Merge pull request #7185 from ethereum-optimism/refcell/position-tp-port

feat(op-challenger): Trace Provider Position Type Port

op-challenger/game/fault/player.go

@@ -80,7 +80,7 @@ func NewGamePlayer(
 	var updater types.OracleUpdater
 	switch cfg.TraceType {
 	case config.TraceTypeCannon:
-		cannonProvider, err := cannon.NewTraceProvider(ctx, logger, m, cfg, client, dir, addr)
+		cannonProvider, err := cannon.NewTraceProvider(ctx, logger, m, cfg, client, dir, addr, gameDepth)
 		if err != nil {
 			return nil, fmt.Errorf("create cannon trace provider: %w", err)
 		}

op-challenger/game/fault/player_test.go

@@ -200,10 +200,10 @@ func newMockTraceProvider(prestateErrors bool, prestate []byte) *mockTraceProvid
 		prestate:       prestate,
 	}
 }
-func (m *mockTraceProvider) Get(ctx context.Context, i uint64) (common.Hash, error) {
+func (m *mockTraceProvider) Get(ctx context.Context, i types.Position) (common.Hash, error) {
 	panic("not implemented")
 }
-func (m *mockTraceProvider) GetStepData(ctx context.Context, i uint64) (prestate []byte, proofData []byte, preimageData *types.PreimageOracleData, err error) {
+func (m *mockTraceProvider) GetStepData(ctx context.Context, i types.Position) (prestate []byte, proofData []byte, preimageData *types.PreimageOracleData, err error) {
 	panic("not implemented")
 }
 func (m *mockTraceProvider) AbsolutePreState(ctx context.Context) ([]byte, error) {

op-challenger/game/fault/solver/solver.go

@@ -97,22 +97,20 @@ func (s *claimSolver) AttemptStep(ctx context.Context, game types.Game, claim ty
 	if err != nil {
 		return StepData{}, err
 	}
-	index := claim.TraceIndex(s.gameDepth)
 	var preState []byte
 	var proofData []byte
 	var oracleData *types.PreimageOracleData
 
 	if !claimCorrect {
 		// Attack the claim by executing step index, so we need to get the pre-state of that index
-		preState, proofData, oracleData, err = s.trace.GetStepData(ctx, index)
+		preState, proofData, oracleData, err = s.trace.GetStepData(ctx, claim.Position)
 		if err != nil {
 			return StepData{}, err
 		}
 	} else {
-		// We agree with the claim so Defend and use this claim as the starting point to execute the step after
-		// Thus we need the pre-state of the next step
-		// Note: This makes our maximum depth 63 because we need to add 1 without overflowing.
-		preState, proofData, oracleData, err = s.trace.GetStepData(ctx, index+1)
+		// We agree with the claim so Defend and use this claim as the starting point to
+		// execute the step after. Thus we need the pre-state of the next step.
+		preState, proofData, oracleData, err = s.trace.GetStepData(ctx, claim.MoveRight())
 		if err != nil {
 			return StepData{}, err
 		}
@@ -166,9 +164,7 @@ func (s *claimSolver) agreeWithClaim(ctx context.Context, claim types.ClaimData)
 
 // traceAtPosition returns the [common.Hash] from internal [TraceProvider] at the given [Position].
 func (s *claimSolver) traceAtPosition(ctx context.Context, p types.Position) (common.Hash, error) {
-	index := p.TraceIndex(s.gameDepth)
-	hash, err := s.trace.Get(ctx, index)
-	return hash, err
+	return s.trace.Get(ctx, p)
 }
 
 // agreeWithClaimPath returns true if the every other claim in the path to root is correct according to the internal [TraceProvider].

op-challenger/game/fault/test/alphabet.go

@@ -11,6 +11,7 @@ import (
 func NewAlphabetWithProofProvider(t *testing.T, maxDepth int, oracleError error) *alphabetWithProofProvider {
 	return &alphabetWithProofProvider{
 		alphabet.NewTraceProvider("abcdefghijklmnopqrstuvwxyz", uint64(maxDepth)),
+		uint64(maxDepth),
 		oracleError,
 	}
 }
@@ -22,14 +23,16 @@ func NewAlphabetClaimBuilder(t *testing.T, maxDepth int) *ClaimBuilder {
 
 type alphabetWithProofProvider struct {
 	*alphabet.AlphabetTraceProvider
+	depth       uint64
 	OracleError error
 }
 
-func (a *alphabetWithProofProvider) GetStepData(ctx context.Context, i uint64) ([]byte, []byte, *types.PreimageOracleData, error) {
+func (a *alphabetWithProofProvider) GetStepData(ctx context.Context, i types.Position) ([]byte, []byte, *types.PreimageOracleData, error) {
 	preimage, _, _, err := a.AlphabetTraceProvider.GetStepData(ctx, i)
 	if err != nil {
 		return nil, nil, nil, err
 	}
-	data := types.NewPreimageOracleData([]byte{byte(i)}, []byte{byte(i - 1)}, uint32(i-1))
-	return preimage, []byte{byte(i - 1)}, data, nil
+	traceIndex := i.TraceIndex(int(a.depth))
+	data := types.NewPreimageOracleData([]byte{byte(traceIndex)}, []byte{byte(traceIndex - 1)}, uint32(traceIndex-1))
+	return preimage, []byte{byte(traceIndex - 1)}, data, nil
 }

op-challenger/game/fault/test/claim_builder.go

@@ -31,54 +31,50 @@ func (c *ClaimBuilder) CorrectTraceProvider() types.TraceProvider {
 	return c.correct
 }
 
-// CorrectClaim returns the canonical claim at a specified trace index
-func (c *ClaimBuilder) CorrectClaim(idx uint64) common.Hash {
-	value, err := c.correct.Get(context.Background(), idx)
-	c.require.NoError(err)
-	return value
-}
-
 // CorrectClaimAtPosition returns the canonical claim at a specified position
 func (c *ClaimBuilder) CorrectClaimAtPosition(pos types.Position) common.Hash {
-	value, err := c.correct.Get(context.Background(), pos.TraceIndex(c.maxDepth))
+	value, err := c.correct.Get(context.Background(), pos)
 	c.require.NoError(err)
 	return value
 }
 
 // CorrectPreState returns the pre-state (not hashed) required to execute the valid step at the specified trace index
 func (c *ClaimBuilder) CorrectPreState(idx uint64) []byte {
-	preimage, _, _, err := c.correct.GetStepData(context.Background(), idx)
+	pos := types.NewPosition(c.maxDepth, int(idx))
+	preimage, _, _, err := c.correct.GetStepData(context.Background(), pos)
 	c.require.NoError(err)
 	return preimage
 }
 
 // CorrectProofData returns the proof-data required to execute the valid step at the specified trace index
 func (c *ClaimBuilder) CorrectProofData(idx uint64) []byte {
-	_, proof, _, err := c.correct.GetStepData(context.Background(), idx)
+	pos := types.NewPosition(c.maxDepth, int(idx))
+	_, proof, _, err := c.correct.GetStepData(context.Background(), pos)
 	c.require.NoError(err)
 	return proof
 }
 
 func (c *ClaimBuilder) CorrectOracleData(idx uint64) *types.PreimageOracleData {
-	_, _, data, err := c.correct.GetStepData(context.Background(), idx)
+	pos := types.NewPosition(c.maxDepth, int(idx))
+	_, _, data, err := c.correct.GetStepData(context.Background(), pos)
 	c.require.NoError(err)
 	return data
 }
 
-func (c *ClaimBuilder) incorrectClaim(idx uint64) common.Hash {
-	return common.BigToHash(new(big.Int).SetUint64(idx))
+func (c *ClaimBuilder) incorrectClaim(pos types.Position) common.Hash {
+	return common.BigToHash(new(big.Int).SetUint64(pos.TraceIndex(c.maxDepth)))
 }
 
-func (c *ClaimBuilder) claim(idx uint64, correct bool) common.Hash {
+func (c *ClaimBuilder) claim(pos types.Position, correct bool) common.Hash {
 	if correct {
-		return c.CorrectClaim(idx)
+		return c.CorrectClaimAtPosition(pos)
 	} else {
-		return c.incorrectClaim(idx)
+		return c.incorrectClaim(pos)
 	}
 }
 
 func (c *ClaimBuilder) CreateRootClaim(correct bool) types.Claim {
-	value := c.claim((1<<c.maxDepth)-1, correct)
+	value := c.claim(types.NewPositionFromGIndex(1), correct)
 	claim := types.Claim{
 		ClaimData: types.ClaimData{
 			Value:    value,
@@ -93,11 +89,11 @@ func (c *ClaimBuilder) CreateLeafClaim(traceIndex uint64, correct bool) types.Cl
 	pos := types.NewPosition(c.maxDepth, int(traceIndex))
 	return types.Claim{
 		ClaimData: types.ClaimData{
-			Value:    c.claim(pos.TraceIndex(c.maxDepth), correct),
+			Value:    c.claim(pos, correct),
 			Position: pos,
 		},
 		Parent: types.ClaimData{
-			Value:    c.claim(parentPos.TraceIndex(c.maxDepth), !correct),
+			Value:    c.claim(parentPos, !correct),
 			Position: parentPos,
 		},
 	}
@@ -107,7 +103,7 @@ func (c *ClaimBuilder) AttackClaim(claim types.Claim, correct bool) types.Claim
 	pos := claim.Position.Attack()
 	return types.Claim{
 		ClaimData: types.ClaimData{
-			Value:    c.claim(pos.TraceIndex(c.maxDepth), correct),
+			Value:    c.claim(pos, correct),
 			Position: pos,
 		},
 		Parent:              claim.ClaimData,
@@ -131,7 +127,7 @@ func (c *ClaimBuilder) DefendClaim(claim types.Claim, correct bool) types.Claim
 	pos := claim.Position.Defend()
 	return types.Claim{
 		ClaimData: types.ClaimData{
-			Value:    c.claim(pos.TraceIndex(c.maxDepth), correct),
+			Value:    c.claim(pos, correct),
 			Position: pos,
 		},
 		Parent:              claim.ClaimData,

op-challenger/game/fault/trace/alphabet/provider.go

@@ -20,6 +20,7 @@ var (
 // indices in the given trace.
 type AlphabetTraceProvider struct {
 	state  []string
+	depth  uint64
 	maxLen uint64
 }
 
@@ -27,12 +28,14 @@ type AlphabetTraceProvider struct {
 func NewTraceProvider(state string, depth uint64) *AlphabetTraceProvider {
 	return &AlphabetTraceProvider{
 		state:  strings.Split(state, ""),
+		depth:  depth,
 		maxLen: uint64(1 << depth),
 	}
 }
 
-func (ap *AlphabetTraceProvider) GetStepData(ctx context.Context, i uint64) ([]byte, []byte, *types.PreimageOracleData, error) {
-	if i == 0 {
+func (ap *AlphabetTraceProvider) GetStepData(ctx context.Context, i types.Position) ([]byte, []byte, *types.PreimageOracleData, error) {
+	traceIndex := i.TraceIndex(int(ap.depth))
+	if traceIndex == 0 {
 		prestate, err := ap.AbsolutePreState(ctx)
 		if err != nil {
 			return nil, nil, nil, err
@@ -40,22 +43,23 @@ func (ap *AlphabetTraceProvider) GetStepData(ctx context.Context, i uint64) ([]b
 		return prestate, []byte{}, nil, nil
 	}
 	// We want the pre-state which is the value prior to the one requested
-	i--
+	traceIndex--
 	// The index cannot be larger than the maximum index as computed by the depth.
-	if i >= ap.maxLen {
+	if traceIndex >= ap.maxLen {
 		return nil, nil, nil, ErrIndexTooLarge
 	}
 	// We extend the deepest hash to the maximum depth if the trace is not expansive.
-	if i >= uint64(len(ap.state)) {
-		return ap.GetStepData(ctx, uint64(len(ap.state)))
+	if traceIndex >= uint64(len(ap.state)) {
+		return ap.GetStepData(ctx, types.NewPosition(int(ap.depth), len(ap.state)))
 	}
-	return BuildAlphabetPreimage(i, ap.state[i]), []byte{}, nil, nil
+	return BuildAlphabetPreimage(traceIndex, ap.state[traceIndex]), []byte{}, nil, nil
 }
 
 // Get returns the claim value at the given index in the trace.
-func (ap *AlphabetTraceProvider) Get(ctx context.Context, i uint64) (common.Hash, error) {
+func (ap *AlphabetTraceProvider) Get(ctx context.Context, i types.Position) (common.Hash, error) {
 	// Step data returns the pre-state, so add 1 to get the state for index i
-	claimBytes, _, _, err := ap.GetStepData(ctx, i+1)
+	postPosition := types.NewPosition(int(ap.depth), int(i.TraceIndex(int(ap.depth)))+1)
+	claimBytes, _, _, err := ap.GetStepData(ctx, postPosition)
 	if err != nil {
 		return common.Hash{}, err
 	}

op-challenger/game/fault/trace/alphabet/provider_test.go

@@ -5,6 +5,7 @@ import (
 	"math/big"
 	"testing"
 
+	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/types"
 	"github.com/ethereum/go-ethereum/common"
 	"github.com/stretchr/testify/require"
 )
@@ -16,23 +17,24 @@ func alphabetClaim(index uint64, letter string) common.Hash {
 // TestAlphabetProvider_Get_ClaimsByTraceIndex tests the [fault.AlphabetProvider] Get function.
 func TestAlphabetProvider_Get_ClaimsByTraceIndex(t *testing.T) {
 	// Create a new alphabet provider.
-	canonicalProvider := NewTraceProvider("abcdefgh", uint64(3))
+	depth := 3
+	canonicalProvider := NewTraceProvider("abcdefgh", uint64(depth))
 
 	// Build a list of traces.
 	traces := []struct {
-		traceIndex   uint64
+		traceIndex   types.Position
 		expectedHash common.Hash
 	}{
 		{
-			7,
+			types.NewPosition(depth, 7),
 			alphabetClaim(7, "h"),
 		},
 		{
-			3,
+			types.NewPosition(depth, 3),
 			alphabetClaim(3, "d"),
 		},
 		{
-			5,
+			types.NewPosition(depth, 5),
 			alphabetClaim(5, "f"),
 		},
 	}
@@ -58,9 +60,11 @@ func FuzzIndexToBytes(f *testing.F) {
 // TestGetPreimage_Succeeds tests the GetPreimage function
 // returns the correct pre-image for a index.
 func TestGetStepData_Succeeds(t *testing.T) {
-	ap := NewTraceProvider("abc", 2)
+	depth := 2
+	ap := NewTraceProvider("abc", uint64(depth))
 	expected := BuildAlphabetPreimage(0, "a")
-	retrieved, proof, data, err := ap.GetStepData(context.Background(), uint64(1))
+	pos := types.NewPosition(depth, 1)
+	retrieved, proof, data, err := ap.GetStepData(context.Background(), pos)
 	require.NoError(t, err)
 	require.Equal(t, expected, retrieved)
 	require.Empty(t, proof)
@@ -70,15 +74,19 @@ func TestGetStepData_Succeeds(t *testing.T) {
 // TestGetPreimage_TooLargeIndex_Fails tests the GetPreimage
 // function errors if the index is too large.
 func TestGetStepData_TooLargeIndex_Fails(t *testing.T) {
-	ap := NewTraceProvider("abc", 2)
-	_, _, _, err := ap.GetStepData(context.Background(), 5)
+	depth := 2
+	ap := NewTraceProvider("abc", uint64(depth))
+	pos := types.NewPosition(depth, 5)
+	_, _, _, err := ap.GetStepData(context.Background(), pos)
 	require.ErrorIs(t, err, ErrIndexTooLarge)
 }
 
 // TestGet_Succeeds tests the Get function.
 func TestGet_Succeeds(t *testing.T) {
-	ap := NewTraceProvider("abc", 2)
-	claim, err := ap.Get(context.Background(), 0)
+	depth := 2
+	ap := NewTraceProvider("abc", uint64(depth))
+	pos := types.NewPosition(depth, 0)
+	claim, err := ap.Get(context.Background(), pos)
 	require.NoError(t, err)
 	expected := alphabetClaim(0, "a")
 	require.Equal(t, expected, claim)
@@ -87,16 +95,20 @@ func TestGet_Succeeds(t *testing.T) {
 // TestGet_IndexTooLarge tests the Get function with an index
 // greater than the number of indices: 2^depth - 1.
 func TestGet_IndexTooLarge(t *testing.T) {
-	ap := NewTraceProvider("abc", 2)
-	_, err := ap.Get(context.Background(), 4)
+	depth := 2
+	ap := NewTraceProvider("abc", uint64(depth))
+	pos := types.NewPosition(depth, 4)
+	_, err := ap.Get(context.Background(), pos)
 	require.ErrorIs(t, err, ErrIndexTooLarge)
 }
 
 // TestGet_Extends tests the Get function with an index that is larger
 // than the trace, but smaller than the maximum depth.
 func TestGet_Extends(t *testing.T) {
-	ap := NewTraceProvider("abc", 2)
-	claim, err := ap.Get(context.Background(), 3)
+	depth := 2
+	ap := NewTraceProvider("abc", uint64(depth))
+	pos := types.NewPosition(depth, 3)
+	claim, err := ap.Get(context.Background(), pos)
 	require.NoError(t, err)
 	expected := alphabetClaim(2, "c")
 	require.Equal(t, expected, claim)

op-challenger/game/fault/trace/cannon/provider.go

@@ -49,13 +49,14 @@ type CannonTraceProvider struct {
 	dir       string
 	prestate  string
 	generator ProofGenerator
+	gameDepth uint64
 
 	// lastStep stores the last step in the actual trace if known. 0 indicates unknown.
 	// Cached as an optimisation to avoid repeatedly attempting to execute beyond the end of the trace.
 	lastStep uint64
 }
 
-func NewTraceProvider(ctx context.Context, logger log.Logger, m CannonMetricer, cfg *config.Config, l1Client bind.ContractCaller, dir string, gameAddr common.Address) (*CannonTraceProvider, error) {
+func NewTraceProvider(ctx context.Context, logger log.Logger, m CannonMetricer, cfg *config.Config, l1Client bind.ContractCaller, dir string, gameAddr common.Address, gameDepth uint64) (*CannonTraceProvider, error) {
 	l2Client, err := ethclient.DialContext(ctx, cfg.CannonL2)
 	if err != nil {
 		return nil, fmt.Errorf("dial l2 client %v: %w", cfg.CannonL2, err)
@@ -69,20 +70,25 @@ func NewTraceProvider(ctx context.Context, logger log.Logger, m CannonMetricer,
 	if err != nil {
 		return nil, fmt.Errorf("fetch local game inputs: %w", err)
 	}
-	return NewTraceProviderFromInputs(logger, m, cfg, localInputs, dir), nil
+	return NewTraceProviderFromInputs(logger, m, cfg, localInputs, dir, gameDepth), nil
 }
 
-func NewTraceProviderFromInputs(logger log.Logger, m CannonMetricer, cfg *config.Config, localInputs LocalGameInputs, dir string) *CannonTraceProvider {
+func NewTraceProviderFromInputs(logger log.Logger, m CannonMetricer, cfg *config.Config, localInputs LocalGameInputs, dir string, gameDepth uint64) *CannonTraceProvider {
 	return &CannonTraceProvider{
 		logger:    logger,
 		dir:       dir,
 		prestate:  cfg.CannonAbsolutePreState,
 		generator: NewExecutor(logger, m, cfg, localInputs),
+		gameDepth: gameDepth,
 	}
 }
 
-func (p *CannonTraceProvider) Get(ctx context.Context, i uint64) (common.Hash, error) {
-	proof, err := p.loadProof(ctx, i)
+func (p *CannonTraceProvider) SetMaxDepth(gameDepth uint64) {
+	p.gameDepth = gameDepth
+}
+
+func (p *CannonTraceProvider) Get(ctx context.Context, pos types.Position) (common.Hash, error) {
+	proof, err := p.loadProof(ctx, pos.TraceIndex(int(p.gameDepth)))
 	if err != nil {
 		return common.Hash{}, err
 	}
@@ -94,8 +100,8 @@ func (p *CannonTraceProvider) Get(ctx context.Context, i uint64) (common.Hash, e
 	return value, nil
 }
 
-func (p *CannonTraceProvider) GetStepData(ctx context.Context, i uint64) ([]byte, []byte, *types.PreimageOracleData, error) {
-	proof, err := p.loadProof(ctx, i)
+func (p *CannonTraceProvider) GetStepData(ctx context.Context, pos types.Position) ([]byte, []byte, *types.PreimageOracleData, error) {
+	proof, err := p.loadProof(ctx, pos.TraceIndex(int(p.gameDepth)))
 	if err != nil {
 		return nil, nil, nil, err
 	}

op-challenger/game/fault/trace/cannon/provider_test.go

@@ -22,11 +22,15 @@ import (
 //go:embed test_data
 var testData embed.FS
 
+func PositionFromTraceIndex(provider *CannonTraceProvider, idx int) types.Position {
+	return types.NewPosition(int(provider.gameDepth), idx)
+}
+
 func TestGet(t *testing.T) {
 	dataDir, prestate := setupTestData(t)
 	t.Run("ExistingProof", func(t *testing.T) {
 		provider, generator := setupWithTestData(t, dataDir, prestate)
-		value, err := provider.Get(context.Background(), 0)
+		value, err := provider.Get(context.Background(), PositionFromTraceIndex(provider, 0))
 		require.NoError(t, err)
 		require.Equal(t, common.HexToHash("0x45fd9aa59768331c726e719e76aa343e73123af888804604785ae19506e65e87"), value)
 		require.Empty(t, generator.generated)
@@ -39,7 +43,7 @@ func TestGet(t *testing.T) {
 			Step:   10,
 			Exited: true,
 		}
-		value, err := provider.Get(context.Background(), 7000)
+		value, err := provider.Get(context.Background(), PositionFromTraceIndex(provider, 7000))
 		require.NoError(t, err)
 		require.Contains(t, generator.generated, 7000, "should have tried to generate the proof")
 		stateHash, err := generator.finalState.EncodeWitness().StateHash()
@@ -49,14 +53,14 @@ func TestGet(t *testing.T) {
 
 	t.Run("MissingPostHash", func(t *testing.T) {
 		provider, generator := setupWithTestData(t, dataDir, prestate)
-		_, err := provider.Get(context.Background(), 1)
+		_, err := provider.Get(context.Background(), PositionFromTraceIndex(provider, 1))
 		require.ErrorContains(t, err, "missing post hash")
 		require.Empty(t, generator.generated)
 	})
 
 	t.Run("IgnoreUnknownFields", func(t *testing.T) {
 		provider, generator := setupWithTestData(t, dataDir, prestate)
-		value, err := provider.Get(context.Background(), 2)
+		value, err := provider.Get(context.Background(), PositionFromTraceIndex(provider, 2))
 		require.NoError(t, err)
 		expected := common.HexToHash("bbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbbb")
 		require.Equal(t, expected, value)
@@ -68,7 +72,7 @@ func TestGetStepData(t *testing.T) {
 	t.Run("ExistingProof", func(t *testing.T) {
 		dataDir, prestate := setupTestData(t)
 		provider, generator := setupWithTestData(t, dataDir, prestate)
-		value, proof, data, err := provider.GetStepData(context.Background(), 0)
+		value, proof, data, err := provider.GetStepData(context.Background(), PositionFromTraceIndex(provider, 0))
 		require.NoError(t, err)
 		expected := common.Hex2Bytes("b8f068de604c85ea0e2acd437cdb47add074a2d70b81d018390c504b71fe26f400000000000000000000000000000000000000000000000000000000000000000000000000")
 		require.Equal(t, expected, value)
@@ -95,7 +99,7 @@ func TestGetStepData(t *testing.T) {
 			OracleValue:  []byte{0xdd},
 			OracleOffset: 10,
 		}
-		preimage, proof, data, err := provider.GetStepData(context.Background(), 4)
+		preimage, proof, data, err := provider.GetStepData(context.Background(), PositionFromTraceIndex(provider, 4))
 		require.NoError(t, err)
 		require.Contains(t, generator.generated, 4, "should have tried to generate the proof")
 
@@ -121,7 +125,7 @@ func TestGetStepData(t *testing.T) {
 			OracleValue:  []byte{0xdd},
 			OracleOffset: 10,
 		}
-		preimage, proof, data, err := provider.GetStepData(context.Background(), 7000)
+		preimage, proof, data, err := provider.GetStepData(context.Background(), PositionFromTraceIndex(provider, 7000))
 		require.NoError(t, err)
 		require.Contains(t, generator.generated, 7000, "should have tried to generate the proof")
 
@@ -147,7 +151,7 @@ func TestGetStepData(t *testing.T) {
 			OracleValue:  []byte{0xdd},
 			OracleOffset: 10,
 		}
-		_, _, _, err := provider.GetStepData(context.Background(), 7000)
+		_, _, _, err := provider.GetStepData(context.Background(), PositionFromTraceIndex(provider, 7000))
 		require.NoError(t, err)
 		require.Contains(t, initGenerator.generated, 7000, "should have tried to generate the proof")
 
@@ -162,7 +166,7 @@ func TestGetStepData(t *testing.T) {
 			StateData:  []byte{0xbb},
 			ProofData:  []byte{0xcc},
 		}
-		preimage, proof, data, err := provider.GetStepData(context.Background(), 7000)
+		preimage, proof, data, err := provider.GetStepData(context.Background(), PositionFromTraceIndex(provider, 7000))
 		require.NoError(t, err)
 		require.Empty(t, generator.generated, "should not have to generate the proof again")
 
@@ -174,7 +178,7 @@ func TestGetStepData(t *testing.T) {
 	t.Run("MissingStateData", func(t *testing.T) {
 		dataDir, prestate := setupTestData(t)
 		provider, generator := setupWithTestData(t, dataDir, prestate)
-		_, _, _, err := provider.GetStepData(context.Background(), 1)
+		_, _, _, err := provider.GetStepData(context.Background(), PositionFromTraceIndex(provider, 1))
 		require.ErrorContains(t, err, "missing state data")
 		require.Empty(t, generator.generated)
 	})
@@ -182,7 +186,7 @@ func TestGetStepData(t *testing.T) {
 	t.Run("IgnoreUnknownFields", func(t *testing.T) {
 		dataDir, prestate := setupTestData(t)
 		provider, generator := setupWithTestData(t, dataDir, prestate)
-		value, proof, data, err := provider.GetStepData(context.Background(), 2)
+		value, proof, data, err := provider.GetStepData(context.Background(), PositionFromTraceIndex(provider, 2))
 		require.NoError(t, err)
 		expected := common.Hex2Bytes("cccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccccc")
 		require.Equal(t, expected, value)
@@ -266,6 +270,7 @@ func setupWithTestData(t *testing.T, dataDir string, prestate string) (*CannonTr
 		dir:       dataDir,
 		generator: generator,
 		prestate:  filepath.Join(dataDir, prestate),
+		gameDepth: 63,
 	}, generator
 }
 

op-challenger/game/fault/types/position.go

@@ -18,6 +18,13 @@ func NewPositionFromGIndex(x uint64) Position {
 	return NewPosition(depth, int(indexAtDepth))
 }
 
+func (p Position) MoveRight() Position {
+	return Position{
+		depth:        p.depth,
+		indexAtDepth: int(p.indexAtDepth + 1),
+	}
+}
+
 func (p Position) Depth() int {
 	return p.depth
 }

op-challenger/game/fault/types/types.go

@@ -64,13 +64,13 @@ type OracleUpdater interface {
 type TraceProvider interface {
 	// Get returns the claim value at the requested index.
 	// Get(i) = Keccak256(GetPreimage(i))
-	Get(ctx context.Context, i uint64) (common.Hash, error)
+	Get(ctx context.Context, i Position) (common.Hash, error)
 
 	// GetStepData returns the data required to execute the step at the specified trace index.
 	// This includes the pre-state of the step (not hashed), the proof data required during step execution
 	// and any pre-image data that needs to be loaded into the oracle prior to execution (may be nil)
 	// The prestate returned from GetStepData for trace 10 should be the pre-image of the claim from trace 9
-	GetStepData(ctx context.Context, i uint64) (prestate []byte, proofData []byte, preimageData *PreimageOracleData, err error)
+	GetStepData(ctx context.Context, i Position) (prestate []byte, proofData []byte, preimageData *PreimageOracleData, err error)
 
 	// AbsolutePreState is the pre-image value of the trace that transitions to the trace value at index 0
 	AbsolutePreState(ctx context.Context) (preimage []byte, err error)

op-e2e/e2eutils/disputegame/cannon_helper.go

@@ -41,7 +41,8 @@ func (g *CannonGameHelper) CreateHonestActor(ctx context.Context, rollupCfg *rol
 	opts = append(opts, options...)
 	cfg := challenger.NewChallengerConfig(g.t, l1Endpoint, opts...)
 	logger := testlog.Logger(g.t, log.LvlInfo).New("role", "CorrectTrace")
-	provider, err := cannon.NewTraceProvider(ctx, logger, metrics.NoopMetrics, cfg, l1Client, filepath.Join(cfg.Datadir, "honest"), g.addr)
+	maxDepth := g.MaxDepth(ctx)
+	provider, err := cannon.NewTraceProvider(ctx, logger, metrics.NoopMetrics, cfg, l1Client, filepath.Join(cfg.Datadir, "honest"), g.addr, uint64(maxDepth))
 	g.require.NoError(err, "create cannon trace provider")
 
 	return &HonestHelper{

op-e2e/e2eutils/disputegame/game_helper.go

@@ -141,6 +141,11 @@ func (g *FaultGameHelper) getClaim(ctx context.Context, claimIdx int64) Contract
 	return claimData
 }
 
+// getClaimPosition retrieves the [types.Position] of a claim at a specific index.
+func (g *FaultGameHelper) getClaimPosition(ctx context.Context, claimIdx int64) types.Position {
+	return types.NewPositionFromGIndex(g.getClaim(ctx, claimIdx).Position.Uint64())
+}
+
 func (g *FaultGameHelper) WaitForClaimAtDepth(ctx context.Context, depth int) {
 	g.waitForClaim(
 		ctx,

op-e2e/e2eutils/disputegame/helper.go

@@ -4,7 +4,6 @@ import (
 	"context"
 	"encoding/binary"
 	"fmt"
-	"math"
 	"math/big"
 	"testing"
 	"time"
@@ -15,6 +14,7 @@ import (
 	"github.com/ethereum-optimism/optimism/op-chain-ops/genesis"
 	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/trace/alphabet"
 	"github.com/ethereum-optimism/optimism/op-challenger/game/fault/trace/cannon"
+	faultTypes "github.com/ethereum-optimism/optimism/op-challenger/game/fault/types"
 	"github.com/ethereum-optimism/optimism/op-challenger/metrics"
 	"github.com/ethereum-optimism/optimism/op-e2e/e2eutils/challenger"
 	"github.com/ethereum-optimism/optimism/op-e2e/e2eutils/l2oo"
@@ -36,6 +36,9 @@ const cannonGameType uint8 = 0
 const alphabetGameDepth = 4
 const lastAlphabetTraceIndex = 1<<alphabetGameDepth - 1
 
+// rootPosition is the position of the root claim.
+var rootPosition = faultTypes.NewPositionFromGIndex(1)
+
 type Status uint8
 
 const (
@@ -104,7 +107,8 @@ func (h *FactoryHelper) StartAlphabetGame(ctx context.Context, claimedAlphabet s
 	defer cancel()
 
 	trace := alphabet.NewTraceProvider(claimedAlphabet, alphabetGameDepth)
-	rootClaim, err := trace.Get(ctx, lastAlphabetTraceIndex)
+	pos := faultTypes.NewPosition(alphabetGameDepth, lastAlphabetTraceIndex)
+	rootClaim, err := trace.Get(ctx, pos)
 	h.require.NoError(err, "get root claim")
 	extraData := make([]byte, 64)
 	binary.BigEndian.PutUint64(extraData[24:], l2BlockNumber)
@@ -172,14 +176,33 @@ func (h *FactoryHelper) StartCannonGameWithCorrectRoot(ctx context.Context, roll
 		L2Claim:       challengedOutput.OutputRoot,
 		L2BlockNumber: challengedOutput.L2BlockNumber,
 	}
-	provider := cannon.NewTraceProviderFromInputs(testlog.Logger(h.t, log.LvlInfo).New("role", "CorrectTrace"), metrics.NoopMetrics, cfg, inputs, cfg.Datadir)
-	rootClaim, err := provider.Get(ctx, math.MaxUint64)
+
+	cannonTypeAddr, err := h.factory.GameImpls(opts, cannonGameType)
+	h.require.NoError(err, "fetch cannon game type impl")
+
+	gameImpl, err := bindings.NewFaultDisputeGameCaller(cannonTypeAddr, h.client)
+	h.require.NoError(err, "bind fault dispute game caller")
+
+	maxDepth, err := gameImpl.MAXGAMEDEPTH(opts)
+	h.require.NoError(err, "fetch max game depth")
+
+	provider := cannon.NewTraceProviderFromInputs(
+		testlog.Logger(h.t, log.LvlInfo).New("role", "CorrectTrace"),
+		metrics.NoopMetrics,
+		cfg,
+		inputs,
+		cfg.Datadir,
+		maxDepth.Uint64(),
+	)
+	rootClaim, err := provider.Get(ctx, rootPosition)
 	h.require.NoError(err, "Compute correct root hash")
 	// Override the VM status to claim the root is invalid
 	// Otherwise creating the game will fail
 	rootClaim[0] = mipsevm.VMStatusInvalid
 
 	game := h.createCannonGame(ctx, l2BlockNumber, l1Head, rootClaim)
+	correctMaxDepth := game.MaxDepth(ctx)
+	provider.SetMaxDepth(uint64(correctMaxDepth))
 	honestHelper := &HonestHelper{
 		t:            h.t,
 		require:      h.require,

op-e2e/e2eutils/disputegame/honest_helper.go

@@ -22,10 +22,9 @@ func (h *HonestHelper) Attack(ctx context.Context, claimIdx int64) {
 	claim := h.game.getClaim(ctx, claimIdx)
 	pos := types.NewPositionFromGIndex(claim.Position.Uint64())
 	attackPos := pos.Attack()
-	traceIdx := attackPos.TraceIndex(int(h.game.MaxDepth(ctx)))
-	h.t.Logf("Attacking at position %v using correct trace from index %v", attackPos.ToGIndex(), traceIdx)
-	value, err := h.correctTrace.Get(ctx, traceIdx)
-	h.require.NoErrorf(err, "Get correct claim at trace index %v", traceIdx)
+	h.t.Logf("Attacking at position %v with g index %v", attackPos, attackPos.ToGIndex())
+	value, err := h.correctTrace.Get(ctx, attackPos)
+	h.require.NoErrorf(err, "Get correct claim at position %v with g index %v", attackPos, attackPos.ToGIndex())
 	h.t.Log("Performing attack")
 	h.game.Attack(ctx, claimIdx, value)
 	h.t.Log("Attack complete")
@@ -37,23 +36,20 @@ func (h *HonestHelper) Defend(ctx context.Context, claimIdx int64) {
 	claim := h.game.getClaim(ctx, claimIdx)
 	pos := types.NewPositionFromGIndex(claim.Position.Uint64())
 	defendPos := pos.Defend()
-	traceIdx := defendPos.TraceIndex(int(h.game.MaxDepth(ctx)))
-	value, err := h.correctTrace.Get(ctx, traceIdx)
-	h.game.require.NoErrorf(err, "Get correct claim at trace index %v", traceIdx)
+	value, err := h.correctTrace.Get(ctx, defendPos)
+	h.game.require.NoErrorf(err, "Get correct claim at position %v with g index %v", defendPos, defendPos.ToGIndex())
 	h.game.Defend(ctx, claimIdx, value)
 }
 
 func (h *HonestHelper) StepFails(ctx context.Context, claimIdx int64, isAttack bool) {
 	ctx, cancel := context.WithTimeout(ctx, 2*time.Minute)
 	defer cancel()
-	claim := h.game.getClaim(ctx, claimIdx)
-	pos := types.NewPositionFromGIndex(claim.Position.Uint64())
-	traceIdx := pos.TraceIndex(int(h.game.MaxDepth(ctx)))
+	pos := h.game.getClaimPosition(ctx, claimIdx)
 	if !isAttack {
 		// If we're defending, then the step will be from the trace to the next one
-		traceIdx += 1
+		pos = pos.MoveRight()
 	}
-	prestate, proofData, _, err := h.correctTrace.GetStepData(ctx, traceIdx)
+	prestate, proofData, _, err := h.correctTrace.GetStepData(ctx, pos)
 	h.require.NoError(err, "Get step data")
 	h.game.StepFails(claimIdx, isAttack, prestate, proofData)
 }