88a7fba0b0
- separate global Host state from tab-local shell and Page state - replicate control-plane snapshots through a versioned BroadcastChannel - handshake new tabs without publishing empty startup state - reject self, stale, and malformed cross-tab messages - suppress broadcast echoes while applying remote snapshots - publish API snapshots and connection state atomically - keep Page state private and update only mounted iframe documents - test initial synchronization and protocol rejection paths