Metadata

Updating page metadata

Before replacing the main element, the runtime updates the parts of <head> that can change from page to page:

• sets document.title from the fetched page
• copies <html lang> and <html dir>, or removes them when absent
• removes current head children matching the page-owned set
• clones matching children from the fetched page into the current head

The boundary between page-owned and persistent elements is explicit:

• data-riebeckite-head="page" nodes are replaced.
• data-riebeckite-head="global" and "runtime" nodes persist.
• Plugin meta and link head tags are marked page-owned automatically.
• Plugin data scripts (application/ld+json, application/json) are also page-owned.
• Executable plugin scripts are left unowned so they are neither cloned nor re-executed.

The following legacy selector set is also page-owned for compatibility:

• link[rel="canonical"], link[hreflang]
• script[type="application/ld+json"]
• meta[name="description"], meta[name="author"], meta[name="robots"]
• meta[name^="twitter:"]
• meta[property^="og:"], meta[property^="article:"]

Everything else in the head persists. An executable <script> is never replaced, even when it has data-riebeckite-head="page", because running it again would repeat its side effects. A <script> or <style> without an ownership attribute also persists.

History, scroll, focus, and announcements

When scroll restoration is enabled, the runtime sets history.scrollRestoration = "manual" and restores the previous value on stop.

It saves the scroll position into history.state with replaceState when scrolling settles and immediately before a click navigation. Back and forward navigation restores the saved position. When no position was saved, it does not restore one.

A click navigation pushes an entry with { scroll: [0, 0] } after a successful commit and scrolls to the top. A URL with a hash scrolls to the matching element instead.

History:

• Click navigations push a new entry after a successful commit.
• popstate navigations do not push.
• Redirects use the response URL.

Focus and announcement:

• Unless the URL has a hash, the runtime adds tabindex="-1" if needed and focuses the new main element with preventScroll.
• It creates or reuses #riebeckite-navigation-announcer, an aria-live="polite" element, and sets its text to the new document title.
• The spa:navigation event carries { url, popstate }.

Prefetch

prefetch: "hover" adds a pointerover listener. prefetch: "intent" also adds focusin, pointerdown, and touchstart listeners. They use the same link eligibility rules as click navigation and ignore hash-only links.

The cache:

• holds at most 20 completed least-recently-used entries, keyed by URL
• deduplicates active requests from prefetch and navigation
• keeps successful responses for 30 seconds
• removes failed and expired entries
• aborts pending work when the runtime stops

Prefetch is skipped for data-saving, slow-2g, and 2g connections. A caller's abort signal rejects only that caller; it does not cancel a shared request.