diff --git a/src/monitor_utils/runner.py b/src/monitor_utils/runner.py
index 2933fea..bc689d4 100644
--- a/src/monitor_utils/runner.py
+++ b/src/monitor_utils/runner.py
@@ -169,7 +169,11 @@ def build_product_details(
     original_price = product["originalPrice"]
 
     percentage = 0
-    has_msrp = product["hasMsrp"]
+    # Defaulted, not indexed: documents written before the field existed have no
+    # hasMsrp at all, and stale ones that drop out of a monitor's feed are never
+    # re-upserted, so they would KeyError here forever. True keeps them on the
+    # pre-existing threshold path rather than silently routing them as MSRP-less.
+    has_msrp = product.get("hasMsrp", True)
     if has_msrp:
         if not original_price:
             LOGGER.warning(
@@ -218,7 +222,7 @@ def build_product_details(
             original_price=original_price,
             price_before_drop=product["priceBeforeDrop"],
             edu_price=product["eduPrice"],
-            past_prices=product["pastPrices"],
+            past_prices=product.get("pastPrices"),
             has_msrp=has_msrp,
         ),
         availability=AvailabilityInfo(