Assistant Runner

What this is

The Runner is for one-shot tasks — you send input, the assistant processes it, you get output back. No memory, no state between calls.

Good for things like:

Generating a summary, email, or report
Extracting structured data from a document
Answering a question based on provided context
Any automation that takes input and produces output

Run and get a response

import client from "./lib/amarsia"

const result = await client.run({
  content: [{ type: "text", text: "Write a 3-sentence product description for a noise-cancelling headphone." }],
})

console.log(result.content)
// → "Experience crystal-clear audio with our noise-cancelling..."

Response shape

Every run returns the same structure:

{
  "content": "Experience crystal-clear audio...",
  "model": "model-name",
  "input_tokens": 42,
  "output_tokens": 61
}

Field	Type	What it is
`content`	string	The assistant's response
`model`	string	Which model processed the request
`input_tokens`	number	Tokens consumed for your input
`output_tokens`	number	Tokens consumed for the response

Streaming response

Instead of waiting for the full response, stream it token by token. Great for showing output live in the UI.

const unsubscribe = client.stream.subscribe((state) => {
  if (state.status === "streaming") {
    process.stdout.write(state.live ?? "")
  }
  if (state.status === "success") {
    console.log("\n✓ Done:", state.data?.content)
    unsubscribe()
  }
})

await client.stream({
  content: [{ type: "text", text: "Write a detailed product spec." }],
})

state.live — partial text as it streams in
state.data — the complete response once done

With variables

Pass dynamic data into your assistant's instructions:

const result = await client.run({
  content: [{ type: "text", text: "Draft a support reply." }],
  variables: {
    CLIENT_NAME: "Sarah",
    ISSUE_TYPE: "billing",
  },
})

See Quickstart — Variables for how variables work.

Next steps

Conversations — need the assistant to remember previous messages? Use the Conversation API
Multimodal — pass images, PDFs, or audio as input
Runner API reference — full method details