Homepage shows deactivated chapters (sidebar fragment invalidation deletes the wrong key)聽#2993
Description
Deactivated chapters stay in the homepage chapter list. The chapter page 404s correctly and the subscriptions list is correct. Seen after several chapters were deactivated by setting active = false directly in the database.
The sidebar caches under a fixed key, and the callback that expires it deletes a key that does not exist:
app/components/chapters_sidebar_component.html.erbcallscache "chapters-sidebar". ActionView stores this asviews/chapters_sidebar_component/chapters-sidebar, plus the cache namespace.Chapter#expire_chapters_sidebar_cachedeleteschapters-sidebar, which resolves to a different entry. The delete has never matched, so no write path invalidates the fragment, not only direct database edits.
Fix: derive the cache key from the data so it changes whenever the chapter set changes. The key must include Chapter.active.count, because a plain SQL update that sets active does not bump updated_at.
Evidence
- The production cache store held one sidebar entry, last written 2026-09-13, under
views/chapters_sidebar_component/chapters-sidebar, and nochapters-sidebarentry. - Toggling
Chapter#update!in a productionrails runnerfired the callbacks and left the homepage unchanged. - Deleting the real entry refreshed the homepage at once.
- The fixed key is shared across locales. A derived key removes that side effect.
- The stale entry is cleared in production as of 2026-10-07. It will go stale again on the next chapter change until this is fixed.
Activity
fix(chapters): derive the sidebar cache key from the rendered chapters
fix(chapters): cache the chapters sidebar with a 10-minute TTL
mroderick commentedon Oct 7, 2026
The fix in #2994 takes a different shape than the suggestion above: instead of deriving the fragment key from the data, the sidebar now caches under a versioned key with a 10-minute TTL (
skip_digest: true, expires_in: 10.minutes), the shape used by the events/past fragment. Every write path shows up within the TTL, a warm cache hit runs no chapter query, and there is no invalidation code left to get wrong.