diff --git a/piker/brokers/ib/feed.py b/piker/brokers/ib/feed.py
index 51305ced..c4f91533 100644
--- a/piker/brokers/ib/feed.py
+++ b/piker/brokers/ib/feed.py
@@ -178,8 +178,8 @@ async def open_history_client(
 
         async def get_hist(
             timeframe: float,
-            end_dt: datetime | None = None,
-            start_dt: datetime | None = None,
+            end_dt: datetime|None = None,
+            start_dt: datetime|None = None,
 
         ) -> tuple[np.ndarray, str]:
 
@@ -262,7 +262,29 @@ async def open_history_client(
             vlm = bars_array['volume']
             vlm[vlm < 0] = 0
 
-            return bars_array, first_dt, last_dt
+            # XXX, if a start-limit was passed ensure we only
+            # return history that far back!
+            if (
+                start_dt
+                and
+                last_dt < start_dt
+            ):
+                bars_array = bars_array[
+                    bars_array['time'] >= start_dt.timestamp()
+                ]
+                # TODO! rm this once we're more confident it never hits!
+                breakpoint()
+                raise RuntimeError(
+                    f'OHLC-bars array start is gt `start_dt` limit !!\n'
+                    f'start_dt: {start_dt}\n'
+                    f'last_dt: {last_dt}\n'
+                )
+
+            return (
+                bars_array,
+                first_dt,
+                last_dt,
+            )
 
         # TODO: it seems like we can do async queries for ohlc
         # but getting the order right still isn't working and I'm not
@@ -397,7 +419,7 @@ async def get_bars(
 
     # blank to start which tells ib to look up the latest datum
     end_dt: str = '',
-    start_dt: str | None = '',
+    start_dt: str|None = '',
 
     # TODO: make this more dynamic based on measured frame rx latency?
     # how long before we trigger a feed reset (seconds)
@@ -451,6 +473,8 @@ async def get_bars(
                     dt_duration,
                 ) = await proxy.bars(
                     fqme=fqme,
+                    # XXX TODO! lol we're not using this..
+                    # start_dt=start_dt,
                     end_dt=end_dt,
                     sample_period_s=timeframe,
 
diff --git a/piker/tsp/_history.py b/piker/tsp/_history.py
index 361b0e23..e11f967d 100644
--- a/piker/tsp/_history.py
+++ b/piker/tsp/_history.py
@@ -242,6 +242,13 @@ async def maybe_fill_null_segments(
             end_dt=end_dt,
         )
 
+        if (
+            from_timestamp(
+                array['time'][0]
+            ) < backfill_until_dt
+        ):
+            await tractor.pause()
+
         # XXX TODO: pretty sure if i plot tsla, btcusdt.binance
         # and mnq.cme.ib this causes a Qt crash XXDDD