New backend op :streams (from seq high-water marks, so compacted streams still
list), threaded through mem-backend + durable serve/io-backend. catalog.sx:
persist/streams, stream-count, stream-exists?, total-events. 143/143.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Backend now tracks last-seq as a monotonic high-water mark (survives
truncation) and exposes :truncate-through. compaction.sx: persist/compact
checkpoints then drops events with seq <= snapshot seq; should-compact?/
maybe-compact give an explicit every-N policy. Determinism: post-compaction
replay value == uncompacted full replay. Phase 3 complete, 76/76.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>