Module local 

Local disk-persisted queue backed by turso (localqueue.v1), multi-process safe.

Connection strategy

turso is async-native and its Connection is Send + Sync, so there is no spawn_blocking boundary and no Mutex<Connection> anywhere. LocalQueue holds one turso::Database handle on <dataDir>/localqueue.sqlite; each operation opens its own short-lived connection from it and drops it when the operation completes, so no statement state leaks between operations.

Correctness under concurrent access (multiple handles on one file, i.e. multiple processes) comes from turso’s multi-process WAL mode — enabled explicitly, experimental upstream, and gated by the multi-handle tests below — plus a busy_timeout (writers wait for the write lock instead of failing with Busy).

Receive design: one BEGIN IMMEDIATE transaction per batch

The pinned localqueue.v1 receive is one atomic UPDATE ... SET receipt_handle = ?uuid ... RETURNING .... A single bound parameter cannot mint a distinct UUID per claimed row, so this implementation uses the sanctioned equivalent: one BEGIN IMMEDIATE transaction per batch that selects the due ids, then runs that exact per-row UPDATE ... RETURNING with a fresh UUID for each, and commits. IMMEDIATE takes the write lock at BEGIN, so concurrent receivers (in any process) serialize on the whole claim: a message is delivered to exactly one receiver per visibility window.

See crates/alien-bindings/FORMAT.md for the on-disk localqueue.v1 contract, including the "{id}:{uuid}" caller-facing receipt-handle format.

Structs

LocalQueue

Local disk-persisted queue on turso (localqueue.v1).