v0.6.0

Pre-release hardening pass over the core NTP client, plus a full offline test suite and packaging verification in CI.

Fixes & hardening

• Instance-scoped state — cache/singleton state moved off module scope; independent new NtpTimeSync(...) instances no longer cross-contaminate.
• Signed clock offset (RFC 5905) — offset now uses ((T2-T1) + (T3-T4))/2 instead of an abs()+heuristic-sign form that returned the wrong result on asymmetric paths.
• IPv6-aware server parsing — supports bracketed IPv6 [::1][:port], bare IPv6 literals, and the existing host / host:port / IPv4[:port] forms with port-range validation.
• Stricter option validation — unknown constructor options now throw Invalid option: <key> instead of being silently ignored.
• Robustness — register the message listener before send (fixes a fast-reply race), count retries on no-progress rounds, and harden socket/listener cleanup on error paths.
• createPacket rewrite — uses Buffer.writeBigUInt64BE, dropping deprecated substr and per-packet string allocations.

Public API

• src/index.ts uses explicit named exports and NtpTimeSyncDefaultOptions is deep-frozen. Same 5 names, runtime mutation blocked.

Dependencies

• ntp-packet-parser bumped to ^0.6.1.

Tooling / CI

• 32 offline unit tests (in-process UDP fixture) covering packet construction, response validation, sample math, instance isolation, retry bounds, socket-leak regression, option validation, and server parsing.
• New verify-package CI job runs npm pack, publint, and attw (0.18.4) to catch exports/files/types regressions before publish.

⚠️ Breaking changes

• Unknown constructor options now throw instead of being ignored.
• Computed offsets change for asymmetric network paths (signed RFC 5905 formula).
• src/index.ts no longer re-exports via export *: RecursivePartial is no longer exported and NtpTimeResult is type-only.

Full changelog: 0.5.0...0.6.0