Discussion on #735, after it was closed, pointed to the need for an issue on inclusion of the cell id in jupytext text formats. I can't find one, and I think it's an enhancement worth considering.

Currently, a cell id is preserved in paired notebooks, but there are cases where the paired notebook is not present. Primary among these is when only text formats are held in a git repository. In this case, collaborators that generate notebooks locally from the text format end up with all cells having a different id. I'm interested to know, is there support for directly incorporating the cell id in the "light" format?

The obvious proposal would be to require a start-of-cell delimiter for every cell and include the id. The id is distinct from metadata because 1) it is first and 2) is not a key=value pair (the "=" character is not permitted in a cell id).

The examples would become:

# +b457cb9f-93c0_456a-a652-3f597535aa2d
# This is a multiline
# Markdown cell

# +a99ac56a-3859_4a15-9023-bab26654380f
# Another Markdown cell


# +4e9a328c-7d49_4e7e-9af4-a9f86ccddd14
# This is a code cell
class A():
    def one():
        return 1

    def two():
        return 2

# +3435c495-ba0c_4ca6-8a65-7b3658b66733
# A single code cell made of two paragraphs
a = 1


def f(x):
    return x+a

# +a8345b4b-8282_47fe-96c4-1d2c02bc92ca key="value"
# A code cell with metadata

# +a8345b4b-8282_47fe-96c4-1d2c02bc92ca [markdown] key="value"
# A Markdown cell with metadata