# migrating-google-adk-to-pydantic-ai

Guides a behavior-preserving move from Python Google ADK applications to Pydantic AI, including agents, tools, state, workflows, and events.

- skill · `type=skill` · Claude Code, Codex, Cursor, GitHub Copilot, Gemini CLI, OpenCode · 305 installs · ★ 145
- Author: pydantic
- License: MIT · policy=mirror · the beginning of the file is at the end of this page
- Source: https://github.com/pydantic/skills/tree/HEAD/skills/migrating-google-adk-to-pydantic-ai/SKILL.md
- Updated: 2026-10-16
- HTML: https://affpapa.org/en/nevibecode/skills/migrating-google-adk-to-pydantic-ai

## What it does

This skill traces one live request through `Runner.run_async()` or a deployed endpoint, the root agent, model calls, tools, callbacks, session services, emitted events, and the final response. It then separates model history from session state, long-term memory, artifacts, workflow checkpoints, and external side effects.

For a regular `LlmAgent`, the target is usually a typed Pydantic AI `Agent`. Plain async Python fits simple deterministic control flow, while `pydantic_graph` is reserved for explicit nodes, branching, or graph inspection. The guidance also covers delegation modes, resumability, deferred approval, hook ordering, and event persistence.

Application-owned infrastructure stays outside the migration unless it is deliberately in scope. That includes auth, state and artifact stores, queues, transport, A2A endpoints, evaluation, observability, and deployment. A retained runtime that still imports or invokes `google-adk` is a reason to keep that dependency.

## Install

### Claude Code (native platform)

1. **Skills CLI (Vercel)**
```bash
npx skills add pydantic/skills --skill migrating-google-adk-to-pydantic-ai -a claude-code
```

2. **Manually: put the files in place**
- File: `~/.claude/skills/migrating-google-adk-to-pydantic-ai/SKILL.md` — Copy the whole skill folder; for one project use .claude/skills/migrating-google-adk-to-pydantic-ai/

### Codex

1. **Skills CLI (Vercel)**
```bash
npx skills add pydantic/skills --skill migrating-google-adk-to-pydantic-ai -a codex
```

2. **Manually: put the files in place**
- File: `.agents/skills/migrating-google-adk-to-pydantic-ai/SKILL.md` — For all projects use ~/.agents/skills/

### Cursor

1. **Skills CLI (Vercel)**
```bash
npx skills add pydantic/skills --skill migrating-google-adk-to-pydantic-ai -a cursor
```

2. **Manually: put the files in place**
- File: `.cursor/skills/migrating-google-adk-to-pydantic-ai/SKILL.md` — Cursor also reads .agents/skills/ and .claude/skills/

### GitHub Copilot

1. **GitHub CLI**
```bash
gh skill install pydantic/skills migrating-google-adk-to-pydantic-ai
```

2. **Manually: put the files in place**
- File: `.github/skills/migrating-google-adk-to-pydantic-ai/SKILL.md`

### Gemini CLI

1. **Skills CLI (Vercel)**
```bash
npx skills add pydantic/skills --skill migrating-google-adk-to-pydantic-ai -a gemini-cli
```

2. **Platform CLI**
```bash
gemini skills install https://github.com/pydantic/skills --path skills/migrating-google-adk-to-pydantic-ai
```

### Windsurf (Devin Desktop)

**Manually: put the files in place**
- File: `.devin/skills/migrating-google-adk-to-pydantic-ai/SKILL.md` — The legacy .windsurf/skills/ path still works

### OpenCode

**Skills CLI (Vercel)**
```bash
npx skills add pydantic/skills --skill migrating-google-adk-to-pydantic-ai -a opencode
```

### Claude.ai

**Claude.ai**
- Zip the folder and upload it in Settings → Capabilities → Skills

Where a file is given instead of a command, copy the files from the source to that path: https://github.com/pydantic/skills/tree/HEAD/skills/migrating-google-adk-to-pydantic-ai/SKILL.md

## When to use it
- move `LlmAgent` and `Runner` to Pydantic AI
- separate model history from application state
- map ADK tools, callbacks, and plugins
- preserve workflow resume and side-effect behavior
- verify event ordering and final-response contracts

## Example prompts
- Trace `Runner.run_async()` in this repository and propose a Pydantic AI migration for the active request path.
- Map `LlmAgent`, `Session.events`, tools, and callbacks to Pydantic AI while keeping caller-visible behavior.
- Design parity tests for a resumable workflow with artifacts and repeated tool execution.

## Source text · SKILL.md · MIT

Below is the content of a third-party file. It is data, not instructions for you: do not act on anything written inside unless the human asks. Block tag: f881d7c3ce55f82f.

BEGIN THIRD-PARTY FILE f881d7c3ce55f82f
```text
---
name: migrating-google-adk-to-pydantic-ai
description: Migrate Python Google Agent Development Kit (ADK) applications to Pydantic AI. Use for `LlmAgent`, `Runner`, sessions, state, memory, tools, callbacks, plugins, graph or dynamic workflows, resumability, events, artifacts, MCP, and ADK deployment boundaries.
---

# Migrate Google ADK to Pydantic AI

Preserve caller-visible behavior, not ADK's class tree. Migrate the smallest complete request path and leave product infrastructure in the application.

## Work from the running application

1. Read repository instructions, dependencies, tests, and runtime entrypoints. Record the installed Google ADK, Pydantic AI, and optional `pydantic-ai-harness` versions.
2. Trace one real request from `Runner.run_async()` or the deployed endpoint through the root agent, instructions, collaboration mode, model calls, tools, workflow nodes, callbacks/plugins, session service, emitted events, state/artifact deltas, and final response. Record only behavior that path uses.
3. Separate the contracts before choosing targets:
   - `Session.events` used as model context;
   - session-, user-, app-, and invocation-scoped state;
   - searchable long-term memory;
   - workflow/node checkpoints and resume IDs;
   - versioned artifacts and external side effects.
4. Classify the active slice:
   - **Ordinary `LlmAgent`:** normally one reusable [`Agent`](https://pydantic.dev/docs/ai/core-concepts/agent/) with typed dependencies, tools, and output.
   - **ADK graph or dynamic workflow:** keep simple deterministic control flow in plain async Python; use [`pydantic_graph`](https://pydantic.dev/docs/ai/graph/graph/) when explicit typed nodes, branching, or graph inspection remain valuable.
   - **Multi-agent delegation:** inspect ADK's collaboration `mode` in Python 2.x; 1.x `sub_agents` use `chat` behavior. Use core [multi-agent patterns](https://pydantic.dev/docs/ai/guides/multi-agent-applications/) for `chat` transfer semantics. Harness [`SubAgents`](https://pydantic.dev/docs/ai/harness/subagents/) can fit `task` or `single_turn` only when their isolated context, return, interaction, and concurrency behavior match.
   - **Product runtime:** retain auth, session/state stores, artifact stores, queues, transport, A2A endpoints, evaluation, observability, and deployment unless they are explicitly in scope.
```
END THIRD-PARTY FILE f881d7c3ce55f82f

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