6.18.4 (2026-05-24) Documentation mark RunnerIO split done in architecture (#167) (824fd72) plan narrow RunnerIO into EnvironmentIO + SessionFactoryIO (#167) (8110fec) retro: add planning stage notes for issue #167 (1aceff7) retro: add retro notes for issue #180 (1fcd0ac) retro: add TDD stage notes for issue #167 (870c767)