diff --git a/.github/workflows/build.yaml b/.github/workflows/build.yaml
index 29165bd..efcf548 100644
--- a/.github/workflows/build.yaml
+++ b/.github/workflows/build.yaml
@@ -35,7 +35,7 @@ jobs:
           java-version: 21
 
       - name: Setup Gradle
-        uses: gradle/actions/setup-gradle@v4
+        uses: gradle/actions/setup-gradle@v6
 
       - name: Check formatting
         run: ./gradlew spotlessCheck --no-daemon
diff --git a/agent/src/main/java/io/github/vicitori/threading/highlighter/agent/ThreadingHighlighterAgent.java b/agent/src/main/java/io/github/vicitori/threading/highlighter/agent/ThreadingHighlighterAgent.java
index 835afd0..429cb9a 100644
--- a/agent/src/main/java/io/github/vicitori/threading/highlighter/agent/ThreadingHighlighterAgent.java
+++ b/agent/src/main/java/io/github/vicitori/threading/highlighter/agent/ThreadingHighlighterAgent.java
@@ -35,12 +35,23 @@ public static void agentmain(String agentArgs, Instrumentation inst) {
         install(inst);
     }
 
+    // Byte Buddy refuses class file versions newer than it officially knows (e.g. the
+    // Java 25 bytecode shipped by the latest JBR) unless experimental mode is enabled.
+    // Turning it on keeps the agent working on bleeding-edge IDE platforms instead of
+    // failing every instrumentation with IllegalArgumentException. The literal is
+    // relocated by the shadow jar together with the rest of net.bytebuddy, so it
+    // matches the property name Byte Buddy actually reads at runtime.
+    private static final String BYTE_BUDDY_EXPERIMENTAL_PROPERTY = "net.bytebuddy.experimental";
+
     private static void install(Instrumentation inst) {
         if (!INSTALLED.compareAndSet(false, true)) {
             AgentLog.info("Agent already installed, skipping duplicate initialization");
             return;
         }
 
+        // must run before any Byte Buddy class file version probing below
+        enableByteBuddyExperimentalIfUnset();
+
         MarkerAdvice.setWriter(new TraceWriter());
         AgentBuilder agent = configureAgent();
         List<MarkerInfo> markers = Markers.getAll();
@@ -50,6 +61,12 @@ private static void install(Instrumentation inst) {
         }
     }
 
+    private static void enableByteBuddyExperimentalIfUnset() {
+        if (System.getProperty(BYTE_BUDDY_EXPERIMENTAL_PROPERTY) == null) {
+            System.setProperty(BYTE_BUDDY_EXPERIMENTAL_PROPERTY, "true");
+        }
+    }
+
     private static void instrumentMarker(AgentBuilder agent, MarkerInfo marker, Instrumentation inst) {
         agent.type(ElementMatchers.named(marker.getClassFqn()))
                 .transform((builder, typeDescription, classLoader, module, protectionDomain) ->
diff --git a/common/src/main/java/io/github/vicitori/threading/highlighter/common/marker/Markers.java b/common/src/main/java/io/github/vicitori/threading/highlighter/common/marker/Markers.java
index 03ad385..0e51b54 100644
--- a/common/src/main/java/io/github/vicitori/threading/highlighter/common/marker/Markers.java
+++ b/common/src/main/java/io/github/vicitori/threading/highlighter/common/marker/Markers.java
@@ -23,9 +23,16 @@
  * recurse into itself or instrument non-assertion code. Extending coverage is a
  * matter of adding an entry here (the agent, filter, trace format and plugin are
  * all marker-agnostic).
+ *
+ * <p>Since platform build ~233 the internal calling code increasingly calls
+ * {@code ThreadingAssertions} directly instead of going through
+ * {@code ApplicationImpl}. Both classes are instrumented so the agent captures
+ * markers regardless of which path the platform takes.
  */
 public final class Markers {
 
+    // --- ApplicationImpl markers (legacy path, still used by plugin code) ---
+
     public static final MarkerInfo SLOW_OPERATION = new MarkerInfo(
             "com.intellij.util.SlowOperations",
             "assertSlowOperationsAreAllowed",
@@ -56,7 +63,38 @@ public final class Markers {
             "Write Access",
             "This code requires write access and must run inside a write action on the EDT (see Application.runWriteAction()).");
 
-    private static final List<MarkerInfo> ALL = List.of(SLOW_OPERATION, NON_EDT, EDT, READ_ACCESS, WRITE_ACCESS);
+    // --- ThreadingAssertions markers (direct path used by platform internals) ---
+
+    private static final String THREADING_ASSERTIONS_CLASS =
+            "com.intellij.util.concurrency.ThreadingAssertions";
+
+    public static final MarkerInfo EDT_DIRECT = new MarkerInfo(
+            THREADING_ASSERTIONS_CLASS,
+            "assertEventDispatchThread",
+            "EDT Thread",
+            "This code must run on the EDT (Event Dispatch Thread). UI operations are allowed.");
+
+    public static final MarkerInfo NON_EDT_DIRECT = new MarkerInfo(
+            THREADING_ASSERTIONS_CLASS,
+            "assertBackgroundThread",
+            "Non-EDT Thread",
+            "This code must NOT run on the EDT. Background/pooled thread required.");
+
+    public static final MarkerInfo READ_ACCESS_DIRECT = new MarkerInfo(
+            THREADING_ASSERTIONS_CLASS,
+            "assertReadAccess",
+            "Read Access",
+            "This code requires read access and must run inside a read action (see Application.runReadAction()).");
+
+    public static final MarkerInfo WRITE_ACCESS_DIRECT = new MarkerInfo(
+            THREADING_ASSERTIONS_CLASS,
+            "assertWriteAccess",
+            "Write Access",
+            "This code requires write access and must run inside a write action on the EDT (see Application.runWriteAction()).");
+
+    private static final List<MarkerInfo> ALL = List.of(
+            SLOW_OPERATION, NON_EDT, EDT, READ_ACCESS, WRITE_ACCESS,
+            EDT_DIRECT, NON_EDT_DIRECT, READ_ACCESS_DIRECT, WRITE_ACCESS_DIRECT);
 
     public static List<MarkerInfo> getAll() {
         return ALL;
diff --git a/plugin/build.gradle.kts b/plugin/build.gradle.kts
index 3e5d78e..3549e58 100644
--- a/plugin/build.gradle.kts
+++ b/plugin/build.gradle.kts
@@ -17,8 +17,7 @@ repositories {
 dependencies {
     implementation(project(":common"))
     intellijPlatform {
-        // Target the local test IDE (IntelliJ IDEA Community 2025.1, build 251)
-        intellijIdeaCommunity("2025.1.1.1")
+        intellijIdeaUltimate("2025.3.1")
         bundledPlugin("org.jetbrains.kotlin")
     }
 
@@ -35,8 +34,8 @@ dependencies {
 intellijPlatform {
     pluginConfiguration {
         ideaVersion {
-            sinceBuild = "251"
-            untilBuild = "251.*"
+            sinceBuild = "253"
+            untilBuild = "253.*"
         }
     }