architecture: ensure business rules live in data layer with web UX and agentic parity

[Sealjay]

Context

Business rules (game mechanics, validation, state transitions) should be enforced at the data/service layer, not duplicated across the web frontend and agentic interfaces. Both the web UX and the agentic layer should be thin clients over the same business logic.

Tasks

• Audit where business rules currently live — identify rules duplicated in frontend, backend routes, and agent code
• Refactor business rules into the service/data layer so they are enforced regardless of access method
• Ensure the web UX and agentic layer have feature parity — anything doable via the UI should be doable via agent API
• Create a feature matrix mapping UI features to API endpoints to agent capabilities
• Identify any features that exist in only one layer and plan convergence

Why

If business rules are scattered across layers, the web UI and agent can produce inconsistent results. A single source of truth in the data/service layer ensures correctness regardless of how the system is accessed.