align with previous PR

fendermint/vm/topdown/src/observation.rs

@@ -1,7 +1,9 @@
 // Copyright 2022-2024 Protocol Labs
 // SPDX-License-Identifier: Apache-2.0, MIT
 
-use crate::{BlockHeight, Bytes};
+use crate::syncer::error::Error;
+use crate::syncer::store::ParentViewStore;
+use crate::{BlockHeight, Bytes, Checkpoint};
 use anyhow::anyhow;
 use arbitrary::Arbitrary;
 use fendermint_crypto::secp::RecoverableECDSASignature;
@@ -41,6 +43,14 @@ pub struct CertifiedObservation {
     signature: RecoverableECDSASignature,
 }
 
+/// check in the store to see if there is a new observation available
+pub fn deduce_new_observation<S: ParentViewStore>(
+    _store: &S,
+    _checkpoint: &Checkpoint,
+) -> Result<Observation, Error> {
+    todo!()
+}
+
 impl TryFrom<&[u8]> for CertifiedObservation {
     type Error = anyhow::Error;
 

fendermint/vm/topdown/src/syncer/mod.rs

@@ -1,7 +1,7 @@
 // Copyright 2022-2024 Protocol Labs
 // SPDX-License-Identifier: Apache-2.0, MIT
 
-use crate::observation::ObservationCommitment;
+use crate::observation::Observation;
 use crate::proxy::ParentQueryProxy;
 use crate::syncer::poll::ParentPoll;
 use crate::syncer::store::ParentViewStore;
@@ -19,7 +19,7 @@ pub mod store;
 pub enum TopDownSyncEvent {
     /// The fendermint node is syncing with peers
     NodeSyncing,
-    NewProposal(Box<ObservationCommitment>),
+    NewProposal(Box<Observation>),
 }
 
 pub struct ParentSyncerConfig {

fendermint/vm/topdown/src/vote/store.rs

@@ -138,13 +138,13 @@ mod tests {
         (sk, ValidatorKey::new(public_key))
     }
 
-    fn random_observation() -> ObservationCommitment {
+    fn random_observation() -> Observation {
         let mut bytes = [0; 100];
         let mut rng = rand::thread_rng();
         rng.fill_bytes(&mut bytes);
 
         let mut unstructured = Unstructured::new(&bytes);
-        ObservationCommitment::arbitrary(&mut unstructured).unwrap()
+        Observation::arbitrary(&mut unstructured).unwrap()
     }
 
     #[test]

fendermint/vm/topdown/src/vote/tally.rs

@@ -230,13 +230,13 @@ mod tests {
         (sk, ValidatorKey::new(public_key))
     }
 
-    fn random_observation() -> ObservationCommitment {
+    fn random_observation() -> Observation {
         let mut bytes = [0; 100];
         let mut rng = rand::thread_rng();
         rng.fill_bytes(&mut bytes);
 
         let mut unstructured = Unstructured::new(&bytes);
-        ObservationCommitment::arbitrary(&mut unstructured).unwrap()
+        Observation::arbitrary(&mut unstructured).unwrap()
     }
 
     #[test]