Make L2 predeploys configurable via --l2-predeploy-json for opstack genesis

README.md

@@ -50,6 +50,7 @@ Flags:
 
 - `--external-builder`: URL of an external builder to use (enables rollup-boost)
 - `--enable-latest-fork` (int): Enables the latest fork (isthmus) at startup (0) or n blocks after genesis.
+- `--predeploy-json` (string[]): One or more paths to JSON files describing L2 predeploy accounts to inject into the L2 genesis (e.g. EntryPoint, paymasters, custom system contracts).
 
 ### Example Commands
 

playground/artifacts.go

@@ -65,6 +65,10 @@ type ArtifactsBuilder struct {
 	genesisDelay      uint64
 	applyLatestL2Fork *uint64
 	OpblockTime       uint64
+
+	// JSON files describing additional L2 predeploy accounts to inject into
+	// the L2 genesis alloc (e.g. EntryPoint, paymasters, or other system contracts).
+	predeployJSONFiles []string
 }
 
 func NewArtifactsBuilder() *ArtifactsBuilder {
@@ -101,6 +105,14 @@ func (b *ArtifactsBuilder) OpBlockTime(blockTimeSeconds uint64) *ArtifactsBuilde
 	return b
 }
 
+// PredeployJSONFiles configures the builder with one or more JSON files
+// that each describe a single L2 predeploy account to inject into the
+// L2 genesis alloc.
+func (b *ArtifactsBuilder) PredeployJSONFiles(files []string) *ArtifactsBuilder {
+	b.predeployJSONFiles = files
+	return b
+}
+
 type Artifacts struct {
 	Out *output
 }
@@ -295,6 +307,27 @@ func (b *ArtifactsBuilder) Build() (*Artifacts, error) {
 			}
 		}
 
+		// Inject any additional L2 predeploy accounts provided via JSON files.
+		for _, path := range b.predeployJSONFiles {
+			data, err := os.ReadFile(path)
+			if err != nil {
+				return nil, fmt.Errorf("failed to read L2 predeploy JSON %q: %w", path, err)
+			}
+
+			genesisAllocMap, err := loadPredeployAlloc(data)
+			if err != nil {
+				return nil, fmt.Errorf("failed to load L2 predeploy from %q: %w", path, err)
+			}
+
+			for addr, account := range genesisAllocMap {
+				if _, exists := allocs[addr.String()]; exists {
+					return nil, fmt.Errorf("L2 predeploy address %s already exists in allocs, cannot inject duplicate address", addr.String())
+				}
+
+				allocs[addr.String()] = account
+			}
+		}
+
 		newOpGenesis, err := overrideJSON(opGenesis, input)
 		if err != nil {
 			return nil, err
@@ -348,6 +381,27 @@ func (b *ArtifactsBuilder) Build() (*Artifacts, error) {
 	return &Artifacts{Out: out}, nil
 }
 
+// PredeployAlloc is a generic JSON schema for describing a single L2
+// predeploy account to be injected into the L2 genesis alloc.
+
+// loadPredeployAlloc parses a JSON blob describing a single L2 predeploy
+// account and returns the address plus a genesis alloc entry.
+func loadPredeployAlloc(raw []byte) (types.GenesisAlloc, error) {
+	if len(raw) == 0 {
+		return nil, fmt.Errorf("predeploy JSON is empty")
+	}
+
+	var genesisAllocMap types.GenesisAlloc
+	err := genesisAllocMap.UnmarshalJSON(raw)
+	if err != nil {
+		return nil, fmt.Errorf("failed to unmarshal predeploy JSON: %w", err)
+	}
+
+	// Validation helpers (kept local; could also live in utils.go)
+
+	return genesisAllocMap, nil
+}
+
 type OpGenesisTmplInput struct {
 	Timestamp  uint64
 	LatestFork *uint64

playground/recipe_opstack.go

@@ -36,6 +36,11 @@ type OpRecipe struct {
 
 	// whether to enable websocket proxy
 	enableWebsocketProxy bool
+
+	// JSON files describing L2 predeploy accounts to inject into L2 genesis
+	// (e.g. ERC-4337 EntryPoint, paymasters, or other system contracts).
+	// Each file should define a single account in a simple JSON format.
+	l2PredeployJSON []string
 }
 
 func (o *OpRecipe) Name() string {
@@ -56,13 +61,22 @@ func (o *OpRecipe) Flags() *flag.FlagSet {
 	flags.BoolVar(&o.baseOverlay, "base-overlay", false, "Whether to use base implementation for flashblocks-rpc")
 	flags.StringVar(&o.flashblocksBuilderURL, "flashblocks-builder", "", "External URL of builder flashblocks stream")
 	flags.BoolVar(&o.enableWebsocketProxy, "enable-websocket-proxy", false, "Whether to enable websocket proxy")
+	flags.StringArrayVar(
+		&o.l2PredeployJSON,
+		"predeploy-json",
+		nil,
+		"Path(s) to JSON file(s) describing L2 predeploy accounts injected into L2 genesis (e.g. EntryPoint)",
+	)
 	return flags
 }
 
 func (o *OpRecipe) Artifacts() *ArtifactsBuilder {
 	builder := NewArtifactsBuilder()
 	builder.ApplyLatestL2Fork(o.enableLatestFork)
 	builder.OpBlockTime(o.blockTime)
+	if len(o.l2PredeployJSON) > 0 {
+		builder.PredeployJSONFiles(o.l2PredeployJSON)
+	}
 	return builder
 }