Building with Pydantic AI Harness Pydantic AI Harness is the official capability library for Pydantic AI. Core ships the agent loop and the capabilities that need model or framework support (thinking, web search, MCP, tool search, workspaces, and provider-native compaction); the harness ships optional capabilities for longer, more involved work: a coding stack, sandboxes, delegation, memory, context management, and controls. Harness capabilities go in and compose with each other and with core capabilities; a few supporting pieces, such as media stores and the ACP server entry point, are used…