Wait for rendering before starting native smoke countdown

runner/src/main/java/org/openpatch/scratch4j/runner/LauncherSource.java

@@ -8,7 +8,8 @@
  * {@code main} when it has one, otherwise instantiates it (the first
  * {@code Stage} creates the library's singleton {@code Window}), and
  * implements the smoke-test switch {@code -Dscratch4j.ide.exitAfter=N}, which
- * closes the window after N seconds so CI can run programs headlessly.
+ * closes the window after N seconds so CI can run programs headlessly. With
+ * the control channel enabled, that countdown starts after the first frame.
  *
  * <p>The class name is fixed so re-running does not litter the build folder;
  * it lives in the default package like the student's classes.
@@ -45,6 +46,11 @@ public static void main(String[] args) throws Exception {
             if (exitAfter > 0) {
               Thread hook = new Thread(() -> {
                 try {
+                  // Native graphics startup can take longer than the smoke duration.
+                  // Give controlled runs their full duration after rendering starts.
+                  if (Boolean.getBoolean("scratch4j.ide.control")) {
+                    while (IdeControl.frames < 1) Thread.sleep(25);
+                  }
                   Thread.sleep(exitAfter * 1000L);
                   Window.getInstance().exit();
                 } catch (InterruptedException e) {

runner/src/test/java/org/openpatch/scratch4j/runner/LauncherSourceTest.java

@@ -56,6 +56,50 @@ public enum TextureSampling { POINT }
         root.resolve("classes")).success()).isTrue();
   }
 
+  @Test
+  void controlledSmokeCountdownWaitsForTheFirstFrame() throws Exception {
+    Path launcher = root.resolve("Scratch4JLauncher.java");
+    Path main = root.resolve("Delayed.java");
+    Path window = root.resolve("org/openpatch/scratch/Window.java");
+    Path classes = root.resolve("classes");
+    Files.createDirectories(window.getParent());
+    Files.writeString(launcher, LauncherSource.generate());
+    Files.writeString(main, """
+        public class Delayed {
+          public static void main(String[] args) throws Exception {
+            Thread.sleep(2000);
+            System.out.println("FIRST_FRAME");
+            Scratch4JLauncher.IdeControl.frames = 1;
+            Thread.sleep(10000);
+          }
+        }
+        """);
+    Files.writeString(window, """
+        package org.openpatch.scratch;
+        public class Window {
+          public static Window getInstance() { return new Window(); }
+          public void setDebug(boolean value) {}
+          public Stage getStage() { return null; }
+          public void exit() { System.out.println("SMOKE_EXIT"); System.exit(0); }
+        }
+        """);
+    Path jar = LibraryJarSource.allJar(root.resolve("bundled"));
+    assertThat(new CompilerService().compile(List.of(launcher, main, window), List.of(jar), classes)
+        .errors()).isEmpty();
+    Process process = new ProcessBuilder(Path.of(System.getProperty("java.home"), "bin", "java").toString(),
+        "-Dscratch4j.ide.control=true", "-Dscratch4j.ide.exitAfter=1", "-cp",
+        classes + java.io.File.pathSeparator + jar, "Scratch4JLauncher", "Delayed")
+        .redirectErrorStream(true).start();
+    try {
+      assertThat(process.waitFor(15, java.util.concurrent.TimeUnit.SECONDS)).isTrue();
+      String output = new String(process.getInputStream().readAllBytes(), java.nio.charset.StandardCharsets.UTF_8);
+      assertThat(process.exitValue()).as(output).isZero();
+      assertThat(output).contains("FIRST_FRAME", "SMOKE_EXIT");
+    } finally {
+      process.destroyForcibly();
+    }
+  }
+
   @Test
   void launcherStartsJava25CompactSourceMain() throws Exception {
     Path launcher = root.resolve("Scratch4JLauncher.java");