Pydantic AI is a typed Python SDK for building AI agents that can use different language models and interfaces, including voice, image generation, and embeddings. Developers use it for applications ranging from structured data extraction to long-running multi-agent work. The catalogue entries provide workflows and configuration for its coding-agent and harness features.
Getting it into your agent
One page per mod, every tool's command on it. A separate URL per tool would split the same page into five that compete with each other.
npx skills add pydantic/pydantic-ai --skill migrating-pi-to-pydantic-aigit clone --depth 1 https://github.com/pydantic/pydantic-aiWrote this? Show the measurements
A badge with what this costs and how it scanned, read live from this page, so it follows the numbers instead of freezing them. Markdown for a README, HTML for a documentation site or a project page.
[](https://agentmods.dev/skills/pydantic/pydantic-ai/migrating-pi-to-pydantic-ai)<a href="https://agentmods.dev/skills/pydantic/pydantic-ai/migrating-pi-to-pydantic-ai"><img src="https://agentmods.dev/badge/skills/pydantic/pydantic-ai/migrating-pi-to-pydantic-ai/github.svg" alt="Measured on agentmods" height="20"></a>Or the 80×15 button, for a site that already has a row of RSS and ATOM ones. Only the verdict fits; the numbers stay here.
<a href="https://agentmods.dev/skills/pydantic/pydantic-ai/migrating-pi-to-pydantic-ai"><img src="https://agentmods.dev/badge/skills/pydantic/pydantic-ai/migrating-pi-to-pydantic-ai.svg" alt="Reviewed on agentmods" width="80" height="20"></a>What it costs to keep this loaded
Counted locally with the o200k_base tokenizer, which is exact for GPT models; Claude uses its own tokenizer and its counts differ. Treat this as one consistent yardstick across the catalogue rather than a bill. Prices are per million input tokens.
| Model | Per session | Once invoked |
|---|---|---|
| Fable 5.1 | $0.00088 | $0.01664 |
| Opus 5.5 | $0.00035 | $0.00666 |
| Sonnet 5.5 | $0.00018 | $0.00333 |
| Haiku 4.5 | $0.00009 | $0.00166 |
Grade A, and why
migrating-pi-to-pydantic-ai scanned grade A with 0 findings against 26 rules in 11 categories — prompt injection, anti-refusal, data exfiltration, privilege escalation, supply chain, agent snooping, system-prompt leakage, SSRF and excessive agency — measured 28d ago.
A static scan of the body, not an audit. Every finding is printed with the line that produced it so you can judge whether it matters here. A mod is markdown that instructs an agent; that is exactly why what it instructs is worth reading.
Nothing flagged
None of the 26 patterns this scan looks for appear in this file: no shell pipes, no recursive deletes, no credential paths, no hidden text, no instruction-override or anti-refusal phrasing, no agent-config snooping. That is not a guarantee, it is the absence of the things that are checkable.
Copies of this mod
1 near-identical copy found in the catalogue:
- migrating-pi-to-pydantic-ai — 100% identical, 0 lines differ
How it starts
The opening of the file, as written. The whole thing — 70 lines — stays where its author put it; the contents beside it link to each section on GitHub.
Migrate Pi to Pydantic AI
Preserve observable behavior, not Pi's TypeScript API. Migrate the smallest complete caller path and keep product/host infrastructure in the application.
Trace the source before choosing a target
- Read repository instructions,
package.json, Pi settings, tests, extension/package manifests, and runtime entrypoints. Record the installed Pi, Pydantic AI, and Harness versions. - Trace one real request from the Pi CLI, RPC boundary, or
createAgentSession().prompt()through resource discovery, system instructions, tools, extensions, model requests, messages, compaction/retry, events, session entries, UI/RPC output, and side effects. Establish a focused baseline or characterization test. - Inventory every active extension factory and package resource. For each
pi.on(...),registerTool,registerCommand, provider registration, renderer/UI contribution, skill, prompt, and persisted entry, record its firing point, trusted inputs, mutations, output, state owner, and caller-visible effect. - Separate these contracts when present:
- model messages, append-only session entries/tree branches, compaction summaries, and extension state;
- model-chosen tool input, trusted host context, project trust, approval, authorization, and OS isolation;
- token deltas, tool lifecycle, Pi extension events, capability events, RPC events, and terminal rendering;
- agent-loop behavior, CLI/TUI host behavior, provider transport, package distribution, and external side effects.
- Record each observed contract, its owner, semantic difference, and executable proof. An installed but inactive Pi package feature is not migration scope.
Read Research and concept mapping for the detected features. Read Verification and cutover before implementation.
Treat extensions as capability candidates
A Pi extension is the closest source concept to a Pydantic AI capability, but it is broader. An extension can combine agent behavior with terminal UI, commands, provider registration, resource discovery, and host lifecycle. Port responsibilities, not the extension file:
What ships with it
3 files beside SKILL.md in the same directory: the scripts, references and assets a skill reads on demand. Not counted in the per-session cost; read them before you install if any of them is executable.
What this file has done since we first saw it
Hashed on every crawl. A supply-chain change to an agent config is a question of when, not whether, so the history is kept rather than the latest state alone.
- 28d ago First seen · 70 lines · 88 tokens per session scan A 3011d66196ad
migrating-pi-to-pydantic-ai is a skill published in the GitHub repository pydantic/pydantic-ai (20,645 stars, last pushed today), licensed MIT. It adds 88 tokens to every session and 1,664 once invoked, about $0.0004 per session on Opus 5.5. A static security scan graded it A with 0 findings. No closer match exists in the catalogue, so it is treated as the original; first seen 2026-09-18.
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