fix(forkchoice): use only "new" pool for safe target (leanSpec #680)

crates/blockchain/src/store.rs

@@ -101,17 +101,24 @@ fn update_head(store: &mut Store, log_tree: bool) {
 }
 
 /// Update the safe target for attestation.
+///
+/// Safe target is an *availability* signal, not a durable-knowledge signal:
+/// only the "new" pool is considered. Migration from "new" to "known" runs at
+/// interval 4, strictly after this computation at interval 3. 3sf-mini chose
+/// that ordering deliberately so safe target sees only freshly received votes
+/// from the current slot and ignores what was carried over from earlier slots
+/// (block-included attestations, previously migrated gossip, self-attestations).
+/// Counting "known" would let a node keep advancing its safe target on stale
+/// evidence even when live participation has collapsed: exactly the failure
+/// mode safe target is supposed to prevent. See leanSpec PR #680.
 fn update_safe_target(store: &mut Store) {
     let head_state = store.get_state(&store.head()).expect("head state exists");
     let num_validators = head_state.validators.len() as u64;
 
     let min_target_score = (num_validators * 2).div_ceil(3);
 
     let blocks = store.get_live_chain();
-    // Merge both attestation pools (known + new).
-    // At interval 3 the promotion (interval 4) hasn't run yet, so we must
-    // merge both pools to get a complete view for safe target computation.
-    let attestations = store.extract_latest_all_attestations();
+    let attestations = store.extract_latest_new_attestations();
     let (safe_target, _weights) = ethlambda_fork_choice::compute_lmd_ghost_head(
         store.latest_justified().root,
         &blocks,

crates/storage/src/store.rs

@@ -992,29 +992,6 @@ impl Store {
             .extract_latest_attestations()
     }
 
-    /// Extract per-validator latest attestations from both known and new payloads.
-    pub fn extract_latest_all_attestations(&self) -> HashMap<u64, AttestationData> {
-        let mut result = self
-            .known_payloads
-            .lock()
-            .unwrap()
-            .extract_latest_attestations();
-        for (vid, data) in self
-            .new_payloads
-            .lock()
-            .unwrap()
-            .extract_latest_attestations()
-        {
-            let should_update = result
-                .get(&vid)
-                .is_none_or(|existing| existing.slot < data.slot);
-            if should_update {
-                result.insert(vid, data);
-            }
-        }
-        result
-    }
-
     // ============ Known Aggregated Payloads ============
     //
     // "Known" aggregated payloads are active in fork choice weight calculations.