Module view_transitions 

View Transitions API + lazy navigation (issue #547).

Opt-in via transitions = true in ssg.toml. When enabled, the plugin:

1. Writes _transitions/ssg-transitions.js to the site dir — a tiny (~3 KB) client script that:
   • Intercepts same-origin <a> clicks
   • Fetches the next page, swaps its <main> content
   • Wraps the swap in document.startViewTransition(...) where supported (Chromium + Safari 18+ as of 2026-06)
   • Falls back to the browser’s default full-reload navigation in non-supporting browsers (Firefox stable as of 2026-06)
   • Skips cross-origin links, modified clicks (ctrl/cmd/shift/alt), non-GET targets and any link that opts out via data-no-transition or target="_blank"
2. Injects a <script type="module" defer> tag and a tiny <style> block that names header and footer as persistent transition roots (so they don’t animate across navigations — AC6).
3. Dispatches a ssg:after-swap CustomEvent after each swap so the islands loader (and any other listener) can re-hydrate components on the new page.

Architecture

Builds on:

• <ssg-island> (crate::plugins::islands) — exposes connectedCallback / disconnectedCallback, so swapping <main> detaches old islands’ listeners cleanly (AC5).
• LiveReloadPlugin (crate::server::livereload) — in dev mode, the reload handler is upgraded to wrap location.reload() in startViewTransition() when structural changes occur (AC7).

Bundle size budget

The injected script must stay ≤ 5 KB uncompressed. Verified by a unit test in this file.

Structs

ViewTransitionsPlugin

Plugin that injects the View Transitions API client + style hooks.

Constants

VIEW_TRANSITIONS_JS

The injected client script. Kept ≤ 5 KB — verified by a unit test.