docs: update documentation to OKF v0.1 format

docs/guides/landing-page.md

@@ -1,9 +1,9 @@
 ---
 type: guide
 title: Landing Page
-description: How the public landing page renders, how the login + registration modal is opened, and what each form does.
-tags: [guide, landing, login, register, ui]
-timestamp: 2026-07-21T18:45:54Z
+description: How the public landing page renders, how the login + registration modal is opened, what each form does, and how the modal stays in sync with admin `registrationsEnabled` changes via SSE.
+tags: [guide, landing, login, register, ui, sse, bootstrap]
+timestamp: 2026-07-22T16:15:00Z
 ---
 
 # What you see
@@ -90,6 +90,31 @@ The modal is dismissible via the **×** button (`landing-modal-close`),
 clicking the overlay backdrop, or pressing `Escape`. Submit-in-flight
 dismissal is suppressed.
 
+# Reacting to admin changes
+
+The Login/Register modal reflects the value of
+`bootstrap.payload().registrationsEnabled`, which is loaded once at app
+boot by `BootstrapService.load()`. Two paths keep the modal consistent
+with the API:
+
+1. `LandingComponent.ngOnInit()` calls `BootstrapService.refresh()` so
+   the public landing page always fetches the latest bootstrap payload
+   before rendering the modal. This covers users who reach `/login`
+   via a hard refresh or fresh tab and have not previously subscribed to
+   the SSE channel.
+2. `BootstrapEventService` (started by `AppComponent.ngOnInit`) opens
+   the public `GET /api/v1/event/stream` SSE channel and listens for
+   `{ topic: 'general' }` frames. Whenever the admin saves a setting via
+   `PUT /api/v1/admin/general/settings`, the backend emits a `general`
+   hub event with `themeKey` and `registrationsEnabled`; the public SSE
+   forwards it on `/api/v1/event/stream` and the SPA calls
+   `BootstrapService.refresh()` to re-apply the new flag (and theme).
+
+The pure helper `landingModalShowsRegister(registrationsEnabled)` in
+`frontend/src/app/features/landing/login-modal.service.ts` mirrors the
+HTML predicate and is asserted in
+`tests/frontend/landing-modal.spec.ts`.
+
 # Server error code → user copy
 
 `buildLoginFailureMessage` (`frontend/src/app/features/landing/login-modal.service.ts`)