v0.20.0

What's Changed

• The buffer's catalog engine carries several connections; each table takes its own slot (T-441) by @chasers in #310
• Deployment docs: dispatch Release with the full SHA, and bump in a stack's top PR by @chasers in #311
• UI: the table page marks a materialized column and shows its expression (T-447, PL-61) by @chasers in #312
• A bare SELECT count(*) FROM t no longer scatters: the footers answer it (T-448) by @chasers in #313
• The table preview reads the fewest hot files that hold its rows, and fetches no stats it cannot use (T-449) by @chasers in #314
• A diverged follower claim heals, and a failing claim backs off instead of retrying on every flush (T-450) by @chasers in #315
• Memory on /metrics: the cgroup's charge, its 60 s peak, the kernel's OOM counters, and the encode budget on the shape line (T-451) by @chasers in #316
• DuckDB returns the encode's pages: allocator_background_threads on every instance open, kept on by Smolquery.Allocator (T-452) by @chasers in #318
• The id-grouped hot read is lazy: no union_by_name, so a LIMIT stops early for every statement shape (T-453) by @chasers in #319
• The preview fetches the hot manifest newest-first by page, never whole (T-449) by @chasers in #320
• Compaction commits through its own catalog connection, and a failing table backs off (T-458) by @chasers in #321
• A buffer node refuses commits once its unsealed backlog is too deep to survive (T-457) by @chasers in #322
• A retire is O(claim) and replies before its maintenance, so a deep partition drains (T-459) by @chasers in #324
• A rebuilt engine spills to its own directory, and a compaction swap that times out is a failure, not a crash (T-460) by @chasers in #325
• A named engine keeps no DuckDB file cache: every long-lived instance reads each file once (T-461) by @chasers in #326
• The kind cluster's MinIO comes from bitnamilegacy, since Docker Hub stopped serving minio/minio to anonymous pulls (T-466) by @chasers in #333
• The hot manifest's read event names the manifest it read, so a test's handler can tell its own reads apart (T-462) by @chasers in #328
• The DuckLake catalog answers a call that exits as an error, so retention, GC and the compactor keep their state (T-464) by @chasers in #329
• The compactor screens candidates by the catalog's own file sizes, so a file at or above the threshold is never opened (T-463) by @chasers in #330
• The cluster page shows each node's version and the commit it was built from (T-465) by @chasers in #331
• Bump to 0.20.0 by @chasers in #334

Full Changelog: v0.19.0...v0.20.0