diff --git a/deltax_forge_cross/logging.py b/deltax_forge_cross/logging.py
index a6fb846..943dc3b 100644
--- a/deltax_forge_cross/logging.py
+++ b/deltax_forge_cross/logging.py
@@ -8,10 +8,17 @@ class RunLog:
     def __init__(self, path: str = "deltax_run.log"):
         self.path = path
 
-    def log(self, entry: dict) -> None:
+    def log(self, entry: dict, venue: str | None = None) -> None:
+        """Append a log entry deterministically.
+
+        Args:
+            entry: The event payload to log (dict-like).
+            venue: Optional venue identifier for cross-venue tracing.
+        """
         with open(self.path, "a", encoding="utf-8") as f:
             payload = {
                 "ts": time.time(),
+                "venue": venue,
                 "event": entry,
             }
             f.write(json.dumps(payload) + "\n")