Parallelized mod builds

- Mod targets run through bounded Gradle workers with separate caches and daemon slots
- Target logs retain verification failures and bounded output summaries
- Nested tests use bounded forks and JVM thread counts
- Lifecycle tests control deadlines through injected clocks

buildSrc/src/test/java/IrisModdedBuildTest.java

@@ -0,0 +1,79 @@
+import org.gradle.api.Project;
+import org.gradle.testfixtures.ProjectBuilder;
+import org.junit.Rule;
+import org.junit.Test;
+import org.junit.rules.TemporaryFolder;
+
+import java.nio.file.Files;
+import java.nio.file.Path;
+import java.util.List;
+import java.util.Map;
+import java.util.Set;
+
+import static org.junit.Assert.assertEquals;
+import static org.junit.Assert.assertFalse;
+import static org.junit.Assert.assertTrue;
+
+public class IrisModdedBuildTest {
+    @Rule
+    public TemporaryFolder temporary = new TemporaryFolder();
+
+    @Test
+    public void capturesTheCompleteTargetConfiguration() throws Exception {
+        Project project = ProjectBuilder.builder().withProjectDir(temporary.newFolder()).build();
+        IrisModdedBuild task = project.getTasks().create("verifyFabric", IrisModdedBuild.class);
+        task.getLabel().set("Fabric 26.3");
+        task.getWorkingDirectory().set(project.getLayout().getProjectDirectory());
+        task.getCommandLine().set(List.of("gradlew", "assemble", "test"));
+        task.getRequiredEntries().set(List.of("fabric.mod.json"));
+        task.getForbiddenCoreClasses().set(Set.of("org/bukkit/Test"));
+        task.getJavaRuntime().set(25);
+        task.getArtifactFile().set(project.getLayout().getProjectDirectory().file("build/mod.jar"));
+        task.getLogFile().set(project.getLayout().getProjectDirectory().file("build/reports/matrix/fabric.log"));
+
+        assertEquals(Map.of(), task.getEnvironment().get());
+        assertEquals(List.of("gradlew", "assemble", "test"), task.getCommandLine().get());
+        assertEquals(List.of("fabric.mod.json"), task.getRequiredEntries().get());
+        assertEquals(Set.of("org/bukkit/Test"), task.getForbiddenCoreClasses().get());
+        assertEquals(Integer.valueOf(25), task.getJavaRuntime().get());
+        assertEquals(Set.of(task.getArtifactFile().get().getAsFile()), task.getOutputs().getFiles().getFiles());
+        assertFalse(task.getOutputs().getFiles().contains(task.getLogFile().get().getAsFile()));
+    }
+
+    @Test
+    public void failureSummaryRetainsTheFinalLinesWithoutReadingAnEntireLog() throws Exception {
+        Path log = temporary.newFile().toPath();
+        StringBuilder content = new StringBuilder("discarded first line\n");
+        for (int index = 0; index < 2000; index++) {
+            content.append("task output ").append(index).append('\n');
+        }
+        content.append("final failure\n");
+        Files.writeString(log, content);
+
+        String tail = IrisModdedBuildAction.logTail(log);
+
+        assertEquals(40, tail.lines().count());
+        assertTrue(tail.endsWith("final failure"));
+        assertFalse(tail.contains("discarded first line"));
+        assertTrue(tail.length() <= 16 * 1024);
+    }
+
+    @Test
+    public void failureSummaryAcceptsEmptyAndUnterminatedLogs() throws Exception {
+        Path log = temporary.newFile().toPath();
+        assertEquals("", IrisModdedBuildAction.logTail(log));
+        Files.writeString(log, "first\r\nlast");
+        assertEquals("first" + System.lineSeparator() + "last", IrisModdedBuildAction.logTail(log));
+    }
+
+    @Test
+    public void failureSummaryBoundsAnUnbrokenFailureLine() throws Exception {
+        Path log = temporary.newFile().toPath();
+        Files.writeString(log, "x".repeat(100_000) + "final failure");
+
+        String tail = IrisModdedBuildAction.logTail(log);
+
+        assertEquals(16 * 1024, tail.length());
+        assertTrue(tail.endsWith("final failure"));
+    }
+}