fix(sse): update readyState to CLOSED on owner disposal; document silent-drop limitation

[JavanPoirier]

Two related gaps in the SSE primitive:

1. readyState stayed stale after owner disposal — onCleanup called teardown() (closes EventSource, clears source signal) but never called setReadyState(CLOSED), leaving the signal inconsistently at OPEN or CONNECTING.

2. No documentation of the fundamental EventSource limitation: a server that drops without a TCP close never fires an error event, so readyState stays OPEN forever and neither browser-native nor app-level reconnect triggers.

Changes

src/sse.ts

Added setReadyState(SSEReadyState.CLOSED) to onCleanup, making it consistent with every other teardown path (disconnect, retries-exhausted, budget-exhausted):

onCleanup(() => {
  clearReconnectTimer();
  teardown();
  setReadyState(SSEReadyState.CLOSED); // ← was missing
});

test/index.test.ts

Two new tests:

• "readyState is CLOSED after owner disposal" — directly covers the fix
• "readyState updates to CONNECTING when server drops connection" — documents the transient-error state transition

README.md

New "A note on server disconnection detection" section covering:

• Why EventSource cannot detect silent server drops
• Heartbeat pattern as the only reliable workaround — client timeout + server-side periodic event
• Why SSE comment lines (: keep-alive) are insufficient (not exposed to JS)

function createSSEWithHeartbeat(url: string) {
  let timer: ReturnType<typeof setTimeout> | undefined;

  const { reconnect, ...rest } = createSSE(url, {
    events: { heartbeat: resetTimer },
    onMessage: resetTimer,
    reconnect: true,
  });

  function resetTimer() {
    clearTimeout(timer);
    timer = setTimeout(() => reconnect(), 15_000);
  }

  onCleanup(() => { clearTimeout(timer); timer = undefined; });
  resetTimer();
  return { reconnect, ...rest };
}

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🦋 Changeset detected

Latest commit: f507436

The changes in this PR will be included in the next version bump.

This PR includes changesets to release 1 package

Name	Type
@solid-primitives/sse	Patch

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[davedbase]

Nice work on this. I like the changes!