How to Transfer Chatter History from Sales to Delivery in Odoo 18: Complete Guide

<?xml version="1.0" encoding="utf-8"?>
<odoo>
    <record id="view_order_form_inherit_chatter_transfer" model="ir.ui.view">
        <field name="name">sale.order.form.chatter.transfer</field>
        <field name="model">sale.order</field>
        <field name="inherit_id" ref="sale.view_order_form"/>
        <field name="arch" type="xml">
            <xpath expr="//button[@name='action_draft']" position="after">
                <button name="action_transfer_chatter_to_delivery"
                        string="Transfer Chatter to Delivery"
                        type="object"
                        class="btn-primary"
                        attrs="{'invisible': [('picking_ids', '=', [])]}" />
            </xpath>
        </field>
    </record>
</odoo>

from odoo import models, api

class SaleOrder(models.Model):
    _inherit = 'sale.order'

    def action_transfer_chatter_to_delivery(self):
        """
        Transfers all chatter messages from sales order to 
        the first non-cancelled delivery order.
        """
        # Fetch all messages from current sales order
        sale_messages = self.env["mail.message"].search([
            ("res_id", "=", self.id),
            ("model", "=", "sale.order")
        ], order='create_date asc')
        
        # Get active delivery orders (exclude cancelled)
        active_deliveries = self.picking_ids.filtered(
            lambda p: p.state != 'cancel'
        )
        
        if not active_deliveries:
            return {
                'type': 'ir.actions.client',
                'tag': 'display_notification',
                'params': {
                    'title': 'No Active Deliveries',
                    'message': 'There are no active delivery orders to transfer chatter to.',
                    'type': 'warning',
                    'sticky': False,
                }
            }
        
        # Transfer to first active delivery
        target_delivery = active_deliveries[0]
        
        for message in sale_messages:
            message.copy({
                "model": "stock.picking",
                "res_id": target_delivery.id
            })
        
        return {
            'type': 'ir.actions.client',
            'tag': 'display_notification',
            'params': {
                'title': 'Success',
                'message': f'{len(sale_messages)} messages transferred to delivery {target_delivery.name}',
                'type': 'success',
                'sticky': False,
            }
        }

from odoo import models, api

class SaleOrder(models.Model):
    _inherit = 'sale.order'

    def action_transfer_chatter_notes_only(self):
        """
        Transfers only internal notes (Log Note messages) from 
        sales order to delivery order.
        """
        # Fetch all messages from sales order
        sale_messages = self.env["mail.message"].search([
            ("res_id", "=", self.id),
            ("model", "=", "sale.order")
        ], order='create_date asc')
        
        # Get active deliveries
        active_deliveries = self.picking_ids.filtered(
            lambda p: p.state != 'cancel'
        )
        
        if not active_deliveries:
            return
        
        target_delivery = active_deliveries[0]
        
        # Filter for "Note" subtype messages only
        notes_only = sale_messages.filtered(
            lambda m: m.subtype_id.name == 'Note'
        )
        
        transferred_count = 0
        for note in notes_only:
            note.copy({
                "model": "stock.picking",
                "res_id": target_delivery.id
            })
            transferred_count += 1
        
        return {
            'type': 'ir.actions.client',
            'tag': 'display_notification',
            'params': {
                'title': 'Notes Transferred',
                'message': f'{transferred_count} internal notes transferred successfully',
                'type': 'success',
            }
        }

from odoo import models, api

class SaleOrder(models.Model):
    _inherit = 'sale.order'

    def action_confirm(self):
        """Override order confirmation to auto-transfer chatter"""
        result = super(SaleOrder, self).action_confirm()
        
        # Transfer relevant messages to newly created deliveries
        self._auto_transfer_chatter_to_deliveries()
        
        return result
    
    def _auto_transfer_chatter_to_deliveries(self):
        """Internal method to auto-transfer important messages"""
        # Get all notes and activities
        important_messages = self.env["mail.message"].search([
            ("res_id", "=", self.id),
            ("model", "=", "sale.order"),
            ("subtype_id.name", "in", ["Note", "Activities"])
        ], order='create_date asc')
        
        # Transfer to all active deliveries
        for delivery in self.picking_ids.filtered(lambda p: p.state != 'cancel'):
            for message in important_messages:
                message.copy({
                    "model": "stock.picking",
                    "res_id": delivery.id
                })