Update cooldown explanation and compact index details

Clarified the explanation of the v2 compact index and its role in the cooldown feature, emphasizing that it is an internal format version and not a public API change.

Author: colby-swandale

_posts/2026-06-03-cooldown-let-new-gems-be-vetted.md

@@ -94,6 +94,8 @@ aws-partitions  1.1251.0  1.1256.0 (cooldown 3d)  = 1.1251.0  default
 
 Cooldown is most useful as one part of the wider security investment happening on rubygems.org. The registry now validates gem contents at push time and checks logins against Have I Been Pwned so that compromised passwords cannot be reused, work described in [Protecting rubygems.org from the outside in]({% post_url 2026-04-09-protecting-rubygems-from-the-outside-in %}). A dedicated team is running [AI-assisted vulnerability scanning against the most critical gems]({% post_url 2026-04-29-scaling-rubys-defenses-with-ai %}), backed by Alpha Omega and Anthropic, and the direction of all of this is tracked on a [public roadmap]({% post_url 2026-04-15-rubygems-org-has-a-public-roadmap %}). Trusted publishing and mandatory 2FA already raise the bar for who can push a release in the first place.
 
-Cooldown itself only works because rubygems.org now publishes the per-version `created_at` timestamp through its [v2 compact index](https://github.com/rubygems/rubygems.org/issues/6412), delivered through a careful dual-write migration and a flagged cutover with no disruption for clients. I'm grateful to the rubygems.org team for that groundwork. Cooldown is a thin client-side filter on top of it.
+Cooldown itself only works because rubygems.org now publishes the per-version `created_at` timestamp through its [v2 compact index](https://github.com/rubygems/rubygems.org/issues/6412) (v2 is an internal format version, not a public API change), delivered through a careful dual-write migration and a flagged cutover with no disruption for clients. I'm grateful to the rubygems.org team for that groundwork. Cooldown is a thin client-side filter on top of it.
+
+Cooldown itself only works because rubygems.org now publishes the per-version created_at timestamp through an updated [compact index](https://github.com/rubygems/rubygems.org/issues/6412) (an internal format version, not a change to the public API), delivered through a careful dual-write migration and a flagged cutover with no disruption for clients.
 
 Each of these defenses covers a different gap, and they compound. Resolving your dependencies against rubygems.org is what puts all of them to work on your behalf, which makes it the safest default for Ruby projects.