feat(op-dispute-mon): Game Resolution Forecasting (#9449)

* fix: typo on cache_test eth_call (#9462)

chore(op-dispute-mon): refactor output validation into a separate component

feat(op-dispute-mon): game forecasting implementation minus testing

fix(op-dispute-mon): bad merge

chore(op-dispute-mon): add more tests

* fix(op-dispute-mon): testing var and use updated log filtering

* fix(op-dispute-mon): functional resolver

* fix(op-dispute-mon): simply bidirectional game tree construction

* fix(op-dispute-mon): remove left bond counter

* fix(op-dispute-mon): construct resolver bidirectional tree

---------
Co-authored-by: Oak <me+git@droak.sh>

op-dispute-mon/mon/metadata.go → op-dispute-mon/mon/caller.go

@@ -13,35 +13,36 @@ import (
 	"github.com/ethereum-optimism/optimism/op-service/sources/caching"
 )
 
-const metricsLabel = "binding_creator"
+const metricsLabel = "game_caller_creator"
 
-type MetadataLoader interface {
+type GameCaller interface {
 	GetGameMetadata(context.Context) (uint64, common.Hash, types.GameStatus, error)
+	GetAllClaims(ctx context.Context) ([]faultTypes.Claim, error)
 }
 
-type metadataCreator struct {
+type gameCallerCreator struct {
 	cache  *caching.LRUCache[common.Address, *contracts.FaultDisputeGameContract]
 	caller *batching.MultiCaller
 }
 
-func NewMetadataCreator(m caching.Metrics, caller *batching.MultiCaller) *metadataCreator {
-	return &metadataCreator{
+func NewGameCallerCreator(m caching.Metrics, caller *batching.MultiCaller) *gameCallerCreator {
+	return &gameCallerCreator{
 		caller: caller,
 		cache:  caching.NewLRUCache[common.Address, *contracts.FaultDisputeGameContract](m, metricsLabel, 100),
 	}
 }
 
-func (m *metadataCreator) CreateContract(game types.GameMetadata) (MetadataLoader, error) {
-	if fdg, ok := m.cache.Get(game.Proxy); ok {
+func (g *gameCallerCreator) CreateContract(game types.GameMetadata) (GameCaller, error) {
+	if fdg, ok := g.cache.Get(game.Proxy); ok {
 		return fdg, nil
 	}
 	switch game.GameType {
 	case faultTypes.CannonGameType, faultTypes.AlphabetGameType:
-		fdg, err := contracts.NewFaultDisputeGameContract(game.Proxy, m.caller)
+		fdg, err := contracts.NewFaultDisputeGameContract(game.Proxy, g.caller)
 		if err != nil {
 			return nil, fmt.Errorf("failed to create FaultDisputeGameContract: %w", err)
 		}
-		m.cache.Add(game.Proxy, fdg)
+		g.cache.Add(game.Proxy, fdg)
 		return fdg, nil
 	default:
 		return nil, fmt.Errorf("unsupported game type: %d", game.GameType)

op-dispute-mon/mon/metadata_test.go → op-dispute-mon/mon/caller_test.go

@@ -43,7 +43,7 @@ func TestMetadataCreator_CreateContract(t *testing.T) {
 		test := test
 		t.Run(test.name, func(t *testing.T) {
 			caller, metrics := setupMetadataLoaderTest(t)
-			creator := NewMetadataCreator(metrics, caller)
+			creator := NewGameCallerCreator(metrics, caller)
 			_, err := creator.CreateContract(test.game)
 			require.Equal(t, test.expectedErr, err)
 			if test.expectedErr == nil {

op-dispute-mon/mon/detector.go

@@ -14,8 +14,8 @@ type OutputValidator interface {
 	CheckRootAgreement(ctx context.Context, blockNum uint64, root common.Hash) (bool, common.Hash, error)
 }
 
-type MetadataCreator interface {
-	CreateContract(game types.GameMetadata) (MetadataLoader, error)
+type GameCallerCreator interface {
+	CreateContract(game types.GameMetadata) (GameCaller, error)
 }
 
 type DetectorMetrics interface {
@@ -26,11 +26,11 @@ type DetectorMetrics interface {
 type detector struct {
 	logger    log.Logger
 	metrics   DetectorMetrics
-	creator   MetadataCreator
+	creator   GameCallerCreator
 	validator OutputValidator
 }
 
-func newDetector(logger log.Logger, metrics DetectorMetrics, creator MetadataCreator, validator OutputValidator) *detector {
+func newDetector(logger log.Logger, metrics DetectorMetrics, creator GameCallerCreator, validator OutputValidator) *detector {
 	return &detector{
 		logger:    logger,
 		metrics:   metrics,

op-dispute-mon/mon/detector_test.go

@@ -5,6 +5,7 @@ import (
 	"errors"
 	"testing"
 
+	faultTypes "github.com/ethereum-optimism/optimism/op-challenger/game/fault/types"
 	"github.com/ethereum-optimism/optimism/op-challenger/game/types"
 	"github.com/ethereum-optimism/optimism/op-service/testlog"
 	"github.com/ethereum/go-ethereum/common"
@@ -33,7 +34,7 @@ func TestDetector_Detect(t *testing.T) {
 	t.Run("CheckAgreementFails", func(t *testing.T) {
 		detector, metrics, creator, rollup, _ := setupDetectorTest(t)
 		rollup.err = errors.New("boom")
-		creator.loader = &mockMetadataLoader{status: types.GameStatusInProgress}
+		creator.caller = &mockGameCaller{status: types.GameStatusInProgress}
 		detector.Detect(context.Background(), []types.GameMetadata{{}})
 		metrics.Equals(t, 1, 0, 0) // Status should still be metriced here!
 		metrics.Mapped(t, map[string]int{})
@@ -41,8 +42,7 @@ func TestDetector_Detect(t *testing.T) {
 
 	t.Run("SingleGame", func(t *testing.T) {
 		detector, metrics, creator, _, _ := setupDetectorTest(t)
-		loader := &mockMetadataLoader{status: types.GameStatusInProgress}
-		creator.loader = loader
+		creator.caller = &mockGameCaller{status: types.GameStatusInProgress}
 		detector.Detect(context.Background(), []types.GameMetadata{{}})
 		metrics.Equals(t, 1, 0, 0)
 		metrics.Mapped(t, map[string]int{"in_progress": 1})
@@ -50,8 +50,7 @@ func TestDetector_Detect(t *testing.T) {
 
 	t.Run("MultipleGames", func(t *testing.T) {
 		detector, metrics, creator, _, _ := setupDetectorTest(t)
-		loader := &mockMetadataLoader{status: types.GameStatusInProgress}
-		creator.loader = loader
+		creator.caller = &mockGameCaller{status: types.GameStatusInProgress}
 		detector.Detect(context.Background(), []types.GameMetadata{{}, {}, {}})
 		metrics.Equals(t, 3, 0, 0)
 		metrics.Mapped(t, map[string]int{"in_progress": 3})
@@ -128,16 +127,14 @@ func TestDetector_FetchGameMetadata(t *testing.T) {
 
 	t.Run("GetGameMetadataFails", func(t *testing.T) {
 		detector, _, creator, _, _ := setupDetectorTest(t)
-		loader := &mockMetadataLoader{err: errors.New("boom")}
-		creator.loader = loader
+		creator.caller = &mockGameCaller{err: errors.New("boom")}
 		_, _, _, err := detector.fetchGameMetadata(context.Background(), types.GameMetadata{})
 		require.Error(t, err)
 	})
 
 	t.Run("Success", func(t *testing.T) {
 		detector, _, creator, _, _ := setupDetectorTest(t)
-		loader := &mockMetadataLoader{status: types.GameStatusInProgress}
-		creator.loader = loader
+		creator.caller = &mockGameCaller{status: types.GameStatusInProgress}
 		_, _, status, err := detector.fetchGameMetadata(context.Background(), types.GameMetadata{})
 		require.NoError(t, err)
 		require.Equal(t, types.GameStatusInProgress, status)
@@ -229,53 +226,67 @@ func TestDetector_CheckAgreement_Succeeds(t *testing.T) {
 	}
 }
 
-func setupDetectorTest(t *testing.T) (*detector, *mockDetectorMetricer, *mockMetadataCreator, *stubOutputValidator, *testlog.CapturingHandler) {
+func setupDetectorTest(t *testing.T) (*detector, *mockDetectorMetricer, *mockGameCallerCreator, *stubOutputValidator, *testlog.CapturingHandler) {
 	logger, capturedLogs := testlog.CaptureLogger(t, log.LvlDebug)
 	metrics := &mockDetectorMetricer{}
-	loader := &mockMetadataLoader{}
-	creator := &mockMetadataCreator{loader: loader}
+	caller := &mockGameCaller{}
+	creator := &mockGameCallerCreator{caller: caller}
 	validator := &stubOutputValidator{}
 	detector := newDetector(logger, metrics, creator, validator)
 	return detector, metrics, creator, validator, capturedLogs
 }
 
 type stubOutputValidator struct {
+	calls int
 	err   error
 }
 
 func (s *stubOutputValidator) CheckRootAgreement(ctx context.Context, blockNum uint64, rootClaim common.Hash) (bool, common.Hash, error) {
+	s.calls++
 	if s.err != nil {
 		return false, common.Hash{}, s.err
 	}
 	return rootClaim == mockRootClaim, mockRootClaim, nil
 }
 
-type mockMetadataCreator struct {
+type mockGameCallerCreator struct {
 	calls  int
 	err    error
-	loader *mockMetadataLoader
+	caller *mockGameCaller
 }
 
-func (m *mockMetadataCreator) CreateContract(game types.GameMetadata) (MetadataLoader, error) {
+func (m *mockGameCallerCreator) CreateContract(game types.GameMetadata) (GameCaller, error) {
 	m.calls++
 	if m.err != nil {
 		return nil, m.err
 	}
-	return m.loader, nil
+	return m.caller, nil
 }
 
-type mockMetadataLoader struct {
+type mockGameCaller struct {
 	calls       int
+	claimsCalls int
+	claims      []faultTypes.Claim
 	status      types.GameStatus
+	rootClaim   common.Hash
 	err         error
+	claimsErr   error
 }
 
-func (m *mockMetadataLoader) GetGameMetadata(ctx context.Context) (uint64, common.Hash, types.GameStatus, error) {
+func (m *mockGameCaller) GetGameMetadata(ctx context.Context) (uint64, common.Hash, types.GameStatus, error) {
 	m.calls++
 	if m.err != nil {
-		return 0, common.Hash{}, m.status, m.err
+		return 0, m.rootClaim, m.status, m.err
+	}
+	return 0, m.rootClaim, m.status, nil
+}
+
+func (m *mockGameCaller) GetAllClaims(ctx context.Context) ([]faultTypes.Claim, error) {
+	m.claimsCalls++
+	if m.claimsErr != nil {
+		return nil, m.claimsErr
 	}
-	return 0, common.Hash{}, m.status, nil
+	return m.claims, nil
 }
 
 type mockDetectorMetricer struct {

op-dispute-mon/mon/forecast.go

+package mon
+
+import (
+	"context"
+	"errors"
+	"fmt"
+
+	"github.com/ethereum-optimism/optimism/op-challenger/game/types"
+
+	"github.com/ethereum/go-ethereum/log"
+)
+
+var (
+	ErrContractCreation = errors.New("failed to create contract")
+	ErrMetadataFetch    = errors.New("failed to fetch game metadata")
+	ErrClaimFetch       = errors.New("failed to fetch game claims")
+	ErrResolver         = errors.New("failed to resolve game")
+	ErrRootAgreement    = errors.New("failed to check root agreement")
+)
+
+type forecast struct {
+	logger log.Logger
+	// TODO(client-pod#536): Add forecast metrics.
+	//                       These should only fire if a game is in progress.
+	//                       otherwise, the detector should record the game status.
+	creator   GameCallerCreator
+	validator OutputValidator
+}
+
+func newForecast(logger log.Logger, creator GameCallerCreator, validator OutputValidator) *forecast {
+	return &forecast{
+		logger:    logger,
+		creator:   creator,
+		validator: validator,
+	}
+}
+
+func (f *forecast) Forecast(ctx context.Context, games []types.GameMetadata) {
+	for _, game := range games {
+		if err := f.forecastGame(ctx, game); err != nil {
+			f.logger.Error("Failed to forecast game", "err", err)
+		}
+	}
+}
+
+func (f *forecast) forecastGame(ctx context.Context, game types.GameMetadata) error {
+	loader, err := f.creator.CreateContract(game)
+	if err != nil {
+		return fmt.Errorf("%w: %w", ErrContractCreation, err)
+	}
+
+	// Get the game status, it must be in progress to forecast.
+	l2BlockNum, rootClaim, status, err := loader.GetGameMetadata(ctx)
+	if err != nil {
+		return fmt.Errorf("%w: %w", ErrMetadataFetch, err)
+	}
+	if status != types.GameStatusInProgress {
+		f.logger.Debug("Game is not in progress, skipping forecast", "game", game, "status", status)
+		return nil
+	}
+
+	// Load all claims for the game.
+	claims, err := loader.GetAllClaims(ctx)
+	if err != nil {
+		return fmt.Errorf("%w: %w", ErrClaimFetch, err)
+	}
+
+	// Compute the resolution status of the game.
+	status, err = Resolve(claims)
+	if err != nil {
+		return fmt.Errorf("%w: %w", ErrResolver, err)
+	}
+
+	// Check the root agreement.
+	agreement, expected, err := f.validator.CheckRootAgreement(ctx, l2BlockNum, rootClaim)
+	if err != nil {
+		return fmt.Errorf("%w: %w", ErrRootAgreement, err)
+	}
+
+	if agreement {
+		// If we agree with the output root proposal, the Defender should win, defending that claim.
+		if status == types.GameStatusChallengerWon {
+			f.logger.Warn("Forecasting unexpected game result", "status", status, "game", game, "rootClaim", rootClaim, "expected", expected)
+		} else {
+			f.logger.Debug("Forecasting expected game result", "status", status, "game", game, "rootClaim", rootClaim, "expected", expected)
+		}
+	} else {
+		// If we disagree with the output root proposal, the Challenger should win, challenging that claim.
+		if status == types.GameStatusDefenderWon {
+			f.logger.Warn("Forecasting unexpected game result", "status", status, "game", game, "rootClaim", rootClaim, "expected", expected)
+		} else {
+			f.logger.Debug("Forecasting expected game result", "status", status, "game", game, "rootClaim", rootClaim, "expected", expected)
+		}
+	}
+
+	return nil
+}

op-dispute-mon/mon/monitor.go

@@ -14,6 +14,7 @@ import (
 )
 
 type Detect func(ctx context.Context, games []types.GameMetadata)
+type Forecast func(ctx context.Context, games []types.GameMetadata)
 type BlockHashFetcher func(ctx context.Context, number *big.Int) (common.Hash, error)
 type BlockNumberFetcher func(ctx context.Context) (uint64, error)
 type FactoryGameFetcher func(ctx context.Context, blockHash common.Hash, earliestTimestamp uint64) ([]types.GameMetadata, error)
@@ -30,6 +31,7 @@ type gameMonitor struct {
 	monitorInterval time.Duration
 
 	detect           Detect
+	forecast         Forecast
 	fetchGames       FactoryGameFetcher
 	fetchBlockHash   BlockHashFetcher
 	fetchBlockNumber BlockNumberFetcher
@@ -42,6 +44,7 @@ func newGameMonitor(
 	monitorInterval time.Duration,
 	gameWindow time.Duration,
 	detect Detect,
+	forecast Forecast,
 	factory FactoryGameFetcher,
 	fetchBlockNumber BlockNumberFetcher,
 	fetchBlockHash BlockHashFetcher,
@@ -54,6 +57,7 @@ func newGameMonitor(
 		monitorInterval:  monitorInterval,
 		gameWindow:       gameWindow,
 		detect:           detect,
+		forecast:         forecast,
 		fetchGames:       factory,
 		fetchBlockNumber: fetchBlockNumber,
 		fetchBlockHash:   fetchBlockHash,
@@ -87,6 +91,7 @@ func (m *gameMonitor) monitorGames() error {
 		return fmt.Errorf("failed to load games: %w", err)
 	}
 	m.detect(m.ctx, games)
+	m.forecast(m.ctx, games)
 	return nil
 }
 

op-dispute-mon/mon/monitor_test.go

@@ -23,20 +23,20 @@ func TestMonitor_MinGameTimestamp(t *testing.T) {
 	t.Parallel()
 
 	t.Run("ZeroGameWindow", func(t *testing.T) {
-		monitor, _, _ := setupMonitorTest(t)
+		monitor, _, _, _ := setupMonitorTest(t)
 		monitor.gameWindow = time.Duration(0)
 		require.Equal(t, monitor.minGameTimestamp(), uint64(0))
 	})
 
 	t.Run("ZeroClock", func(t *testing.T) {
-		monitor, _, _ := setupMonitorTest(t)
+		monitor, _, _, _ := setupMonitorTest(t)
 		monitor.gameWindow = time.Minute
 		monitor.clock = clock.NewDeterministicClock(time.Unix(0, 0))
 		require.Equal(t, uint64(0), monitor.minGameTimestamp())
 	})
 
 	t.Run("ValidArithmetic", func(t *testing.T) {
-		monitor, _, _ := setupMonitorTest(t)
+		monitor, _, _, _ := setupMonitorTest(t)
 		monitor.gameWindow = time.Minute
 		frozen := time.Unix(int64(time.Hour.Seconds()), 0)
 		monitor.clock = clock.NewDeterministicClock(frozen)
@@ -49,7 +49,7 @@ func TestMonitor_MonitorGames(t *testing.T) {
 	t.Parallel()
 
 	t.Run("FailedFetchBlocknumber", func(t *testing.T) {
-		monitor, _, _ := setupMonitorTest(t)
+		monitor, _, _, _ := setupMonitorTest(t)
 		boom := errors.New("boom")
 		monitor.fetchBlockNumber = func(ctx context.Context) (uint64, error) {
 			return 0, boom
@@ -59,7 +59,7 @@ func TestMonitor_MonitorGames(t *testing.T) {
 	})
 
 	t.Run("FailedFetchBlockHash", func(t *testing.T) {
-		monitor, _, _ := setupMonitorTest(t)
+		monitor, _, _, _ := setupMonitorTest(t)
 		boom := errors.New("boom")
 		monitor.fetchBlockHash = func(ctx context.Context, number *big.Int) (common.Hash, error) {
 			return common.Hash{}, boom
@@ -69,7 +69,7 @@ func TestMonitor_MonitorGames(t *testing.T) {
 	})
 
 	t.Run("DetectsWithNoGames", func(t *testing.T) {
-		monitor, factory, detector := setupMonitorTest(t)
+		monitor, factory, detector, _ := setupMonitorTest(t)
 		factory.games = []types.GameMetadata{}
 		err := monitor.monitorGames()
 		require.NoError(t, err)
@@ -77,7 +77,7 @@ func TestMonitor_MonitorGames(t *testing.T) {
 	})
 
 	t.Run("DetectsMultipleGames", func(t *testing.T) {
-		monitor, factory, detector := setupMonitorTest(t)
+		monitor, factory, detector, _ := setupMonitorTest(t)
 		factory.games = []types.GameMetadata{{}, {}, {}}
 		err := monitor.monitorGames()
 		require.NoError(t, err)
@@ -89,7 +89,7 @@ func TestMonitor_StartMonitoring(t *testing.T) {
 	t.Run("MonitorsGames", func(t *testing.T) {
 		addr1 := common.Address{0xaa}
 		addr2 := common.Address{0xbb}
-		monitor, factory, detector := setupMonitorTest(t)
+		monitor, factory, detector, _ := setupMonitorTest(t)
 		factory.games = []types.GameMetadata{newFDG(addr1, 9999), newFDG(addr2, 9999)}
 		factory.maxSuccess = len(factory.games) // Only allow two successful fetches
 
@@ -102,7 +102,7 @@ func TestMonitor_StartMonitoring(t *testing.T) {
 	})
 
 	t.Run("FailsToFetchGames", func(t *testing.T) {
-		monitor, factory, detector := setupMonitorTest(t)
+		monitor, factory, detector, _ := setupMonitorTest(t)
 		factory.fetchErr = errors.New("boom")
 
 		monitor.StartMonitoring()
@@ -121,7 +121,7 @@ func newFDG(proxy common.Address, timestamp uint64) types.GameMetadata {
 	}
 }
 
-func setupMonitorTest(t *testing.T) (*gameMonitor, *mockFactory, *mockDetector) {
+func setupMonitorTest(t *testing.T) (*gameMonitor, *mockFactory, *mockDetector, *mockForecast) {
 	logger := testlog.Logger(t, log.LvlDebug)
 	fetchBlockNum := func(ctx context.Context) (uint64, error) {
 		return 1, nil
@@ -134,6 +134,7 @@ func setupMonitorTest(t *testing.T) (*gameMonitor, *mockFactory, *mockDetector)
 	cl.Start()
 	factory := &mockFactory{}
 	detect := &mockDetector{}
+	forecast := &mockForecast{}
 	monitor := newGameMonitor(
 		context.Background(),
 		logger,
@@ -141,11 +142,20 @@ func setupMonitorTest(t *testing.T) (*gameMonitor, *mockFactory, *mockDetector)
 		monitorInterval,
 		time.Duration(10*time.Second),
 		detect.Detect,
+		forecast.Forecast,
 		factory.GetGamesAtOrAfter,
 		fetchBlockNum,
 		fetchBlockHash,
 	)
-	return monitor, factory, detect
+	return monitor, factory, detect, forecast
+}
+
+type mockForecast struct {
+	calls int
+}
+
+func (m *mockForecast) Forecast(ctx context.Context, games []types.GameMetadata) {
+	m.calls++
 }
 
 type mockDetector struct {

op-dispute-mon/mon/resolver.go

+package mon
+
+import (
+	"fmt"
+
+	faultTypes "github.com/ethereum-optimism/optimism/op-challenger/game/fault/types"
+	"github.com/ethereum-optimism/optimism/op-challenger/game/types"
+	"github.com/ethereum/go-ethereum/common"
+)
+
+type BidirectionalClaim struct {
+	Claim    *faultTypes.Claim
+	Children []*BidirectionalClaim
+}
+
+// Resolve creates the bidirectional tree of claims and then computes the resolved game status.
+func Resolve(claims []faultTypes.Claim) (types.GameStatus, error) {
+	flatBidireactionalTree, err := createBidirectionalTree(claims)
+	if err != nil {
+		return 0, fmt.Errorf("failed to create bidirectional tree: %w", err)
+	}
+	return resolveTree(flatBidireactionalTree), nil
+}
+
+// createBidirectionalTree walks backwards through the list of claims and creates a bidirectional
+// tree of claims. The root claim must be at index 0. The tree is returned as a flat array so it
+// can be easily traversed following the resolution process.
+func createBidirectionalTree(claims []faultTypes.Claim) ([]*BidirectionalClaim, error) {
+	claimMap := make(map[int]*BidirectionalClaim)
+	res := make([]*BidirectionalClaim, 0, len(claims))
+	for _, claim := range claims {
+		claim := claim
+		bidirectionalClaim := &BidirectionalClaim{
+			Claim: &claim,
+		}
+		claimMap[claim.ContractIndex] = bidirectionalClaim
+		if !claim.IsRoot() {
+			// SAFETY: the parent must exist in the list prior to the current claim.
+			parent := claimMap[claim.ParentContractIndex]
+			parent.Children = append(parent.Children, bidirectionalClaim)
+		}
+		res = append(res, bidirectionalClaim)
+	}
+	return res, nil
+}
+
+// resolveTree iterates backwards over the bidirectional tree, iteratively
+// checking the leftmost counter of each claim, and updating the claim's counter
+// claimant. Once the root claim is reached, the resolution game status is returned.
+func resolveTree(tree []*BidirectionalClaim) types.GameStatus {
+	for i := len(tree) - 1; i >= 0; i-- {
+		claim := tree[i]
+		counterClaimant := common.Address{}
+		for _, child := range claim.Children {
+			if child.Claim.CounteredBy == (common.Address{}) {
+				counterClaimant = child.Claim.Claimant
+			}
+		}
+		claim.Claim.CounteredBy = counterClaimant
+	}
+	if (len(tree) == 0 || tree[0].Claim.CounteredBy == common.Address{}) {
+		return types.GameStatusDefenderWon
+	} else {
+		return types.GameStatusChallengerWon
+	}
+}

op-dispute-mon/mon/resolver_test.go

+package mon
+
+import (
+	"math"
+	"math/big"
+	"testing"
+
+	"github.com/ethereum/go-ethereum/common"
+	"github.com/stretchr/testify/require"
+
+	faultTypes "github.com/ethereum-optimism/optimism/op-challenger/game/fault/types"
+	"github.com/ethereum-optimism/optimism/op-challenger/game/types"
+)
+
+func TestResolver_Resolve(t *testing.T) {
+	t.Run("NoClaims", func(t *testing.T) {
+		status, err := Resolve([]faultTypes.Claim{})
+		require.NoError(t, err)
+		require.Equal(t, types.GameStatusDefenderWon, status)
+	})
+
+	t.Run("SingleClaim", func(t *testing.T) {
+		status, err := Resolve(createDeepClaimList()[:1])
+		require.NoError(t, err)
+		require.Equal(t, types.GameStatusDefenderWon, status)
+	})
+
+	t.Run("MultipleClaims", func(t *testing.T) {
+		status, err := Resolve(createDeepClaimList()[:2])
+		require.NoError(t, err)
+		require.Equal(t, types.GameStatusChallengerWon, status)
+	})
+
+	t.Run("MultipleClaimsAndChildren", func(t *testing.T) {
+		status, err := Resolve(createDeepClaimList())
+		require.NoError(t, err)
+		require.Equal(t, types.GameStatusDefenderWon, status)
+	})
+}
+
+func TestResolver_CreateBidirectionalTree(t *testing.T) {
+	t.Run("SingleClaim", func(t *testing.T) {
+		claims := createDeepClaimList()[:1]
+		claims[0].CounteredBy = common.Address{}
+		tree, err := createBidirectionalTree(claims)
+		require.NoError(t, err)
+		require.Len(t, tree, 1)
+		require.Equal(t, claims[0], *tree[0].Claim)
+		require.Empty(t, tree[0].Children)
+	})
+
+	t.Run("MultipleClaims", func(t *testing.T) {
+		claims := createDeepClaimList()[:2]
+		claims[1].CounteredBy = common.Address{}
+		tree, err := createBidirectionalTree(claims)
+		require.NoError(t, err)
+		require.Len(t, tree, 2)
+		require.Equal(t, claims[0], *tree[0].Claim)
+		require.Len(t, tree[0].Children, 1)
+		require.Equal(t, claims[1], *tree[0].Children[0].Claim)
+		require.Equal(t, claims[1], *tree[1].Claim)
+		require.Empty(t, tree[1].Children)
+	})
+
+	t.Run("MultipleClaimsAndChildren", func(t *testing.T) {
+		claims := createDeepClaimList()
+		tree, err := createBidirectionalTree(claims)
+		require.NoError(t, err)
+		require.Len(t, tree, 3)
+		require.Equal(t, claims[0], *tree[0].Claim)
+		require.Len(t, tree[0].Children, 1)
+		require.Equal(t, tree[0].Children[0], tree[1])
+		require.Equal(t, claims[1], *tree[1].Claim)
+		require.Len(t, tree[1].Children, 1)
+		require.Equal(t, tree[1].Children[0], tree[2])
+		require.Equal(t, claims[2], *tree[2].Claim)
+		require.Empty(t, tree[2].Children)
+	})
+}
+
+func TestResolver_ResolveTree(t *testing.T) {
+	t.Run("NoClaims", func(t *testing.T) {
+		status := resolveTree([]*BidirectionalClaim{})
+		require.Equal(t, types.GameStatusDefenderWon, status)
+	})
+
+	t.Run("SingleRootClaim", func(t *testing.T) {
+		list := createBidirectionalClaimList()[:1]
+		list[0].Claim.CounteredBy = common.Address{}
+		status := resolveTree(list)
+		require.Equal(t, types.GameStatusDefenderWon, status)
+	})
+
+	t.Run("ChallengerWon", func(t *testing.T) {
+		list := createBidirectionalClaimList()[:2]
+		list[1].Claim.CounteredBy = common.Address{}
+		list[1].Children = make([]*BidirectionalClaim, 0)
+		status := resolveTree(list)
+		require.Equal(t, types.GameStatusChallengerWon, status)
+	})
+
+	t.Run("DefenderWon", func(t *testing.T) {
+		status := resolveTree(createBidirectionalClaimList())
+		require.Equal(t, types.GameStatusDefenderWon, status)
+	})
+}
+
+func createBidirectionalClaimList() []*BidirectionalClaim {
+	claimList := createDeepClaimList()
+	bidirectionalClaimList := make([]*BidirectionalClaim, len(claimList))
+	bidirectionalClaimList[2] = &BidirectionalClaim{
+		Claim:    &claimList[2],
+		Children: make([]*BidirectionalClaim, 0),
+	}
+	bidirectionalClaimList[1] = &BidirectionalClaim{
+		Claim:    &claimList[1],
+		Children: []*BidirectionalClaim{bidirectionalClaimList[2]},
+	}
+	bidirectionalClaimList[0] = &BidirectionalClaim{
+		Claim:    &claimList[0],
+		Children: []*BidirectionalClaim{bidirectionalClaimList[1]},
+	}
+	return bidirectionalClaimList
+}
+
+func createDeepClaimList() []faultTypes.Claim {
+	return []faultTypes.Claim{
+		{
+			ClaimData: faultTypes.ClaimData{
+				Position: faultTypes.NewPosition(0, big.NewInt(0)),
+			},
+			ContractIndex:       0,
+			CounteredBy:         common.HexToAddress("0x222222"),
+			ParentContractIndex: math.MaxInt64,
+			Claimant:            common.HexToAddress("0x111111"),
+		},
+		{
+			ClaimData: faultTypes.ClaimData{
+				Position: faultTypes.NewPosition(1, big.NewInt(0)),
+			},
+			CounteredBy:         common.HexToAddress("0x111111"),
+			ContractIndex:       1,
+			ParentContractIndex: 0,
+			Claimant:            common.HexToAddress("0x222222"),
+		},
+		{
+			ClaimData: faultTypes.ClaimData{
+				Position: faultTypes.NewPosition(2, big.NewInt(0)),
+			},
+			ContractIndex:       2,
+			ParentContractIndex: 1,
+			Claimant:            common.HexToAddress("0x111111"),
+		},
+	}
+}

op-dispute-mon/mon/service.go

@@ -34,7 +34,8 @@ type Service struct {
 
 	cl clock.Clock
 
-	metadata     *metadataCreator
+	forecast     *forecast
+	game         *gameCallerCreator
 	rollupClient *sources.RollupClient
 	detector     *detector
 	validator    *outputValidator
@@ -78,9 +79,9 @@ func (s *Service) initFromConfig(ctx context.Context, cfg *config.Config) error
 	if err := s.initOutputRollupClient(ctx, cfg); err != nil {
 		return fmt.Errorf("failed to init rollup client: %w", err)
 	}
-	s.initMetadataCreator()
 	s.initOutputValidator()
-	s.initDetector()
+	s.initGameCallerCreator()
+	s.initForecast(cfg)
 	s.initDetector()
 	s.initMonitor(ctx, cfg)
 
@@ -94,8 +95,16 @@ func (s *Service) initOutputValidator() {
 	s.validator = newOutputValidator(s.rollupClient)
 }
 
+func (s *Service) initGameCallerCreator() {
+	s.game = NewGameCallerCreator(s.metrics, batching.NewMultiCaller(s.l1Client.Client(), batching.DefaultBatchSize))
+}
+
+func (s *Service) initForecast(cfg *config.Config) {
+	s.forecast = newForecast(s.logger, s.game, s.validator)
+}
+
 func (s *Service) initDetector() {
-	s.detector = newDetector(s.logger, s.metrics, s.metadata, s.validator)
+	s.detector = newDetector(s.logger, s.metrics, s.game, s.validator)
 }
 
 func (s *Service) initOutputRollupClient(ctx context.Context, cfg *config.Config) error {
@@ -107,10 +116,6 @@ func (s *Service) initOutputRollupClient(ctx context.Context, cfg *config.Config
 	return nil
 }
 
-func (s *Service) initMetadataCreator() {
-	s.metadata = NewMetadataCreator(s.metrics, batching.NewMultiCaller(s.l1Client.Client(), batching.DefaultBatchSize))
-}
-
 func (s *Service) initL1Client(ctx context.Context, cfg *config.Config) error {
 	l1Client, err := dial.DialEthClientWithTimeout(ctx, dial.DefaultDialTimeout, s.logger, cfg.L1EthRpc)
 	if err != nil {
@@ -180,6 +185,7 @@ func (s *Service) initMonitor(ctx context.Context, cfg *config.Config) {
 		cfg.MonitorInterval,
 		cfg.GameWindow,
 		s.detector.Detect,
+		s.forecast.Forecast,
 		s.factoryContract.GetGamesAtOrAfter,
 		s.l1Client.BlockNumber,
 		blockHashFetcher,