AI SDK harness layer now supports native subscription authentication
Vercel’s AI SDK harness can reuse host-side subscriptions for supported coding agents, reducing credential setup while keeping agent-switching behind one interface.
The AI SDK harness now supports **native subscription authentication** for Claude Code, Codex, Cursor and six other listed adapters. Credentials remain on the host, where OAuth tokens can be refreshed and injected into outbound requests.
Existing harness applications need **no code or settings changes**. Check each authentication mode before deployment: direct and auto can fall back to a host subscription under stated conditions, while explicit provider credentials still take precedence.
The AI SDK harness now supports **native subscription authentication** for Claude Code, Codex, Cursor and six other listed adapters. Credentials remain on the host, where OAuth tokens can be refreshed and injected into outbound requests. Existing harness applications need **no code or settings changes**. Check each authentication mode before deployment: direct and auto can fall back to a host subscription under stated conditions, while explicit provider credentials still take precedence. The **ai-gateway mode never reads native subscriptions**, and support depends on each underlying harness and sandbox. Placeholder credentials with host-side token injection are available only where the sandbox supports them.
HarnessAgent’s portability now extends from runtime selection to reuse of host-held subscription credentials, removing another integration step for existing applications. The benefit is narrower than universal authentication portability: fallback behavior varies by mode, provider credentials retain priority, AI Gateway is excluded, and each harness and sandbox still needs deployment-specific validation.