Pydantic AI vs Pi
Pi is a TypeScript coding agent from Earendil Works: a terminal agent you extend with hooks, skills and packages, or embed through createAgentSession. In Pydantic AI, a coding agent is one configuration of a general Agent, and the skills, sandbox and sub-agents are each a capability you can swap.
Pydantic AI is one part of a stack: the Harness SDK for capabilities and complete agents, Pydantic Evals for evaluation, Pydantic Graph for graph-based workflows, Pydantic Logfire for observability, and Pydantic itself for validation. The tables below cover the whole of it.
Already built on Pi? The migrating-pi-to-pydantic-ai skill ports an existing application to Pydantic AI one working path at a time, preserving behavior rather than translating API names.
| Pi | Pydantic AI and Harness SDK | |
|---|---|---|
| Language | TypeScript | Python |
| License | MIT | MIT |
| Model providers | Many | Many |
| Extensibility | Extensions, skills, pi install | Capabilities and toolsets; 90+ with the Harness SDK |
| Harnesses | Pi itself; extend it or embed it | Built-in Coder and Researcher, or compose your own |
| Observability | Telemetry contract, no exporter | OpenTelemetry, including Pydantic Logfire |
| Enterprise support | None documented | For the framework itself, no platform required |
| Durable execution | No | Nine integrations |
| Interfaces | CLI | CLI, web chat, AG-UI, Vercel AI, ACP (experimental), GitHub Agentic Workflows |
| Realtime voice | No | Realtime |
| Evals | No | Pydantic Evals |
| Image generation | No | Image Generation |
| Pi | Pydantic AI and Harness SDK | |
|---|---|---|
| Multi-agent | No | Subagents, delegation, or pydantic-graph |
| Planning | No | Planning |
| Skills | Yes | Skills |
| Memory | No | Memory |
| Compaction | Yes | Compaction |
| Guardrails | Yes (tool_call hook) | Guardrails |
| Code sandboxes | No | Execution environments |
| Browser use | No | Web & research |
Can I build a coding agent like this in Python? Yes. Give your agent the
Coder() capability, or start from the harness
repository’s complete coding agent,
built from the pieces Coder puts together.
Last checked: 2026-09-26