0.8.1

Performance

• File: a resumed handle whose journal changed in the last two seconds re-checks the committed
  prefix by comparing it byte for byte with the bytes it verified, instead of hashing it with
  SHA-256. Every refusal stands; the read stays and the hash goes. A handle now keeps its
  committed prefix in memory, once, shared between its writer and capture views: the committed
  size of events.jsonl after open, up to about twice that as its own appends grow the buffer.
  Nothing persisted and eventlog-file/1 are unchanged. On the probe in
  #42 (2,000 one-event appends, 4.8 MB journal),
  reading 40 streams inside the window fell from about 1.4 s to about 60 ms and the run's CPU time
  from about 21 s to 1 s. Per-append wall time is bound by the commit's synchronizations and no
  longer grows with the journal: from 200 to 2,000 events it rose about 1.4 times before and did
  not rise after.
• File: stream_version, read_stream, the receipt a retried command or group returns and the
  event redact rewrites are found through a per-stream index kept beside the events, so each
  reads only the stream asked about (a head lookup reads no event, a window the events it returns
  plus one) instead of every event in the store. Folding history no longer rescans the store for
  each event's order check, which made replay quadratic: 160 events took 12,720 reads, now 0, and
  a complete open of 5,191 events fell from 674 ms to 288 ms (median, one machine). Feed, catch-up
  and projection rebuild still walk the store in global order. eventlog-file/1 is unchanged.
  #42