amber-laravel/app/Models/Chat.php

<?php

namespace App\Models;

use Illuminate\Database\Eloquent\Model;
use Illuminate\Database\Eloquent\Relations\BelongsTo;
use Illuminate\Database\Eloquent\Relations\HasMany;

class Chat extends Model
{
    public const ROLE_USER = 'user';

    public const ROLE_ASSISTANT = 'assistant';

    public const ROLE_SYSTEM = 'system';

    public const ROLE_META = 'meta';

    protected $fillable = [
        'name',
        'assistant_id',
        'user_id',
    ];

    public function assistant(): BelongsTo
    {
        return $this->belongsTo(Assistant::class);
    }

    public function user(): BelongsTo
    {
        return $this->belongsTo(User::class);
    }

    public function histories(): HasMany
    {
        return $this->hasMany(ChatHistory::class);
    }
}