Fix attestation source divergence (leanSpec PR #506)

produce_attestation_data used store.latest_justified (global max across all
forks) as the attestation source, while build_block filters by
head_state.latest_justified. When a non-head fork block advances the
store-wide justified past the head chain's justified, every attestation
gets rejected during block building, producing blocks with 0 attestations
and stalling justification/finalization indefinitely.

Align with the 3sf-mini reference: derive the attestation source from the
head state's justified checkpoint. Also handle the genesis edge case where
the zero-hash root must be substituted with the real genesis block root,
matching the existing logic in build_block.

Update LEAN_SPEC_COMMIT_HASH to include the new spec test that exercises
the divergence scenario.

Author: pablodeymo

Makefile

@@ -24,7 +24,7 @@ docker-build: ## 🐳 Build the Docker image
 		-t ghcr.io/lambdaclass/ethlambda:$(DOCKER_TAG) .
 	@echo
 
-LEAN_SPEC_COMMIT_HASH:=d39d10195414921e979e2fdd43723d89cee13c8b
+LEAN_SPEC_COMMIT_HASH:=9c30436bf4c073d1a994f37a3241e83ef5a3ce6f
 
 leanSpec:
 	git clone https://github.com/leanEthereum/leanSpec.git --single-branch

crates/blockchain/src/store.rs

@@ -740,12 +740,32 @@ pub fn get_attestation_target(store: &Store) -> Checkpoint {
 }
 
 /// Produce attestation data for the given slot.
+///
+/// The attestation source comes from the head state's justified checkpoint,
+/// not the store-wide global max. This ensures voting aligns with the block
+/// builder's attestation filter (which also uses head state).
+///
+/// See: <https://github.com/leanEthereum/leanSpec/pull/506>
 pub fn produce_attestation_data(store: &Store, slot: u64) -> AttestationData {
-    // Get the head block the validator sees for this slot
+    let head_root = store.head();
+    let head_state = store.get_state(&head_root).expect("head state exists");
+
+    // Derive source from head state's justified checkpoint.
+    // At genesis the checkpoint root is H256::ZERO; substitute the real
+    // genesis block root so attestation validation can look it up.
+    let source = if head_state.latest_block_header.slot == 0 {
+        Checkpoint {
+            root: head_root,
+            slot: head_state.latest_justified.slot,
+        }
+    } else {
+        head_state.latest_justified
+    };
+
     let head_checkpoint = Checkpoint {
-        root: store.head(),
+        root: head_root,
         slot: store
-            .get_block_header(&store.head())
+            .get_block_header(&head_root)
             .expect("head block exists")
             .slot,
     };
@@ -758,7 +778,7 @@ pub fn produce_attestation_data(store: &Store, slot: u64) -> AttestationData {
         slot,
         head: head_checkpoint,
         target: target_checkpoint,
-        source: store.latest_justified(),
+        source,
     }
 }