g.due_date = item.get("due_date")
        phone = item.get("phone", "")
        unsub = f"{cfg.UNSUBSCRIBE_BASE or cfg.BASE_URL}/unsubscribe/{rec.unsub_token}" if c.unsubscribe_enabled else ""
        extra = {"unsubscribe_link": unsub, "company_phone": phone}

        body_html = ""
        subject = ""
        warn_list = list(item.get("warnings") or []) if isinstance(item.get("warnings"), list) else ([item["warnings"]] if item.get("warnings") else [])
        if tpl:
            res = engine.substitute(tpl.body_html, rec, g,
                                    custom_fields=rec.custom_fields or {}, extra=extra)
            body_html = res.text
            subject = subj.subject if subj else (tpl.subject_hint or tpl.name)
            for u in res.unknown:
                warn_list.append(f"Unknown variable in body: {u}")
            for m_ in res.missing:
                warn_list.append(f"Missing data for: {m_}")
        if subj:
            res_s = engine.substitute(subj.subject, rec, g,
                                      custom_fields=rec.custom_fields or {}, extra=extra)
            subject = res_s.text
            for u in res_s.unknown:
                warn_list.append(f"Unknown variable in subject: {u}")
            for m_ in res_s.missing:
                warn_list.append(f"Missing data in subject: {m_}")
        out.append({
            "recipient": {"id": rec.id, "email": rec.email,
                          "first_name": rec.first_name, "last_name": rec.last_name},
            "from_account": item.get("account", ""),
            "subject": subject,
            "body_html": sanitize_preview(body_html),
            "raw_variables": {"invoice_number": g.invoice_number,
                              "amount": g.amount, "shipping": g.shipping,
                              "phone": phone},
            "warnings": warn_list,
        })
    return {"campaign_id": c.id, "sample_size": len(out), "messages": out,
            "plan_summary": result.get("summary", {})}


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