What was going on
In `@tursodatabase/sync-wasm`, calling `connect()` against a hosted Turso database that negotiates MVCC sync rejects before any application SQL runs: `Internal error: unexpected path fresh-[random-id].db-log: files must be created in advance for OPFS IO`. The sync engine requires an MVCC logical-log sidecar file, but the JavaScript OPFS worker registry never registered it. It registered only the main db, `-wal`, `-wal-revert`, `-info`, and `-changes` paths. Affected versions: 0.7.2 and every 0.8.0 prerelease through 0.8.0-pre.7.
What fixed it
Fixed in PR #8524, which registers the MVCC log path with the OPFS worker before the sync engine connects. Use `@tursodatabase/sync-wasm` 0.8.0-pre.9 or newer. The maintainer re-tagged main to push it to npm after the pre.8 release job failed. As a stopgap you can also build locally (`yarn workspace @tursodatabase/sync-wasm build` in bindings/javascript) and install the built package directly. Source: https://github.com/tursodatabase/turso/issues/8516