[davidmillen50]

related to #2982

[mroderick]

What this changes

DashboardQuery.upcoming_events joined :sponsors and :workshop_host in a single eager_load. Both associations go through workshop_sponsors, so the scoped has_one (where(host: true)) shares the join alias with :sponsors — the alias trap from #2975. Depending on the plan and row order, workshop_host came back nil or bound to a non-host sponsor.

The dashboard card reads the venue through WorkshopPresenter#venue (app/presenters/workshop_presenter.rb:31 → model.host), so a lost host renders the homepage card with no venue, or with the wrong sponsor as the venue.

The fix keeps :sponsors in the join and loads the host on its own with preload(workshop_host: :sponsor): one query for the scoped WorkshopSponsor, one batched query for its sponsors. Fixed cost of two queries per dashboard render, independent of the number of cards. The extracted upcoming_workshops method is a plain refactor.

Review

Verified against the diff, the post-image files, Workshop associations, and the presenter/render path: the production change is correct and the query shape improves on the eager_load baseline. Ship it, with one non-blocking note.

The new spec would still pass if the preload were removed. spec/queries/dashboard_query_spec.rb:34 asserts values only:

expect(result.values.flatten.select { |event| event.is_a?(Workshop) }.map(&:host))
  .to all(eq(host))

Workshop#host lazy-loads through workshop_host&.sponsor, so deleting preload(workshop_host: :sponsor) from app/queries/dashboard_query.rb:60 leaves every dashboard spec green while restoring a per-card query on the homepage. The events path already guards this with a query-count spec at spec/requests/event_card_render_query_cost_spec.rb:38; the dashboard path has no equivalent. Suggested: a dashboard counterpart to that spec, asserting the query count stays flat as the card count grows.

Two follow-ups, both pre-existing and outside this diff:

• DashboardQuery.upcoming_events_for_user (app/queries/dashboard_query.rb:27-40) still eager_loads :sponsors without :workshop_host, and the dashboard action renders through the same presenter, so hosts lazy-load per workshop there.
• The spec covers the happy path only. Host nil for a workshop with only non-host sponsors (the other half of the Events listing can render the wrong sponsor as venue (eager_load host loss) #2975 failure mode) is not asserted.