Sanitize WhatsApp messages and remove extra log messages.

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.