---
title: 'ARCCHR0007: Command handler injects IEventLog'
editUrl: https://github.com/Cratis/Arc/edit/main/Documentation/backend/csharp/chronicle/code-analysis/ARCCHR0007.md
description: Express command writes through returned events or transactional appends.
lastUpdated: 2026-10-15T00:00:00.000Z
---


## Rule

**Warning**. A command injects `IEventLog` in Handle or Provide. Return events
instead of bypassing Arc's append pipeline. To close a stream, return `CompleteStream`.

Under On, immediate appends are refused, even inside `[Unprotected("why")]`
method bodies: that declaration permits advisory reads, not immediate writes.
Use `IEventLog.Transactional` when returning events is not possible.

## Boundaries

This signature rule does not prove whether an injected log is actually used or
whether its appends are transactional. Suppress with a justification for a deliberate
transactional-only dependency. No code fix is offered.