sam-api/app/Models/MainRequestFlow.php

<?php

namespace App\Models;

use App\Models\MainRequest;
use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\MorphTo;

/**
 * @mixin IdeHelperMainRequestFlow
 */
class MainRequestFlow extends Model
{
    /**
     * 업무 전체/상세 흐름 이력(폴리모픽)
     */
    protected $table = 'main_request_flows';

    protected $fillable = [
        'main_request_id',
        'flowable_type',   // 폴리모픽 타입(모델명)
        'flowable_id',     // 폴리모픽 PK
        'status_code',
        'action',
        'content',
        'actor_id',
        'created_at',
        'updated_at',
    ];

    /**
     * 메인 업무 엔터티
     */
    public function mainRequest(): BelongsTo
    {
        return $this->belongsTo(MainRequest::class, 'main_request_id');
    }

    /**
     * 폴리모픽 관계(견적, 주문, 발주 등)
     */
    public function flowable(): MorphTo
    {
        return $this->morphTo();
    }
}