fix(sessions): apply afterTimestamp and numRecentEvents together in VertexAiSessionService

core/src/main/java/com/google/adk/sessions/VertexAiSessionService.java

@@ -249,14 +249,11 @@ public Maybe<Session> getSession(
   }
 
   /**
-   * Builds the server-side events filter for {@code afterTimestamp}, mirroring the Python and Go
-   * implementations (inclusive {@code timestamp>=}). The filter is only applied when {@code
-   * numRecentEvents} is not set, matching the precedence in {@link #filterEvents}.
+   * Inclusive server-side {@code timestamp>=} filter for {@code afterTimestamp}, or null. Applied
+   * independently of {@code numRecentEvents} (see {@link #filterEvents}), so both filters compose.
    */
   private static @Nullable String afterTimestampFilter(Optional<GetSessionConfig> config) {
-    if (config.isPresent()
-        && config.get().numRecentEvents().isEmpty()
-        && config.get().afterTimestamp().isPresent()) {
+    if (config.isPresent() && config.get().afterTimestamp().isPresent()) {
       return "timestamp>=\"" + config.get().afterTimestamp().get() + "\"";
     }
     return null;

core/src/test/java/com/google/adk/sessions/VertexAiSessionServiceTest.java

@@ -587,6 +587,52 @@ public void getSession_numRecentEventsConfig_returnsMostRecentEvents() {
     assertThat(session.events().stream().map(Event::id)).containsExactly("e2", "e3").inOrder();
   }
 
+  @Test
+  public void getSession_afterTimestampNarrowerThanNumRecentEvents_appliesBothFilters() {
+    sessionMap.put("10", mockSessionJson("10", "2024-12-12T12:00:30.000000Z"));
+    eventMap.put(
+        "10",
+        mockEventsJson(
+            mockEventJson("e1", "2024-12-12T12:00:05.000000Z"),
+            mockEventJson("e2", "2024-12-12T12:00:10.000000Z"),
+            mockEventJson("e3", "2024-12-12T12:00:15.000000Z"),
+            mockEventJson("e4", "2024-12-12T12:00:20.000000Z")));
+    GetSessionConfig config =
+        GetSessionConfig.builder()
+            .afterTimestamp(Instant.parse("2024-12-12T12:00:15.000000Z"))
+            .numRecentEvents(3)
+            .build();
+
+    Session session =
+        vertexAiSessionService.getSession("123", "user", "10", Optional.of(config)).blockingGet();
+
+    // afterTimestamp must be applied: without it, numRecentEvents(3) would keep e2, e3, e4.
+    assertThat(session.events().stream().map(Event::id)).containsExactly("e3", "e4").inOrder();
+  }
+
+  @Test
+  public void getSession_numRecentEventsNarrowerThanAfterTimestamp_appliesBothFilters() {
+    sessionMap.put("11", mockSessionJson("11", "2024-12-12T12:00:30.000000Z"));
+    eventMap.put(
+        "11",
+        mockEventsJson(
+            mockEventJson("e1", "2024-12-12T12:00:05.000000Z"),
+            mockEventJson("e2", "2024-12-12T12:00:10.000000Z"),
+            mockEventJson("e3", "2024-12-12T12:00:15.000000Z"),
+            mockEventJson("e4", "2024-12-12T12:00:20.000000Z")));
+    GetSessionConfig config =
+        GetSessionConfig.builder()
+            .afterTimestamp(Instant.parse("2024-12-12T12:00:10.000000Z"))
+            .numRecentEvents(2)
+            .build();
+
+    Session session =
+        vertexAiSessionService.getSession("123", "user", "11", Optional.of(config)).blockingGet();
+
+    // afterTimestamp keeps e2, e3, e4; numRecentEvents must then trim to the 2 most recent.
+    assertThat(session.events().stream().map(Event::id)).containsExactly("e3", "e4").inOrder();
+  }
+
   private static String mockSessionJson(String sessionId, String updateTime) {
     return String.format(
         """