Save Playgrounds by default

[adamziel]

What it does

Makes browser Playgrounds save by default without changing reusable setup URLs.

A fresh visit to playground.wordpress.net/?php=8.3&plugin=... now creates an autosaved OPFS Playground, keeps the original setup URL in the address bar, and shows an Autosaved status menu. storage=temp and can-save=no still opt out.

If a matching recent autosave exists, Playground starts a new site immediately and shows a non-blocking restore nudge. Choosing Restore opens the previous autosave. Choosing Keep new starts autosaving the new site.

Rationale

Autosave prevents accidental data loss, but replacing setup URLs with site-slug broke a core Playground workflow: refreshing the same URL to start again with the same parameters.

This keeps both properties:

• user changes are protected by default
• setup URLs remain stable, shareable, and refreshable

The restore nudge avoids blocking WordPress startup. New Playgrounds also stay temporary until the user chooses whether to restore or keep them, so a discarded fresh site does not consume one of the last 5 autosave slots.

Implementation

Adds autosave metadata for persistence state, last-used time, and setup URL fingerprinting. The fingerprint ignores transient parameters such as site-slug, modal state, and cache busters.

The site selection flow now:

1. loads an explicit site-slug when present
2. otherwise creates a fresh temporary site from the setup URL
3. looks for a recent matching autosave
4. shows the restore nudge while WordPress continues loading
5. autosaves the fresh site only after Keep new

Autosaves are kept as the last 5 recent autosaves unless the user chooses Store permanently.

The saved Playgrounds UI was adjusted around that model: autosaves appear first, the status indicator owns Unsaved / Autosaved actions, creation buttons are intent-driven, and GitHub import opens its modal before creating a site.

Supporting storage changes let new OPFS Playgrounds become usable before the full initial file copy finishes while still flushing queued writes in the background.

Testing instructions

Automated coverage:

npm exec nx test playground-website --testFile=setup-url.spec.ts
npm exec nx test php-wasm-web --testFile=directory-handle-mount.spec.ts
npm exec nx typecheck playground-website
npm exec nx typecheck php-wasm-web
npm exec nx lint playground-website
npx playwright test --config=packages/playground/website/playwright/playwright.config.ts website-ui.spec.ts --project=chromium --workers=1 --grep "Default Playground storage"
npx playwright test --config=packages/playground/website/playwright/playwright.config.ts sites-api.spec.ts opfs.spec.ts --project=chromium --workers=1 --grep "playgroundSites.list\\(\\) returns the active site|should switch between sites"

GitHub CI passed on edcc8ed93 with 48 jobs.