Build Core Database

Create ecs/core-database/ — core-database.ts plus one single-export file per facet the feature actually uses (components, resources, archetypes are each optional on Database.Plugin.create). Create only the facet files you need; omit the rest rather than shipping empty Database.components({}) boilerplate. A feature with no entities (a singleton whose whole state is resources) is just resources.ts + core-database.ts.

• components.ts → Database.components({ document, settings, presence, session }) (scopes optional) — only if the feature has entities.
• resources.ts → Database.resources({ … }) (every entry needs a default) — for singleton / global state.
• archetypes.ts → Database.archetypes(components, { … }) — only alongside components.
• core-database.ts → Database.Plugin.create({ imports?, components?, resources?, archetypes? }), exporting the CoreDatabase namespace.

The schema root; comes after data/ (and services/). Bind each schema from its data/ type — don't author shapes here. Components use JSON schemas; resources use the { default } convention (a schemaless aggregate binds via { default: State.create() }).

The how is in the auto-loading features/ecs/index.md + components.md / resources.md / archetypes.md rules.