7.2.1 (2026-05-25) Documentation mark Layer 2 done and update health metrics in architecture doc (ad00426) plan align tool interfaces for structural typing (#194) (36e56b0) retro: add planning stage notes for issue #194 (63a5763) retro: add retro notes for issue #193 (8987f90) retro: add TDD stage notes for issue #194 (f692323)