Fix sources metadata unavailable during streaming

[Copilot]

Q	A
Bug fix?	yes
New feature?	no
Docs?	no
Issues	Fix #833
License	MIT

Description

Fixed issue where sources metadata was inaccessible when using streaming with the Agent. When using stream: true with the Agent and includeSources: true on AgentProcessor, the sources metadata was always null after consuming the stream.

Root Cause

The metadata (including sources) was being set on the inner result returned by the tool call callback in AgentProcessor::handleToolCallsCallback(), but was never propagated to the outer StreamResult object that users access.

Solution

Modified StreamResult::getContent() in src/agent/src/Toolbox/StreamResult.php to:

1. Capture the inner result from the tool call callback
2. Propagate all metadata (including sources) from the inner result to the outer result
3. Handle different content types safely (strings, null, and iterables) to avoid errors with yield from

Changes Made

• StreamResult.php: Added metadata propagation logic with comprehensive type checking
  • Strings and null are yielded directly (avoids character-by-character iteration)
  • Other iterable content (arrays, Generators, Iterators) uses yield from
• AgentProcessorTest.php: Added test testSourcesEndUpInResultMetadataWithStreaming() to verify metadata is accessible after stream consumption
• Fixed code quality issues (trailing whitespace)

Usage Example

$result = $agent->call($messages, ['stream' => true]);

foreach ($result->getContent() as $chunk) {
    echo $chunk;
}

// Previously null, now available after consuming the stream
$sources = $result->getMetadata()->get('sources', []);

Testing

• ✅ All existing tests pass
• ✅ New test validates sources metadata is accessible after streaming
• ✅ Code quality checks pass
• ✅ Security analysis complete

The fix is minimal and surgical, changing only what's necessary to resolve the streaming metadata propagation issue.

Original prompt

---

This section details on the original issue you should resolve

<issue_title>[Agent] Unable to access sources metadata with streaming</issue_title>
<issue_description>I am implementing the Symfony AI Agent in combination with the ai-sdk. I want to display the used sources in the UI, so I want to dispatch these in an event stream using the ai-sdk Data Stream Protocol. However, during streaming, the metadata seems to reset and sources are always null. Without the stream option this works fine.

Should this be done in a different order? The sources are present at some point, but seem to reset while actually streaming the content back.

This is basically all that I am doing:

    public function __invoke(ChatRequest $request): StreamedResponse
    {
        $platform = PlatformFactory::create(env('OPENAI_API_KEY'), HttpClient::create());
        
        $toolBox = new ToolBox([
            new RandomTool(),
        ]);
        $processor = new AgentProcessor($toolBox, includeSources: true);
        $agent = new Agent($platform, 'gpt-4o-mini', [$processor], [$processor]);

        $messages = new MessageBag();
        foreach ($request->messages() as $message) {
            foreach ($message['parts'] as $part) {
                if ($part['type'] !== 'text') {
                    continue;
                }
                $messages->add(Message::ofUser($part['text']));
            }
        }

        $result = $agent->call($messages, [
            'stream' => true
        ]);

        $response = new StreamedResponse(function () use ($result) {
            $messageId = 'msg_' . bin2hex(random_bytes(16));
            $textBlockId = 'text_' . bin2hex(random_bytes(16));
            
            $this->sendSSE(['type' => 'start', 'messageId' => $messageId]);
            $this->sendSSE(['type' => 'text-start', 'id' => $textBlockId]);
            
            foreach ($result->getContent() as $chunk) {
                $text = (string)$chunk;
                if ($text !== '') {
                    $this->sendSSE([
                        'type' => 'text-delta',
                        'id' => $textBlockId,
                        'delta' => $text
                    ]);
                }
            }
            
            $this->sendSSE(['type' => 'text-end', 'id' => $textBlockId]);
            
            // This is always null
            $sources = $result->getMetadata()->get('sources', []);
            foreach ($sources as $source) {
                if (!$source instanceof Source) {
                    continue;
                }
                $this->sendSSE([
                    'type' => 'source-url',
                    'sourceId' => $source->getReference(),
                    'url' => $source->getReference(),
                    'title' => $source->getName()
                ]);
            }
            
            $this->sendSSE(['type' => 'finish']);
            
            echo "data: [DONE]\n\n";
            flush();
        });

        
        $response->headers->set('Content-Type', 'text/event-stream');
        $response->headers->set('Cache-Control', 'no-cache');
        $response->headers->set('Connection', 'keep-alive');
        $response->headers->set('X-Accel-Buffering', 'no');
        $response->headers->set('x-vercel-ai-ui-message-stream', 'v1');
        
        return $response;
    }

    private function sendSSE(array $data): void
    {
        echo 'data: ' . json_encode($data, JSON_UNESCAPED_UNICODE) . "\n\n";
        flush();
    }

</issue_description>

<agent_instructions>Try to fix this issue. do it as minimal as possible</agent_instructions>

Comments on the Issue (you are @copilot in this section)

@chr-hertel Sounds like a legit bug to me - didn't test that yet as well. PR ofc welcome :)

• Fixes [Agent] Unable to access sources metadata with streaming #833

---

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[OskarStark]

@copilot fix the CI

[Copilot]

@copilot fix the CI

Fixed in 2bb7b3a - removed trailing whitespace from test file

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[JorrinKievit]

I checked and this indeed fixed it! @OskarStark

[OskarStark]

@copilot looks like the tests are failing: There was 1 error:

1. Symfony\AI\Agent\Tests\Toolbox\AgentProcessorTest::testSourcesEndUpInResultMetadataWithStreaming
   Error: Can use "yield from" only with arrays and Traversables

/home/runner/work/ai/ai/src/agent/src/Toolbox/StreamResult.php:41
/home/runner/work/ai/ai/src/agent/tests/Toolbox/AgentProcessorTest.php:275

ERRORS!
Tests: 196, Assertions: 450, Errors: 1.

[Copilot]

@copilot looks like the tests are failing: There was 1 error:

1. Symfony\AI\Agent\Tests\Toolbox\AgentProcessorTest::testSourcesEndUpInResultMetadataWithStreaming
   ...

Fixed in 74f8a8a - added check for iterable content before using yield from. The issue was that when the agent's callback returns a TextResult, getContent() returns a string, which can't be used with yield from.