@harness-one/anthropic

Anthropic Messages API adapter for the harness-one AgentAdapter interface. Supports chat, streaming, and tool_use.

Install

pnpm add @harness-one/anthropic @anthropic-ai/sdk

Peer Dependencies

• @anthropic-ai/sdk >= 0.30.0
• harness-one (workspace)

Quick Start

import Anthropic from '@anthropic-ai/sdk';
import { createAnthropicAdapter } from '@harness-one/anthropic';
import { createAgentLoop } from 'harness-one';

const client = new Anthropic({ apiKey: process.env.ANTHROPIC_API_KEY });
const adapter = createAnthropicAdapter({
  client,
  model: 'claude-sonnet-4-20250514',
});

const loop = createAgentLoop({ adapter });

for await (const ev of loop.run([
  { role: 'user', content: 'Write a haiku about TypeScript.' },
])) {
  if (ev.type === 'text_delta') process.stdout.write(ev.text);
  if (ev.type === 'done') break;
}

The adapter:

• Maps harness-one Message to Anthropic content blocks (text + tool_use + tool_result).
• Forwards ChatParams.signal so the loop's AbortSignal cancels in-flight requests.
• Surfaces cache_read_input_tokens / cache_creation_input_tokens as TokenUsage.cacheReadTokens / cacheWriteTokens.
• Accepts an optional logger (Pick<Logger, 'warn' | 'error'>) for non-fatal warnings.

See the main repository README.