@agentium/harness. Install matching versions and read the v4 migration guide before upgrading from 3.x.
What changes in v4
- Separate harness package. Definitions, abilities, drivers, runtime controls, policies, manifests, and watches live in
@agentium/harness. Core exposes a neutral execution-services contract. - Explicit execution boundaries. Workspace read/write mode and local/authenticated hosting mode must be chosen. Removed Agent entrypoints and protocol aliases have replacements in the migration guide.
- Broader schema support. Public tools and structured output accept Zod 3, Zod 4 Classic, and Zod Mini. Use schema helpers when inspecting parameters.
- Opt-in durable systems. Tasks, actions, approvals, event/artifact records, queue delivery, protocol bridges, and watches have explicit storage and recovery contracts.
- Updated integrations. Voice and telephony, MCP/A2A protocols, BullMQ migration, sandbox adapters, evaluators, and metadata-first telemetry have updated contracts.
- Runtime support. Node.js
^22.18.0or^24.11.0.