feat(sentinel): emit lifecycle events

[raashish1601]

Summary

Fixes #3012.

createSentinel() exposes isOpen and isReady, but it did not emit the lifecycle events that standalone clients expose. This adds connect and ready emissions after Sentinel finishes connecting, and emits end after closing or destroying an instance that was open.

The change is additive and keeps the event ordering aligned with the state a Sentinel consumer can observe.

Validation

• .\node_modules\.bin\tsc.cmd --build packages/client --force --verbose
• npm run lint:changed
• git diff --check

Note: the focused Sentinel mocha test could not run locally because Docker is not installed in this Windows environment (spawn docker ENOENT).

---

Note

Low Risk
Low risk additive behavior change: emits connect/ready after successful RedisSentinel.connect() and emits end on close()/destroy() when previously open; could affect consumers that assume no events or different ordering.

Overview
RedisSentinel now emits lifecycle events consistent with standalone clients: connect and ready are emitted after connect() completes, and end is emitted after close() or destroy() when the instance was previously open.

Adds a focused sentinel test (lifecycle-events.spec.ts) asserting the connect → ready → end event sequence and that end is observable via once() after shutdown.

^{Reviewed by Cursor Bugbot for commit ffdc7b5. Bugbot is set up for automated code reviews on this repo. Configure here.}

[nkaradzhov]

Hi @raashish1601, thanks for the PR, i will look into it, hopefully soon!

[nkaradzhov]

Needs rework before merge.

1. Wire emits to state transitions, not method bodies

Current PR emits from connect()/close()/destroy() directly. Standalone client emits from socket transitions (client/index.ts:946-973). Follow same pattern via #isOpen/#isReady setters:

#setOpen(value: boolean) {
  if (this.#isOpen === value) return;
  this.#isOpen = value;
  this.emit(value ? 'connect' : 'end');
}

#setReady(value: boolean) {
  if (this.#isReady === value) return;
  this.#isReady = value;
  if (value) {
    this.emit('ready');
  } else if (this.#isOpen && !this.#destroy) {
    this.emit('reconnecting');
  }
}

Replace raw #isOpen =/#isReady = assignments in connect(), close(), destroy(), #reset() with these. Single source of truth. end fires regardless of caller. reconnecting (currently missing — issue #3012 calls it out) falls out via #reset(). No async destroy() signature change needed.

2. Docs

No update to README.md events table (L360-377, RedisClient-only) or docs/sentinel.md (no events section). Add sentinel events table; note any divergence from standalone.

3. Tests

Spec covers happy connect → close → end only. Add:

• destroy() path.
• Double-close / double-destroy: end fires exactly once.
• Failover: reconnecting + re-emitted ready.