fix: suppress banner in completion and redirected output

cmd/picoclaw/main.go

@@ -9,8 +9,10 @@ package main
 import (
 	"fmt"
 	"os"
+	"strings"
 
 	"github.com/spf13/cobra"
+	"golang.org/x/term"
 
 	"github.com/sipeed/picoclaw/cmd/picoclaw/internal"
 	"github.com/sipeed/picoclaw/cmd/picoclaw/internal/agent"
@@ -52,6 +54,7 @@ func NewPicoclawCommand() *cobra.Command {
 const (
 	colorBlue   = "\033[1;38;2;62;93;185m"
 	colorRed    = "\033[1;38;2;213;70;70m"
+	noBannerEnv = "PICOCLAW_NO_BANNER"
 	banner      = "\r\n" +
 		colorBlue + "██████╗ ██╗ ██████╗ ██████╗ " + colorRed + " ██████╗██╗      █████╗ ██╗    ██╗\n" +
 		colorBlue + "██╔══██╗██║██╔════╝██╔═══██╗" + colorRed + "██╔════╝██║     ██╔══██╗██║    ██║\n" +
@@ -62,8 +65,35 @@ const (
 		"\033[0m\r\n"
 )
 
+func bannerDisabledByEnv() bool {
+	value := strings.TrimSpace(strings.ToLower(os.Getenv(noBannerEnv)))
+	switch value {
+	case "", "0", "false", "no", "off":
+		return false
+	default:
+		return true
+	}
+}
+
+func shouldPrintBanner(args []string, stdoutIsTerminal bool) bool {
+	if bannerDisabledByEnv() || !stdoutIsTerminal {
+		return false
+	}
+
+	if len(args) > 1 {
+		switch args[1] {
+		case "completion", cobra.ShellCompRequestCmd, cobra.ShellCompNoDescRequestCmd:
+			return false
+		}
+	}
+
+	return true
+}
+
 func main() {
+	if shouldPrintBanner(os.Args, term.IsTerminal(int(os.Stdout.Fd()))) {
 		fmt.Printf("%s", banner)
+	}
 	cmd := NewPicoclawCommand()
 	if err := cmd.Execute(); err != nil {
 		os.Exit(1)

cmd/picoclaw/main_test.go

@@ -5,6 +5,7 @@ import (
 	"slices"
 	"testing"
 
+	"github.com/spf13/cobra"
 	"github.com/stretchr/testify/assert"
 	"github.com/stretchr/testify/require"
 
@@ -55,3 +56,27 @@ func TestNewPicoclawCommand(t *testing.T) {
 		assert.False(t, subcmd.Hidden)
 	}
 }
+
+func TestShouldPrintBanner(t *testing.T) {
+	t.Run("interactive command prints banner", func(t *testing.T) {
+		t.Setenv(noBannerEnv, "")
+		assert.True(t, shouldPrintBanner([]string{"picoclaw", "agent"}, true))
+	})
+
+	t.Run("redirected stdout suppresses banner", func(t *testing.T) {
+		t.Setenv(noBannerEnv, "")
+		assert.False(t, shouldPrintBanner([]string{"picoclaw", "agent"}, false))
+	})
+
+	t.Run("completion command suppresses banner", func(t *testing.T) {
+		t.Setenv(noBannerEnv, "")
+		assert.False(t, shouldPrintBanner([]string{"picoclaw", "completion", "zsh"}, true))
+		assert.False(t, shouldPrintBanner([]string{"picoclaw", cobra.ShellCompRequestCmd}, true))
+		assert.False(t, shouldPrintBanner([]string{"picoclaw", cobra.ShellCompNoDescRequestCmd}, true))
+	})
+
+	t.Run("env disables banner", func(t *testing.T) {
+		t.Setenv(noBannerEnv, "1")
+		assert.False(t, shouldPrintBanner([]string{"picoclaw", "agent"}, true))
+	})
+}