diff --git a/monitor/graph_json.py b/monitor/graph_json.py
index 6aba69f..d4aeed5 100644
--- a/monitor/graph_json.py
+++ b/monitor/graph_json.py
@@ -117,11 +117,17 @@ def _serialise_pe_state(pe_id: int, snapshot: StateSnapshot) -> dict[str, Any]:
 
     frames_json = [[_serialise_slot(s) for s in frame] for frame in pe_snap.frames]
 
+    tag_store_json = {
+        str(act_id): {"frame_id": fid, "lane": lane}
+        for act_id, (fid, lane) in pe_snap.tag_store.items()
+    }
+
     return {
         "pe_id": pe_snap.pe_id,
         "iram": iram_json,
         "frames": frames_json,
-        "tag_store": pe_snap.tag_store,
+        "tag_store": tag_store_json,
+        "lane_count": pe_snap.lane_count,
         "free_frames": list(pe_snap.free_frames),
         "input_queue_size": len(pe_snap.input_queue),
     }