ExecuteWriteAsync only caught SqlException, so a live outage surfacing as
InvalidOperationException/SocketException/IOException/TimeoutException escaped
unclassified and crashed the script actor instead of buffering. Mirror the HTTP
path: propagate OperationCanceledException on cancellation, classify transport
exceptions as transient (buffer+retry), let unexpected exceptions propagate.
CachedWrite buffered ALL write failures and retried forever, never returning a
synchronous failure to the script — permanent SQL errors (constraint/syntax/
permission) were treated as transient. Mirror the External-System API path:
attempt immediately, return Failed synchronously on permanent SQL errors (no
buffering), buffer only transient errors; the S&F retry path parks permanent
failures instead of retrying forever. New SqlErrorClassifier + PermanentDatabaseException.
Joseph Doherty