✨ feat: add config handling to settler application

Introduce a new configuration package to manage SettlerEngine's settings and integrate it into the main application. This update adds functionality to load, save, and prompt for configuration values, which enhances the app's configurability and user experience.

Author: nathfavour

cmd/settler/main.go

@@ -17,6 +17,7 @@ import (
 	"github.com/nathfavour/settlerengine/internal/adapters/crypto/mantle"
 	"github.com/nathfavour/settlerengine/internal/domain"
 	"github.com/nathfavour/settlerengine/pkg/anyisland"
+	"github.com/nathfavour/settlerengine/pkg/config"
 	"github.com/nathfavour/settlerengine/pkg/crypto"
 	"github.com/nathfavour/settlerengine/pkg/storage"
 	"github.com/nathfavour/settlerengine/pkg/uds"
@@ -46,6 +47,8 @@ func main() {
 		runPay(os.Args[2:])
 	case "demo":
 		runDemo(os.Args[2:])
+	case "config":
+		runConfig(os.Args[2:])
 	case "help":
 		printUsage()
 	default:
@@ -64,27 +67,72 @@ func printUsage() {
 	fmt.Println("  facilitator  Start the settlement facilitator daemon")
 	fmt.Println("  pay          Execute a policy-protected payment")
 	fmt.Println("  demo         Run a full agentic demo with Mantle on-chain anchoring")
+	fmt.Println("  config       Interactively configure SettlerEngine")
 	fmt.Println("  help         Show this help message")
 }
 
+func runConfig(args []string) {
+	cfg, err := config.LoadConfig()
+	if err != nil {
+		// Default config if none exists
+		cfg = &config.SettlerConfig{
+			RPCURL:          "https://rpc.sepolia.mantle.xyz",
+			RegistryAddress: "0x33aE8331a2406EEc3A33483001aC5650DA2e0662",
+			AgentID:         "42",
+		}
+	}
+
+	cfg.Prompt()
+
+	if err := config.SaveConfig(cfg); err != nil {
+		log.Fatalf("❌ Failed to save config: %v", err)
+	}
+
+	path, _ := config.GetConfigPath()
+	fmt.Printf("✅ Configuration saved to: %s\n", path)
+}
+
 func runDemo(args []string) {
 	fmt.Println("🎬 Starting SettlerEngine Agentic Demo...")
 
+	cfg, _ := config.LoadConfig()
+	if cfg == nil {
+		cfg = &config.SettlerConfig{}
+	}
+
 	privKey := os.Getenv("PRIVATE_KEY")
 	if privKey == "" {
-		log.Fatal("❌ PRIVATE_KEY environment variable is required for demo")
+		privKey = cfg.PrivateKey
+	}
+	if privKey == "" {
+		log.Fatal("❌ PRIVATE_KEY required (set env or run 'settler config')")
+	}
+
+	rpcURL := cfg.RPCURL
+	if rpcURL == "" {
+		rpcURL = "https://rpc.sepolia.mantle.xyz"
+	}
+
+	registryAddr := cfg.RegistryAddress
+	if registryAddr == "" {
+		registryAddr = "0x33aE8331a2406EEc3A33483001aC5650DA2e0662"
+	}
+
+	agentIDStr := cfg.AgentID
+	if agentIDStr == "" {
+		agentIDStr = "42"
 	}
+	agentID, _ := new(big.Int).SetString(agentIDStr, 10)
 
 	// 1. ERC-8004 Identity Resolution
 	fmt.Println("🤖 [1/3] Resolving Agent Identity (ERC-8004)...")
 	registry, _ := erc8004.NewRegistryClient(
-		"https://rpc.sepolia.mantle.xyz",
+		rpcURL,
 		common.HexToAddress("0x8004000000000000000000000000000000000001"),
 		common.HexToAddress("0x8004000000000000000000000000000000000002"),
 		common.HexToAddress("0x8004000000000000000000000000000000000003"),
 	)
 
-	agentID := big.NewInt(42)
 	identity, _ := registry.ResolveAgent(context.Background(), agentID)
 	fmt.Printf("✅ Identity Verified: %s\n", identity.Metadata.Name)
 
@@ -104,8 +152,8 @@ func runDemo(args []string) {
 	// 3. Mantle On-Chain Anchoring
 	fmt.Println("⚓ [3/3] Anchoring transaction to Mantle Sepolia...")
 	mantleClient, err := mantle.NewRegistryClient(
-		"https://rpc.sepolia.mantle.xyz",
-		common.HexToAddress("0x33aE8331a2406EEc3A33483001aC5650DA2e0662"),
+		rpcURL,
+		common.HexToAddress(registryAddr),
 		big.NewInt(5003),
 	)
 	if err != nil {

pkg/config/config.go

@@ -0,0 +1,87 @@
+package config
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+	"path/filepath"
+)
+
+type SettlerConfig struct {
+	RPCURL          string `json:"rpc_url"`
+	PrivateKey      string `json:"private_key"`
+	RegistryAddress string `json:"registry_address"`
+	AgentID         string `json:"agent_id"`
+}
+
+func GetConfigPath() (string, error) {
+	configDir, err := os.UserConfigDir()
+	if err != nil {
+		return "", err
+	}
+	dir := filepath.Join(configDir, "settlerengine")
+	if err := os.MkdirAll(dir, 0755); err != nil {
+		return "", err
+	}
+	return filepath.Join(dir, "config.json"), nil
+}
+
+func LoadConfig() (*SettlerConfig, error) {
+	path, err := GetConfigPath()
+	if err != nil {
+		return nil, err
+	}
+	data, err := os.ReadFile(path)
+	if err != nil {
+		return nil, err
+	}
+	var cfg SettlerConfig
+	if err := json.Unmarshal(data, &cfg); err != nil {
+		return nil, err
+	}
+	return &cfg, nil
+}
+
+func SaveConfig(cfg *SettlerConfig) error {
+	path, err := GetConfigPath()
+	if err != nil {
+		return err
+	}
+	data, err := json.MarshalIndent(cfg, "", "  ")
+	if err != nil {
+		return err
+	}
+	return os.WriteFile(path, data, 0600)
+}
+
+func (c *SettlerConfig) Prompt() {
+	fmt.Println("⚙️ SettlerEngine Configuration Setup")
+	
+	fmt.Printf("Ethereum RPC URL [%s]: ", c.RPCURL)
+	var rpc string
+	fmt.Scanln(&rpc)
+	if rpc != "" {
+		c.RPCURL = rpc
+	}
+
+	fmt.Printf("Private Key (hex) [hidden]: ")
+	var key string
+	fmt.Scanln(&key)
+	if key != "" {
+		c.PrivateKey = key
+	}
+
+	fmt.Printf("Registry Contract Address [%s]: ", c.RegistryAddress)
+	var reg string
+	fmt.Scanln(&reg)
+	if reg != "" {
+		c.RegistryAddress = reg
+	}
+
+	fmt.Printf("Agent ID [%s]: ", c.AgentID)
+	var id string
+	fmt.Scanln(&id)
+	if id != "" {
+		c.AgentID = id
+	}
+}