Shared libraries

nxt-backend uses three shared libraries to keep cross-app concerns consistent while preserving app-level ownership of business behavior.

Libraries

libs/core: shared NestJS domain/infrastructure modules used by all apps.
- Core database access (CoreTypeOrmModule, CorePgModule, GlobalSupabaseModule).
- Shared clients for CALIN, Victron, Solcast, Make, SendGrid.
- Shared entities/services for accounts, grids, meters, payouts, routers, and related domain records.
libs/helpers: framework-agnostic TypeScript helper functions plus a small NestJS pipe set.
- Includes shared array/number/query/time/promise helpers and provider-specific utility wrappers.
- query-helpers supports loading raw SQL files at runtime from app query folders.
libs/timeseries: named TypeORM data source and entity layer for TimescaleDB.
- Exposes TimeseriesTypeOrmModule with timescale connection.
- Defines snapshot entities (meter/grid/mppt/router/DCU/order/exchange/business snapshots).
- Contains dedicated Timescale migration tooling (libs/timeseries/migration, ormconfig.ts).

Shared libraries should contain cross-app capabilities, not single-app business logic.
Domain behavior owned by one app stays in that app unless there is proven reuse.
Library changes should include impact checks for all known consumers.

API and workflow services (tiamat, talos, loch, yeti) import from @core for shared modules/services/entities.
Utility-only behavior should come from @helpers; avoid embedding framework/service state in helper modules.
Any app writing/reading Timescale entities should use @timeseries for consistent schema mapping.

Prefer additive changes to avoid breaking multiple apps.
Track coupling risks when shared interfaces are changed.
For risky shared changes, verify at minimum:
- app build/serve across affected services,
- core module bootstrapping,
- cross-app data/entity compatibility.