Normalize chat history API

Normalizes a chat history for replay: merges consecutive same-role messages, drops empty messages, and validates roles — fixing the 'messages must alternate' / 'consecutive roles not allowed' errors many chat APIs throw. Answers 'how do I fix consecutive same-role messages?', 'how do I clean a chat history before resending it?'.

Price$0.02per request

MethodPOST

Route/v1/llm/normalize-messages

StatusLive

MIME typeapplication/json

Rate limit120/minute

Cache0s public

llmmessagesnormalizechat-historymergealternatededupagent

API URLhttps://x402.hexl.dev/v1/llm/normalize-messages

Integration docs

Example request

{
  "messages": [
    {
      "role": "system",
      "content": "sys"
    },
    {
      "role": "user",
      "content": "a"
    },
    {
      "role": "user",
      "content": "b"
    },
    {
      "role": "assistant",
      "content": "c"
    }
  ]
}

Example response

{
  "messages": [
    {
      "role": "system",
      "content": "sys"
    },
    {
      "role": "user",
      "content": "a\n\nb"
    },
    {
      "role": "assistant",
      "content": "c"
    }
  ],
  "originalCount": 4,
  "mergedCount": 3,
  "collapsed": 1
}

Input schema

{
  "type": "object",
  "required": [
    "messages"
  ],
  "properties": {
    "messages": {
      "type": "array",
      "items": {
        "type": "object"
      }
    },
    "joiner": {
      "type": "string",
      "default": "\n\n"
    }
  }
}

Output schema

{
  "type": "object",
  "additionalProperties": true
}