Beancount - Fix payee/narration behavior to always have payee first and narration optional

fix_payee_narration.py

#!python3
"""
Beancount has inconsistent behavior with payee/narrations. 

If you have a line like this:

    2020-01-01 * "Text1"

Then "Text1" is the narration

If you have a line like this:

    2020-01-01 * "Text1" "Text2"

Then "Text1" is the payee, and "Text2" is the narration

-----

This plugin takes the cases where the text was entered with only a single string
and assumes the "narration" was actually meant to be the "payee". For my data, this
is always true.
"""

from beancount.core import data

__plugins__ = ('fix_payee_narration',)

def fix(entry):
    if not isinstance(entry, data.Transaction):
        return entry

    # don't run if the entry is auto-added by beancount
    if 'Padding inserted for Balance' in entry.narration:             
        return entry

    if entry.narration and not entry.payee:
        return entry._replace(payee=entry.narration, narration="")

    return entry

def fix_payee_narration(entries, options_map=None, config=None):
    ret = []
    for entry in entries:
        ret.append( fix(entry) )

    return ret, []