the Evented pg.Pool (ev_db) approach was broken — io_uring netLookup is unimplemented upstream, so no DNS and no outbound TCP from Evented fibers. this replaces ev_db with a DbRequestQueue (MPSC FIFO ring buffer) that routes general DB traffic through pool_io (Threaded) worker threads: - add DbRequest + DbRequestQueue to event_log.zig (4096-slot ring, spinlock push, CAS pop, 2 worker threads) - convert xrpc/admin handlers to typed DbRequest structs with @fieldParentPtr callbacks that write JSON into stack buffers - convert slurper: pullHosts on own std.Thread (parallel with spawnWorkers), addHost phased (DB via queue, HTTP via temp thread) - convert broadcaster firstSeq to DbRequest - convert backfiller/cleaner from Io.Future to std.Thread + direct persist.db access, with cooperative shutdown checks - remove all *Ev methods and ev_db infrastructure from DiskPersist - explicit join paths for backfiller/cleaner/db-workers on shutdown DbRequest.wait() never returns before done — preserves stack lifetime of caller-embedded request structs during shutdown drain. Co-Authored-By: Claude Opus 4.6 <noreply@anthropic.com>