# ADR-004: Injectable clients, no module-level side effects

## Status

Accepted

## Context

Module-level side effects (auto-connections, env-based configuration) make testing difficult and conflict with containerized deployment patterns. The hub needs to create database instances with different configurations.

## Decision

`createSqliteDatabase(client)` receives a pre-created client. Module-level side effects are forbidden. The factory enables in-memory testing (`createClient({ url: ":memory:" })`) and custom client configuration.

## Consequences

- No global database state — each consumer explicitly creates and injects
- Testing with in-memory databases is straightforward
- Containerized deployment patterns are supported
- Consumer controls client lifecycle (connections, cleanup)

## References

- [sqlite-host.md](../sqlite-host.md)