Test
+    void java8FallsBackToBaselineDistribution() {
+        assertThat(OpenRewriteModelBuilder.defaultGradleVersion(8)).isEqualTo("8.12");
+    }
+
+    @Test
+    void java23StaysOnBaselineDistribution() {
+        assertThat(OpenRewriteModelBuilder.defaultGradleVersion(23)).isEqualTo("8.12");
+    }
+
+    @Test
+    void java24RequiresGradle814() {
+        assertThat(OpenRewriteModelBuilder.defaultGradleVersion(24)).isEqualTo("8.14.3");
+    }
+
+    @Test
+    void java25RequiresGradle91() {
+        assertThat(OpenRewriteModelBuilder.defaultGradleVersion(25)).isEqualTo("9.1.0");
+    }
+
+    @Test
+    void futureJavaVersionsResolveToLatestKnownDistribution() {
+        assertThat(OpenRewriteModelBuilder.defaultGradleVersion(99)).isEqualTo("9.1.0");
+    }
+}