`last-modified` is not working as expected when rendering on github actions as Git does not store last modified date

In a github action rendering, there will be a checkout at each rendering. This implies that the last modified date of each file will be the same as the git checkout date. This is because of the fact that git does not store last modified date information.

There are workaround to restore date of file to last commit date for the files:

• https://github.com/BenLubar/git-last-modified
• https://stackoverflow.com/questions/21735435/git-clone-changes-file-modification-time/55609950#55609950

Maybe we could try be clever when inside a git project, or leverage the _freeze state for project to store information.

Discussed in https://github.com/quarto-dev/quarto-cli/discussions/5899

^{Originally posted by adityam June 13, 2023}

Description

I am using github actions to publish my website.

1. Website: https://adityam.github.io/stochastic-control/
2. Github action: https://github.com/adityam/stochastic-control/blob/quarto/.github/workflows/quarto-render.yml

In _quarto.yml, I have set

format:
  html:
    published-title: Updated
    date: last-modified

but all my pages have today's date.

I suspect that the last modified date is coming from the date the date when github CI clones the repo (and hence today's date) rather than when the file was checked into the repo (which is the true last-modified date).

Is it possible to somehow use the date when the file was last committed to git, for example, similar to what is available for hugo

Reproduce the rendering from the referenced .github/workflows/quarto-render.yml and inspect how date: last-modified is determined during a GitHub Actions checkout. Compare the checkout timestamp with the file's last commit date, then verify that rendered pages use the committed date rather than the checkout date.