# Decisions

The Architecture Decision Records: decisions that are hard to reverse, why they were made, and the status of each.

| ADR | Decision | Status |
|---|---|---|
| 0001 | [KDF fixed-input layout follows RFC 9946 Appendix A](0001-kdf-fixed-input-layout-from-appendix-a.md) | Accepted |
| 0002 | [Stop traffic after 1 s of silence, tear down the Test Connection at 3 s](0002-stop-traffic-at-1s-tear-down-at-3s.md) | Accepted |
| 0003 | [Tokio runs the Control Phase; nothing precise runs on Tokio timers](0003-tokio-control-plane-precise-data-phase-engine.md) | Accepted |
| 0004 | [Sending Rate Structure sizes are IPv4-based; IPv6 senders subtract 20 bytes](0004-ipv4-based-sizes-in-sending-rate-structure.md) | Accepted |
| 0005 | [Congestion uses a back-to-back Errored Interval counter and a latched Congestion Confirmed state](0005-latched-congestion-confirmed-state.md) | Accepted |
| 0006 | [Transport errors are classified on both receive and send, not suppressed](0006-classify-transport-errors-on-receive-and-send.md) | Accepted |
| 0007 | [The Server learns each Setup Request's arrival address through nix, or quinn-udp on Windows](0007-arrival-address-via-nix-and-quinn-udp-on-windows-listener.md) | Accepted |
| 0008 | [The Data Phase Engine: a pool of Engine Threads on a Linux Server, one per Test Connection elsewhere, with bounded catch-up](0008-data-phase-engine-per-core-epoll-with-bounded-catch-up.md) | Accepted |
| 0009 | [authUnixTime is checked within ±5 s inclusive modulo 2^32, the first Setup Request is signed with the Client key, and digests cover the PDU as received](0009-authunixtime-window-and-setup-signing-interpretations.md) | Accepted |
| 0010 | [Key Table rows follow RFC 7210 with an HMAC-SHA-256 AlgID, lifetimes checked on our clock, and an Operator extension](0010-key-table-rows-lifetimes-and-extensions.md) | Accepted |
| 0011 | [Over-rate policing judges against the highest rate assigned in the last second](0011-over-rate-policing-uses-the-highest-rate-assigned-in-the-last-second.md) | Accepted |
| 0012 | [Catch-up is bounded by a time budget](0012-catch-up-by-time-budget.md) | Accepted |
| 0013 | [udpstp's stable interfaces from 0.1.0](0013-stable-interfaces-from-0-1-0.md) | Accepted |
| 0014 | [The Server runs as a Windows service of its own, under a virtual account, logging to daily files](0014-the-server-as-a-windows-service.md) | Accepted |
| 0015 | [Windows Shared Key files use a bounded private-file policy and a native inspection adapter](0015-windows-shared-key-private-file-policy.md) | Accepted |