Per-package daily download history via the REST API

stat_download returns rolling windows (cnt_1d/7d/30d/total) but not a series, so to build a daily history each consumer has to poll once a day and store the result. I do that for https://github.com/r-observatory/autoobs-downloads.

The daily data is already collected, though. agg_download_pkg holds one row per (period, dt, metapkg_id, folder_id, country):

https://github.com/openSUSE/MirrorCache/blob/fb90e38583b3d702a48b9c828972d3d3f2ee9cb3/lib/MirrorCache/resources/migrations/Pg.sql#L450-L458

StatAggPkg already writes period='day' rows on a schedule:

https://github.com/openSUSE/MirrorCache/blob/fb90e38583b3d702a48b9c828972d3d3f2ee9cb3/lib/MirrorCache/Task/StatAggPkg.pm#L38-L39

Cleanup keeps them for 6 months:

https://github.com/openSUSE/MirrorCache/blob/fb90e38583b3d702a48b9c828972d3d3f2ee9cb3/lib/MirrorCache/Task/Cleanup.pm#L178-L183

And stat_download already reads period='day' (last 30 days) before collapsing it into windows:

https://github.com/openSUSE/MirrorCache/blob/fb90e38583b3d702a48b9c828972d3d3f2ee9cb3/lib/MirrorCache/WebAPI/Controller/Rest/Metapkg.pm#L176-L199

Could you expose those rows directly, e.g. GET /rest/package/<id>/stat_download_daily returning [{date, count}, ...]? It would be a near-copy of stat_download:

select to_char(dt,'YYYY-MM-DD') as date, sum(cnt) as count
from agg_download_pkg
where metapkg_id = ? and period = 'day'
group by dt order by dt;

plus one route line next to the existing stat_download route:

https://github.com/openSUSE/MirrorCache/blob/fb90e38583b3d702a48b9c828972d3d3f2ee9cb3/lib/MirrorCache/WebAPI.pm#L194

That saves every downstream from running its own snapshotter, and gives up to 6 months of backfill.

Start with lib/MirrorCache/WebAPI/Controller/Rest/Metapkg.pm, where stat_download reads daily rows, and lib/MirrorCache/WebAPI.pm for the adjacent route. Check the agg_download_pkg schema and existing day aggregation, then expose the requested date/count response ordered by date; verify the endpoint returns the retained daily history for a package.