Compatibility Matrix

Meta Harness has one portable skill source and four actively supported runtime targets. First-class means that the target has an owned adapter guide, capability mapping, and validation responsibility; it does not mean every feature is identical in every configuration.

Support levels

Runtime Status Skill path Native execution material Typical capabilities
Pi First-class .agents/skills/harness/ Optional Pi extension; no required mirror Skills; model/provider routing; workers and rich coordination with pi-safe-agent-team
Codex First-class .agents/skills/harness/ or ~/.agents/skills/harness/ Optional .codex/agents/ Skills; custom agents; runtime-dependent isolation, messaging, and persistence
Antigravity First-class .agents/skills/harness/ Optional runtime-native agent profiles Skills; subagents and model/tool controls where enabled by the runtime
Cursor CLI / Agent First-class .agents/skills/harness/ Optional .cursor/agents/ Skills; native profiles; runtime-dependent background execution and isolation
Generic Best effort Client-defined Agent Skills path, commonly .agents/skills/ None guaranteed Portable instructions only; no assumed workers, isolation, messaging, or model routing

The portable source remains .agents/skills/harness/ in a project and ~/.agents/skills/harness/ for a user-level install. Native profiles are adapters or generated artifacts, never a second source of truth.

Capability and degradation policy

Adapters report capabilities as supported, supported with extension, advisory, or unsupported. If a runtime cannot enforce exclusive writes, use an isolated workspace, explicit non-overlapping ownership, or serialize the work. If native communication is unavailable, use a parent summary or a _workspace/ handoff. Never silently claim a stronger guarantee.

Rippability

You can remove .codex/agents/, .cursor/agents/, or other native profiles without removing .agents/skills/, docs/harness/, or _workspace/. Runtime settings, retries, and model choices belong in removable adapters.

Legacy clients

ForgeCode, Droid, OpenHands, and Aider are retained as unverified and deprecated migration notes only. They are not first-class support targets. Use the generic guide unless you have independently verified the client’s Agent Skills behavior.

See the installation guide for the currently shipped installer surface. Runtime-native generation remains optional and must not replace the portable contract.