lightstreamer

# Changelog

All notable changes to this project will be documented in this file.

The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.1.0/),
and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).

## [0.1.0] - 2026-09-08

### Added

- Session management over WebSocket (TLCP 2.5.0): `Lightstreamer.connect/2`,
  `subscribe/2`, `unsubscribe/2`, `close/1`, and `child_spec/1` for
  supervision trees. No global state, no application config — everything is a
  per-call option.
- MERGE-mode subscriptions delivering updates as plain messages to a
  configurable owner pid: merged current field state plus the set of fields
  changed by each event, with correct decoding of the TLCP delta wire format
  (unchanged / null / empty / `^n` skip). Owner processes are monitored and
  auto-unsubscribed on death.
- Connection resilience: transparent `LOOP` rebinds preserving per-item
  state; keepalive watchdog on the server's authoritative interval plus a
  configurable grace; on connection loss, rebind first then full re-create
  with capped exponential backoff, re-issuing subscriptions with state reset
  so each item starts from a fresh snapshot. `CONERR` code 1 (bad
  credentials) is never retried; `reconnect: :never` opts out of recovery.
- Outbound heartbeats when `:inactivity_millis` is advertised.
- `^P`/`^T` diff values are refused at session creation
  (`LS_supported_diffs=`) and kill the affected subscription with an explicit
  error if ever received — never a silently wrong value.
- Pure, fully unit-tested protocol codec (`Lightstreamer.Protocol`,
  `.Protocol.Frame`, `.Protocol.Update`) usable without any process — the
  test tables transcribe the TLCP 2.5.0 specification's example stream
  verbatim.
- Swappable transport behaviour (`Lightstreamer.Transport`) with a
  Mint/Mint.WebSocket production implementation; runtime dependencies are
  exactly `mint`, `mint_web_socket` and `castore`.