NUtil Release Note 2026-08-16

The repository was split out of nqbook as the place for host-side tools, and took its first two.

• feed_sim.py — publishes a repeated virtual order framed exactly as nqbook's RunFeed expects (tag byte plus nlib::order host layout), so the service can be run end to end without a real feed. The layout is hand-written and unchecked: a field added to nlib::order must be mirrored here or every frame is silently dropped as the wrong size.
• md/kraken — reads Kraken's authenticated spot level3 websocket feed and discards it, to measure the feed's shape and rate. It builds its own popularity ranking from AssetPairs and Ticker (Kraken publishes none), shards symbols across connections at Kraken's 200-per-connection cap, spends at most half the subscribe rate budget per second, and reconnects with capped backoff when a connection errors or goes quiet for 20 seconds.
• Credentials stay outside the repository — environment variables, or a mode-600 file under ~/.config.