store-persist/

Persisted page store

A page store that opts into browser persistence with persist "local", so a shared cart survives reloads and SPA navigation.

store cart ui.CartState = ui.NewCartState() persist "local"

• ui/cart.go — the user-owned Go state. GOWDK serializes only its declared fields; it adds no opinions to the struct.
• shop.page.gwdk — declares the persisted store and renders the two islands.
• add-button.cmp.gwdk — shares the store via client { use cart }, mutates it (Count++), and resets it with the bounded clear cart statement.
• cart-badge.cmp.gwdk — references the store's fields through a typed use cart ui.CartState, so it needs no separate state declaration of the same shape.

Build it

gowdk build --out ./dist \
  examples/store-persist/shop.page.gwdk \
  examples/store-persist/add-button.cmp.gwdk \
  examples/store-persist/cart-badge.cmp.gwdk

The generated shop/index.html carries the persist config on the store seed:

<script type="application/json" data-gowdk-store="cart"
  data-gowdk-persist="local"
  data-gowdk-persist-key="gowdk:store:cart"
  data-gowdk-persist-version="…">{"Count":0}</script>

and assets/gowdk/islands/stores.js hydrates the store from localStorage on load and writes it back on every change.

What to try

1. Open /shop, click Add to cart a few times — the badge counts up.
2. Reload the page. The badge keeps your count (restored from localStorage).
3. Change CartState's shape in ui/cart.go and rebuild. The old persisted value is discarded automatically (the embedded schema hash changes), so the store falls back to its init value instead of restoring stale data.

Scopes

• persist "local" — localStorage; survives a browser restart, shared across all tabs and routes on the origin.
• persist "session" — sessionStorage; survives reload and SPA navigation, cleared when the tab closes.

Persisted store state is browser-visible: never persist secrets, session tokens, or trusted authorization state. The compiler warns (page_store_persist_secret_field) when a persisted field name resembles a secret.