AI SDKのカスタムプロバイダーを作る

interface TextProvider
{
    public function prompt(AgentPrompt $prompt): AgentResponse;
    public function stream(AgentPrompt $prompt): StreamableAgentResponse;
    public function textGateway(): TextGateway;
    public function useTextGateway(TextGateway $gateway): self;
    public function defaultTextModel(): string;
    public function cheapestTextModel(): string;
    public function smartestTextModel(): string;
}

interface TextGateway
{
    public function generateText(
        Provider $provider,
        ?string $model,
        string $systemPrompt,
        array $messages,
        array $tools,
        ?ObjectSchema $schema,
        TextGenerationOptions $options,
        ?int $timeout,
    ): GatewayResponse;

    public function stream(
        Provider $provider,
        ?string $model,
        string $systemPrompt,
        array $messages,
        array $tools,
        ?ObjectSchema $schema,
        TextGenerationOptions $options,
        ?int $timeout,
    ): Generator;

    public function onToolInvocation(
        Closure $invoking,
        Closure $invoked,
    ): void;
}

<?php

declare(strict_types=1);

namespace App\Ai\Gateway;

use Closure;
use Generator;
use Illuminate\Http\Client\Factory as HttpFactory;
use Illuminate\Support\Facades\Http;
use Laravel\Ai\Contracts\Gateway\TextGateway;
use Laravel\Ai\Gateway\TextGenerationOptions;
use Laravel\Ai\ObjectSchema;
use Laravel\Ai\Providers\Provider;
use Laravel\Ai\Responses\GatewayResponse;
use Laravel\Ai\Responses\Usage;

class MyInferenceGateway implements TextGateway
{
    protected ?Closure $onInvoking = null;
    protected ?Closure $onInvoked = null;

    public function generateText(
        Provider $provider,
        ?string $model,
        string $systemPrompt,
        array $messages,
        array $tools,
        ?ObjectSchema $schema,
        TextGenerationOptions $options,
        ?int $timeout,
    ): GatewayResponse {
        $credentials = $provider->providerCredentials();
        $config      = $provider->additionalConfiguration();

        $response = Http::withToken($credentials['key'])
            ->baseUrl($config['url'])
            ->post('/chat/completions', [
                'model'    => $model ?? $provider->defaultTextModel(),
                'messages' => $this->formatMessages($systemPrompt, $messages),
            ]);

        $data = $response->json();

        return new GatewayResponse(
            text: $data['choices'][0]['message']['content'] ?? '',
            usage: new Usage(
                inputTokens: $data['usage']['prompt_tokens'] ?? 0,
                outputTokens: $data['usage']['completion_tokens'] ?? 0,
            ),
        );
    }

    public function stream(
        Provider $provider,
        ?string $model,
        string $systemPrompt,
        array $messages,
        array $tools,
        ?ObjectSchema $schema,
        TextGenerationOptions $options,
        ?int $timeout,
    ): Generator {
        // ストリーミングの実装（省略）
        yield '';
    }

    public function onToolInvocation(Closure $invoking, Closure $invoked): void
    {
        $this->onInvoking = $invoking;
        $this->onInvoked  = $invoked;
    }

    protected function formatMessages(string $systemPrompt, array $messages): array
    {
        $formatted = [['role' => 'system', 'content' => $systemPrompt]];

        foreach ($messages as $message) {
            $formatted[] = [
                'role'    => $message->role->value,
                'content' => $message->content,
            ];
        }

        return $formatted;
    }
}

public function __construct(
    protected array $config,
    protected Dispatcher $events,
) {}

/**
 * Get the provider's text gateway.
 */
public function textGateway(): TextGateway
{
    return $this->textGateway ??= new MyInferenceGateway;
}

<?php

namespace Tests\Feature;

use App\Ai\Agents\SummaryAgent;
use Illuminate\Foundation\Testing\RefreshDatabase;
use Tests\TestCase;

class SummaryAgentTest extends TestCase
{
    use RefreshDatabase;

    public function test_summary_agent_returns_text(): void
    {
        SummaryAgent::fake(['これは要約です。']);

        $response = SummaryAgent::make()->prompt('長い記事のテキスト...', provider: 'my-inference');

        $this->assertEquals('これは要約です。', $response->text);

        SummaryAgent::assertPrompted('長い記事のテキスト...');
    }
}

public function test_with_mock_provider(): void
{
    $this->app->make(AiManager::class)->extend(
        'my-inference',
        function (array $config) {
            $gateway = $this->app->make(\Laravel\Ai\Gateway\Prism\PrismGateway::class);
            $events  = $this->app->make(\Illuminate\Contracts\Events\Dispatcher::class);

            return new MyInferenceProvider($config, $events);
        }
    );

    // テストコード
}