fix(exex): do not finalize WAL with a block higher than finalized hea…

…der (#11420)

crates/exex/exex/src/manager.rs

@@ -350,14 +350,17 @@ where
             .collect::<Result<Vec<_>, _>>()?;
         if exex_finished_heights.iter().all(|(_, _, is_canonical)| *is_canonical) {
             // If there is a finalized header and all ExExs are on the canonical chain, finalize
-            // the WAL with the lowest finished height among all ExExes
+            // the WAL with either the lowest finished height among all ExExes, or finalized header
+            // – whichever is lower.
             let lowest_finished_height = exex_finished_heights
                 .iter()
                 .copied()
                 .filter_map(|(_, num_hash, _)| num_hash)
-                .min_by_key(|num_hash| num_hash.number);
-            self.wal
-                .finalize(lowest_finished_height.expect("ExExManager has at least one ExEx"))?;
+                .chain([(finalized_header.num_hash())])
+                .min_by_key(|num_hash| num_hash.number)
+                .unwrap();
+
+            self.wal.finalize(lowest_finished_height)?;
         } else {
             let unfinalized_exexes = exex_finished_heights
                 .into_iter()