diff --git a/core/src/main/java/com/google/adk/runner/Runner.java b/core/src/main/java/com/google/adk/runner/Runner.java
index b96a5605c..ae0dd6b87 100644
--- a/core/src/main/java/com/google/adk/runner/Runner.java
+++ b/core/src/main/java/com/google/adk/runner/Runner.java
@@ -225,7 +225,12 @@ public Flowable<Event> runAsync(String userId, String sessionId, Content newMess
     return runAsync(userId, sessionId, newMessage, RunConfig.builder().build());
   }
 
-  /** See {@link #runAsync(Session, Content, RunConfig, Map)}. */
+  /**
+   * See {@link #runAsync(Session, Content, RunConfig, Map)}.
+   *
+   * @deprecated Use runAsync with sessionId.
+   */
+  @Deprecated(since = "0.4.0", forRemoval = true)
   public Flowable<Event> runAsync(Session session, Content newMessage, RunConfig runConfig) {
     return runAsync(session, newMessage, runConfig, /* stateDelta= */ null);
   }
@@ -238,7 +243,9 @@ public Flowable<Event> runAsync(Session session, Content newMessage, RunConfig r
    * @param runConfig Configuration for the agent run.
    * @param stateDelta Optional map of state updates to merge into the session for this run.
    * @return A Flowable stream of {@link Event} objects generated by the agent during execution.
+   * @deprecated Use runAsync with sessionId.
    */
+  @Deprecated(since = "0.4.0", forRemoval = true)
   public Flowable<Event> runAsync(
       Session session,
       Content newMessage,
@@ -321,14 +328,20 @@ public Flowable<Event> runAsync(
                                                       this.sessionService
                                                           .appendEvent(updatedSession, agentEvent)
                                                           .flatMap(
-                                                              registeredEvent ->
-                                                                  contextWithUpdatedSession
-                                                                      .pluginManager()
-                                                                      .runOnEventCallback(
-                                                                          contextWithUpdatedSession,
-                                                                          registeredEvent)
-                                                                      .defaultIfEmpty(
-                                                                          registeredEvent))
+                                                              registeredEvent -> {
+                                                                // TODO: remove this hack after
+                                                                // deprecating runAsync with
+                                                                // Session.
+                                                                copySessionStates(
+                                                                    updatedSession, session);
+                                                                return contextWithUpdatedSession
+                                                                    .pluginManager()
+                                                                    .runOnEventCallback(
+                                                                        contextWithUpdatedSession,
+                                                                        registeredEvent)
+                                                                    .defaultIfEmpty(
+                                                                        registeredEvent);
+                                                              })
                                                           .toFlowable());
 
                                       // If beforeRunCallback returns content, emit it and skip
@@ -359,6 +372,13 @@ public Flowable<Event> runAsync(
     }
   }
 
+  private void copySessionStates(Session source, Session target) {
+    // TODO: remove this hack when deprecating all runAsync with Session.
+    for (var entry : source.state().entrySet()) {
+      target.state().put(entry.getKey(), entry.getValue());
+    }
+  }
+
   /**
    * Creates an {@link InvocationContext} for a live (streaming) run.
    *