@@ -26,13 +26,14 @@ }
 
 // Slot contains relevant information of a slot
 type Slot struct {
-	SlotNum        int64
-	DefaultSlotBid *big.Int
-	StartBlock     int64
-	EndBlock       int64
-	BatchesLen     int
-	BidValue       *big.Int
-	BootCoord      bool
+	SlotNum          int64
+	DefaultSlotBid   *big.Int
+	StartBlock       int64
+	EndBlock         int64
+	ForgerCommitment bool
+	// BatchesLen       int
+	BidValue  *big.Int
+	BootCoord bool
 	// Bidder, Forer and URL correspond to the winner of the slot (which is
 	// not always the highest bidder).  These are the values of the
 	// coordinator that is able to forge exclusively before the deadline.

@@ -47,7 +47,7 @@
 // DebugStore is a debug function to store the BatchInfo as a json text file in
 // storePath
 func (b *BatchInfo) DebugStore(storePath string) error {
-	batchJSON, err := json.Marshal(b)
+	batchJSON, err := json.MarshalIndent(b, "", "  ")
 	if err != nil {
 		return tracerr.Wrap(err)
 	}

@@ -190,9 +190,10 @@ }
 
 func (c *Coordinator) canForge(stats *synchronizer.Stats) bool {
 	anyoneForge := false
-	if stats.Sync.Auction.CurrentSlot.BatchesLen == 0 &&
-		c.consts.Auction.RelativeBlock(stats.Eth.LastBlock.Num+1) > int64(c.vars.Auction.SlotDeadline) {
-		log.Debug("Coordinator: anyone can forge in the current slot (slotDeadline passed)")
+	if !stats.Sync.Auction.CurrentSlot.ForgerCommitment &&
+		c.consts.Auction.RelativeBlock(stats.Eth.LastBlock.Num+1) >= int64(c.vars.Auction.SlotDeadline) {
+		log.Debugw("Coordinator: anyone can forge in the current slot (slotDeadline passed)",
+			"block", stats.Eth.LastBlock.Num)
 		anyoneForge = true
 	}
 	if stats.Sync.Auction.CurrentSlot.Forger == c.cfg.ForgerAddress || anyoneForge {

@@ -213,6 +213,7 @@ if os.Getenv("TEST_COORD_FLOW") == "" {
 		return
 	}
 	ethClientSetup := test.NewClientSetupExample()
+	ethClientSetup.ChainID = big.NewInt(int64(chainID))
 	var timer timer
 	ethClient := test.NewClient(true, &timer, &bidder, ethClientSetup)
 	modules := newTestModules(t)
@@ -294,6 +295,7 @@ }
 
 func TestCoordinatorStartStop(t *testing.T) {
 	ethClientSetup := test.NewClientSetupExample()
+	ethClientSetup.ChainID = big.NewInt(int64(chainID))
 	var timer timer
 	ethClient := test.NewClient(true, &timer, &bidder, ethClientSetup)
 	modules := newTestModules(t)
@@ -304,6 +306,7 @@ }
 
 func TestCoordCanForge(t *testing.T) {
 	ethClientSetup := test.NewClientSetupExample()
+	ethClientSetup.ChainID = big.NewInt(int64(chainID))
 	bootForger := ethClientSetup.AuctionVariables.BootCoordinator
 
 	var timer timer
@@ -356,6 +359,7 @@ }
 
 func TestCoordHandleMsgSyncBlock(t *testing.T) {
 	ethClientSetup := test.NewClientSetupExample()
+	ethClientSetup.ChainID = big.NewInt(int64(chainID))
 	bootForger := ethClientSetup.AuctionVariables.BootCoordinator
 
 	var timer timer
@@ -417,6 +421,7 @@ }
 
 func TestPipelineShouldL1L2Batch(t *testing.T) {
 	ethClientSetup := test.NewClientSetupExample()
+	ethClientSetup.ChainID = big.NewInt(int64(chainID))
 
 	var timer timer
 	ctx := context.Background()
@@ -562,6 +567,7 @@ }
 
 func TestPipeline1(t *testing.T) {
 	ethClientSetup := test.NewClientSetupExample()
+	ethClientSetup.ChainID = big.NewInt(int64(chainID))
 
 	var timer timer
 	ctx := context.Background()
@@ -646,6 +652,7 @@ return
 	}
 	log.Info("Begin Test Coord Stress")
 	ethClientSetup := test.NewClientSetupExample()
+	ethClientSetup.ChainID = big.NewInt(int64(chainID))
 	var timer timer
 	ethClient := test.NewClient(true, &timer, &bidder, ethClientSetup)
 	modules := newTestModules(t)
@@ -691,7 +698,7 @@ select {
 			case <-ctx.Done():
 				wg.Done()
 				return
-			case <-time.After(100 * time.Millisecond):
+			case <-time.After(1 * time.Second):
 				ethClient.CtlMineBlock()
 			}
 		}

@@ -293,11 +293,15 @@ )
 	return db.SlicePtrsToSlice(batches).([]common.Batch), tracerr.Wrap(err)
 }
 
-// GetBatchesLen retrieve number of batches from the DB, given a slotNum
-func (hdb *HistoryDB) GetBatchesLen(slotNum int64) (int, error) {
-	row := hdb.db.QueryRow("SELECT COUNT(*) FROM batch WHERE slot_num = $1;", slotNum)
-	var batchesLen int
-	return batchesLen, tracerr.Wrap(row.Scan(&batchesLen))
+// GetFirstBatchBlockNumBySlot returns the ethereum block number of the first
+// batch within a slot
+func (hdb *HistoryDB) GetFirstBatchBlockNumBySlot(slotNum int64) (int64, error) {
+	row := hdb.db.QueryRow(
+		`SELECT eth_block_num FROM batch
+		WHERE slot_num = $1 ORDER BY batch_num ASC LIMIT 1;`, slotNum,
+	)
+	var blockNum int64
+	return blockNum, tracerr.Wrap(row.Scan(&blockNum))
 }
 
 // GetLastBatchNum returns the BatchNum of the latest forged batch

@@ -1051,6 +1051,70 @@ _, err := historyDB.GetLastTxsPosition(0)
 	assert.Equal(t, sql.ErrNoRows.Error(), err.Error())
 }
 
+func TestGetFirstBatchBlockNumBySlot(t *testing.T) {
+	test.WipeDB(historyDB.DB())
+
+	set := `
+		Type: Blockchain
+
+		// Slot = 0
+
+		> block // 2
+		> block // 3
+		> block // 4
+		> block // 5
+
+		// Slot = 1
+
+		> block // 6
+		> block // 7
+		> batch
+		> block // 8
+		> block // 9
+
+		// Slot = 2
+
+		> batch
+		> block // 10
+		> block // 11
+		> block // 12
+		> block // 13
+
+	`
+	tc := til.NewContext(uint16(0), common.RollupConstMaxL1UserTx)
+	blocks, err := tc.GenerateBlocks(set)
+	assert.NoError(t, err)
+
+	tilCfgExtra := til.ConfigExtra{
+		CoordUser: "A",
+	}
+	err = tc.FillBlocksExtra(blocks, &tilCfgExtra)
+	require.NoError(t, err)
+
+	for i := range blocks {
+		for j := range blocks[i].Rollup.Batches {
+			blocks[i].Rollup.Batches[j].Batch.SlotNum = int64(i) / 4
+		}
+	}
+
+	// Add all blocks
+	for i := range blocks {
+		err = historyDB.AddBlockSCData(&blocks[i])
+		require.NoError(t, err)
+	}
+
+	_, err = historyDB.GetFirstBatchBlockNumBySlot(0)
+	require.Equal(t, sql.ErrNoRows, tracerr.Unwrap(err))
+
+	bn1, err := historyDB.GetFirstBatchBlockNumBySlot(1)
+	require.NoError(t, err)
+	assert.Equal(t, int64(8), bn1)
+
+	bn2, err := historyDB.GetFirstBatchBlockNumBySlot(2)
+	require.NoError(t, err)
+	assert.Equal(t, int64(10), bn2)
+}
+
 // setTestBlocks WARNING: this will delete the blocks and recreate them
 func setTestBlocks(from, to int64) []common.Block {
 	test.WipeDB(historyDB.DB())

@@ -288,7 +288,8 @@ }
 
 // MockClient is a mock ServerProof to be used in tests.  It doesn't calculate anything
 type MockClient struct {
-	Delay time.Duration
+	counter int64
+	Delay   time.Duration
 }
 
 // CalculateProof sends the *common.ZKInputs to the ServerProof to compute the
@@ -302,7 +303,24 @@ func (p *MockClient) GetProof(ctx context.Context) (*Proof, []*big.Int, error) {
 	// Simulate a delay
 	select {
 	case <-time.After(p.Delay): //nolint:gomnd
-		return &Proof{}, []*big.Int{big.NewInt(1234)}, nil //nolint:gomnd
+		i := p.counter * 100 //nolint:gomnd
+		p.counter++
+		return &Proof{
+				PiA: [3]*big.Int{
+					big.NewInt(i), big.NewInt(i + 1), big.NewInt(1), //nolint:gomnd
+				},
+				PiB: [3][2]*big.Int{
+					{big.NewInt(i + 2), big.NewInt(i + 3)}, //nolint:gomnd
+					{big.NewInt(i + 4), big.NewInt(i + 5)}, //nolint:gomnd
+					{big.NewInt(1), big.NewInt(0)},         //nolint:gomnd
+				},
+				PiC: [3]*big.Int{
+					big.NewInt(i + 6), big.NewInt(i + 7), big.NewInt(1), //nolint:gomnd
+				},
+				Protocol: "groth",
+			},
+			[]*big.Int{big.NewInt(i + 42)}, //nolint:gomnd
+			nil
 	case <-ctx.Done():
 		return nil, nil, tracerr.Wrap(common.ErrDone)
 	}

@@ -177,17 +177,12 @@ }
 
 // Config is the Synchronizer configuration
 type Config struct {
-	// StartBlockNum StartBlockNum
-	// InitialVariables   SCVariables
 	StatsRefreshPeriod time.Duration
 }
 
 // Synchronizer implements the Synchronizer type
 type Synchronizer struct {
-	ethClient eth.ClientInterface
-	// auctionConstants  common.AuctionConstants
-	// rollupConstants   common.RollupConstants
-	// wDelayerConstants common.WDelayerConstants
+	ethClient     eth.ClientInterface
 	consts        SCConsts
 	historyDB     *historydb.HistoryDB
 	stateDB       *statedb.StateDB
@@ -196,8 +191,6 @@ initVars      SCVariables
 	startBlockNum int64
 	vars          SCVariables
 	stats         *StatsHolder
-	// firstSavedBlock  *common.Block
-	// mux sync.Mutex
 }
 
 // NewSynchronizer creates a new Synchronizer
@@ -286,24 +279,28 @@ WDelayer: s.vars.WDelayer.Copy(),
 	}
 }
 
-func (s *Synchronizer) updateCurrentSlotIfSync(batchesLen int) error {
+// firstBatchBlockNum is the blockNum of first batch in that block, if any
+func (s *Synchronizer) updateCurrentSlotIfSync(reset bool, firstBatchBlockNum *int64) error {
 	slot := common.Slot{
-		SlotNum:    s.stats.Sync.Auction.CurrentSlot.SlotNum,
-		BatchesLen: int(s.stats.Sync.Auction.CurrentSlot.BatchesLen),
+		SlotNum:          s.stats.Sync.Auction.CurrentSlot.SlotNum,
+		ForgerCommitment: s.stats.Sync.Auction.CurrentSlot.ForgerCommitment,
 	}
 	// We want the next block because the current one is already mined
 	blockNum := s.stats.Sync.LastBlock.Num + 1
 	slotNum := s.consts.Auction.SlotNum(blockNum)
-	if batchesLen == -1 {
-		dbBatchesLen, err := s.historyDB.GetBatchesLen(slotNum)
-		if err != nil {
-			return tracerr.Wrap(fmt.Errorf("historyDB.GetBatchesLen: %w", err))
+	if reset {
+		dbFirstBatchBlockNum, err := s.historyDB.GetFirstBatchBlockNumBySlot(slotNum)
+		if err != nil && tracerr.Unwrap(err) != sql.ErrNoRows {
+			return tracerr.Wrap(fmt.Errorf("historyDB.GetFirstBatchBySlot: %w", err))
+		} else if tracerr.Unwrap(err) == sql.ErrNoRows {
+			firstBatchBlockNum = nil
+		} else {
+			firstBatchBlockNum = &dbFirstBatchBlockNum
 		}
-		slot.BatchesLen = dbBatchesLen
+		slot.ForgerCommitment = false
 	} else if slotNum > slot.SlotNum {
-		slot.BatchesLen = batchesLen
-	} else {
-		slot.BatchesLen += batchesLen
+		// We are in a new slotNum, start from default values
+		slot.ForgerCommitment = false
 	}
 	slot.SlotNum = slotNum
 	slot.StartBlock, slot.EndBlock = s.consts.Auction.SlotBlocks(slot.SlotNum)
@@ -332,6 +329,11 @@ slot.BootCoord = true
 				slot.Forger = s.vars.Auction.BootCoordinator
 				slot.URL = s.vars.Auction.BootCoordinatorURL
 			}
+		}
+		if firstBatchBlockNum != nil &&
+			s.consts.Auction.RelativeBlock(*firstBatchBlockNum) <
+				int64(s.vars.Auction.SlotDeadline) {
+			slot.ForgerCommitment = true
 		}
 
 		// TODO: Remove this SANITY CHECK once this code is tested enough
@@ -499,11 +501,6 @@ Auction:  *auctionData,
 		WDelayer: *wDelayerData,
 	}
 
-	// log.Debugw("Sync()", "block", blockData)
-	// err = s.historyDB.AddBlock(blockData.Block)
-	// if err != nil {
-	// 	return err
-	// }
 	err = s.historyDB.AddBlockSCData(&blockData)
 	if err != nil {
 		return nil, nil, tracerr.Wrap(err)
@@ -522,9 +519,14 @@ lastForgeL1TxsNum = batchData.Batch.ForgeL1TxsNum
 			}
 		}
 		s.stats.UpdateSync(ethBlock,
-			&rollupData.Batches[batchesLen-1].Batch.BatchNum, lastL1BatchBlock, lastForgeL1TxsNum)
+			&rollupData.Batches[batchesLen-1].Batch.BatchNum,
+			lastL1BatchBlock, lastForgeL1TxsNum)
+	}
+	var firstBatchBlockNum *int64
+	if len(rollupData.Batches) > 0 {
+		firstBatchBlockNum = &rollupData.Batches[0].Batch.EthBlockNum
 	}
-	if err := s.updateCurrentSlotIfSync(len(rollupData.Batches)); err != nil {
+	if err := s.updateCurrentSlotIfSync(false, firstBatchBlockNum); err != nil {
 		return nil, nil, tracerr.Wrap(err)
 	}
 
@@ -674,7 +676,7 @@ }
 
 	s.stats.UpdateSync(block, &batchNum, &lastL1BatchBlockNum, lastForgeL1TxsNum)
 
-	if err := s.updateCurrentSlotIfSync(-1); err != nil {
+	if err := s.updateCurrentSlotIfSync(true, nil); err != nil {
 		return tracerr.Wrap(err)
 	}
 	return nil

@@ -271,18 +271,25 @@ }
 	}
 }
 
-func TestSync(t *testing.T) {
-	//
-	// Setup
-	//
+var chainID uint16 = 0
+var deleteme = []string{}
+
+func TestMain(m *testing.M) {
+	exitVal := m.Run()
+	for _, dir := range deleteme {
+		if err := os.RemoveAll(dir); err != nil {
+			panic(err)
+		}
+	}
+	os.Exit(exitVal)
+}
 
-	ctx := context.Background()
+func newTestModules(t *testing.T) (*statedb.StateDB, *historydb.HistoryDB) {
 	// Int State DB
 	dir, err := ioutil.TempDir("", "tmpdb")
 	require.NoError(t, err)
-	defer assert.Nil(t, os.RemoveAll(dir))
+	deleteme = append(deleteme, dir)
 
-	chainID := uint16(0)
 	stateDB, err := statedb.NewStateDB(dir, statedb.TypeSynchronizer, 32, chainID)
 	require.NoError(t, err)
 
@@ -294,9 +301,20 @@ historyDB := historydb.NewHistoryDB(db)
 	// Clear DB
 	test.WipeDB(historyDB.DB())
 
+	return stateDB, historyDB
+}
+
+func TestSyncGeneral(t *testing.T) {
+	//
+	// Setup
+	//
+
+	stateDB, historyDB := newTestModules(t)
+
 	// Init eth client
 	var timer timer
 	clientSetup := test.NewClientSetupExample()
+	clientSetup.ChainID = big.NewInt(int64(chainID))
 	bootCoordAddr := clientSetup.AuctionVariables.BootCoordinator
 	client := test.NewClient(true, &timer, &ethCommon.Address{}, clientSetup)
 
@@ -305,6 +323,8 @@ s, err := NewSynchronizer(client, historyDB, stateDB, Config{
 		StatsRefreshPeriod: 0 * time.Second,
 	})
 	require.NoError(t, err)
+
+	ctx := context.Background()
 
 	//
 	// First Sync from an initial state
@@ -659,3 +679,129 @@ require.NoError(t, err)
 	assert.Equal(t, 2, len(dbAccounts))
 	assertEqualAccountsHistoryDBStateDB(t, dbAccounts, sdbAccounts)
 }
+
+func TestSyncForgerCommitment(t *testing.T) {
+	stateDB, historyDB := newTestModules(t)
+
+	// Init eth client
+	var timer timer
+	clientSetup := test.NewClientSetupExample()
+	clientSetup.ChainID = big.NewInt(int64(chainID))
+	clientSetup.AuctionConstants.GenesisBlockNum = 2
+	clientSetup.AuctionConstants.BlocksPerSlot = 4
+	clientSetup.AuctionVariables.SlotDeadline = 2
+	bootCoordAddr := clientSetup.AuctionVariables.BootCoordinator
+	client := test.NewClient(true, &timer, &ethCommon.Address{}, clientSetup)
+
+	// Create Synchronizer
+	s, err := NewSynchronizer(client, historyDB, stateDB, Config{
+		StatsRefreshPeriod: 0 * time.Second,
+	})
+	require.NoError(t, err)
+
+	ctx := context.Background()
+
+	set := `
+		Type: Blockchain
+
+		// Slot = 0
+
+		> block // 2
+		> block // 3
+		> block // 4
+		> block // 5
+
+		// Slot = 1
+
+		> block // 6
+		> batch
+		> block // 7
+		> block // 8
+		> block // 9
+
+		// Slot = 2
+
+		> block // 10
+		> block // 11
+		> batch
+		> block // 12
+		> block // 13
+
+	`
+	// For each block, true when the slot that belongs to the following
+	// block has forgerCommitment
+	commitment := map[int64]bool{
+		2: false,
+		3: false,
+		4: false,
+		5: false,
+
+		6: false,
+		7: true,
+		8: true,
+		9: false,
+
+		10: false,
+		11: false,
+		12: false,
+		13: false,
+	}
+	tc := til.NewContext(chainID, common.RollupConstMaxL1UserTx)
+	blocks, err := tc.GenerateBlocks(set)
+	assert.NoError(t, err)
+
+	tilCfgExtra := til.ConfigExtra{
+		BootCoordAddr: bootCoordAddr,
+		CoordUser:     "A",
+	}
+	err = tc.FillBlocksExtra(blocks, &tilCfgExtra)
+	require.NoError(t, err)
+
+	// for i := range blocks {
+	// 	for j := range blocks[i].Rollup.Batches {
+	// 		blocks[i].Rollup.Batches[j].Batch.SlotNum = int64(i) / 4
+	// 	}
+	// }
+
+	// be in sync
+	for {
+		syncBlock, discards, err := s.Sync2(ctx, nil)
+		require.NoError(t, err)
+		require.Nil(t, discards)
+		if syncBlock == nil {
+			break
+		}
+	}
+	stats := s.Stats()
+	require.Equal(t, int64(1), stats.Sync.LastBlock.Num)
+
+	// Store ForgerComitmnent observed at every block by the live synchronizer
+	syncCommitment := map[int64]bool{}
+	// Store ForgerComitmnent observed at every block by a syncrhonizer that is restarted
+	syncRestartedCommitment := map[int64]bool{}
+	for _, block := range blocks {
+		// Add block data to the smart contracts
+		err = client.CtlAddBlocks([]common.BlockData{block})
+		require.NoError(t, err)
+
+		syncBlock, discards, err := s.Sync2(ctx, nil)
+		require.NoError(t, err)
+		require.Nil(t, discards)
+		if syncBlock == nil {
+			break
+		}
+		stats := s.Stats()
+		require.True(t, stats.Synced())
+		syncCommitment[syncBlock.Block.Num] = stats.Sync.Auction.CurrentSlot.ForgerCommitment
+
+		s2, err := NewSynchronizer(client, historyDB, stateDB, Config{
+			StatsRefreshPeriod: 0 * time.Second,
+		})
+		require.NoError(t, err)
+		stats = s2.Stats()
+		require.True(t, stats.Synced())
+		syncRestartedCommitment[syncBlock.Block.Num] = stats.Sync.Auction.CurrentSlot.ForgerCommitment
+	}
+	assert.Equal(t, commitment, syncCommitment)
+	assert.Equal(t, commitment, syncRestartedCommitment)
+}

@@ -399,6 +399,8 @@ hasher      hasher
 
 	forgeBatchArgsPending map[ethCommon.Hash]*batch
 	forgeBatchArgs        map[ethCommon.Hash]*batch
+
+	startBlock int64
 }
 
 // NewClient returns a new test Client that implements the eth.IClient
@@ -480,7 +482,10 @@ blockNum:              blockNum,
 		maxBlockNum:           blockNum,
 	}
 
-	for i := int64(1); i < setup.AuctionConstants.GenesisBlockNum+1; i++ {
+	if c.startBlock == 0 {
+		c.startBlock = 2
+	}
+	for i := int64(1); i < c.startBlock; i++ {
 		c.CtlMineBlock()
 	}
 

@@ -180,7 +180,7 @@ s.proof = fmt.Sprintf(`{
 				"pi_a": ["%v", "%v", "1"],
 				"pi_b": [["%v", "%v"],["%v", "%v"],["1", "0"]],
 				"pi_c": ["%v", "%v", "1"],
-				"protocol": "groth16"
+				"protocol": "groth"
 			}`, i, i+1, i+2, i+3, i+4, i+5, i+6, i+7) //nolint:gomnd
 			s.pubData = fmt.Sprintf(`[
 				"%v"