Component hydration patterns that actually work with Jaspr

Jaspr, a Dart-based web framework inspired by Flutter, addresses SSR hydration complexity through automatic state synchronization. Unlike React or Vue where developers manually manage server-client data boundaries with directives like 'use client', Jaspr uses the @sync annotation and PreloadStateMixin to automatically serialize and transfer component state from server to client. The post covers handling non-serializable state (WebSockets, DOM refs) via kIsWeb checks, rendering mode selection (SSR/SSG/CSR via pubspec.yaml), Islands Architecture support via @island for reduced JS payloads, and testing hydration with the jaspr_test package without a real browser. The tradeoff is reduced control over serialization timing in exchange for fewer hydration bugs.