Sanitize WhatsApp messages and remove extra log messages.

pkg/channels/whatsapp_native.go

@@ -174,6 +174,9 @@ func (c *WhatsAppNativeChannel) handleIncoming(evt *events.Message) {
 	if content == "" && evt.Message.ExtendedTextMessage != nil {
 		content = evt.Message.ExtendedTextMessage.GetText()
 	}
+	content = utils.SanitizeMessageContent(content)
+
+	if content == "" { return } // ignore empty messages
 
 	var mediaPaths []string
 	// Optional: resolve media to local paths if needed; for now we only forward text to the bus.

pkg/utils/string.go

@@ -1,5 +1,31 @@
 package utils
 
+import (
+	"strings"
+	"unicode"
+)
+
+// SanitizeMessage removes Unicode control characters, format characters (RTL overrides, 
+// zero-width characters), and other non-graphic characters that could confuse an LLM 
+// or cause display issues in the agent UI.
+func SanitizeMessageContent(input string) string {
+	var sb strings.Builder
+	// Pre-allocate memory to avoid multiple allocations
+	sb.Grow(len(input))
+
+	for _, r := range input {
+		// unicode.IsGraphic returns true if the rune is a Unicode graphic character.
+		// This includes letters, marks, numbers, punctuation, and symbols.
+		// It excludes control characters (Cc), format characters (Cf), 
+		// surrogates (Cs), and private use (Co).
+		if unicode.IsGraphic(r) || r == '\n' || r == '\r' || r == '\t' {
+			sb.WriteRune(r)
+		}
+	}
+
+	return sb.String()
+}
+
 // Truncate returns a truncated version of s with at most maxLen runes.
 // Handles multi-byte Unicode characters properly.
 // If the string is truncated, "..." is appended to indicate truncation.

pkg/utils/string_test.go

@@ -104,3 +104,27 @@ func TestTruncate(t *testing.T) {
 		})
 	}
 }
+
+func TestSanitizeMessageContent(t *testing.T) {
+	tests := []struct {
+		name  string
+		input string
+		want  string
+	}{
+		{"empty", "", ""},
+		{"plain text unchanged", "Hello world", "Hello world"},
+		{"strip ZWSP", "Hello\u200bworld", "Helloworld"},
+		{"strip RTL override", "Hi\u202eevil", "Hievil"},
+		{"strip BOM", "\uFEFFcontent", "content"},
+		{"strip multiple", "a\u200c\u202ab\u202cc", "abc"},
+		{"unicode letters preserved", "café 日本語", "café 日本語"},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			got := SanitizeMessageContent(tt.input)
+			if got != tt.want {
+				t.Errorf("SanitizeMessageContent(%q) = %q, want %q", tt.input, got, tt.want)
+			}
+		})
+	}
+}