diff --git a/webapp/services/imaging_status.py b/webapp/services/imaging_status.py
index 1f2fc1b..096c940 100644
--- a/webapp/services/imaging_status.py
+++ b/webapp/services/imaging_status.py
@@ -66,20 +66,28 @@ def update_session(payload: dict) -> dict:
         except (json.JSONDecodeError, OSError):
             state = {}
 
-    # Reimage detection: if the new payload's stage_index is <= 1 and we have
-    # an existing session that was further along, treat this as a fresh run.
-    # Clear log_tail + reset started_at; preserve serial. Without this, a
-    # reimage on the same bay leaves stale "succeeded" / high-idx state on
-    # the dashboard until the new run progresses past idx 1.
+    # Reimage detection: if the new payload's stage_index <= 2 (WinPE startnet
+    # = 2, Run-ShopfloorSetup start = 1) AND that's lower than the cached
+    # stage_index, treat as a fresh imaging run on the same bay. Clear
+    # log_tail + reset started_at; preserve serial; remember the previous
+    # run's last_updated for audit. Without this, a reimage leaves stale
+    # "succeeded" / high-idx state visible until the new run progresses
+    # past idx 2.
+    #
+    # Threshold of 2 covers the first signal of a new run: the WinPE-phase
+    # status push from startnet.cmd at idx=2 (fires within seconds of PXE
+    # menu choice). Previously the threshold was 1, which meant the reset
+    # only triggered once Run-ShopfloorSetup ran post-PPKG, ~10-20 minutes
+    # into a new run.
     if state:
         try:
             old_idx = int(state.get("stage_index") or 0)
             new_idx = int(payload.get("stage_index") or 0)
         except (TypeError, ValueError):
             old_idx, new_idx = 0, 0
-        rewind = new_idx > 0 and new_idx < old_idx and new_idx <= 1
+        rewind = new_idx > 0 and new_idx < old_idx and new_idx <= 2
         prev_done = state.get("status") in ("succeeded", "failed")
-        if rewind or (prev_done and new_idx > 0 and new_idx <= 1):
+        if rewind or (prev_done and new_idx > 0 and new_idx <= 2):
             state = {"serial": serial, "previous_run_at": state.get("last_updated"), "log_tail": []}
 
     if not state: