Constant DEFAULT_INGEST_MEMORY_CAP 

pub const DEFAULT_INGEST_MEMORY_CAP: usize = _; // 268_435_456usize

Default cap for the in-memory ingest fallback — see spool_or_buffer.

This is the worst case peak of an ingest that could not get a spool file. It has to be generous enough that ordinary NARs keep flowing when the spool volume is unavailable, and small enough that a handful of concurrent ones cannot fill a 6 GiB pod. 256 MiB gives ~20 concurrent uploads of headroom.