Merge branch 'develop' into inphi/mips-bin

cannon/mipsevm/evm_test.go

@@ -63,6 +63,8 @@ func TestEVM(t *testing.T) {
 			if strings.HasPrefix(f.Name(), "oracle") {
 				oracle = staticOracle(t, []byte("hello world"))
 			}
+			// Short-circuit early for exit_group.bin
+			exitGroup := f.Name() == "exit_group.bin"
 
 			env, evmState := NewEVMEnv(contracts, addrs)
 			env.Config.Tracer = tracer
@@ -83,6 +85,9 @@ func TestEVM(t *testing.T) {
 				if us.state.PC == endAddr {
 					break
 				}
+				if exitGroup && us.state.Exited {
+					break
+				}
 				insn := state.Memory.GetMemory(state.PC)
 				t.Logf("step: %4d pc: 0x%08x insn: 0x%08x", state.Step, state.PC, insn)
 
@@ -122,11 +127,17 @@ func TestEVM(t *testing.T) {
 				require.Equal(t, hexutil.Bytes(uniPost).String(), hexutil.Bytes(evmPost).String(),
 					"mipsevm produced different state than EVM")
 			}
+			if exitGroup {
+				require.NotEqual(t, uint32(endAddr), us.state.PC, "must not reach end")
+				require.True(t, us.state.Exited, "must set exited state")
+				require.Equal(t, uint8(1), us.state.ExitCode, "must exit with 1")
+			} else {
 				require.Equal(t, uint32(endAddr), state.PC, "must reach end")
 				// inspect test result
 				done, result := state.Memory.GetMemory(baseAddrEnd+4), state.Memory.GetMemory(baseAddrEnd+8)
 				require.Equal(t, done, uint32(1), "must be done")
 				require.Equal(t, result, uint32(1), "must have success result")
+			}
 		})
 	}
 }

cannon/mipsevm/open_mips_tests/test/brk.asm

+.section .test, "x"
+    .balign 4
+    .set    noreorder
+    .global test
+    .ent    test
+
+test:
+  li $v0, 4045
+  syscall
+  lui $t0, 0x4000
+  subu $v0, $v0, $t0
+  sltiu $v0, $v0, 1
+
+# save results
+  lui     $s0, 0xbfff         # Load the base address 0xbffffff0
+  ori     $s0, 0xfff0
+  ori     $s1, $0, 1          # Prepare the 'done' status
+
+  sw      $v0, 8($s0)         # Set the test result
+  sw      $s1, 4($s0)         # Set 'done'
+
+$done:
+  jr $ra
+  nop
+
+  .end test

cannon/mipsevm/open_mips_tests/test/clone.asm

+.section .test, "x"
+    .balign 4
+    .set    noreorder
+    .global test
+    .ent    test
+
+test:
+  li $v0, 4120
+  syscall
+  li $t0, 0x1
+  subu $v0, $v0, $t0
+  sltiu $v0, $v0, 1
+
+# save results
+  lui     $s0, 0xbfff         # Load the base address 0xbffffff0
+  ori     $s0, 0xfff0
+  ori     $s1, $0, 1          # Prepare the 'done' status
+
+  sw      $v0, 8($s0)         # Set the test result
+  sw      $s1, 4($s0)         # Set 'done'
+
+$done:
+  jr $ra
+  nop
+
+  .end test

cannon/mipsevm/open_mips_tests/test/exit_group.asm

+.section .test, "x"
+    .balign 4
+    .set    noreorder
+    .global test
+    .ent    test
+
+test:
+  li $a0, 1
+  li $v0, 4246
+  syscall
+
+  # Unreachable ....
+  # set test result to fail.
+  # Test runner should short-circuit before reaching this point.
+  li $v0, 0
+
+  # save results
+  lui     $s0, 0xbfff         # Load the base address 0xbffffff0
+  ori     $s0, 0xfff0
+  ori     $s1, $0, 1          # Prepare the 'done' status
+
+  sw      $v0, 8($s0)         # Set the test result
+  sw      $s1, 4($s0)         # Set 'done'
+
+$done:
+  jr $ra
+  nop
+
+  .end test

cannon/mipsevm/open_mips_tests/test/fcntl.asm

+.section .test, "x"
+    .balign 4
+    .set    noreorder
+    .global test
+    .ent    test
+
+test:
+  # fnctl(0, 3)
+  li $v0, 4055
+  li $a0, 0x0
+  li $a1, 0x3
+  syscall
+  sltiu $v0, $v0, 1
+
+# save results
+  lui     $s0, 0xbfff         # Load the base address 0xbffffff0
+  ori     $s0, 0xfff0
+  ori     $s1, $0, 1          # Prepare the 'done' status
+
+  sw      $v0, 8($s0)         # Set the test result
+  sw      $s1, 4($s0)         # Set 'done'
+
+$done:
+  jr $ra
+  nop
+
+  .end test

cannon/mipsevm/open_mips_tests/test/mmap.asm

+.section .test, "x"
+    .balign 4
+    .set    noreorder
+    .global test
+    .ent    test
+
+test:
+  li $v0, 4090
+  lui $a0, 0x3000
+  li $a1, 4096
+  syscall
+  lui $t0, 0x3000
+  subu $v0, $v0, $t0
+  sltiu $v0, $v0, 1
+
+ # save results
+  lui     $s0, 0xbfff         # Load the base address 0xbffffff0
+  ori     $s0, 0xfff0
+  ori     $s1, $0, 1          # Prepare the 'done' status
+
+  sw      $v0, 8($s0)         # Set the test result
+  sw      $s1, 4($s0)         # Set 'done'
+
+$done:
+  jr $ra
+  nop
+
+  .end test

cannon/mipsevm/open_mips_tests/test/oracle.asm

@@ -69,6 +69,10 @@ $readloop:
   addiu $t0, $t0, -1
   bnez $t0, $readloop
   nop
+# reading the pre-image stream at EOF should have no effect
+  li $a1, 0x31000008
+  li $v0, 4003
+  syscall
 
 # length at 0x31000000. We also check that the lower 32 bits are zero
   lui $s1, 0x3100

cannon/mipsevm/state_test.go

@@ -35,6 +35,9 @@ func TestState(t *testing.T) {
 			if strings.HasPrefix(f.Name(), "oracle") {
 				oracle = staticOracle(t, []byte("hello world"))
 			}
+			// Short-circuit early for exit_group.bin
+			exitGroup := f.Name() == "exit_group.bin"
+
 			// TODO: currently tests are compiled as flat binary objects
 			// We can use more standard tooling to compile them to ELF files and get remove maketests.py
 			fn := path.Join("open_mips_tests/test/bin", f.Name())
@@ -57,14 +60,24 @@ func TestState(t *testing.T) {
 				if us.state.PC == endAddr {
 					break
 				}
+				if exitGroup && us.state.Exited {
+					break
+				}
 				_, err := us.Step(false)
 				require.NoError(t, err)
 			}
+
+			if exitGroup {
+				require.NotEqual(t, uint32(endAddr), us.state.PC, "must not reach end")
+				require.True(t, us.state.Exited, "must set exited state")
+				require.Equal(t, uint8(1), us.state.ExitCode, "must exit with 1")
+			} else {
 				require.Equal(t, uint32(endAddr), us.state.PC, "must reach end")
-			// inspect test result
 				done, result := state.Memory.GetMemory(baseAddrEnd+4), state.Memory.GetMemory(baseAddrEnd+8)
+				// inspect test result
 				require.Equal(t, done, uint32(1), "must be done")
 				require.Equal(t, result, uint32(1), "must have success result")
+			}
 		})
 	}
 }

docs/op-stack/src/docs/build/getting-started.md

@@ -30,7 +30,7 @@ You’ll need the following software installed to follow this tutorial:
 - [Git](https://git-scm.com/)
 - [Go](https://go.dev/)
 - [Node](https://nodejs.org/en/)
-- [Yarn](https://classic.yarnpkg.com/lang/en/docs/install/)
+- [Pnpm](https://classic.yarnpkg.com/lang/en/docs/install/)
 - [Foundry](https://github.com/foundry-rs/foundry#installation)
 - [Make](https://linux.die.net/man/1/make)
 - [jq](https://github.com/jqlang/jq)
@@ -44,7 +44,7 @@ This tutorial was checked on:
 | git, curl, jq, and make | OS default | `sudo apt install -y git curl make jq` |
 | Go       | 1.20       | `sudo apt update` <br> `wget https://go.dev/dl/go1.20.linux-amd64.tar.gz` <br> `tar xvzf go1.20.linux-amd64.tar.gz` <br> `sudo cp go/bin/go /usr/bin/go` <br> `sudo mv go /usr/lib` <br> `echo export GOROOT=/usr/lib/go >> ~/.bashrc`
 | Node     | 16.19.0    | `curl -fsSL https://deb.nodesource.com/setup_16.x | sudo -E bash -` <br> `sudo apt-get install -y nodejs npm`
-| yarn     | 1.22.19    | `sudo npm install -g yarn`
+| pnpm     | 8.5.6      | `sudo npm install -g pnpm`
 | Foundry  | 0.2.0      | `yarn install:foundry`
 
 ## Build the Source Code
@@ -69,14 +69,14 @@ We’re going to be spinning up an EVM Rollup from the OP Stack source code.  Yo
 1. Install required modules. This is a slow process, while it is running you can already start building `op-geth`, as shown below.
 
     ```bash
-    yarn install
+    pnpm install
     ```
 
 1. Build the various packages inside of the Optimism Monorepo.
 
     ```bash
     make op-node op-batcher op-proposer
-    yarn build
+    pnpm build
     ```
 
 ### Build op-geth
@@ -278,7 +278,7 @@ We’ve set up the L1 side of things, but now we need to set up the L2 side of t
 
     You should then see the `genesis.json` and `rollup.json` files inside the `op-node` package.
 
-1. Next, generate the `jwt.txt` file with the following command:
+ 1. Next, generate the `jwt.txt` file with the following command:
 
     ```bash
     openssl rand -hex 32 > jwt.txt
@@ -307,24 +307,6 @@ We’re almost ready to run our chain! Now we just need to run a few commands to
     mkdir datadir
     ```
 
-1. Put a password file into the data directory folder:
-
-    ```bash
-    echo "pwd" > datadir/password
-    ```
-
-1. Put the `Sequencer` private key into the data directory folder (don’t include a “0x” prefix):
-
-    ```bash
-    echo "<SEQUENCER KEY HERE>" > datadir/block-signer-key
-    ```
-
-1. Import the key into `op-geth`:
-
-    ```bash
-    ./build/bin/geth account import --datadir=datadir --password=datadir/password datadir/block-signer-key
-    ```
-
 1. Next we need to initialize `op-geth` with the genesis file we generated and copied earlier:
 
     ```bash
@@ -344,7 +326,6 @@ Set these environment variables for the configuration
 
 | Variable       | Value |
 | -------------- | -
-| `SEQ_ADDR`     | Address of the `Sequencer` account
 | `SEQ_KEY`      | Private key of the `Sequencer` account
 | `BATCHER_KEY`  | Private key of the `Batcher` accounts, which should have at least 1 ETH
 | `PROPOSER_KEY` | Private key of the `Proposer` account
@@ -380,12 +361,7 @@ cd ~/op-geth
         --authrpc.addr=0.0.0.0 \
         --authrpc.port=8551 \
         --authrpc.jwtsecret=./jwt.txt \
-	--rollup.disabletxpoolgossip=true \
-	--password=./datadir/password \
-	--allow-insecure-unlock \
-	--mine \
-	--miner.etherbase=$SEQ_ADDR \
-	--unlock=$SEQ_ADDR
+        --rollup.disabletxpoolgossip=true
 ```
 
 And `op-geth` should be running! You should see some output, but you won’t see any blocks being created yet because `op-geth` is driven by the `op-node`. We’ll need to get that running next.

nx.json

@@ -7,6 +7,8 @@
     "nx.json": "*",
     "tsconfig.json": "*",
     ".foundryrc": "*",
+    "pnpm.lock.yaml": "*",
+    ".npmrc": "*",
     ".nvmrc":  "*"
   },
   "tasksRunnerOptions": {

op-challenger/challenger.go

 package op_challenger
 
 import (
+	"fmt"
+	"time"
+
+	"github.com/ethereum-optimism/optimism/op-bindings/bindings"
 	"github.com/ethereum-optimism/optimism/op-challenger/config"
+	"github.com/ethereum-optimism/optimism/op-challenger/fault"
+	"github.com/ethereum-optimism/optimism/op-service/txmgr"
+	"github.com/ethereum-optimism/optimism/op-service/txmgr/metrics"
+	"github.com/ethereum/go-ethereum/ethclient"
 	"github.com/ethereum/go-ethereum/log"
 )
 
 // Main is the programmatic entry-point for running op-challenger
 func Main(logger log.Logger, cfg *config.Config) error {
+	client, err := ethclient.Dial(cfg.L1EthRpc)
+	if err != nil {
+		return fmt.Errorf("failed to dial L1: %w", err)
+	}
+
+	txMgr, err := txmgr.NewSimpleTxManager("challenger", logger, &metrics.NoopTxMetrics{}, cfg.TxMgrConfig)
+	if err != nil {
+		return fmt.Errorf("failed to create the transaction manager: %w", err)
+	}
+
+	contract, err := bindings.NewFaultDisputeGameCaller(cfg.GameAddress, client)
+	if err != nil {
+		return fmt.Errorf("failed to bind the fault dispute game contract: %w", err)
+	}
+
+	loader := fault.NewLoader(logger, contract)
+	responder, err := fault.NewFaultResponder(logger, txMgr, cfg.GameAddress)
+	if err != nil {
+		return fmt.Errorf("failed to create the responder: %w", err)
+	}
+	gameDepth := 4
+	trace := fault.NewAlphabetProvider(cfg.AlphabetTrace, uint64(gameDepth))
+
+	agent := fault.NewAgent(loader, gameDepth, trace, responder, cfg.AgreeWithProposedOutput, logger)
+
 	logger.Info("Fault game started")
-	return nil
+
+	for {
+		logger.Info("Performing action")
+		_ = agent.Act()
+		time.Sleep(300 * time.Millisecond)
+	}
 }

op-challenger/charlie.sh

+#!/bin/bash
+set -euo pipefail
+
+DIR=$(cd $(dirname "${BASH_SOURCE[0]}") && pwd)
+cd "$DIR"
+
+DISPUTE_GAME_PROXY="0xB7f8BC63BbcaD18155201308C8f3540b07f84F5e"
+
+CHARLIE_ADDRESS="0xF45B7537828CB2fffBC69996B054c2Aaf36DC778"
+CHARLIE_KEY="74feb147d72bfae943e6b4e483410933d9e447d5dc47d52432dcc2c1454dabb7"
+
+MALLORY_ADDRESS="0x4641c704a6c743f73ee1f36C7568Fbf4b80681e4"
+MALLORY_KEY="28d7045146193f5f4eeb151c4843544b1b0d30a7ac1680c845a416fac65a7715"
+
+FAULT_GAME_ADDRESS="0x8daf17a20c9dba35f005b6324f493785d239719d"
+
+./bin/op-challenger --l1-eth-rpc http://localhost:8545 --alphabet "abcdefgh" --game-address $FAULT_GAME_ADDRESS --private-key $CHARLIE_KEY --num-confirmations 1 --agree-with-proposed-output=true

op-challenger/cmd/main_test.go

 package main
 
 import (
+	"fmt"
 	"testing"
 
 	"github.com/ethereum-optimism/optimism/op-challenger/config"
@@ -14,6 +15,7 @@ var (
 	l1EthRpc                = "http://example.com:8545"
 	gameAddressValue        = "0xaa00000000000000000000000000000000000000"
 	alphabetTrace           = "abcdefghijz"
+	agreeWithProposedOutput = "true"
 )
 
 func TestLogLevel(t *testing.T) {
@@ -33,12 +35,12 @@ func TestLogLevel(t *testing.T) {
 
 func TestDefaultCLIOptionsMatchDefaultConfig(t *testing.T) {
 	cfg := configForArgs(t, addRequiredArgs())
-	defaultCfg := config.NewConfig(l1EthRpc, common.HexToAddress(gameAddressValue), alphabetTrace)
+	defaultCfg := config.NewConfig(l1EthRpc, common.HexToAddress(gameAddressValue), alphabetTrace, true)
 	require.Equal(t, defaultCfg, cfg)
 }
 
 func TestDefaultConfigIsValid(t *testing.T) {
-	cfg := config.NewConfig(l1EthRpc, common.HexToAddress(gameAddressValue), alphabetTrace)
+	cfg := config.NewConfig(l1EthRpc, common.HexToAddress(gameAddressValue), alphabetTrace, true)
 	require.NoError(t, cfg.Check())
 }
 
@@ -89,6 +91,24 @@ func TestTxManagerFlagsSupported(t *testing.T) {
 	require.Equal(t, uint64(7), cfg.TxMgrConfig.NumConfirmations)
 }
 
+func TestAgreeWithProposedOutput(t *testing.T) {
+	t.Run("MustBeProvided", func(t *testing.T) {
+		verifyArgsInvalid(t, "flag agree-with-proposed-output is required", addRequiredArgsExcept("--agree-with-proposed-output"))
+	})
+	t.Run("Enabled", func(t *testing.T) {
+		cfg := configForArgs(t, addRequiredArgs("--agree-with-proposed-output"))
+		require.True(t, cfg.AgreeWithProposedOutput)
+	})
+	t.Run("EnabledWithArg", func(t *testing.T) {
+		cfg := configForArgs(t, addRequiredArgs("--agree-with-proposed-output=true"))
+		require.True(t, cfg.AgreeWithProposedOutput)
+	})
+	t.Run("Disabled", func(t *testing.T) {
+		cfg := configForArgs(t, addRequiredArgs("--agree-with-proposed-output=false"))
+		require.False(t, cfg.AgreeWithProposedOutput)
+	})
+}
+
 func verifyArgsInvalid(t *testing.T, messageContains string, cliArgs []string) {
 	_, _, err := runWithArgs(cliArgs)
 	require.ErrorContains(t, err, messageContains)
@@ -103,7 +123,7 @@ func configForArgs(t *testing.T, cliArgs []string) config.Config {
 func runWithArgs(cliArgs []string) (log.Logger, config.Config, error) {
 	cfg := new(config.Config)
 	var logger log.Logger
-	fullArgs := append([]string{"op-program"}, cliArgs...)
+	fullArgs := append([]string{"op-challenger"}, cliArgs...)
 	err := run(fullArgs, func(log log.Logger, config *config.Config) error {
 		logger = log
 		cfg = config
@@ -126,6 +146,7 @@ func addRequiredArgsExcept(name string, optionalArgs ...string) []string {
 
 func requiredArgs() map[string]string {
 	return map[string]string{
+		"--agree-with-proposed-output": agreeWithProposedOutput,
 		"--l1-eth-rpc":                 l1EthRpc,
 		"--game-address":               gameAddressValue,
 		"--alphabet":                   alphabetTrace,
@@ -135,8 +156,7 @@ func requiredArgs() map[string]string {
 func toArgList(req map[string]string) []string {
 	var combined []string
 	for name, value := range req {
-		combined = append(combined, name)
-		combined = append(combined, value)
+		combined = append(combined, fmt.Sprintf("%s=%s", name, value))
 	}
 	return combined
 }

op-challenger/config/config.go

@@ -24,19 +24,23 @@ type Config struct {
 	L1EthRpc                string         // L1 RPC Url
 	GameAddress             common.Address // Address of the fault game
 	AlphabetTrace           string         // String for the AlphabetTraceProvider
+	AgreeWithProposedOutput bool           // Temporary config if we agree or disagree with the posted output
 
 	TxMgrConfig txmgr.CLIConfig
 }
 
-func NewConfig(l1EthRpc string,
+func NewConfig(
+	l1EthRpc string,
 	GameAddress common.Address,
 	AlphabetTrace string,
+	AgreeWithProposedOutput bool,
 ) Config {
 	return Config{
 		L1EthRpc:                l1EthRpc,
 		GameAddress:             GameAddress,
 		AlphabetTrace:           AlphabetTrace,
 		TxMgrConfig:             txmgr.NewCLIConfig(l1EthRpc),
+		AgreeWithProposedOutput: AgreeWithProposedOutput,
 	}
 }
 
@@ -73,6 +77,7 @@ func NewConfigFromCLI(ctx *cli.Context) (*Config, error) {
 		L1EthRpc:                ctx.String(flags.L1EthRpcFlag.Name),
 		GameAddress:             dgfAddress,
 		AlphabetTrace:           ctx.String(flags.AlphabetFlag.Name),
+		AgreeWithProposedOutput: ctx.Bool(flags.AgreeWithProposedOutputFlag.Name),
 		TxMgrConfig:             txMgrConfig,
 	}, nil
 }

op-challenger/config/config_test.go

@@ -12,10 +12,11 @@ var (
 	validL1EthRpc           = "http://localhost:8545"
 	validGameAddress        = common.HexToAddress("0x7bdd3b028C4796eF0EAf07d11394d0d9d8c24139")
 	validAlphabetTrace      = "abcdefgh"
+	agreeWithProposedOutput = true
 )
 
 func validConfig() Config {
-	cfg := NewConfig(validL1EthRpc, validGameAddress, validAlphabetTrace)
+	cfg := NewConfig(validL1EthRpc, validGameAddress, validAlphabetTrace, agreeWithProposedOutput)
 	return cfg
 }
 

op-challenger/fault/agent.go

@@ -3,6 +3,7 @@ package fault
 import (
 	"context"
 	"errors"
+	"fmt"
 
 	"github.com/ethereum/go-ethereum/log"
 )
@@ -13,16 +14,18 @@ type Agent struct {
 	loader                  Loader
 	responder               Responder
 	maxDepth                int
+	agreeWithProposedOutput bool
 	log                     log.Logger
 }
 
-func NewAgent(loader Loader, maxDepth int, trace TraceProvider, responder Responder, log log.Logger) Agent {
+func NewAgent(loader Loader, maxDepth int, trace TraceProvider, responder Responder, agreeWithProposedOutput bool, log log.Logger) Agent {
 	return Agent{
 		solver:                  NewSolver(maxDepth, trace),
 		trace:                   trace,
 		loader:                  loader,
 		responder:               responder,
 		maxDepth:                maxDepth,
+		agreeWithProposedOutput: agreeWithProposedOutput,
 		log:                     log,
 	}
 }
@@ -36,11 +39,15 @@ func (a *Agent) Act() error {
 	}
 	// Create counter claims
 	for _, claim := range game.Claims() {
-		_ = a.move(claim, game)
+		if err := a.move(claim, game); err != nil {
+			log.Error("Failed to move", "err", err)
+		}
 	}
 	// Step on all leaf claims
 	for _, claim := range game.Claims() {
-		_ = a.step(claim, game)
+		if err := a.step(claim, game); err != nil {
+			log.Error("Failed to step", "err", err)
+		}
 	}
 	return nil
 }
@@ -49,34 +56,33 @@ func (a *Agent) Act() error {
 func (a *Agent) newGameFromContracts(ctx context.Context) (Game, error) {
 	claims, err := a.loader.FetchClaims(ctx)
 	if err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to fetch claims: %w", err)
 	}
 	if len(claims) == 0 {
 		return nil, errors.New("no claims")
 	}
-	game := NewGameState(claims[0], uint64(a.maxDepth))
+	game := NewGameState(a.agreeWithProposedOutput, claims[0], uint64(a.maxDepth))
 	if err := game.PutAll(claims[1:]); err != nil {
-		return nil, err
+		return nil, fmt.Errorf("failed to load claims into the local state: %w", err)
 	}
 	return game, nil
 }
 
-// move determines & executes the next move given a claim pair
+// move determines & executes the next move given a claim
 func (a *Agent) move(claim Claim, game Game) error {
-	a.log.Info("Fetching claims")
-	nextMove, err := a.solver.NextMove(claim)
+	nextMove, err := a.solver.NextMove(claim, game.AgreeWithClaimLevel(claim))
 	if err != nil {
 		a.log.Warn("Failed to execute the next move", "err", err)
 		return err
 	}
 	if nextMove == nil {
-		a.log.Info("No next move")
+		a.log.Debug("No next move")
 		return nil
 	}
 	move := *nextMove
-	log := a.log.New("is_defend", move.DefendsParent(), "depth", move.Depth(), "index_at_depth", move.IndexAtDepth(), "value", move.Value,
-		"letter", string(move.Value[31:]), "trace_index", move.Value[30],
-		"parent_letter", string(claim.Value[31:]), "parent_trace_index", claim.Value[30])
+	log := a.log.New("is_defend", move.DefendsParent(), "depth", move.Depth(), "index_at_depth", move.IndexAtDepth(),
+		"value", move.Value, "trace_index", move.TraceIndex(a.maxDepth),
+		"parent_value", claim.Value, "parent_trace_index", claim.TraceIndex(a.maxDepth))
 	if game.IsDuplicate(move) {
 		log.Debug("Duplicate move")
 		return nil
@@ -85,25 +91,30 @@ func (a *Agent) move(claim Claim, game Game) error {
 	return a.responder.Respond(context.TODO(), move)
 }
 
-// step attempts to execute the step through the responder
+// step determines & executes the next step against a leaf claim through the responder
 func (a *Agent) step(claim Claim, game Game) error {
 	if claim.Depth() != 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 {
-		a.log.Info("Failed to get a step", "err", err)
+		a.log.Warn("Failed to get a step", "err", err)
+		return err
+	}
+	stateData, err := a.trace.GetPreimage(step.PreStateTraceIndex)
+	if err != nil {
+		a.log.Warn("Failed to get a state data", "err", err)
 		return err
 	}
 
 	a.log.Info("Performing step",
 		"depth", step.LeafClaim.Depth(), "index_at_depth", step.LeafClaim.IndexAtDepth(), "value", step.LeafClaim.Value,
-		"is_attack", step.IsAttack)
+		"is_attack", step.IsAttack, "prestate_trace_index", step.PreStateTraceIndex)
 	callData := StepCallData{
 		ClaimIndex: uint64(step.LeafClaim.ContractIndex),
 		IsAttack:   step.IsAttack,
+		StateData:  stateData,
 	}
 	return a.responder.Step(context.TODO(), callData)
 }

op-challenger/fault/alphabet_provider.go

@@ -5,6 +5,7 @@ import (
 	"strings"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
 )
 
 // AlphabetProvider is a [TraceProvider] that provides claims for specific
@@ -32,7 +33,7 @@ func (ap *AlphabetProvider) GetPreimage(i uint64) ([]byte, error) {
 	if i >= uint64(len(ap.state)) {
 		return ap.GetPreimage(uint64(len(ap.state)) - 1)
 	}
-	return buildAlphabetClaimBytes(i, ap.state[i]), nil
+	return BuildAlphabetPreimage(i, ap.state[i]), nil
 }
 
 // Get returns the claim value at the given index in the trace.
@@ -41,17 +42,25 @@ func (ap *AlphabetProvider) Get(i uint64) (common.Hash, error) {
 	if err != nil {
 		return common.Hash{}, err
 	}
-	return common.BytesToHash(claimBytes), nil
+	return crypto.Keccak256Hash(claimBytes), nil
 }
 
-// buildAlphabetClaimBytes constructs the claim bytes for the index and state item.
-func buildAlphabetClaimBytes(i uint64, letter string) []byte {
-	return append(IndexToBytes(i), []byte(letter)...)
+// BuildAlphabetPreimage constructs the claim bytes for the index and state item.
+func BuildAlphabetPreimage(i uint64, letter string) []byte {
+	return append(IndexToBytes(i), LetterToBytes(letter)...)
 }
 
 // IndexToBytes converts an index to a byte slice big endian
 func IndexToBytes(i uint64) []byte {
 	big := new(big.Int)
 	big.SetUint64(i)
-	return big.Bytes()
+	out := make([]byte, 32)
+	return big.FillBytes(out)
+}
+
+// LetterToBytes converts a letter to a 32 byte array
+func LetterToBytes(letter string) []byte {
+	out := make([]byte, 32)
+	out[31] = byte(letter[0])
+	return out
 }

op-challenger/fault/alphabet_provider_test.go

@@ -20,15 +20,15 @@ func TestAlphabetProvider_Get_ClaimsByTraceIndex(t *testing.T) {
 	}{
 		{
 			7,
-			common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000768"),
+			alphabetClaim(7, "h"),
 		},
 		{
 			3,
-			common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000364"),
+			alphabetClaim(3, "d"),
 		},
 		{
 			5,
-			common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000566"),
+			alphabetClaim(5, "f"),
 		},
 	}
 
@@ -54,7 +54,7 @@ func FuzzIndexToBytes(f *testing.F) {
 // returns the correct pre-image for a index.
 func TestGetPreimage_Succeeds(t *testing.T) {
 	ap := NewAlphabetProvider("abc", 2)
-	expected := append(IndexToBytes(uint64(0)), []byte("a")...)
+	expected := BuildAlphabetPreimage(0, "a'")
 	retrieved, err := ap.GetPreimage(uint64(0))
 	require.NoError(t, err)
 	require.Equal(t, expected, retrieved)
@@ -73,8 +73,7 @@ func TestGet_Succeeds(t *testing.T) {
 	ap := NewAlphabetProvider("abc", 2)
 	claim, err := ap.Get(0)
 	require.NoError(t, err)
-	concatenated := append(IndexToBytes(0), []byte("a")...)
-	expected := common.BytesToHash(concatenated)
+	expected := alphabetClaim(0, "a")
 	require.Equal(t, expected, claim)
 }
 
@@ -92,7 +91,6 @@ func TestGet_Extends(t *testing.T) {
 	ap := NewAlphabetProvider("abc", 2)
 	claim, err := ap.Get(3)
 	require.NoError(t, err)
-	concatenated := append(IndexToBytes(2), []byte("c")...)
-	expected := common.BytesToHash(concatenated)
+	expected := alphabetClaim(2, "c")
 	require.Equal(t, expected, claim)
 }

op-challenger/fault/cmd/examples/full.go

@@ -26,6 +26,6 @@ func FullGame() {
 		},
 	}
 
-	o := fault.NewOrchestrator(maxDepth, []fault.TraceProvider{canonicalProvider, disputedProvider}, []string{"charlie", "mallory"}, root)
+	o := fault.NewOrchestrator(maxDepth, []fault.TraceProvider{canonicalProvider, disputedProvider}, []string{"charlie", "mallory"}, []bool{false, true}, root)
 	o.Start()
 }

op-challenger/fault/cmd/examples/solver.go

@@ -53,19 +53,19 @@ func SolverExampleOne() {
 	fmt.Println()
 	PrettyPrintAlphabetClaim("Root claim", root)
 
-	claim1, err := cannonicalSolver.NextMove(root)
+	claim1, err := cannonicalSolver.NextMove(root, false)
 	if err != nil {
 		fmt.Printf("error getting claim from provider: %v", err)
 	}
 	PrettyPrintAlphabetClaim("Cannonical move", *claim1)
 
-	claim2, err := disputedSolver.NextMove(*claim1)
+	claim2, err := disputedSolver.NextMove(*claim1, false)
 	if err != nil {
 		fmt.Printf("error getting claim from provider: %v", err)
 	}
 	PrettyPrintAlphabetClaim("Disputed moved", *claim2)
 
-	claim3, err := cannonicalSolver.NextMove(*claim2)
+	claim3, err := cannonicalSolver.NextMove(*claim2, false)
 	if err != nil {
 		fmt.Printf("error getting claim from provider: %v", err)
 	}

op-challenger/fault/game.go

@@ -33,17 +33,20 @@ type Game interface {
 	// PostStateClaim gets the claim which commits to the post-state of this specific claim.
 	// This will return an error if it is called with a non-leaf claim.
 	PostStateClaim(claim Claim) (Claim, error)
+
+	// AgreeWithLevel returns if the game state agrees with the provided claim level.
+	AgreeWithClaimLevel(claim Claim) bool
 }
 
 type extendedClaim struct {
 	self     Claim
-	contractIndex int
 	children []ClaimData
 }
 
 // gameState is a struct that represents the state of a dispute game.
 // The game state implements the [Game] interface.
 type gameState struct {
+	agreeWithProposedOutput bool
 	root                    ClaimData
 	claims                  map[ClaimData]*extendedClaim
 	depth                   uint64
@@ -51,20 +54,32 @@ type gameState struct {
 
 // NewGameState returns a new game state.
 // The provided [Claim] is used as the root node.
-func NewGameState(root Claim, depth uint64) *gameState {
+func NewGameState(agreeWithProposedOutput bool, root Claim, depth uint64) *gameState {
 	claims := make(map[ClaimData]*extendedClaim)
 	claims[root.ClaimData] = &extendedClaim{
 		self:     root,
-		contractIndex: 0,
 		children: make([]ClaimData, 0),
 	}
 	return &gameState{
+		agreeWithProposedOutput: agreeWithProposedOutput,
 		root:                    root.ClaimData,
 		claims:                  claims,
 		depth:                   depth,
 	}
 }
 
+// AgreeWithLevel returns if the game state agrees with the provided claim level.
+func (g *gameState) AgreeWithClaimLevel(claim Claim) bool {
+	isOddLevel := claim.Depth()%2 == 1
+	// If we agree with the proposed output, we agree with odd levels
+	// If we disagree with the proposed output, we agree with the root claim level & even levels
+	if g.agreeWithProposedOutput {
+		return isOddLevel
+	} else {
+		return !isOddLevel
+	}
+}
+
 // PutAll adds a list of claims into the [Game] state.
 // If any of the claims already exist in the game state, an error is returned.
 func (g *gameState) PutAll(claims []Claim) error {
@@ -81,14 +96,14 @@ func (g *gameState) Put(claim Claim) error {
 	if claim.IsRoot() || g.IsDuplicate(claim) {
 		return ErrClaimExists
 	}
-	if parent, ok := g.claims[claim.Parent]; !ok {
+	parent, ok := g.claims[claim.Parent]
+	if !ok {
 		return errors.New("no parent claim")
 	} else {
 		parent.children = append(parent.children, claim.ClaimData)
 	}
 	g.claims[claim.ClaimData] = &extendedClaim{
 		self:     claim,
-		contractIndex: claim.ContractIndex,
 		children: make([]ClaimData, 0),
 	}
 	return nil

op-challenger/fault/game_test.go

@@ -48,7 +48,7 @@ func createTestClaims() (Claim, Claim, Claim, Claim) {
 func TestIsDuplicate(t *testing.T) {
 	// Setup the game state.
 	root, top, middle, bottom := createTestClaims()
-	g := NewGameState(root, testMaxDepth)
+	g := NewGameState(false, root, testMaxDepth)
 	require.NoError(t, g.Put(top))
 
 	// Root + Top should be duplicates
@@ -65,7 +65,7 @@ func TestIsDuplicate(t *testing.T) {
 func TestGame_Put_RootAlreadyExists(t *testing.T) {
 	// Setup the game state.
 	top, _, _, _ := createTestClaims()
-	g := NewGameState(top, testMaxDepth)
+	g := NewGameState(false, top, testMaxDepth)
 
 	// Try to put the root claim into the game state again.
 	err := g.Put(top)
@@ -77,7 +77,7 @@ func TestGame_Put_RootAlreadyExists(t *testing.T) {
 func TestGame_PutAll_RootAlreadyExists(t *testing.T) {
 	// Setup the game state.
 	root, _, _, _ := createTestClaims()
-	g := NewGameState(root, testMaxDepth)
+	g := NewGameState(false, root, testMaxDepth)
 
 	// Try to put the root claim into the game state again.
 	err := g.PutAll([]Claim{root})
@@ -88,7 +88,7 @@ func TestGame_PutAll_RootAlreadyExists(t *testing.T) {
 // instance errors when the given claim already exists in state.
 func TestGame_PutAll_AlreadyExists(t *testing.T) {
 	root, top, middle, bottom := createTestClaims()
-	g := NewGameState(root, testMaxDepth)
+	g := NewGameState(false, root, testMaxDepth)
 
 	err := g.PutAll([]Claim{top, middle})
 	require.NoError(t, err)
@@ -101,7 +101,7 @@ func TestGame_PutAll_AlreadyExists(t *testing.T) {
 func TestGame_PutAll_ParentsAndChildren(t *testing.T) {
 	// Setup the game state.
 	root, top, middle, bottom := createTestClaims()
-	g := NewGameState(root, testMaxDepth)
+	g := NewGameState(false, root, testMaxDepth)
 
 	// We should not be able to get the parent of the root claim.
 	parent, err := g.getParent(root)
@@ -127,7 +127,7 @@ func TestGame_PutAll_ParentsAndChildren(t *testing.T) {
 func TestGame_Put_AlreadyExists(t *testing.T) {
 	// Setup the game state.
 	top, middle, _, _ := createTestClaims()
-	g := NewGameState(top, testMaxDepth)
+	g := NewGameState(false, top, testMaxDepth)
 
 	// Put the next claim into state.
 	err := g.Put(middle)
@@ -142,7 +142,7 @@ func TestGame_Put_AlreadyExists(t *testing.T) {
 func TestGame_Put_ParentsAndChildren(t *testing.T) {
 	// Setup the game state.
 	root, top, middle, bottom := createTestClaims()
-	g := NewGameState(root, testMaxDepth)
+	g := NewGameState(false, root, testMaxDepth)
 
 	// We should not be able to get the parent of the root claim.
 	parent, err := g.getParent(root)
@@ -175,7 +175,7 @@ func TestGame_Put_ParentsAndChildren(t *testing.T) {
 func TestGame_ClaimPairs(t *testing.T) {
 	// Setup the game state.
 	root, top, middle, bottom := createTestClaims()
-	g := NewGameState(root, testMaxDepth)
+	g := NewGameState(false, root, testMaxDepth)
 
 	// Add top claim to the game state.
 	err := g.Put(top)
@@ -199,7 +199,7 @@ func TestGame_ClaimPairs(t *testing.T) {
 // those functions return an error.
 func TestPrePostStateOnlyOnLeafClaim(t *testing.T) {
 	root, top, middle, bottom := createTestClaims()
-	g := NewGameState(root, testMaxDepth)
+	g := NewGameState(false, root, testMaxDepth)
 	require.NoError(t, g.PutAll([]Claim{top, middle, bottom}))
 
 	_, err := g.PreStateClaim(middle)
@@ -210,7 +210,7 @@ func TestPrePostStateOnlyOnLeafClaim(t *testing.T) {
 
 func TestPreStateClaim(t *testing.T) {
 	root, top, middle, bottom := createTestClaims()
-	g := NewGameState(root, testMaxDepth)
+	g := NewGameState(false, root, testMaxDepth)
 	require.NoError(t, g.Put(top))
 	require.NoError(t, g.Put(middle))
 	require.NoError(t, g.Put(bottom))
@@ -224,7 +224,7 @@ func TestPreStateClaim(t *testing.T) {
 
 func TestPostStateClaim(t *testing.T) {
 	root, top, middle, bottom := createTestClaims()
-	g := NewGameState(root, testMaxDepth)
+	g := NewGameState(false, root, testMaxDepth)
 	require.NoError(t, g.Put(top))
 	require.NoError(t, g.Put(middle))
 	require.NoError(t, g.Put(bottom))
@@ -234,3 +234,27 @@ func TestPostStateClaim(t *testing.T) {
 	require.NoError(t, err)
 	require.Equal(t, middle, post)
 }
+
+func TestAgreeWithClaimLevelDisagreeWithOutput(t *testing.T) {
+	// Setup the game state.
+	root, top, middle, bottom := createTestClaims()
+	g := NewGameState(false, root, testMaxDepth)
+	require.NoError(t, g.PutAll([]Claim{top, middle, bottom}))
+
+	require.True(t, g.AgreeWithClaimLevel(root))
+	require.False(t, g.AgreeWithClaimLevel(top))
+	require.True(t, g.AgreeWithClaimLevel(middle))
+	require.False(t, g.AgreeWithClaimLevel(bottom))
+}
+
+func TestAgreeWithClaimLevelAgreeWithOutput(t *testing.T) {
+	// Setup the game state.
+	root, top, middle, bottom := createTestClaims()
+	g := NewGameState(true, root, testMaxDepth)
+	require.NoError(t, g.PutAll([]Claim{top, middle, bottom}))
+
+	require.False(t, g.AgreeWithClaimLevel(root))
+	require.True(t, g.AgreeWithClaimLevel(top))
+	require.False(t, g.AgreeWithClaimLevel(middle))
+	require.True(t, g.AgreeWithClaimLevel(bottom))
+}

op-challenger/fault/loader.go

@@ -29,17 +29,13 @@ type Loader interface {
 // loader pulls in fault dispute game claim data periodically and over subscriptions.
 type loader struct {
 	log          log.Logger
-
-	state Game
-
 	claimFetcher ClaimFetcher
 }
 
 // NewLoader creates a new [loader].
-func NewLoader(log log.Logger, state Game, claimFetcher ClaimFetcher) *loader {
+func NewLoader(log log.Logger, claimFetcher ClaimFetcher) *loader {
 	return &loader{
 		log:          log,
-		state:        state,
 		claimFetcher: claimFetcher,
 	}
 }
@@ -60,6 +56,8 @@ func (l *loader) fetchClaim(ctx context.Context, arrIndex uint64) (Claim, error)
 			Value:    fetchedClaim.Claim,
 			Position: NewPositionFromGIndex(fetchedClaim.Position.Uint64()),
 		},
+		ContractIndex:       int(arrIndex),
+		ParentContractIndex: int(fetchedClaim.ParentIndex),
 	}
 
 	if !claim.IsRootPosition() {

op-challenger/fault/loader_test.go

@@ -15,46 +15,8 @@ import (
 var (
 	mockClaimDataError = fmt.Errorf("claim data errored")
 	mockClaimLenError  = fmt.Errorf("claim len errored")
-	mockPutError       = fmt.Errorf("put errored")
 )
 
-type mockGameState struct {
-	putCalled int
-	putErrors bool
-}
-
-func (m *mockGameState) Put(claim Claim) error {
-	m.putCalled++
-	if m.putErrors {
-		return mockPutError
-	}
-	return nil
-}
-
-func (m *mockGameState) PutAll(claims []Claim) error {
-	m.putCalled += len(claims)
-	if m.putErrors {
-		return mockPutError
-	}
-	return nil
-}
-
-func (m *mockGameState) Claims() []Claim {
-	return []Claim{}
-}
-
-func (m *mockGameState) IsDuplicate(claim Claim) bool {
-	return false
-}
-
-func (m *mockGameState) PreStateClaim(claim Claim) (Claim, error) {
-	panic("unimplemented")
-}
-
-func (m *mockGameState) PostStateClaim(claim Claim) (Claim, error) {
-	panic("unimplemented")
-}
-
 type mockClaimFetcher struct {
 	claimDataError bool
 	claimLenError  bool
@@ -126,7 +88,7 @@ func TestLoader_FetchClaims_Succeeds(t *testing.T) {
 	log := testlog.Logger(t, log.LvlError)
 	mockClaimFetcher := newMockClaimFetcher()
 	expectedClaims := mockClaimFetcher.returnClaims
-	loader := NewLoader(log, &mockGameState{}, mockClaimFetcher)
+	loader := NewLoader(log, mockClaimFetcher)
 	claims, err := loader.FetchClaims(context.Background())
 	require.NoError(t, err)
 	require.ElementsMatch(t, []Claim{
@@ -139,6 +101,7 @@ func TestLoader_FetchClaims_Succeeds(t *testing.T) {
 				Value:    expectedClaims[0].Claim,
 				Position: NewPositionFromGIndex(expectedClaims[0].Position.Uint64()),
 			},
+			ContractIndex: 0,
 		},
 		{
 			ClaimData: ClaimData{
@@ -149,6 +112,7 @@ func TestLoader_FetchClaims_Succeeds(t *testing.T) {
 				Value:    expectedClaims[0].Claim,
 				Position: NewPositionFromGIndex(expectedClaims[1].Position.Uint64()),
 			},
+			ContractIndex: 1,
 		},
 		{
 			ClaimData: ClaimData{
@@ -159,6 +123,7 @@ func TestLoader_FetchClaims_Succeeds(t *testing.T) {
 				Value:    expectedClaims[0].Claim,
 				Position: NewPositionFromGIndex(expectedClaims[2].Position.Uint64()),
 			},
+			ContractIndex: 2,
 		},
 	}, claims)
 }
@@ -169,7 +134,7 @@ func TestLoader_FetchClaims_ClaimDataErrors(t *testing.T) {
 	log := testlog.Logger(t, log.LvlError)
 	mockClaimFetcher := newMockClaimFetcher()
 	mockClaimFetcher.claimDataError = true
-	loader := NewLoader(log, &mockGameState{}, mockClaimFetcher)
+	loader := NewLoader(log, mockClaimFetcher)
 	claims, err := loader.FetchClaims(context.Background())
 	require.ErrorIs(t, err, mockClaimDataError)
 	require.Empty(t, claims)
@@ -181,7 +146,7 @@ func TestLoader_FetchClaims_ClaimLenErrors(t *testing.T) {
 	log := testlog.Logger(t, log.LvlError)
 	mockClaimFetcher := newMockClaimFetcher()
 	mockClaimFetcher.claimLenError = true
-	loader := NewLoader(log, &mockGameState{}, mockClaimFetcher)
+	loader := NewLoader(log, mockClaimFetcher)
 	claims, err := loader.FetchClaims(context.Background())
 	require.ErrorIs(t, err, mockClaimLenError)
 	require.Empty(t, claims)

op-challenger/fault/orchestrator.go

@@ -15,7 +15,7 @@ type Orchestrator struct {
 	claimLen, stepLen, step int
 }
 
-func NewOrchestrator(maxDepth uint64, traces []TraceProvider, names []string, root Claim) Orchestrator {
+func NewOrchestrator(maxDepth uint64, traces []TraceProvider, names []string, agreeWithProposedOutput []bool, root Claim) Orchestrator {
 	o := Orchestrator{
 		agents: make([]Agent, len(traces)),
 		claims: []Claim{root},
@@ -23,7 +23,7 @@ func NewOrchestrator(maxDepth uint64, traces []TraceProvider, names []string, ro
 	}
 	log.Info("Starting game", "root_letter", string(root.Value[31:]))
 	for i, trace := range traces {
-		o.agents[i] = NewAgent(&o, int(maxDepth), trace, &o, log.New("role", names[i]))
+		o.agents[i] = NewAgent(&o, int(maxDepth), trace, &o, agreeWithProposedOutput[i], log.New("role", names[i]))
 	}
 	return o
 }

op-challenger/fault/solver.go

@@ -9,7 +9,6 @@ import (
 // Solver uses a [TraceProvider] to determine the moves to make in a dispute game.
 type Solver struct {
 	TraceProvider
-
 	gameDepth int
 }
 
@@ -22,7 +21,11 @@ func NewSolver(gameDepth int, traceProvider TraceProvider) *Solver {
 }
 
 // NextMove returns the next move to make given the current state of the game.
-func (s *Solver) NextMove(claim Claim) (*Claim, error) {
+func (s *Solver) NextMove(claim Claim, agreeWithClaimLevel bool) (*Claim, error) {
+	if agreeWithClaimLevel {
+		return nil, nil
+	}
+
 	// Special case of the root claim
 	if claim.IsRoot() {
 		return s.handleRoot(claim)
@@ -30,33 +33,14 @@ func (s *Solver) NextMove(claim Claim) (*Claim, error) {
 	return s.handleMiddle(claim)
 }
 
-type StepData struct {
-	LeafClaim Claim
-	IsAttack  bool
-}
-
-// AttemptStep determines what step should occur for a given leaf claim.
-// An error will be returned if the claim is not at the max depth.
-func (s *Solver) AttemptStep(claim Claim) (StepData, error) {
-	if claim.Depth() != s.gameDepth {
-		return StepData{}, errors.New("cannot step on non-leaf claims")
-	}
-	claimCorrect, err := s.agreeWithClaim(claim.ClaimData)
-	if err != nil {
-		return StepData{}, err
-	}
-	return StepData{
-		LeafClaim: claim,
-		IsAttack:  claimCorrect,
-	}, nil
-}
-
 func (s *Solver) handleRoot(claim Claim) (*Claim, error) {
 	agree, err := s.agreeWithClaim(claim.ClaimData)
 	if err != nil {
 		return nil, err
 	}
 	// Attack the root claim if we do not agree with it
+	// Note: We always disagree with the claim level at this point,
+	// so if we agree with claim maybe we should also attack?
 	if !agree {
 		return s.attack(claim)
 	} else {
@@ -65,10 +49,6 @@ func (s *Solver) handleRoot(claim Claim) (*Claim, error) {
 }
 
 func (s *Solver) handleMiddle(claim Claim) (*Claim, error) {
-	parentCorrect, err := s.agreeWithClaim(claim.Parent)
-	if err != nil {
-		return nil, err
-	}
 	claimCorrect, err := s.agreeWithClaim(claim.ClaimData)
 	if err != nil {
 		return nil, err
@@ -76,25 +56,39 @@ func (s *Solver) handleMiddle(claim Claim) (*Claim, error) {
 	if claim.Depth() == s.gameDepth {
 		return nil, errors.New("game depth reached")
 	}
-	if parentCorrect && claimCorrect {
-		// We agree with the parent, but the claim is disagreeing with it.
-		// Since we agree with the claim, the difference must be to the right of the claim
+	if claimCorrect {
 		return s.defend(claim)
-	} else if parentCorrect && !claimCorrect {
-		// We agree with the parent, but the claim disagrees with it.
-		// Since we disagree with the claim, the difference must be to the left of the claim
-		return s.attack(claim)
-	} else if !parentCorrect && claimCorrect {
-		// Do nothing, we disagree with the parent, but this claim has correctly countered it
-		return nil, nil
-	} else if !parentCorrect && !claimCorrect {
-		// We disagree with the parent so want to counter it (which the claim is doing)
-		// but we also disagree with the claim so there must be a difference to the left of claim
-		// Note that we will create the correct counter-claim for parent when it is evaluated, no need to do it here
+	} else {
 		return s.attack(claim)
 	}
-	// This should not be reached
-	return nil, errors.New("no next move")
+}
+
+type StepData struct {
+	LeafClaim          Claim
+	IsAttack           bool
+	PreStateTraceIndex uint64
+}
+
+// AttemptStep determines what step should occur for a given leaf claim.
+// An error will be returned if the claim is not at the max depth.
+func (s *Solver) AttemptStep(claim Claim) (StepData, error) {
+	if claim.Depth() != s.gameDepth {
+		return StepData{}, errors.New("cannot step on non-leaf claims")
+	}
+	claimCorrect, err := s.agreeWithClaim(claim.ClaimData)
+	if err != nil {
+		return StepData{}, err
+	}
+	index := claim.TraceIndex(s.gameDepth)
+	// TODO(CLI-4198): Handle case where we dispute trace index 0
+	if !claimCorrect {
+		index -= 1
+	}
+	return StepData{
+		LeafClaim:          claim,
+		IsAttack:           !claimCorrect,
+		PreStateTraceIndex: index,
+	}, nil
 }
 
 // attack returns a response that attacks the claim.
@@ -107,6 +101,7 @@ func (s *Solver) attack(claim Claim) (*Claim, error) {
 	return &Claim{
 		ClaimData:           ClaimData{Value: value, Position: position},
 		Parent:              claim.ClaimData,
+		ParentContractIndex: claim.ContractIndex,
 	}, nil
 }
 
@@ -120,6 +115,7 @@ func (s *Solver) defend(claim Claim) (*Claim, error) {
 	return &Claim{
 		ClaimData:           ClaimData{Value: value, Position: position},
 		Parent:              claim.ClaimData,
+		ParentContractIndex: claim.ContractIndex,
 	}, nil
 }
 

op-challenger/fault/solver_test.go

@@ -4,9 +4,14 @@ import (
 	"testing"
 
 	"github.com/ethereum/go-ethereum/common"
+	"github.com/ethereum/go-ethereum/crypto"
 	"github.com/stretchr/testify/require"
 )
 
+func alphabetClaim(index uint64, letter string) common.Hash {
+	return crypto.Keccak256Hash(BuildAlphabetPreimage(index, letter))
+}
+
 // TestSolver_NextMove_Opponent tests the [Solver] NextMove function
 // with an [fault.AlphabetProvider] as the [TraceProvider].
 func TestSolver_NextMove_Opponent(t *testing.T) {
@@ -18,73 +23,87 @@ func TestSolver_NextMove_Opponent(t *testing.T) {
 	// The following claims are created using the state: "abcdexyz".
 	// The responses are the responses we expect from the solver.
 	indices := []struct {
-		traceIndex int
 		claim    Claim
 		response ClaimData
 	}{
 		{
-			7,
 			Claim{
 				ClaimData: ClaimData{
-					Value:    common.HexToHash("0x000000000000000000000000000000000000000000000000000000000000077a"),
+					Value:    alphabetClaim(7, "z"),
 					Position: NewPosition(0, 0),
 				},
 				// Root claim has no parent
 			},
 			ClaimData{
-				Value:    common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000364"),
+				Value:    alphabetClaim(3, "d"),
 				Position: NewPosition(1, 0),
 			},
 		},
 		{
-			3,
 			Claim{
 				ClaimData: ClaimData{
-					Value:    common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000364"),
+					Value:    alphabetClaim(3, "d"),
 					Position: NewPosition(1, 0),
 				},
 				Parent: ClaimData{
-					Value:    common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000768"),
+					Value:    alphabetClaim(7, "h"),
 					Position: NewPosition(0, 0),
 				},
 			},
 			ClaimData{
-				Value:    common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000566"),
+				Value:    alphabetClaim(5, "f"),
 				Position: NewPosition(2, 2),
 			},
 		},
 		{
-			5,
 			Claim{
 				ClaimData: ClaimData{
-					Value:    common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000578"),
+					Value:    alphabetClaim(5, "x"),
 					Position: NewPosition(2, 2),
 				},
 				Parent: ClaimData{
-					Value:    common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000768"),
+					Value:    alphabetClaim(7, "h"),
 					Position: NewPosition(1, 1),
 				},
 			},
 			ClaimData{
-				Value:    common.HexToHash("0x0000000000000000000000000000000000000000000000000000000000000465"),
+				Value:    alphabetClaim(4, "e"),
 				Position: NewPosition(3, 4),
 			},
 		},
 	}
 
 	for _, test := range indices {
-		res, err := solver.NextMove(test.claim)
+		res, err := solver.NextMove(test.claim, false)
 		require.NoError(t, err)
 		require.Equal(t, test.response, res.ClaimData)
 	}
 }
 
+func TestNoMoveAgainstOwnLevel(t *testing.T) {
+	maxDepth := 3
+	mallory := NewAlphabetProvider("abcdepqr", uint64(maxDepth))
+	solver := NewSolver(maxDepth, mallory)
+
+	claim := Claim{
+		ClaimData: ClaimData{
+			Value:    alphabetClaim(7, "z"),
+			Position: NewPosition(0, 0),
+		},
+		// Root claim has no parent
+	}
+
+	move, err := solver.NextMove(claim, true)
+	require.Nil(t, move)
+	require.Nil(t, err)
+}
+
 func TestAttemptStep(t *testing.T) {
 	maxDepth := 3
 	canonicalProvider := NewAlphabetProvider("abcdefgh", uint64(maxDepth))
 	solver := NewSolver(maxDepth, canonicalProvider)
 	root, top, middle, bottom := createTestClaims()
-	g := NewGameState(root, testMaxDepth)
+	g := NewGameState(false, root, testMaxDepth)
 	require.NoError(t, g.Put(top))
 	require.NoError(t, g.Put(middle))
 	require.NoError(t, g.Put(bottom))

op-challenger/flags/flags.go

@@ -33,6 +33,11 @@ var (
 		Usage:   "Alphabet Trace (temporary)",
 		EnvVars: prefixEnvVars("ALPHABET"),
 	}
+	AgreeWithProposedOutputFlag = &cli.BoolFlag{
+		Name:    "agree-with-proposed-output",
+		Usage:   "Temporary hardcoded flag if we agree or disagree with the proposed output.",
+		EnvVars: prefixEnvVars("AGREE_WITH_PROPOSED_OUTPUT"),
+	}
 	// Optional Flags
 )
 
@@ -41,6 +46,7 @@ var requiredFlags = []cli.Flag{
 	L1EthRpcFlag,
 	DGFAddressFlag,
 	AlphabetFlag,
+	AgreeWithProposedOutputFlag,
 }
 
 // optionalFlags is a list of unchecked cli flags

op-challenger/init_game.sh

+#!/bin/bash
+set -euo pipefail
+
+DIR=$(cd $(dirname "${BASH_SOURCE[0]}") && pwd)
+cd "$DIR"
+
+# build the challenger to keep it up to date
+make
+
+cd ..
+
+make devnet-clean
+make devnet-up-deploy
+
+DEVNET_SPONSOR="ac0974bec39a17e36ba4a6b4d238ff944bacb478cbed5efcae784d7bf4f2ff80"
+DISPUTE_GAME_PROXY="0xB7f8BC63BbcaD18155201308C8f3540b07f84F5e"
+
+CHARLIE_ADDRESS="0xF45B7537828CB2fffBC69996B054c2Aaf36DC778"
+CHARLIE_KEY="74feb147d72bfae943e6b4e483410933d9e447d5dc47d52432dcc2c1454dabb7"
+
+MALLORY_ADDRESS="0x4641c704a6c743f73ee1f36C7568Fbf4b80681e4"
+MALLORY_KEY="28d7045146193f5f4eeb151c4843544b1b0d30a7ac1680c845a416fac65a7715"
+
+
+
+echo "----------------------------------------------------------------"
+echo " - Fetching balance of the sponsor"
+echo " - Balance: $(cast balance 0xf39Fd6e51aad88F6F4ce6aB8827279cffFb92266)"
+echo "----------------------------------------------------------------"
+
+
+echo "Funding Charlie"
+cast send $CHARLIE_ADDRESS --value 5ether --private-key $DEVNET_SPONSOR
+
+echo "Funding Mallory"
+cast send $MALLORY_ADDRESS --value 5ether --private-key $DEVNET_SPONSOR
+
+
+# Fault game type = 0
+GAME_TYPE=0
+# Root claim commits to the entire trace.
+# Alphabet game claim construction: keccak256(abi.encode(trace_index, trace[trace_index]))
+ROOT_CLAIM=$(cast keccak $(cast abi-encode "f(uint256,uint256)" 15 122))
+# Extra data is a dynamic `bytes` type that contains the L2 Block Number of the output proposal that the root claim disagrees with
+# Doesn't matter right now since we're not deleting outputs, so just set it to 1
+EXTRA_DATA=$(cast to-bytes32 1)
+
+
+
+echo "Initializing the game"
+cast call --private-key $MALLORY_KEY $DISPUTE_GAME_PROXY "create(uint8,bytes32,bytes)" $GAME_TYPE $ROOT_CLAIM $EXTRA_DATA
+cast send --private-key $MALLORY_KEY $DISPUTE_GAME_PROXY "create(uint8,bytes32,bytes)" $GAME_TYPE $ROOT_CLAIM $EXTRA_DATA

op-challenger/mallory.sh

+#!/bin/bash
+set -euo pipefail
+
+
+DIR=$(cd $(dirname "${BASH_SOURCE[0]}") && pwd)
+cd "$DIR"
+
+DISPUTE_GAME_PROXY="0xB7f8BC63BbcaD18155201308C8f3540b07f84F5e"
+
+CHARLIE_ADDRESS="0xF45B7537828CB2fffBC69996B054c2Aaf36DC778"
+CHARLIE_KEY="74feb147d72bfae943e6b4e483410933d9e447d5dc47d52432dcc2c1454dabb7"
+
+MALLORY_ADDRESS="0x4641c704a6c743f73ee1f36C7568Fbf4b80681e4"
+MALLORY_KEY="28d7045146193f5f4eeb151c4843544b1b0d30a7ac1680c845a416fac65a7715"
+
+FAULT_GAME_ADDRESS="0x8daf17a20c9dba35f005b6324f493785d239719d"
+
+./bin/op-challenger --l1-eth-rpc http://localhost:8545 --alphabet "abcdexyz" --game-address $FAULT_GAME_ADDRESS --private-key $MALLORY_KEY --num-confirmations 1 --agree-with-proposed-output=false

op-challenger/visualize.sh

+#!/bin/bash
+
+set -euo pipefail
+
+DISPUTE_GAME_PROXY="0xB7f8BC63BbcaD18155201308C8f3540b07f84F5e"
+
+FAULT_GAME_ADDRESS="0x8daf17a20c9dba35f005b6324f493785d239719d"
+
+dir=$(cd $(dirname "${BASH_SOURCE[0]}") && pwd)
+cd "$dir"
+cd ../packages/contracts-bedrock
+
+forge script scripts/FaultDisputeGameViz.s.sol --sig "remote(address)" $FAULT_GAME_ADDRESS --fork-url http://localhost:8545
+mv dispute_game.svg "$dir"

op-node/rollup/derive/frame.go

@@ -27,7 +27,7 @@ type Frame struct {
 	ID          ChannelID `json:"id"`
 	FrameNumber uint16    `json:"frame_number"`
 	Data        []byte    `json:"data"`
-	IsLast      bool      `'json:"is_last"`
+	IsLast      bool      `json:"is_last"`
 }
 
 // MarshalBinary writes the frame to `w`.

ops/check-changed/main.py

@@ -3,6 +3,7 @@ import os
 import re
 import subprocess
 import sys
+import json
 
 from github import Github
 
@@ -13,9 +14,11 @@ REBUILD_ALL_PATTERNS = [
     r'ops/check-changed/.*',
     r'^go\.mod',
     r'^go\.sum',
-    r'^pnpm-lock\.yaml',
     r'ops/check-changed/.*'
 ]
+with open("../../nx.json") as file:
+    nx_json_data = json.load(file)
+REBUILD_ALL_PATTERNS += nx_json_data["implicitDependencies"].keys()
 
 WHITELISTED_BRANCHES = {
     'master',

packages/contracts-bedrock/.gas-snapshot

@@ -331,6 +331,9 @@ OptimismPortal_Test:test_receive_succeeds() (gas: 127513)
 OptimismPortal_Test:test_simple_isOutputFinalized_succeeds() (gas: 32971)
 OptimismPortal_Test:test_unpause_onlyGuardian_reverts() (gas: 46098)
 OptimismPortal_Test:test_unpause_succeeds() (gas: 31756)
+PreimageOracle_Test:test_computePreimageKey_succeeds() (gas: 6267)
+PreimageOracle_Test:test_loadKeccak256PreimagePart_outOfBoundsOffset_reverts() (gas: 9025)
+PreimageOracle_Test:test_loadKeccak256PreimagePart_succeeds() (gas: 77552)
 ProxyAdmin_Test:test_chugsplashChangeProxyAdmin_succeeds() (gas: 35586)
 ProxyAdmin_Test:test_chugsplashGetProxyAdmin_succeeds() (gas: 15675)
 ProxyAdmin_Test:test_chugsplashGetProxyImplementation_succeeds() (gas: 51084)

packages/contracts-bedrock/contracts/cannon/PreimageOracle.sol

 // SPDX-License-Identifier: MIT
-pragma solidity 0.8.15;
+pragma solidity ^0.8.15;
 
+/// @title PreimageOracle
+/// @notice A contract for storing permissioned pre-images.
 contract PreimageOracle {
+    /// @notice Mapping of pre-image keys to pre-image lengths.
     mapping(bytes32 => uint256) public preimageLengths;
+
+    /// @notice Mapping of pre-image keys to pre-image parts.
     mapping(bytes32 => mapping(uint256 => bytes32)) public preimageParts;
+
+    /// @notice Mapping of pre-image keys to pre-image part offsets.
     mapping(bytes32 => mapping(uint256 => bool)) public preimagePartOk;
 
-    function readPreimage(bytes32 key, uint256 offset)
+    /// @notice Reads a pre-image from the oracle.
+    /// @param _key The key of the pre-image to read.
+    /// @param _offset The offset of the pre-image to read.
+    /// @return dat_ The pre-image data.
+    /// @return datLen_ The length of the pre-image data.
+    function readPreimage(bytes32 _key, uint256 _offset)
         external
         view
-        returns (bytes32 dat, uint256 datLen)
+        returns (bytes32 dat_, uint256 datLen_)
     {
-        require(preimagePartOk[key][offset], "preimage must exist");
-        datLen = 32;
-        uint256 length = preimageLengths[key];
-        // add 8 for the length-prefix part
-        if (offset + 32 >= length + 8) {
-            datLen = length + 8 - offset;
+        require(preimagePartOk[_key][_offset], "pre-image must exist");
+
+        // Calculate the length of the pre-image data
+        // Add 8 for the length-prefix part
+        datLen_ = 32;
+        uint256 length = preimageLengths[_key];
+        if (_offset + 32 >= length + 8) {
+            datLen_ = length + 8 - _offset;
         }
-        dat = preimageParts[key][offset];
+
+        // Retrieve the pre-image data
+        dat_ = preimageParts[_key][_offset];
     }
 
     // TODO(CLI-4104):
@@ -37,17 +53,47 @@ contract PreimageOracle {
         preimageLengths[key] = size;
     }
 
-    // loadKeccak256PreimagePart prepares the pre-image to be read by keccak256 key,
-    // starting at the given offset, up to 32 bytes (clipped at preimage length, if out of data).
-    function loadKeccak256PreimagePart(uint256 partOffset, bytes calldata preimage) external {
+    /// @notice Computes and returns the key for a pre-image.
+    /// @param _preimage The pre-image.
+    /// @return key_ The pre-image key.
+    function computePreimageKey(bytes calldata _preimage) external pure returns (bytes32 key_) {
+        uint256 size;
+        assembly {
+            size := calldataload(0x24)
+
+            // Leave slots 0x40 and 0x60 untouched,
+            // and everything after as scratch-memory.
+            let ptr := 0x80
+
+            // Store size as a big-endian uint64 at the start of pre-image
+            mstore(ptr, shl(192, size))
+            ptr := add(ptr, 8)
+
+            // Copy preimage payload into memory so we can hash and read it.
+            calldatacopy(ptr, _preimage.offset, size)
+
+            // Compute the pre-image keccak256 hash (aka the pre-image key)
+            let h := keccak256(ptr, size)
+
+            // Mask out prefix byte, replace with type 2 byte
+            key_ := or(and(h, not(shl(248, 0xFF))), shl(248, 2))
+        }
+    }
+
+    /// @notice Prepares a pre-image to be read by keccak256 key, starting at
+    ///         the given offset and up to 32 bytes (clipped at pre-image length, if out of data).
+    /// @param _partOffset The offset of the pre-image to read.
+    /// @param _preimage The preimage data.
+    function loadKeccak256PreimagePart(uint256 _partOffset, bytes calldata _preimage) external {
         uint256 size;
         bytes32 key;
         bytes32 part;
         assembly {
             // len(sig) + len(partOffset) + len(preimage offset) = 4 + 32 + 32 = 0x44
             size := calldataload(0x44)
-            // revert if part offset >= size+8 (i.e. parts must be within bounds)
-            if iszero(lt(partOffset, add(size, 8))) {
+
+            // revert if part offset > size+8 (i.e. parts must be within bounds)
+            if gt(_partOffset, add(size, 8)) {
                 revert(0, 0)
             }
             // we leave solidity slots 0x40 and 0x60 untouched,
@@ -57,16 +103,16 @@ contract PreimageOracle {
             mstore(ptr, shl(192, size))
             ptr := add(ptr, 8)
             // copy preimage payload into memory so we can hash and read it.
-            calldatacopy(ptr, preimage.offset, size)
+            calldatacopy(ptr, _preimage.offset, size)
             // Note that it includes the 8-byte big-endian uint64 length prefix.
             // this will be zero-padded at the end, since memory at end is clean.
-            part := mload(add(sub(ptr, 8), partOffset))
+            part := mload(add(sub(ptr, 8), _partOffset))
             let h := keccak256(ptr, size) // compute preimage keccak256 hash
             // mask out prefix byte, replace with type 2 byte
             key := or(and(h, not(shl(248, 0xFF))), shl(248, 2))
         }
-        preimagePartOk[key][partOffset] = true;
-        preimageParts[key][partOffset] = part;
+        preimagePartOk[key][_partOffset] = true;
+        preimageParts[key][_partOffset] = part;
         preimageLengths[key] = size;
     }
 }

packages/contracts-bedrock/contracts/cannon/interfaces/IPreimageOracle.sol

+// SPDX-License-Identifier: MIT
+pragma solidity 0.7.6;
+
+/// @title IPreimageOracle
+/// @notice Interface for a preimage oracle.
+interface IPreimageOracle {
+    /// @notice Reads a preimage from the oracle.
+    /// @param _key The key of the preimage to read.
+    /// @param _offset The offset of the preimage to read.
+    /// @return dat_ The preimage data.
+    /// @return datLen_ The length of the preimage data.
+    function readPreimage(bytes32 _key, uint256 _offset)
+        external
+        view
+        returns (bytes32 dat_, uint256 datLen_);
+
+    /// @notice Computes and returns the key for a pre-image.
+    /// @param _preimage The pre-image.
+    /// @return key_ The pre-image key.
+    function computePreimageKey(bytes calldata _preimage) external pure returns (bytes32 key_);
+
+    /// @notice Prepares a preimage to be read by keccak256 key, starting at
+    ///         the given offset and up to 32 bytes (clipped at preimage length, if out of data).
+    /// @param _partOffset The offset of the preimage to read.
+    /// @param _preimage The preimage data.
+    function loadKeccak256PreimagePart(uint256 _partOffset, bytes calldata _preimage) external;
+}

packages/contracts-bedrock/contracts/test/PreimageOracle.t.sol

+// SPDX-License-Identifier: MIT
+pragma solidity ^0.8.15;
+
+import { Test } from "forge-std/Test.sol";
+
+import { PreimageOracle } from "../cannon/PreimageOracle.sol";
+
+contract PreimageOracle_Test is Test {
+    PreimageOracle oracle;
+
+    /// @notice Sets up the testing suite.
+    function setUp() public {
+        oracle = new PreimageOracle();
+        vm.label(address(oracle), "PreimageOracle");
+    }
+
+    /// @notice Test the pre-image key computation with a known pre-image.
+    function test_computePreimageKey_succeeds() public {
+        bytes memory preimage = hex"deadbeef";
+        bytes32 key = oracle.computePreimageKey(preimage);
+        bytes32 known = 0x02fd4e189132273036449fc9e11198c739161b4c0116a9a2dccdfa1c492006f1;
+        assertEq(key, known);
+    }
+
+    /// @notice Tests that a pre-image is correctly set.
+    function test_loadKeccak256PreimagePart_succeeds() public {
+        // Set the pre-image
+        bytes memory preimage = hex"deadbeef";
+        bytes32 key = oracle.computePreimageKey(preimage);
+        uint256 offset = 0;
+        oracle.loadKeccak256PreimagePart(offset, preimage);
+
+        // Validate the pre-image part
+        bytes32 part = oracle.preimageParts(key, offset);
+        bytes32 expectedPart = 0x0000000000000004deadbeef0000000000000000000000000000000000000000;
+        assertEq(part, expectedPart);
+
+        // Validate the pre-image length
+        uint256 length = oracle.preimageLengths(key);
+        assertEq(length, preimage.length);
+
+        // Validate that the pre-image part is set
+        bool ok = oracle.preimagePartOk(key, offset);
+        assertTrue(ok);
+    }
+
+    /// @notice Tests that a pre-image cannot be set with an out-of-bounds offset.
+    function test_loadKeccak256PreimagePart_outOfBoundsOffset_reverts() public {
+        bytes memory preimage = hex"deadbeef";
+        uint256 offset = preimage.length + 9;
+
+        vm.expectRevert();
+        oracle.loadKeccak256PreimagePart(offset, preimage);
+    }
+
+    /// @notice Reading a pre-image part that has not been set should revert.
+    function testFuzz_readPreimage_missingPreimage_reverts(bytes32 key, uint256 offset) public {
+        vm.expectRevert("pre-image must exist");
+        oracle.readPreimage(key, offset);
+    }
+}