> ## Documentation Index
> Fetch the complete documentation index at: https://internal.softcrum.com/llms.txt
> Use this file to discover all available pages before exploring further.

# ADR-004 — Transactional Outbox as the Only Event Path

> Status: Proposed (RECONSTRUCTION — requires validation) · Date: 2026-08-17 (reconstructed) Refs: ../constitution/founding-constitution.md.

Status: **Proposed (RECONSTRUCTION — requires validation)** · Date: 2026-08-17 (reconstructed)
Refs: [`../constitution/founding-constitution.md`](/constitution/founding-constitution)

> ⚠️ Reconstructed from the material we have, not recovered. Tags: **\[derived]** is supported by
> evidence in the repository · **\[inferred]** is deduced · **\[proposed]** is a gap I filled.

## Context

A command that changes state and then publishes an event has two failure modes that both corrupt the
system: the publish fails and the event is lost, or the publish succeeds and the transaction rolls
back and the event is a lie. Neither is acceptable when the event awards points or sends an email.
**\[inferred]**

## Decision

**Domain events are written to a transactional outbox inside the command's transaction, and a relay
publishes them afterwards.** \[derived] Direct publication from application code is forbidden.

A single event stream feeds **six consumers**: realtime, outgoing webhooks, notifications, cache
invalidation, metering, and search or analytics indexing. **\[inferred]** — the drop names "six
consumers" repeatedly and names the first five; the sixth is my reconstruction.

Consumers are idempotent. At-least-once delivery is the contract, exactly-once is not offered, and
every consumer is written to survive seeing a message twice. \[derived]

## Consequences

* An event exists if and only if the state change it describes exists. That property is what makes
  the whole system reasonable about.
* Adding a consumer is additive and touches no producer.
  − Events are eventually published, not instantly. Latency budgets account for it.
  − The outbox is a hot table and a partitioning candidate at volume.

## What I could not determine

The sixth consumer. Five are named across the material; I have proposed search/analytics indexing as
the sixth. **\[proposed]**