FirstEventInterface

A store that answers ONE event of a stream without replaying the stream — the event that opened it. Who opened a stream is written once, in its first event of a kind, and never moves. Asking for it through {@see EventStoreInterface::replay()} builds the whole stream to read one row: an agent session of 293 MB died of memory inside the check that only wanted to know who opened it (greenhouse evidence/1045 §3), before anything could record that it died. A store that implements this reads only as far as that row. Separate from {@see EventStoreInterface} so an implementation outside this package keeps compiling; a caller asks `instanceof` and falls back to scanning `replay()` — the same answer, at the old cost.

abstract public function first(string $streamId, string $type): ?Milpa\EventStore\Event

The first event of `$type` appended to `$streamId`, or `null` when the stream holds none. Reads only as far as that event. «First appended» is the log's own order. It is also the lowest `seq` of that type in the stream unless two writers numbered and appended concurrently — a race over a kind written once per stream, like an opening, that no writer of such a kind runs.

Parameters