Http3

WASM runtime (client and server)

• Added runtimeMode: 'wasm' for HTTP/3 and raw QUIC clients
  (connect()/connectAsync()/connectQuic()/connectQuicAsync()),
  backed by a wasm32-wasip1 build of the same quiche + BoringSSL
  protocol core used natively (crates/http3-wasm's h3c_*/qc_*
  extern-C ABI) — no native .node addon required in the process.
• Added Node-only server-side runtimeMode: 'wasm' support
  (Http3SecureServer.listen()/QuicServer.listen()), via the same
  crate's hs_*/qs_* ABI. ConnectionMap/QuicConnectionMap's
  retry-token HMAC moved from ring to boring::hash::hmac_sha256 so
  the server-side connection-routing/token logic compiles for wasm too.
• Verified the full native x wasm x client x server x QUIC x HTTP/3
  matrix (8 cells), including a wasm client talking to a wasm server
  over real loopback UDP with no native code involved at all.
• Verified the client build running inside real Cloudflare workerd
  (wrangler dev and wrangler deploy --dry-run) — see
  examples/workerd-client. The only remaining blocker to a real
  workerd deployment is outside this package: Workers has no outbound
  UDP client socket API yet (cloudflare/workerd#4463).
• See docs/WASM_RUNTIME.md for the usage
  guide and current Node/workerd support matrix, and
  docs/WASM_CLIENT_PLAN.md for the
  design and decision log.

Correctness

• Fixed buffer_pool.rs's right-sized pool checkin bucketing: it
  reused the checkout-side "smallest class >= request" classification
  instead of "largest class <= capacity," so a buffer whose capacity
  fell strictly between two class thresholds was filed into a bucket
  whose declared capacity it didn't meet — the same bug class as an
  earlier chunk_pool.rs fix, now caught by a Kani proof of the
  general property rather than by inspection.
• Fixed a retry-token validation panic: the clock-skew check cast a
  parsed (attacker/corruption-controlled) timestamp to i64 and took
  .saturating_sub(..).abs(), which can panic on i64::MIN for a
  hostile byte pattern. Replaced with u64::abs_diff, proven correct
  over the entire u64 domain.
• Fixed Http3EventSource's reconnect path (_startConnection())
  having no internal error handling, unlike its sibling
  _finalizeClose() — a _closeSession() rejection or a synchronous
  connect() throw would have escaped as an unhandled promise
  rejection instead of triggering the class's own reconnect/error flow.
• Replaced void asyncCall() throughout lib/ (constructors,
  event-handler callbacks, timers kicking off background work) with a
  drainable task registry (lib/run-detached.ts): every detached
  operation's rejection is now observed, and Http3ClientSession,
  QuicClientSession, and Http3SecureServer await all of theirs
  before their own close()/destroy() completes, instead of leaving
  background work to finish unobserved after shutdown.

Formal verification and fuzzing

• Added Kani proofs for chunk_pool/buffer_pool size-class
  arithmetic (largest-class-<=-capacity, and that every checkout
  allocation is accepted back on checkin) and for retry-token
  mint/parse (round-trip correctness, no panic on arbitrary bytes, and
  the clock-skew regression above, all proven rather than just
  example-tested).
• Extracted the retry-token payload build/parse logic (previously
  duplicated verbatim between connection_map.rs and
  quic_worker.rs) into a single shared proof_core model.
• Added a retry_token_roundtrip fuzz target exercising the real
  HMAC-integrated ConnectionMap mint/validate path under libFuzzer's
  coverage-guided mutation.

CI and infrastructure

• Fixed a Linux-only Rust compile failure (TxDatagram's data/
  payload_len fields needed pub(crate) visibility after their
  extraction into an always-compiled module).
• Fixed the npm-audit-and-sbom CI job choking on optional
  dependencies that are fully resolved in the lockfile but skipped via
  --no-optional (pnpm licenses list needs them actually installed
  to inspect).
• Fixed the Docker build contexts (Dockerfile, Dockerfile.test,
  Dockerfile.runtime-test) missing crates/ after
  crates/http3-wasm became a Cargo workspace member.
• Fixed a flaky high-connection-count interop test
  (quic-high-conn.test.ts): it connected clients strictly
  sequentially, so under CI thread-scheduling contention a handful of
  slow handshakes serialized into a very long stall instead of racing
  concurrently; connections are now established concurrently, matching
  the test's own stream-handling phase.