From 3abc17a68727e22c31a7a113be935943f717ee63 Mon Sep 17 00:00:00 2001
From: Hex <165055168+hexshire@users.noreply.github.com>
Date: Tue, 3 Dec 2024 16:21:41 -0300
Subject: [PATCH] interop: add `L2ToL2CrossDomainMessenger` predeploy
 invariants (#469)

* chore: add missing invariants

* chore: address review comment

* chore: run fix lint
---
 specs/interop/predeploys.md | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/specs/interop/predeploys.md b/specs/interop/predeploys.md
index da3401213..8dc22c2a3 100644
--- a/specs/interop/predeploys.md
+++ b/specs/interop/predeploys.md
@@ -16,6 +16,7 @@
   - [`Identifier` Getters](#identifier-getters)
 - [L2ToL2CrossDomainMessenger](#l2tol2crossdomainmessenger)
   - [`relayMessage` Invariants](#relaymessage-invariants)
+  - [`sendMessage` Invariants](#sendmessage-invariants)
   - [Message Versioning](#message-versioning)
   - [No Native Support for Cross Chain Ether Sends](#no-native-support-for-cross-chain-ether-sends)
   - [Interfaces](#interfaces)
@@ -277,6 +278,12 @@ as well as domain binding, ie the executing transaction can only be valid on a s
 
 - The `Identifier.origin` MUST be `address(L2ToL2CrossDomainMessenger)`
 - The `_destination` chain id MUST be equal to the local chain id
+- Messages MUST NOT be relayed more than once
+
+### `sendMessage` Invariants
+
+- Sent Messages MUST be uniquely identifiable
+- It must emit the `SentMessage` event
 
 ### Message Versioning