Changelog

All notable changes to this project are documented here. The format follows Keep a Changelog, and this project adheres to Semantic Versioning.

[Unreleased]

Listener flow control. PhiAccrualUdp.Listener now opens its UDP socket with active: N (default N=100, configurable via the :active_count option) instead of active: true. Re-arms on :udp_passive. This bounds the per-burst mailbox growth under packet floods.

Telemetry event [:phi_accrual_udp, :listener, :passive], emitted each time the listener re-arms after consuming active_count packets. Useful for observing ingress saturation.

Initial public release. Alpha — public API and wire format may change before v1.0 based on real-deployment feedback.

Wire format v1 (PhiAccrualUdp.Packet) — 12-byte fixed format with magic 0xCEA6, version 0x01, reserved flags byte (must be zero in v1), and 64-bit unsigned millisecond timestamp.
UDP listener (PhiAccrualUdp.Listener) — opens a UDP socket on a configurable port, decodes incoming packets, calls PhiAccrual.observe/2 with local monotonic receipt time. Decode failures emit [:phi_accrual_udp, :decode, :error] telemetry with reason classification.
Periodic UDP sender (PhiAccrualUdp.Sender) — sends heartbeat packets to a list of {host, port} targets at a configurable interval. Configurable timestamp source.
Custom node resolution — listener accepts a :node_resolver function mapping (ip, port) to user-defined node identifiers. Default: {ip, port} tuple.
Telemetry schema — [:listener, :started], [:sample, :received], [:decode, :error], [:sender, :started], [:sender, :tick].

Wire format and telemetry schema are not yet committed. Both may change before v1.0. Magic/version/flags structure is deliberately chosen to permit format evolution without breaking on-the-wire compatibility for v1 senders.
Receiver-driven clock discipline: the EWMA uses local monotonic receipt time, never the packet timestamp. This preserves phi_accrual's contract that cross-node timestamps are meaningless.