fix(cli): tighten chain command validation

Co-Authored-By: Charon <charon@lethean.io>

chain_commands.go

@@ -6,6 +6,8 @@
 package blockchain
 
 import (
+	"fmt"
+	"net"
 	"os"
 	"path/filepath"
 
@@ -75,3 +77,16 @@ func ensureChainDataDirExists(dataDir string) error {
 	}
 	return nil
 }
+
+func validateChainOptions(dataDir, seed string) error {
+	if dataDir == "" {
+		return coreerr.E("validateChainOptions", "data dir is required", nil)
+	}
+	if seed == "" {
+		return coreerr.E("validateChainOptions", "seed is required", nil)
+	}
+	if _, _, err := net.SplitHostPort(seed); err != nil {
+		return coreerr.E("validateChainOptions", fmt.Sprintf("seed %q must be host:port", seed), err)
+	}
+	return nil
+}

commands_test.go

@@ -46,3 +46,68 @@ func TestAddChainCommands_Good_PersistentFlags(t *testing.T) {
 	assert.NotNil(t, chainCmd.PersistentFlags().Lookup("seed"))
 	assert.NotNil(t, chainCmd.PersistentFlags().Lookup("testnet"))
 }
+
+func TestValidateChainOptions_Good(t *testing.T) {
+	err := validateChainOptions("/tmp/lethean", "seed.example:36942")
+	require.NoError(t, err)
+}
+
+func TestValidateChainOptions_Bad(t *testing.T) {
+	tests := []struct {
+		name    string
+		dataDir string
+		seed    string
+		want    string
+	}{
+		{name: "missing data dir", dataDir: "", seed: "seed.example:36942", want: "data dir is required"},
+		{name: "missing seed", dataDir: "/tmp/lethean", seed: "", want: "seed is required"},
+		{name: "malformed seed", dataDir: "/tmp/lethean", seed: "seed.example", want: "must be host:port"},
+	}
+
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			err := validateChainOptions(tt.dataDir, tt.seed)
+			require.Error(t, err)
+			assert.Contains(t, err.Error(), tt.want)
+		})
+	}
+}
+
+func TestChainSyncCommand_BadMutuallyExclusiveFlags(t *testing.T) {
+	dataDir := t.TempDir()
+	seed := "seed.example:36942"
+	testnet := false
+
+	cmd := newChainSyncCommand(&dataDir, &seed, &testnet)
+	cmd.SetArgs([]string{"--daemon", "--stop"})
+
+	err := cmd.Execute()
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "cannot be combined")
+}
+
+func TestChainSyncCommand_BadArgsRejected(t *testing.T) {
+	dataDir := t.TempDir()
+	seed := "seed.example:36942"
+	testnet := false
+
+	cmd := newChainSyncCommand(&dataDir, &seed, &testnet)
+	cmd.SetArgs([]string{"extra"})
+
+	err := cmd.Execute()
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "unknown command")
+}
+
+func TestChainExplorerCommand_BadSeedRejected(t *testing.T) {
+	dataDir := t.TempDir()
+	seed := "bad-seed"
+	testnet := false
+
+	cmd := newChainExplorerCommand(&dataDir, &seed, &testnet)
+	cmd.SetArgs(nil)
+
+	err := cmd.Execute()
+	require.Error(t, err)
+	assert.Contains(t, err.Error(), "must be host:port")
+}

explorer_command.go

@@ -34,6 +34,10 @@ func newChainExplorerCommand(dataDir, seed *string, testnet *bool) *cobra.Comman
 		Use:   "explorer",
 		Short: "TUI block explorer",
 		Long:  "Interactive terminal block explorer with live sync status.",
+		Args:  cobra.NoArgs,
+		PreRunE: func(cmd *cobra.Command, args []string) error {
+			return validateChainOptions(*dataDir, *seed)
+		},
 		RunE: func(cmd *cobra.Command, args []string) error {
 			return runChainExplorer(*dataDir, *seed, *testnet)
 		},

sync_command.go

@@ -42,6 +42,13 @@ func newChainSyncCommand(dataDir, seed *string, testnet *bool) *cobra.Command {
 		Use:   "sync",
 		Short: "Headless P2P chain sync",
 		Long:  "Sync the blockchain from P2P peers without the TUI explorer.",
+		Args:  cobra.NoArgs,
+		PreRunE: func(cmd *cobra.Command, args []string) error {
+			if daemon && stop {
+				return coreerr.E("newChainSyncCommand", "flags --daemon and --stop cannot be combined", nil)
+			}
+			return validateChainOptions(*dataDir, *seed)
+		},
 		RunE: func(cmd *cobra.Command, args []string) error {
 			if stop {
 				return stopChainSyncDaemon(*dataDir)