# Backend Architecture Guardrails

These rules supplement the repository's root `AGENTS.md`.

- **Configuration ownership.** `config` owns source configuration, drafts and
  persistence. The effects layer owns patch orchestration. Rollbackable
  transactions publish state after persistence and commit; already applied
  runtime and independently committed state remain authoritative even when a
  later step fails. Preserve that state, its notifications and the error.
- **Effect ownership.** The declarative registry classifies every Verge patch field,
  including fields without effects and platform-specific fields. Effects
  reconcile toward the requested state with explicit dependencies and ordering.
  Configuration rollback does not imply reversal of OS or lifecycle effects.
- **Shared wire contract.** Notifications are typed. Event names, status values
  and payload shapes stay compatible with frontend producers and consumers.
- **Synchronization ownership.** Configuration-write serialization precedes
  configuration-update ownership, which precedes Core lifecycle ownership.
  When both are held, the lifecycle lock precedes the DNS lock. Independent
  transactions retain their ownership boundaries; asynchronous work does not
  hold synchronous data guards across suspension.
- **Retry ownership.** Bounded retries share backend policy while preserving
  attempts, delays and terminal errors. Background monitors own their lifetime
  and cancellation separately; waiting for a condition or traversing distinct
  candidates is not a retry policy.