v2.0.0

zrk speaks HTTP/2.

zrk --http2 http://host/path      # h2c, prior knowledge
zrk --http2 https://host/path     # ALPN; fails if the server declines h2

One request is in flight per connection, exactly as over HTTP/1.1. -c, the
pacing, the coordinated-omission correction, the deadline shedding and every
latency number keep the meaning they had — only the wire format changed. That is
deliberate, and multiplexing is tracked separately in #50 because it is a
measurement question before it is a code change.

Breaking: no more Windows binaries

If you run zrk on Windows, this release does not include a binary for you, and
v1.4.3 remains the last one that does.

HTTP/2 over TLS is selected by ALPN, which std.crypto.tls does not implement,
so --http2 could only ever have worked over cleartext. Getting it required a
TLS stack that does — ztls — and ztls is
Linux and macOS by design: its entropy shim is a compile error anywhere else.

This cost a working platform. Windows binaries did HTTP/1.1 over TLS perfectly
well, and they were traded for HTTP/2 over TLS on the others. The alternative —
keeping Windows on the old TLS stack behind a compile-time seam — was considered
and not taken, in favour of one code path everywhere.

Releases now ship four archives: x86_64 and aarch64, Linux and macOS.

Breaking: different TLS

https:// benchmarks now run on ztls with a Zig-built BoringSSL, not on
std.crypto.tls. Same protocol, different implementation — if you compare
numbers across this boundary, compare them knowing that.

zrk also links C for the first time. BoringSSL is built by Zig and linked in
statically, so the binaries still have nothing to install alongside them, and
every target is still cross-compiled from one machine.

Also in this release

• --http2 (--h2c), documented in --help and the README, which are now
  checked against each other by a test rather than kept in step by hand.
• The HTTP/2 codec is its own package,
  zoxy-io/h2 — RFC 9113 framing, RFC 7541
  HPACK, and the RFC 9113 §8.2/§8.3 field rules, with no allocator in its
  public API. It is shared with zoxy.
• The request block is HPACK-encoded once at startup and replayed
  byte-identically on every stream, so a fixed request costs no per-request
  compression work.
• SETTINGS_HEADER_TABLE_SIZE = 0 is advertised, which forbids the peer the
  dynamic table and keeps response decoding stateless — HPACK makes header
  decoding mandatory where HTTP/1.1 was a scan for CRLF, and this keeps that off
  the hot path.
• CI now cross-compiles every release target on every change, so a dependency
  that breaks one is caught before a tag rather than by it.

Upgrading

Nothing changes for existing HTTP/1.1 invocations except the TLS implementation
under https://. --http2 is opt-in.