diff --git a/src/google/adk/apps/_configs.py b/src/google/adk/apps/_configs.py
index 87f3666ebdd..e5813155af1 100644
--- a/src/google/adk/apps/_configs.py
+++ b/src/google/adk/apps/_configs.py
@@ -58,14 +58,22 @@ class EventsCompactionConfig(BaseModel):
   summarizer: Optional[BaseEventsSummarizer] = None
   """The event summarizer to use for compaction."""
 
-  compaction_interval: int
+  compaction_interval: int = Field(gt=0)
   """The number of *new* user-initiated invocations that, once
-  fully represented in the session's events, will trigger a compaction."""
+  fully represented in the session's events, will trigger a compaction.
 
-  overlap_size: int
+  Must be greater than 0. A value of 0 (or negative) would make the
+  sliding-window trigger fire on *every* invocation, because the guard
+  ``len(new_invocation_ids) < compaction_interval`` can never hold.
+  """
+
+  overlap_size: int = Field(ge=0)
   """The number of preceding invocations to include from the
   end of the last compacted range. This creates an overlap between consecutive
-  compacted summaries, maintaining context."""
+  compacted summaries, maintaining context.
+
+  Must be greater than or equal to 0 (0 means no overlap).
+  """
 
   token_threshold: Optional[int] = Field(
       default=None,
diff --git a/tests/unittests/apps/test_compaction.py b/tests/unittests/apps/test_compaction.py
index 2f53e1e937a..cf2dee231ab 100644
--- a/tests/unittests/apps/test_compaction.py
+++ b/tests/unittests/apps/test_compaction.py
@@ -487,6 +487,24 @@ def test_events_compaction_config_rejects_missing_modes(self):
     with pytest.raises(ValidationError):
       EventsCompactionConfig()
 
+  def test_events_compaction_config_rejects_non_positive_interval(self):
+    # compaction_interval must be > 0. A value of 0 (or negative) would make
+    # the sliding-window trigger fire on every invocation because the guard
+    # `len(new_invocation_ids) < compaction_interval` can never hold.
+    with pytest.raises(ValidationError):
+      EventsCompactionConfig(compaction_interval=0, overlap_size=0)
+
+    with pytest.raises(ValidationError):
+      EventsCompactionConfig(compaction_interval=-1, overlap_size=0)
+
+  def test_events_compaction_config_rejects_negative_overlap(self):
+    with pytest.raises(ValidationError):
+      EventsCompactionConfig(compaction_interval=2, overlap_size=-1)
+
+  def test_events_compaction_config_allows_zero_overlap(self):
+    config = EventsCompactionConfig(compaction_interval=2, overlap_size=0)
+    self.assertEqual(config.overlap_size, 0)
+
   def test_latest_prompt_token_count_fallback_applies_compaction(self):
     events = [
         self._create_event(1.0, 'inv1', 'a' * 40),