social/mail_activity_creator/models/mail_activity.py

# Copyright 2020 Creu Blanca
# License AGPL-3.0 or later (http://www.gnu.org/licenses/agpl).

from odoo import fields, models


class MailActivity(models.Model):

    _inherit = "mail.activity"

    creator_uid = fields.Many2one(
        "res.users",
        default=lambda r: r.env.user.id,
        string="Creator",
    )