Essay proposes Co-generative Systems Design（共生成的システム設計）

The essay builds its argument by borrowing from architecture and urban design rather than treating software design as a purely technical exercise. It notes that software design already drew heavily from Christopher Alexander's pattern language, and that Eric Evans's domain-driven design shares the concern with growing a shared language between experts and designers. But it draws a distinction between a building and a city: a building is used and renovated after completion, while a city hosts many actors pursuing their own goals, so no single person can fix the final form. The essay suggests software may take on a similar character once AI moves beyond writing code into specs, design, testing, operations and proposing the next change.

The proposal then separates design authority into roles. A lead designer sets the scope delegated to AI, the change procedures and where responsibility sits. Developer citizen-designers extend and modify the shared mechanisms. User citizen-designers change their own environment, monitor AI judgments and file objections. AI is positioned as an agent that designs, generates and executes within delegated scope. The essay stresses that delegating design capability to AI should not narrow human participation.

From Ruby and Rails, the essay wants to carry over the freedom to modify existing mechanisms, citing the Rails Doctrine's "Provide sharp knives" principle of trusting developer judgment rather than removing powerful tools. It argues this freedom should extend to users who cannot write programs, while noting that giving human developers strong extension power differs from giving autonomous AI unlimited authority. It closes with open questions about who represents users, whether objection can keep pace with fast AI changes, and how to verify that a system has improved overall.