docs: adr 0015 transactional outbox

2026-10-26 01:39:01 +01:00
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@@ -77,6 +77,8 @@ SQLite is the only supported backend (see [ADR-0012](docs/adr/0012-sqlite-is-the

 ### Federation (ActivityPub)

+Events: never publish from a use case after the fact. Pass the events to the repository/command-port method that writes the data so they land in the outbox (`event_queue`) in the same transaction (ADR-0015). The worker delivers them at-least-once and a ledger skips handlers already done, so every handler must be idempotent.
+
 Federation is feature-gated (`#[cfg(feature = "federation")]`). If your feature should federate, add domain events, handle them in `crates/adapters/activitypub/src/event_handler.rs`, and create an AP object + inbound handler.

 ## Code style