Gate attestations until justified checkpoint advances from anchor

lean_client/fork_choice/src/handlers.rs

@@ -502,6 +502,7 @@ fn process_block_internal(
             "Store justified checkpoint updated!"
         );
         store.latest_justified = new_state.latest_justified.clone();
+        store.justified_ever_updated = true;
         METRICS.get().map(|metrics| {
             let Some(slot) = new_state.latest_justified.slot.0.try_into().ok() else {
                 warn!("unable to set latest_justified slot in metrics");

lean_client/fork_choice/src/store.rs

@@ -33,6 +33,13 @@ pub struct Store {
 
     pub latest_finalized: Checkpoint,
 
+    /// Set to `true` the first time `on_block` drives a justified checkpoint
+    /// update beyond the initial anchor value. Validator duties (attestation,
+    /// block proposal) must not run while this is `false` — the store's
+    /// `latest_justified` is still the placeholder anchor checkpoint and using
+    /// it as an attestation source would produce wrong source checkpoints.
+    pub justified_ever_updated: bool,
+
     pub blocks: HashMap<H256, Block>,
 
     pub states: HashMap<H256, State>,
@@ -209,6 +216,7 @@ pub fn get_forkchoice_store(
         safe_target: block_root,
         latest_justified,
         latest_finalized,
+        justified_ever_updated: false,
         blocks: [(block_root, block)].into(),
         states: [(block_root, anchor_state)].into(),
         latest_known_attestations: HashMap::new(),

lean_client/src/main.rs

@@ -997,8 +997,20 @@ async fn main() -> Result<()> {
                             let _ = sender.send(result);
                         }
                         ValidatorChainMessage::BuildAttestationData { slot, sender } => {
-                            let result = store.read().produce_attestation_data(slot);
-                            let _ = sender.send(result);
+                            let store_read = store.read();
+                            if !store_read.justified_ever_updated {
+                                warn!(
+                                    slot = slot.0,
+                                    "Skipping attestation: justified checkpoint has not yet \
+                                     advanced from anchor — node is not ready to attest"
+                                );
+                                let _ = sender.send(Err(anyhow::anyhow!(
+                                    "not ready: justified checkpoint has not advanced from anchor value"
+                                )));
+                            } else {
+                                let result = store_read.produce_attestation_data(slot);
+                                let _ = sender.send(result);
+                            }
                         }
                     }
                 }