From 22a68756c71a4a4e3408600c69ef5b6cf7169461 Mon Sep 17 00:00:00 2001
From: Matthias Seitz <matthias.seitz@outlook.de>
Date: Fri, 23 Jan 2026 12:26:57 +0100
Subject: [PATCH] fix(tree): evict changeset cache even when finalized block is
 unset (#21354)

---
 crates/engine/tree/src/tree/mod.rs | 40 ++++++++++++++++++++----------
 1 file changed, 27 insertions(+), 13 deletions(-)

diff --git a/crates/engine/tree/src/tree/mod.rs b/crates/engine/tree/src/tree/mod.rs
index 1e04d19dba..1e4a631594 100644
--- a/crates/engine/tree/src/tree/mod.rs
+++ b/crates/engine/tree/src/tree/mod.rs
@@ -85,6 +85,12 @@ pub mod state;
 /// backfill this gap.
 pub(crate) const MIN_BLOCKS_FOR_PIPELINE_RUN: u64 = EPOCH_SLOTS;
 
+/// The minimum number of blocks to retain in the changeset cache after eviction.
+///
+/// This ensures that recent trie changesets are kept in memory for potential reorgs,
+/// even when the finalized block is not set (e.g., on L2s like Optimism).
+const CHANGESET_CACHE_RETENTION_BLOCKS: u64 = 64;
+
 /// A builder for creating state providers that can be used across threads.
 #[derive(Clone, Debug)]
 pub struct StateProviderBuilder<N: NodePrimitives, P> {
@@ -1378,19 +1384,27 @@ where
         debug!(target: "engine::tree", ?last_persisted_block_hash, ?last_persisted_block_number, elapsed=?start_time.elapsed(), "Finished persisting, calling finish");
         self.persistence_state.finish(last_persisted_block_hash, last_persisted_block_number);
 
-        // Evict trie changesets for blocks below the finalized block, but keep at least 64 blocks
-        if let Some(finalized) = self.canonical_in_memory_state.get_finalized_num_hash() {
-            let min_threshold = last_persisted_block_number.saturating_sub(64);
-            let eviction_threshold = finalized.number.min(min_threshold);
-            debug!(
-                target: "engine::tree",
-                last_persisted = last_persisted_block_number,
-                finalized_number = finalized.number,
-                eviction_threshold,
-                "Evicting changesets below threshold"
-            );
-            self.changeset_cache.evict(eviction_threshold);
-        }
+        // Evict trie changesets for blocks below the eviction threshold.
+        // Keep at least CHANGESET_CACHE_RETENTION_BLOCKS from the persisted tip, and also respect
+        // the finalized block if set.
+        let min_threshold =
+            last_persisted_block_number.saturating_sub(CHANGESET_CACHE_RETENTION_BLOCKS);
+        let eviction_threshold =
+            if let Some(finalized) = self.canonical_in_memory_state.get_finalized_num_hash() {
+                // Use the minimum of finalized block and retention threshold to be conservative
+                finalized.number.min(min_threshold)
+            } else {
+                // When finalized is not set (e.g., on L2s), use the retention threshold
+                min_threshold
+            };
+        debug!(
+            target: "engine::tree",
+            last_persisted = last_persisted_block_number,
+            finalized_number = ?self.canonical_in_memory_state.get_finalized_num_hash().map(|f| f.number),
+            eviction_threshold,
+            "Evicting changesets below threshold"
+        );
+        self.changeset_cache.evict(eviction_threshold);
 
         self.on_new_persisted_block()?;
         Ok(())