Disable color output when stdout is not a TTY

pterm v0.12.80 forces color on regardless of the output target, so the
CLI emitted raw ANSI escape codes when stdout was piped or captured
(e.g. in a headless/programmatic environment), garbling the output.

Gate pterm styling in initConfig on an interactive-terminal check and
honor the NO_COLOR convention, so non-TTY output is plain text.
Interactive terminals are unaffected and the --no-color flag still works.

Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>

Author: rgarcia

cmd/color_test.go

@@ -0,0 +1,24 @@
+package cmd
+
+import "testing"
+
+func TestShouldEnableColor(t *testing.T) {
+	tests := []struct {
+		name       string
+		noColorEnv string
+		isTTY      bool
+		want       bool
+	}{
+		{"tty, no env", "", true, true},
+		{"not tty, no env", "", false, false},
+		{"tty, NO_COLOR set", "1", true, false},
+		{"not tty, NO_COLOR set", "1", false, false},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			if got := shouldEnableColor(tt.noColorEnv, tt.isTTY); got != tt.want {
+				t.Errorf("shouldEnableColor(%q, %v) = %v, want %v", tt.noColorEnv, tt.isTTY, got, tt.want)
+			}
+		})
+	}
+}

cmd/root.go

@@ -15,6 +15,7 @@ import (
 	"github.com/kernel/cli/cmd/mcp"
 	"github.com/kernel/cli/cmd/proxies"
 	"github.com/kernel/cli/pkg/auth"
+	"github.com/kernel/cli/pkg/table"
 	"github.com/kernel/cli/pkg/update"
 	"github.com/kernel/cli/pkg/util"
 	"github.com/kernel/kernel-go-sdk"
@@ -177,9 +178,22 @@ func init() {
 	}
 }
 
+// shouldEnableColor decides whether pterm color styling should be on.
+// NO_COLOR (any non-empty value) always wins per https://no-color.org.
+// Otherwise color is enabled only when stdout is an interactive terminal.
+func shouldEnableColor(noColorEnv string, isTTY bool) bool {
+	if noColorEnv != "" {
+		return false
+	}
+	return isTTY
+}
+
 func initConfig() {
-	// Placeholder for future configuration (env vars, config files, etc.)
-	pterm.EnableStyling() // ensure pterm is initialised in case env disables it
+	if shouldEnableColor(os.Getenv("NO_COLOR"), table.IsStdoutTTY()) {
+		pterm.EnableStyling()
+	} else {
+		pterm.DisableStyling()
+	}
 }
 
 // Execute executes the root command.