fix: guard transient controls and verify timeline endpoints

artemis/agents/validator/execution_loop.py

@@ -484,6 +484,15 @@ async def run_validation_loop(node, state: State) -> dict:
         skipped_copy["attempts"] = [BURST_SKIPPED_MARKER if burst else "Skipped"]
         execution.append(skipped_copy)
 
+    # A checkpoint may run before the next perception turn. Preserve the end of
+    # a native sequence now, without introducing captures between burst members.
+    # Saturated controls legitimately produce the same image hash as before.
+    sequence_post_image = None
+    if success and any(item.get("action") == "action_sequence" for item in execution):
+        captured = await _capture_live_screenshot(session, "post-sequence evidence")
+        if captured:
+            sequence_post_image = _absorb_post_screenshot(ctx, state, captured)
+
     report = {
         "execution": execution,
         "status": "dispatched" if success else "failed",
@@ -494,7 +503,7 @@ async def run_validation_loop(node, state: State) -> dict:
         report["pre_image_valid"] = False
 
     # Determine if a distinct post-action screenshot was captured
-    distinct_post_image_name = (
+    distinct_post_image_name = sequence_post_image or (
         last_screenshot_name
         if (last_screenshot_name and last_screenshot_name != decision_screenshot_name)
         else None