diff --git a/src/Observable.sol b/src/Observable.sol
new file mode 100644
index 0000000..334b750
--- /dev/null
+++ b/src/Observable.sol
@@ -0,0 +1,9 @@
+// SPDX-License-Identifier: Unlicense
+pragma solidity ^0.8.23;
+
+abstract contract ObservableOrderflow {
+    event SentBundle(bytes32 bundleHash);
+    event SentBundle(bytes32 bundleHash, bytes32[] txHashes);
+    event SentTransaction(bytes32 txHash);
+    event SentTransactions(bytes32[] txHashes);
+}