Where a site stands against the version of an extension it is running, read and drawn.

Setting a site up installs what it is missing and never touches what it has, which is the only safe thing a button called "Set up" can do — and it leaves a site that was provisioned months ago on months-old components and months-old pages for ever. This is the other half, and it has two halves of its own because a site has two things to fall behind on:

• MishkaCmsCore.Runtime.Handlers.UiKitUpgrade says where each of the kit's COMPONENTS stands, and writes the ones the admin chooses;
• MishkaCmsCore.Runtime.PageSamples says where each of the extension's sample PAGES stands, and offers the newer ones as drafts. A page is somebody's work in a way a kit component is not — it is what their readers are looking at — so nothing here writes a live page at all. A page whose newer version draws a component this site has not got is not offered either: the two halves fall behind together, and publishing that draft would put an error message where the block should be.

Both report BEFORE anything is written, and the admin decides.

Wiring

One call in mount/3 and three event clauses. Nothing draws this directly: standings/1 is drawn inside the modal MishkaCmsCoreWeb.Live.Admin.Components.ExtensionInstallerPanel.doctor_modal/1 opens, which is where the site picker and the kit_check form live.

socket =
  KitUpgradePanel.setup(socket,
    bundle: MishkaBlog.Kit.bundle_path(),
    noun: "blog components",
    pages: &MishkaBlog.Provision.sample_pages/2,
    draft_label: "Blog sample page"
  )

def handle_event("kit_check", params, socket),
  do: {:noreply, KitUpgradePanel.check(socket, chosen_site(socket, params), socket.assigns.may_provision?)}

def handle_event("kit_upgrade", %{"mode" => mode}, socket),
  do: {:noreply, KitUpgradePanel.upgrade(socket, mode, socket.assigns.may_provision?)}

def handle_event("page_drafts", _params, socket),
  do: {:noreply, KitUpgradePanel.offer(socket, socket.assigns.may_provision?)}

Which site the check runs against is the dashboard's answer, not this module's: a tenant admin has one site and a master picks from the ones their page offered, and that is the same question the "Set up" button already answers. check/3 takes what chosen_site/2 decided — a site id, :none or :refused — and the permission the dashboard already computed, so the wording of a refusal is written once here rather than once per extension.

Why the two component buttons are two

The write is upgrade!/3 with :safe or :all, and nothing here presses :all on the admin's behalf. A row whose fingerprint no longer matches what the kit installed is a row somebody worked on, and the only honest thing to do with it is to say so and wait — which is why the second button spells out that the version being replaced stays in the component's history.

The pages have one button and it is the safe one, because there is no unsafe one to offer: a draft is the whole of what this can do to a page.