native: add committee change events

Port neo-project/neo#3158.

Close #3326

Signed-off-by: Ekaterina Pavlova <ekt@morphbits.io>

pkg/core/native/native_neo.go

@@ -265,6 +265,10 @@ func newNEO(cfg config.ProtocolConfiguration) *NEO {
 		manifest.NewParameter("to", smartcontract.PublicKeyType),
 		manifest.NewParameter("amount", smartcontract.IntegerType),
 	)
+	n.AddEvent("CommitteeChanged",
+		manifest.NewParameter("old", smartcontract.ArrayType),
+		manifest.NewParameter("new", smartcontract.ArrayType),
+	)
 
 	return n
 }
@@ -425,11 +429,54 @@ func (n *NEO) OnPersist(ic *interop.Context) error {
 		cache := ic.DAO.GetRWCache(n.ID).(*NeoCache)
 		// Cached newEpoch* values always have proper value set (either by PostPersist
 		// during the last epoch block handling or by initialization code).
+
+		// Extract previous committee public keys for comparison
+		prevCommitteePublicKeys := make([]*keys.PublicKey, len(cache.committee))
+		for i, member := range cache.committee {
+			pub, err := member.PublicKey()
+			if err != nil {
+				return fmt.Errorf("failed to get public key: %w", err)
+			}
+			prevCommitteePublicKeys[i] = pub
+		}
+		// Prepare for potential committee change
 		cache.nextValidators = cache.newEpochNextValidators
 		cache.committee = cache.newEpochCommittee
 		cache.committeeHash = cache.newEpochCommitteeHash
 		cache.votesChanged = false
 
+		// Extract new committee public keys for comparison
+		newCommitteePublicKeys := make([]*keys.PublicKey, len(cache.committee))
+		for i, member := range cache.committee {
+			pub, err := member.PublicKey()
+			if err != nil {
+				return fmt.Errorf("failed to get public key: %w", err)
+			}
+			newCommitteePublicKeys[i] = pub
+		}
+		// Check if the committee has changed by comparing public keys directly
+		committeeChanged := len(prevCommitteePublicKeys) != len(newCommitteePublicKeys)
+		for i := 0; i < len(prevCommitteePublicKeys) && !committeeChanged; i++ {
+			if !prevCommitteePublicKeys[i].Equal(newCommitteePublicKeys[i]) {
+				committeeChanged = true
+			}
+		}
+
+		// Notify subscribers if the committee has changed
+		if committeeChanged {
+			publicKeysToStackItems := func(publicKeys []*keys.PublicKey) []stackitem.Item {
+				items := make([]stackitem.Item, len(publicKeys))
+				for i, pubKey := range publicKeys {
+					items[i] = stackitem.NewByteArray(pubKey.Bytes())
+				}
+				return items
+			}
+			prevCommitteeStackItems := publicKeysToStackItems(prevCommitteePublicKeys)
+			newCommitteeStackItems := publicKeysToStackItems(newCommitteePublicKeys)
+			ic.AddNotification(n.Hash, "CommitteeChanged", stackitem.NewArray([]stackitem.Item{
+				stackitem.NewArray(prevCommitteeStackItems), stackitem.NewArray(newCommitteeStackItems),
+			}))
+		}
 		// We need to put in storage anyway, as it affects dumps
 		ic.DAO.PutStorageItem(n.ID, prefixCommittee, cache.committee.Bytes(ic.DAO.GetItemCtx()))
 	}

pkg/core/native/native_test/neo_test.go

@@ -64,6 +64,8 @@ func TestNEO_RegisterPriceCache(t *testing.T) {
 }
 
 func TestNEO_CandidateEvents(t *testing.T) {
+	neoCommitteeInvoker := newNeoCommitteeClient(t, 100_0000_0000)
+	neoValidatorsInvoker := neoCommitteeInvoker.WithSigners(neoCommitteeInvoker.Validator)
 	c := newNativeClient(t, nativenames.Neo)
 	singleSigner := c.Signers[0].(neotest.MultiSigner).Single(0)
 	cc := c.WithSigners(c.Signers[0], singleSigner)
@@ -116,6 +118,17 @@ func TestNEO_CandidateEvents(t *testing.T) {
 	tx = cc.Invoke(t, true, "unregisterCandidate", pkb)
 	aer = e.GetTxExecResult(t, tx)
 	require.Equal(t, 0, len(aer.Events))
+	neoValidatorsInvoker.AddNewBlock(t)
+	e.CheckHalt(t, tx, stackitem.Make(true))
+	e.CheckTxNotificationEvent(t, tx, 0, state.NotificationEvent{
+		ScriptHash: c.Hash,
+		Name:       "CommitteeChanged",
+		Item: stackitem.NewArray([]stackitem.Item{
+			stackitem.NewByteArray(pkb),
+			stackitem.NewBool(true),
+			stackitem.Make(0),
+		}),
+	})
 }
 
 func TestNEO_Vote(t *testing.T) {

pkg/rpcclient/neo/neo.go

@@ -75,6 +75,12 @@ type CandidateStateEvent struct {
 	Votes      *big.Int
 }
 
+// CommitteeChangedEvent represents a CommitteeChanged NEO event.
+type CommitteeChangedEvent struct {
+	Old []keys.PublicKey
+	New []keys.PublicKey
+}
+
 // VoteEvent represents a Vote NEO event.
 type VoteEvent struct {
 	Account util.Uint160