Effect v4 backbone

packages/capabilities owns application behavior as Effect v4 services, schemas, and tagged errors. The web, API, and background Workers compose these services instead of implementing separate use cases.

Services and adapters

Services use Context.Service. Live adapters read and write D1; Seed adapters implement the same contracts in memory for tests and fixture-backed execution. Tests can provide a Seed layer without starting a Worker.

Contracts and errors

Effect Schema defines capability values and HTTP payloads. packages/api composes those schemas into HttpApi groups, which drive server routing, OpenAPI, and the typed client.

Tagged errors distinguish expected refusals from unexpected failures. HTTP annotations assign statuses such as WorkspaceNotFound 404, AuthorizationDenied 403, and RateLimited 429. MCP handlers return expected operation refusals as tool errors. Web handlers translate allowlisted errors into safe UI messages.

The web app loads server state through TanStack Start loaders and server functions. Browser modules must not import server adapters or their runtime dependencies.

Follow First business feature to add a workspace-owned resource through D1, Effect adapters, permissions, UI, and REST.