fix

internal/model/record.go

@@ -55,7 +55,9 @@ func normalizeName(name string) string {
 // normalizeValue canonicalizes a single RR value for comparison.
 func normalizeValue(t RecordType, content string) string {
 	if t == TXT {
-		return content // byte-exact — case and whitespace are significant (DKIM/SPF/DMARC)
+		// byte-exact — case and whitespace are significant (DKIM/SPF/DMARC);
+		// only the presentation quoting/chunking is stripped.
+		return TXTPayload(content)
 	}
 	c := strings.Join(strings.Fields(content), " ") // collapse whitespace
 	switch t {
@@ -95,3 +97,47 @@ func (r Record) Equal(o Record) bool {
 	}
 	return slices.Equal(r.NormalizedValues(), o.NormalizedValues())
 }
+
+// TXTPayload returns the logical content of a TXT value. A value written as
+// one or more quoted strings ("a" "b") is the concatenation of their
+// contents; an unquoted value is returned as is. This makes a template value
+// without quotes comparable with the quoted form providers store.
+func TXTPayload(v string) string {
+	t := strings.TrimSpace(v)
+	if !strings.HasPrefix(t, `"`) {
+		return v
+	}
+	var b strings.Builder
+	inQ := false
+	for i := 0; i < len(t); i++ {
+		c := t[i]
+		switch {
+		case inQ && c == '\\' && i+1 < len(t):
+			i++
+			b.WriteByte(t[i])
+		case c == '"':
+			inQ = !inQ
+		case inQ:
+			b.WriteByte(c)
+		}
+	}
+	return b.String()
+}
+
+// QuoteTXT renders a TXT value in the quoted form providers require: payload
+// split into <=255-byte strings, each quoted. Already-quoted values pass
+// through unchanged.
+func QuoteTXT(v string) string {
+	if strings.HasPrefix(strings.TrimSpace(v), `"`) {
+		return v
+	}
+	const max = 255
+	esc := strings.NewReplacer(`\`, `\\`, `"`, `\"`)
+	var parts []string
+	for len(v) > max {
+		parts = append(parts, `"`+esc.Replace(v[:max])+`"`)
+		v = v[max:]
+	}
+	parts = append(parts, `"`+esc.Replace(v)+`"`)
+	return strings.Join(parts, " ")
+}