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

# Concurrent Conversation Append

> Another writer advanced the conversation version while this run was in flight.

**Surface:** `GET /agents/runs/{id}`, `error.type = "AgentLoopConcurrentConversationAppend"`

## When this error occurs

`FinalizeAgentRunActivity` writes the run's produced messages + bumps `agent_conversations.version`
in a single CAS-protected transaction. This error means the CAS failed: between the API's
pre-flight version check at `POST .../runs` time and the workflow's finalize, another writer
(a concurrent run, or a manual database edit) bumped the version.

Only one run at a time can finalize cleanly on a given conversation. The losing run terminates
with this error and its messages are not persisted.

## How to fix

This is **expected behavior under concurrent runs on the same conversation**. Treat it as a
retryable signal:

1. `GET /agents/conversations/{id}/messages?since={prior_version}` to see what landed.
2. Start a fresh run with the new version as `expected_version`. Re-post the original prompt
   or tool outputs.

If you don't expect concurrency on this conversation, look at the messages stream — the
"other" writer's identity will be in the latest message's `run_id`.