Use ACP-compatible harnesses with the AI SDK harness layer
AI SDK now abstracts away harness diversity. One layer, any ACP-compatible coding runtime.
Why it matters
Vercel's AI SDK added a meta-adapter for Agent Client Protocol (ACP)-compatible harnesses, reducing integration friction for developers building with multiple coding runtimes. A practical feature for teams standardizing on ACP.
The key facts
11 to knowNew @ai-sdk/harness-acp package enables any ACP-compatible harness via single abstraction
Meta-adapter pattern: wraps the protocol, not individual runtimes (Claude Code, Codex, Pi, Deep Agents, OpenCode previously required separate adapters)
Recommendation: use direct adapters (@ai-sdk/harness-claude-code, @ai-sdk/harness-codex) when available for tighter integration; fall back to ACP adapter for runtimes lacking direct adapters
HarnessAgent API unchanged; existing code works with new ACP-wrapped harnesses
Published August 13, 2026
New @ai-sdk/harness-acp package wraps Agent Client Protocol instead of specific runtimes
Supports any ACP-compatible harness (Claude Code, Codex, Pi, Deep Agents, OpenCode mentioned as prior single-runtime adapters)
@ai-sdk/harness-acp acts as meta-adapter; direct adapters (@ai-sdk/harness-claude-code, @ai-sdk/harness-codex) still recommended for tighter integration
ACP abstraction deliberately kept decoupled from harness layer—not all harnesses support ACP; direct adapters may expose better internal behavior
Use case: prefer direct adapters for Claude Code and Codex; reach for ACP adapter when no direct adapter exists but harness ships ACP-compatible package
Published August 2026 (future-dated changelog entry; treat as product announcement)
Go to the source
Vercel Blogvercel.com
Publisher excerpt: The now supports any Agent Client Protocol (ACP)-compatible harness with through the new package.AI SDK harness layerHarnessAgent@ai-sdk/harness-acp Previously, every harness adapter wrapped one specific runtime (Claude Code, Codex, Pi, Deep Agents, OpenCode). wraps the protocol instead. It is a…