Fix agent stepping.

op-challenger/fault/agent.go

@@ -94,6 +94,17 @@ func (a *Agent) step(claim Claim, game Game) error {
 	if claim.Depth() != a.maxDepth {
 		return nil
 	}
+
+	if game.AgreeWithClaimLevel(claim) {
+		a.log.Warn("Agree with leaf claim, skipping step", "claim_depth", claim.Depth(), "maxDepth", a.maxDepth)
+		return nil
+	}
+
+	if claim.Countered {
+		a.log.Info("Claim already stepped on", "claim_depth", claim.Depth(), "maxDepth", a.maxDepth)
+		return nil
+	}
+
 	a.log.Info("Attempting step", "claim_depth", claim.Depth(), "maxDepth", a.maxDepth)
 	step, err := a.solver.AttemptStep(claim)
 	if err != nil {

op-challenger/fault/loader.go

@@ -56,6 +56,8 @@ func (l *loader) fetchClaim(ctx context.Context, arrIndex uint64) (Claim, error)
 			Value:    fetchedClaim.Claim,
 			Position: NewPositionFromGIndex(fetchedClaim.Position.Uint64()),
 		},
+		Countered:           fetchedClaim.Countered,
+		Clock:               fetchedClaim.Clock.Uint64(),
 		ContractIndex:       int(arrIndex),
 		ParentContractIndex: int(fetchedClaim.ParentIndex),
 	}

op-challenger/fault/loader_test.go

@@ -42,14 +42,20 @@ func newMockClaimFetcher() *mockClaimFetcher {
 			{
 				Claim:     [32]byte{0x00},
 				Position:  big.NewInt(0),
+				Countered: false,
+				Clock:     big.NewInt(0),
 			},
 			{
 				Claim:     [32]byte{0x01},
 				Position:  big.NewInt(0),
+				Countered: false,
+				Clock:     big.NewInt(0),
 			},
 			{
 				Claim:     [32]byte{0x02},
 				Position:  big.NewInt(0),
+				Countered: false,
+				Clock:     big.NewInt(0),
 			},
 		},
 	}
@@ -101,6 +107,8 @@ func TestLoader_FetchClaims_Succeeds(t *testing.T) {
 				Value:    expectedClaims[0].Claim,
 				Position: NewPositionFromGIndex(expectedClaims[0].Position.Uint64()),
 			},
+			Countered:     false,
+			Clock:         uint64(0),
 			ContractIndex: 0,
 		},
 		{
@@ -112,6 +120,8 @@ func TestLoader_FetchClaims_Succeeds(t *testing.T) {
 				Value:    expectedClaims[0].Claim,
 				Position: NewPositionFromGIndex(expectedClaims[1].Position.Uint64()),
 			},
+			Countered:     false,
+			Clock:         uint64(0),
 			ContractIndex: 1,
 		},
 		{
@@ -123,6 +133,8 @@ func TestLoader_FetchClaims_Succeeds(t *testing.T) {
 				Value:    expectedClaims[0].Claim,
 				Position: NewPositionFromGIndex(expectedClaims[2].Position.Uint64()),
 			},
+			Countered:     false,
+			Clock:         uint64(0),
 			ContractIndex: 2,
 		},
 	}, claims)

op-challenger/fault/types.go

@@ -49,6 +49,12 @@ func (c *ClaimData) ValueBytes() [32]byte {
 // and the Parent field is empty & meaningless.
 type Claim struct {
 	ClaimData
+	// WARN: Countered is a mutable field in the FaultDisputeGame contract
+	//       and rely on it for determining whether to step on leaf claims.
+	//       When caching is implemented for the Challenger, this will need
+	//       to be changed/removed to avoid invalid/stale contract state.
+	Countered bool
+	Clock     uint64
 	Parent    ClaimData
 	// Location of the claim & it's parent inside the contract. Does not exist
 	// for claims that have not made it to the contract.