To automate analytic distribution in purchase orders, ensure you're using the correct syntax to update One2many fields. In your code, analytic_distribution should be written as a write operation on line, not dictionary-style assignment. Try this:

for record in records:
    tag_ids = [record.x_studio_compte_analytique.id]
    for line in record.order_line:
        line.write({'analytic_distribution': [(6, 0, tag_ids)]})

Also, make sure analytic_distribution is a Many2many field. This approach correctly assigns the analytic tag to each line. Test it on sample data to confirm it updates as expected.

line['analytic_distribution']={str(analytic_account_id): 100.0, str(Location_account_id): 100.0, 128: 100.0 }

you can try to use above. it's working for me in the analytic distribution but creating 2 or 3 analytic items which i am trying to resolve.