Up next: channel mutex migration, named registry, gen_server call timeout. Later: RFC 004 (tunable scheduler idle policy), unbounded slab, handle_info, IO fd hygiene, arm-port.
Single source of truth: v0.4 history, v0.5 phases, v0.6 open tracks, and invariants/gotchas. Old task.md and ROADMAP_v0.5.md removed.