0.3.0

Release notes for 0.3.0.

Released: 2026-06-22

Features

• Multi-instance support. configurePanel(config) now returns a PanelInstanceHandle and supports multiple independent panel instances on one page. Calling it with a distinct storagePrefix registers a new instance (independent storage keys, DOM root, toggle event, apply target). Calling it again with the same prefix and structurally-equal config is a no-op that returns the same handle (covers Astro view-transition reruns). Calling it with the same prefix but a structurally-different config throws immediately (RECONFIGURE_RULE = 'reject-with-error'); call handle.destroy() first to re-configure a prefix. Additive and backward-compatible — single-panel hosts observe no change. (#353)

• PanelInstanceHandle. configurePanel now returns a handle with { instanceId, open(), close(), toggle(), destroy() }. instanceId equals storagePrefix. destroy() deregisters the instance, unmounts its Preact tree, removes its DOM root, and unbinds its toggle-event listener — freeing the prefix for re-configuration. (#353)

• Per-instance toggle events. The default instance (the historical storagePrefix) keeps toggle-design-token-panel unchanged. Any instance with a non-default prefix listens on config.toggleEvent when supplied, or toggle-${storagePrefix} by default — giving each instance its own independent toggle channel. PanelConfig.toggleEvent?: string is a new optional field. (#354)

• PanelConfig.applySink. An optional { apply(pairs), clear(names) } sink routes this instance's CSS-var writes and clears through a caller-supplied object instead of document.documentElement. Useful for shadow DOM, iframe, or test-spy contexts. apply = upsert; clear = remove. Reset sends the full token-name set for the instance to sink.clear so the sink target is completely cleaned. Sink errors are non-fatal (console.warn). The host owns the sink target's lifecycle. applySink carries function references and must not be passed through the Astro inline JSON config. (#355)