result_text = engine.substitute(template.body_text or _plain_fallback(result_html),
                                        rec, g, custom_fields=cf,
                                        extra={"unsubscribe_link": unsub_url}).text

        attachments, att_names = [], []
        if campaign.attach_mode == "pdf" and campaign.attach_pdf:
            att_html = ""
            if campaign.attach_pdf_template_id:
                att_tpl = db.get(EmailTemplate, campaign.attach_pdf_template_id)
                if att_tpl:
                    att_html = engine.substitute(att_tpl.body_html, rec, g, custom_fields=cf,
                                                 extra={"unsubscribe_link": unsub_url}).text
            elif campaign.attachment_id:
                att = db.get(Attachment, campaign.attachment_id)
                if att and att.kind == "html":
                    att_html = engine.substitute(att.html_attachment_body or "", rec, g,
                                                 custom_fields=cf,
                                                 extra={"unsubscribe_link": unsub_url}).text
            if att_html:
                pdf_bytes = message_builder.html_to_pdf(att_html)
                fname = message_builder.generate_attachment_filename(
                    var_cfg.get("attachment_kind", "invoice"), cr.generated_invoice_number)
                attachments.append({"filename": fname, "content": pdf_bytes,
                                    "mime_type": "application/pdf"})
                att_names.append(fname)
        if campaign.attach_mode in ("file", "image") and campaign.attachment_id:
            att = db.get(Attachment, campaign.attachment_id)
            if att:
                data = attachments_service.read_attachment_bytes(att)
                if data is not None:
                    attachments.append({"filename": att.filename, "content": data,
                                        "mime_type": att.mime_type})
                    att_names.append(att.filename)

        html_problems = message_builder.validate_html(result_html)
        if html_problems:
            log.warning("HTML validation warnings for %s: %s", cr.email, html_problems)

        mime = message_builder.build_mime_message(
            from_email=account.email,   # real authenticated account; never spoofed
            to_email=cr.email,
            subject=subject,
            html_body=result_html if campaign.message_type != "plain" else "",
            text_body=result_text,
            attachments=attachments,
            unsubscribe_url=unsub_url if campaign.unsubscribe_enabled else "",
===ATT MODEL FIELDS OK===
146:    description = Column(Text, default="")
295:    mime_type = Column(String(120), default="application/octet-stream")
298:    description = Column(Text, default="")
388:    description = Column(String(300), default="")