Add ciphertext-safe Postbox search source

src/govoplan_postbox/backend/service.py

@@ -845,6 +845,32 @@ class PostboxService:
         )
         return self._message_ref(message, account_id=actor.account_id)
 
+    def can_read_message(
+        self,
+        session: object,
+        *,
+        tenant_id: str,
+        message_id: str,
+        actor: PostboxActorRef,
+    ) -> bool:
+        """Recheck message access without creating a read or denial event."""
+
+        db = _session(session)
+        message = self._get_message(
+            db,
+            tenant_id=tenant_id,
+            message_id=message_id,
+            required=False,
+        )
+        if message is None:
+            return False
+        return self._message_access_decision(
+            db,
+            message=message,
+            actor=actor,
+            action="read",
+        ).allowed
+
     def mark_message(
         self,
         session: object,