Postgres is the authoritative central database. A read-path sync engine receives an initial snapshot and ongoing logical replication changes, filters changes to a declared subset, and sends that subset to the application runtime. A local store materializes the selected rows and columns in memory, an embedded database, or an edge cache. Application queries and their results remain local. Animation timing is illustrative, not a latency measurement. The three steps advance automatically; select a tab to jump to that step.