Wave-3 review gate: contract conformance clean; two findings fixed inline — substrate boundary move (open_writer_connection → seam.rs), writer-slot release on with_writer/begin/commit error arms + regression tests (task review-wave-3)

alkstore-sqlite/src/substrate/mod.rs

@@ -66,13 +66,3 @@ pub(crate) use schema::Error as SchemaError;
 pub(crate) use schema::open_conn_bootstrapped;
 pub(crate) use schema::{Readers, Writer};
 pub(crate) use watcher::{SharedUpdateWatcher, WatcherConfig};
-
-/// Provision a fresh connection into the writer slot after a
-/// cancellation-path connection was consumed. Private helper over the
-/// substrate's bootstrapped open; the engine's tx handle captures it
-/// as its `reopen` closure's body.
-pub(crate) fn open_writer_connection(path: &str) -> Result<rusqlite::Connection, alkstore::Error> {
-    open_conn_bootstrapped(path).map_err(|e| match e {
-        SchemaError::Sqlite(inner) => alkstore::Error::database(inner),
-    })
-}