reader_executor_max_tail_for_drain
Drain bound for the experimentalReaderExecutor: a long source connection dropped within this many bytes of its right bound is read out to the bound first, so it completes and returns to the connection pool reusable instead of counting as an incomplete connection.
reader_executor_min_bytes_for_seek
Forward-gap bound for the experimentalReaderExecutor: a gap up to this is skipped on the open source connection (bridged / read through) instead of issuing a separate source read or reopening. Set near the bandwidth/request cost breakeven so bridging stays cost-positive.
reader_executor_use_long_connections
Reuse a bounded long source connection across windows in the experimentalReaderExecutor. A long connection is one whose range exceeds the current read window; when disabled, the executor takes no connection-pool budget and every window opens a short-lived one-shot connection (the stateless path).