Adapter Capabilities

The runtime adapter is where the shipped harness path declares what it supports before a run ever reaches the host.

This page explains the capability boundary conceptually. For the exact adapter implementation, request builder, and host payload shape, continue into Agent Harness Internals.

Current behavior

The current shipped pi adapter declares:

• supportsWaitingUser: true
• supportsSkills: true
• supportsMcpTools: true
• supportsStructuredOutput: false

That is the current contract the runtime is working with, not an aspirational roadmap.

What these flags affect

These capability flags influence how the runtime prepares a run:

• whether it can rely on skill support
• whether it can project MCP tools
• whether waiting-user style interactions are valid
• whether structured output should be treated as native harness behavior or as something the runtime must handle elsewhere

This gives the runtime a concrete statement of what the selected executor can handle.

More than a flag list

The adapter also defines the runner prep plan and the reduced host request shape. So in practice, adapter capabilities are part of a broader boundary:

• capability flags
• runner prep behavior
• host request building
• readiness reporting

That is what makes the adapter a real systems seam rather than just a static config object.