ModelRefs / Message Threading — AI Glossary
Message Threading — AI Glossary
Organizing conversation history into a structured thread of alternating roles (system/user/assistant) as required by chat completion APIs.
Overview
Chat APIs require messages in a specific role sequence—system (optional, first), then alternating user/assistant. The sequence must be valid: no two consecutive same-role messages. Frameworks like LangChain, LlamaIndex, and the Vercel AI SDK manage thread construction. Incorrect threading causes API errors or degraded quality.
Reference details
| Topic | prompting |
|---|---|
| Also known as | chat thread, conversation thread |
| Last reviewed | 2026-06-24 |
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Frequently asked questions
What is Message Threading?
Organizing conversation history into a structured thread of alternating roles (system/user/assistant) as required by chat completion APIs.
Is Message Threading the same as chat thread?
Yes — chat thread, conversation thread are common aliases for Message Threading.
What concepts are related to Message Threading?
Closely related concepts include multi turn, system message, user message.