When It Exists

ctx.message represents the assistant message generated during the current turn.

This value is only available in post-turn hooks that run after the model finishes generating a response.

During prompt construction (onContextBuild), ctx.message is always null.

It becomes populated when the host invokes hooks such as:

• onTurnEnd
• onToolCall
• onError

In these hooks, ctx.message refers to the assistant message that was just produced.

Shape

interface TurnMessage {
  id: string
  role: 'assistant'
  content: string | null
  finishReason?: 'stop' | 'length' | 'tool_calls' | 'error'
  toolCalls?: ToolCall[]
}

Fields

• id – unique identifier of the assistant message
• role – always "assistant"
• content – textual content produced by the model
• finishReason – reason the model stopped generating
• toolCalls – tool calls issued during this turn (if any)

content may be null in cases such as:

• the model produced only tool calls
• generation failed
• the turn was aborted

Practical Use

Strategies typically use ctx.message in post-turn hooks to:

• skip post-processing after aborted or failed turns
• extract structured memory from generated text
• inspect tool calls produced during the turn

Example:

export async function onTurnEnd(ctx) {
  if (!ctx.message) return

  if (ctx.message.finishReason !== 'stop') {
    return
  }

  const text = ctx.message.content
  if (!text) return

  // perform memory extraction or post-processing
}

Notes

ctx.message represents only the assistant message generated in the current turn.

It does not expose earlier messages.

To access conversation history, use:

ctx.history