> ## Documentation Index
> Fetch the complete documentation index at: https://lab.pollack.ai/llms.txt
> Use this file to discover all available pages before exploring further.

# Lesson 2: Multi-Provider

> Run the same task with Claude, Codex, and Gemini — the client code stays the same

<Card title="Source Code" icon="github" href="https://github.com/markpollack/agent-client-tutorial">
  This lesson is doc-only — concepts apply to any tutorial module
</Card>

## What You'll Learn

How to run the exact same goal with three different providers. The model construction changes, but `AgentClient` usage is identical.

## The Pattern

Provider-specific code is isolated to model construction. Everything after `AgentClient.create(model)` is portable:

```java theme={null}
// Provider-specific: build the model
AgentModel model = buildModel(provider);

// Portable: same code regardless of provider
AgentClient client = AgentClient.create(model);
AgentClientResponse response = client.run("Create hello.txt with 'Hello!'");
```

## Step 1: Run with Claude

```java theme={null}
ClaudeAgentModel model = ClaudeAgentModel.builder()
    .defaultOptions(ClaudeAgentOptions.builder()
        .model("claude-sonnet-4-5")
        .yolo(true)
        .build())
    .build();

AgentClient client = AgentClient.create(model);
AgentClientResponse response = client.run(
    "Create a file named hello.txt with 'Hello from Claude!'"
);
```

## Step 2: Run with Codex

Swap the model — the client code is identical:

```java theme={null}
CodexAgentModel model = new CodexAgentModel(
    CodexClient.create(),
    CodexAgentOptions.builder()
        .model("gpt-5-codex")
        .skipGitCheck(true)
        .build(),
    null
);

AgentClient client = AgentClient.create(model);
AgentClientResponse response = client.run(
    "Create a file named hello.txt with 'Hello from Codex!'"
);
```

<Note>
  `skipGitCheck(true)` lets Codex work in any directory. Without it, Codex requires a git repository. See [Codex Reference](/docs/agent-client/reference/codex-reference#skipgitcheck-and-mode-interaction) for details.
</Note>

## Step 3: Run with Gemini

```java theme={null}
GeminiAgentModel model = new GeminiAgentModel(
    GeminiClient.create(),
    GeminiAgentOptions.builder()
        .model("gemini-2.5-flash")
        .yolo(true)
        .build(),
    null
);

AgentClient client = AgentClient.create(model);
AgentClientResponse response = client.run(
    "Create a file named hello.txt with 'Hello from Gemini!'"
);
```

## What Stayed the Same

Across all three providers, these two lines are identical:

```java theme={null}
AgentClient client = AgentClient.create(model);
AgentClientResponse response = client.run(goal);
```

The only difference is *which model you construct*. That's the portable API — `AgentClient` doesn't know or care which provider is behind it.

## Provider Differences

While the client API is portable, providers have different capabilities:

| Capability        | Claude      | Codex                       | Gemini        |
| ----------------- | ----------- | --------------------------- | ------------- |
| Non-git directory | Works       | Works (`skipGitCheck=true`) | Works         |
| Structured output | JSON Schema | Not supported               | Not supported |
| Session resume    | Supported   | Not supported               | Not supported |
| Permission modes  | Multiple    | full-auto only              | yolo only     |

## With Spring Boot

In Spring Boot applications, you don't construct models manually. Use starter dependencies and Maven profiles to switch providers without changing code at all — see the [Switching Providers](/docs/agent-client/howto/switching-providers) how-to guide.

## Next Steps

* [Switching Providers](/docs/agent-client/howto/switching-providers) — The Spring Boot profile pattern for zero-code provider switching
* [Configuration Reference](/docs/agent-client/reference/portable-options) — All configuration options across providers
* [Defaults Philosophy](/docs/agent-client/explanation/defaults-philosophy) — Why LOOSE mode exists and how it affects each provider