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Merged
wachterjohannes merged 1 commit into from
Jun 1, 2026
Merged

Add tool/function calling support for Google Gemini adapter #147

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30 changes: 27 additions & 3 deletions packages/google-gemini-adapter/phpstan-baseline.neon
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Original file line number Diff line number Diff line change
Expand Up @@ -21,19 +21,43 @@ parameters:
-
message: '#^Call to method PHPUnit\\Framework\\Assert\:\:assertInstanceOf\(\) with ''ModelflowAi\\\\Chat\\\\Response\\\\AIChatResponse'' and ModelflowAi\\Chat\\Response\\AIChatResponse will always evaluate to true\.$#'
identifier: method.alreadyNarrowedType
count: 4
count: 5
path: tests/Unit/Chat/GoogleGeminiChatAdapterTest.php

-
message: '#^Call to method PHPUnit\\Framework\\Assert\:\:assertSame\(\) with ModelflowAi\\Chat\\ToolInfo\\ToolTypeEnum\:\:FUNCTION and ModelflowAi\\Chat\\ToolInfo\\ToolTypeEnum will always evaluate to true\.$#'
identifier: method.alreadyNarrowedType
count: 1
path: tests/Unit/Chat/GoogleGeminiChatAdapterTest.php

-
message: '#^Cannot access offset 0 on mixed\.$#'
identifier: offsetAccess.nonOffsetAccessible
count: 4
count: 6
path: tests/Unit/Chat/GoogleGeminiChatAdapterTest.php

-
message: '#^Cannot access property \$functionCall on mixed\.$#'
identifier: property.nonObject
count: 1
path: tests/Unit/Chat/GoogleGeminiChatAdapterTest.php

-
message: '#^Cannot access property \$functionResponse on mixed\.$#'
identifier: property.nonObject
count: 1
path: tests/Unit/Chat/GoogleGeminiChatAdapterTest.php

-
message: '#^Cannot access property \$parts on mixed\.$#'
identifier: property.nonObject
count: 4
count: 6
path: tests/Unit/Chat/GoogleGeminiChatAdapterTest.php

-
message: '#^Cannot access property \$role on mixed\.$#'
identifier: property.nonObject
count: 2
path: tests/Unit/Chat/GoogleGeminiChatAdapterTest.php

-
Expand Down
170 changes: 148 additions & 22 deletions packages/google-gemini-adapter/src/Chat/GoogleGeminiChatAdapter.php
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Original file line number Diff line number Diff line change
Expand Up @@ -17,10 +17,16 @@
use Gemini\Contracts\Resources\GenerativeModelContract;
use Gemini\Data\Blob;
use Gemini\Data\Content;
use Gemini\Data\FunctionCall;
use Gemini\Data\FunctionCallingConfig;
use Gemini\Data\FunctionResponse;
use Gemini\Data\GenerationConfig;
use Gemini\Data\Part;
use Gemini\Data\Schema;
use Gemini\Data\ToolConfig;
use Gemini\Enums\DataType;
use Gemini\Enums\MimeType;
use Gemini\Enums\Mode;
use Gemini\Enums\ResponseMimeType;
use Gemini\Enums\Role;
use Gemini\Responses\GenerativeModel\GenerateContentResponse;
Expand All @@ -31,15 +37,20 @@
use ModelflowAi\Chat\Request\Message\AIChatMessageRoleEnum;
use ModelflowAi\Chat\Request\Message\ImageBase64Part;
use ModelflowAi\Chat\Request\Message\TextPart;
use ModelflowAi\Chat\Request\Message\ToolCallPart;
use ModelflowAi\Chat\Request\Message\ToolCallsPart;
use ModelflowAi\Chat\Request\ResponseFormat\JsonResponseFormat;
use ModelflowAi\Chat\Request\ResponseFormat\JsonSchemaResponseFormat;
use ModelflowAi\Chat\Request\ResponseFormat\ResponseFormatInterface;
use ModelflowAi\Chat\Request\ResponseFormat\SupportsResponseFormatInterface;
use ModelflowAi\Chat\Response\AIChatResponse;
use ModelflowAi\Chat\Response\AIChatResponseMessage;
use ModelflowAi\Chat\Response\AIChatResponseStream;
use ModelflowAi\Chat\Response\AIChatToolCall;
use ModelflowAi\Chat\Response\StreamingUsageTracker;
use ModelflowAi\Chat\Response\Usage;
use ModelflowAi\Chat\ToolInfo\ToolChoiceEnum;
use ModelflowAi\Chat\ToolInfo\ToolTypeEnum;
use Webmozart\Assert\Assert;

final readonly class GoogleGeminiChatAdapter implements AIChatAdapterInterface, SupportsResponseFormatInterface
Expand All @@ -48,6 +59,7 @@
AIChatMessageRoleEnum::SYSTEM,
AIChatMessageRoleEnum::ASSISTANT,
AIChatMessageRoleEnum::USER,
AIChatMessageRoleEnum::TOOL,
];

public function __construct(
Expand All @@ -69,24 +81,38 @@ public function handleRequest(AIChatRequest $request): AIChatResponse
throw new \Exception('Not supported message role.');
}

$message = [];
$parts = [];

foreach ($aiMessage->parts as $part) {
if ($part instanceof TextPart) {
$message[] = $part->text;
$parts[] = new Part(text: $part->text);
} elseif ($part instanceof ImageBase64Part) {
$message[] = new Blob(MimeType::from($part->mimeType), $part->content);
$parts[] = new Part(inlineData: new Blob(MimeType::from($part->mimeType), $part->content));
} elseif ($part instanceof ToolCallsPart) {
foreach ($part->toolCalls as $toolCall) {
$parts[] = new Part(functionCall: new FunctionCall(
name: $toolCall->name,
args: $toolCall->arguments,
id: '' !== $toolCall->id ? $toolCall->id : null,
));
}
} elseif ($part instanceof ToolCallPart) {
$parts[] = new Part(functionResponse: new FunctionResponse(
name: $part->toolName,
response: $this->decodeToolResult($part->content),
id: '' !== $part->toolCallId ? $part->toolCallId : null,
));
} else {
throw new \Exception('Not supported message part type.');
}
}

$geminiRole = match ($aiMessage->role) {
AIChatMessageRoleEnum::USER => Role::USER,
AIChatMessageRoleEnum::USER, AIChatMessageRoleEnum::TOOL => Role::USER,
default => Role::MODEL,
};

$messages[] = Content::parse($message, $geminiRole);
$messages[] = new Content(parts: $parts, role: $geminiRole);
}

$responseFormat = $request->getResponseFormat();
Expand All @@ -95,6 +121,15 @@ public function handleRequest(AIChatRequest $request): AIChatResponse
$model = $this->client->generativeModel($this->model);
$model = $model->withGenerationConfig($config);

if ($request->hasTools()) {
$model = $model->withTool(ToolFormatter::formatTools($request->getToolInfos()));
$model = $model->withToolConfig(new ToolConfig(
functionCallingConfig: new FunctionCallingConfig(
mode: ToolChoiceEnum::NONE === $request->getToolChoice() ? Mode::NONE : Mode::AUTO,
),
));
}

if ($request instanceof AIChatStreamedRequest) {
return $this->createStreamed($request, $messages, $model);
}
Expand Down Expand Up @@ -182,14 +217,23 @@ private function create(AIChatRequest $request, array $messages, GenerativeModel
{
$result = $model->generateContent(...$messages);

try {
$text = $result->text();
} catch (\ValueError $exception) {
throw new \RuntimeException(
message: \sprintf('Request blocked by safety settings: %s', $exception->getMessage()),
code: $exception->getCode(),
previous: $exception,
);
$toolCalls = $this->extractToolCalls($result);

if ([] === $toolCalls) {
// Pure text response: keep the strict single-part accessor so blocked prompts still surface.
try {
$text = $result->text();
} catch (\ValueError $exception) {
throw new \RuntimeException(
message: \sprintf('Request blocked by safety settings: %s', $exception->getMessage()),
code: $exception->getCode(),
previous: $exception,
);
}
} else {
// Tool-call responses are not simple text (functionCall parts, optionally mixed with text),
// so gather any text parts without tripping the single-part accessor.
$text = $this->extractText($result);
}

if (\str_starts_with($text, '```json') && \str_ends_with($text, '```')) {
Expand All @@ -201,6 +245,7 @@ private function create(AIChatRequest $request, array $messages, GenerativeModel
new AIChatResponseMessage(
AIChatMessageRoleEnum::ASSISTANT,
$text,
$toolCalls,
),
new Usage(
$result->usageMetadata->promptTokenCount,
Expand All @@ -210,6 +255,81 @@ private function create(AIChatRequest $request, array $messages, GenerativeModel
);
}

/**
* Extract function calls from the first candidate of the response.
*
* Gemini does not always return an id for a function call; fall back to the function name,
* which is also what the API uses to correlate the matching functionResponse.
*
* @return AIChatToolCall[]
*/
private function extractToolCalls(GenerateContentResponse $result): array
{
$toolCalls = [];
foreach ($result->candidates as $candidate) {
foreach ($candidate->content->parts as $part) {
if (!$part->functionCall instanceof FunctionCall) {
continue;
}

$toolCalls[] = new AIChatToolCall(
ToolTypeEnum::FUNCTION,
$part->functionCall->id ?? $part->functionCall->name,
$part->functionCall->name,
$part->functionCall->args,
);
}

// The quick accessors only consider the first candidate, mirror that here.
break;
}

return $toolCalls;
}

/**
* Concatenate the text parts of the first candidate without throwing when the response
* also contains non-text parts (e.g. function calls).
*/
private function extractText(GenerateContentResponse $result): string
{
$text = '';
foreach ($result->candidates as $candidate) {
foreach ($candidate->content->parts as $part) {
if (null !== $part->text) {
$text .= $part->text;
}
}

break;
}

return $text;
}

/**
* Gemini expects a function response as a JSON object. Decode JSON object results so the
* structure is preserved, otherwise wrap the raw content so it is still handed back to the model.
*
* @return array<string, mixed>
*/
private function decodeToolResult(string $content): array
{
/** @var mixed $decoded */
$decoded = \json_decode($content, true);
if (!\is_array($decoded) || \array_is_list($decoded)) {
return ['content' => $content];
}

$response = [];
/** @var mixed $value */
foreach ($decoded as $key => $value) {
$response[(string) $key] = $value;
}

return $response;
}

/**
* @param Content[] $messages
*/
Expand Down Expand Up @@ -246,17 +366,23 @@ private function createStreamedMessages(\Iterator $responses, ?StreamingUsageTra
);
}

try {
$text = $response->text();
} catch (\ValueError $exception) {
throw new \RuntimeException(
message: \sprintf('Request blocked by safety settings: %s', $exception->getMessage()),
code: $exception->getCode(),
previous: $exception,
);
$toolCalls = $this->extractToolCalls($response);

if ([] === $toolCalls) {
try {
$text = $response->text();
} catch (\ValueError $exception) {
throw new \RuntimeException(
message: \sprintf('Request blocked by safety settings: %s', $exception->getMessage()),
code: $exception->getCode(),
previous: $exception,
);
}
} else {
$text = $this->extractText($response);
}

yield new AIChatResponseMessage(AIChatMessageRoleEnum::ASSISTANT, $text);
yield new AIChatResponseMessage(AIChatMessageRoleEnum::ASSISTANT, $text, $toolCalls);

$responses->next();
}
Expand Down
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