refactor: enhance stream processing in Adapter class

.gitignore

@@ -5,4 +5,5 @@ tests/chunk.php
 .idea/
 .env
 example.php
-example.md
+example.md
+/blueprints/

README.md

@@ -23,9 +23,11 @@ Utopia Framework requires PHP 8.0 or later. We recommend using the latest PHP ve
 
 - **Multiple AI Providers** - Support for OpenAI, Anthropic, Deepseek, Perplexity, XAI, Gemini, and OpenRouter APIs
 - **Flexible Message Types** - Support for text and structured content in messages
+- **Message Attachments** - Attach files (for example images) directly to conversation turns
 - **Conversation Management** - Easy-to-use conversation handling between agents and users
 - **Model Selection** - Choose from various AI models (GPT-4, Claude 3, Deepseek Chat, Sonar, Grok, etc.)
 - **Parameter Control** - Fine-tune model behavior with temperature and token controls
+- **Streaming Output** - Consume incremental model output through callback-driven Server-Sent Events (SSE) streams
 
 ## Usage
 
@@ -35,8 +37,8 @@ Utopia Framework requires PHP 8.0 or later. We recommend using the latest PHP ve
 <?php
 
 use Utopia\Agents\Agent;
+use Utopia\Agents\Message;
 use Utopia\Agents\Roles\User;
-use Utopia\Agents\Messages\Text;
 use Utopia\Agents\Conversation;
 use Utopia\Agents\Adapters\OpenAI;
 
@@ -50,7 +52,7 @@ $user = new User('user-1', 'John');
 // Start a conversation
 $conversation = new Conversation($agent);
 $conversation
-    ->message($user, new Text('What is artificial intelligence?'))
+    ->message($user, new Message('What is artificial intelligence?'))
     ->send();
 ```
 
@@ -182,7 +184,7 @@ $openrouter = new OpenRouter(
 ```php
 use Utopia\Agents\Roles\User;
 use Utopia\Agents\Roles\Assistant;
-use Utopia\Agents\Messages\Text;
+use Utopia\Agents\Message;
 
 // Create a conversation with system instructions
 $agent = new Agent($adapter);
@@ -197,26 +199,190 @@ $assistant = new Assistant('assistant-1');
 
 $conversation = new Conversation($agent);
 $conversation
-    ->message($user, new Text('Hello!'))
-    ->message($assistant, new Text('Hi! How can I help you today?'))
-    ->message($user, new Text('What is the capital of France?'));
+    ->message($user, new Message('Hello!'))
+    ->message($assistant, new Message('Hi! How can I help you today?'))
+    ->message($user, new Message('What is the capital of France?'));
+
+// Add a user message with attachments
+$conversation->message(
+    $user,
+    new Message('Please summarize this screenshot'),
+    [new Message($imageBinaryContent)]
+);
 
 // Send and get response
 $response = $conversation->send();
 ```
 
+### Streaming Responses (SSE)
+
+The conversation layer supports incremental output streaming through `Conversation::listen(callable $listener)`.  
+The callback receives each text delta as it arrives from the provider's SSE stream, while `send()` still returns the final aggregated `Message`.
+
+#### Streaming in CLI / Worker Contexts
+
+```php
+use Utopia\Agents\Agent;
+use Utopia\Agents\Conversation;
+use Utopia\Agents\Adapters\OpenAI;
+use Utopia\Agents\Message;
+use Utopia\Agents\Roles\User;
+
+$agent = new Agent(new OpenAI('your-api-key', OpenAI::MODEL_GPT_4O));
+$conversation = new Conversation($agent);
+$user = new User('user-1', 'John');
+
+$conversation
+    ->listen(function (string $chunk): void {
+        echo $chunk; // render partial output as soon as it is received
+    })
+    ->message($user, new Message('Explain vector databases in one paragraph.'));
+
+$final = $conversation->send(); // final, complete assistant message
+```
+
+#### Exposing Model Output as HTTP SSE
+
+```php
+use Utopia\Agents\Agent;
+use Utopia\Agents\Conversation;
+use Utopia\Agents\Adapters\OpenAI;
+use Utopia\Agents\Message;
+use Utopia\Agents\Roles\User;
+
+header('Content-Type: text/event-stream');
+header('Cache-Control: no-cache');
+header('Connection: keep-alive');
+
+$agent = new Agent(new OpenAI('your-api-key', OpenAI::MODEL_GPT_4O));
+$conversation = new Conversation($agent);
+$user = new User('user-1', 'John');
+
+$conversation
+    ->listen(function (string $chunk): void {
+        // Send each token delta as an SSE frame
+        echo 'data: '.json_encode(['delta' => $chunk], JSON_UNESCAPED_UNICODE)."\n\n";
+
+        if (function_exists('ob_flush')) {
+            @ob_flush();
+        }
+        flush();
+    })
+    ->message($user, new Message('Write a short release note for today''s deployment.'));
+
+$final = $conversation->send();
+
+// Optional terminal event with complete text
+echo 'event: done'."\n";
+echo 'data: '.json_encode(['message' => $final->getContent()], JSON_UNESCAPED_UNICODE)."\n\n";
+echo 'data: [DONE]'."\n\n";
+flush();
+```
+
+#### Operational Notes
+
+- Streaming is adapter-dependent and available for chat-capable providers that expose incremental output.
+- The listener is optional; if omitted, responses are still collected and returned as a single final message.
+- Keep callbacks non-blocking and lightweight to avoid slowing downstream token delivery.
+- When serving SSE over HTTP, send `Content-Type: text/event-stream`, flush frequently, and disable intermediary buffering where applicable.
+- Usage metrics (input/output tokens and cache counters, where supported) remain available after `send()` completes.
+
 ### Working with Messages
 
 ```php
-use Utopia\Agents\Messages\Text;
-use Utopia\Agents\Messages\Image;
+use Utopia\Agents\Message;
 
-// Text message
-$textMessage = new Text('Hello, how are you?');
+// Message content is always text
+$textMessage = new Message('Hello, how are you?');
 
-// Image message
-$imageMessage = new Image($imageBinaryContent);
+// Attachments are binary payloads (for example images)
+$imageMessage = new Message($imageBinaryContent);
 $mimeType = $imageMessage->getMimeType(); // Get the MIME type of the image
+
+// Attach image to a text prompt
+$message = (new Message('Describe this image'))->addAttachment($imageMessage);
+```
+
+### Attachment Examples
+
+```php
+use Utopia\Agents\Conversation;
+use Utopia\Agents\Message;
+use Utopia\Agents\Roles\User;
+
+$conversation = new Conversation($agent);
+$user = new User('user-1', 'John');
+
+// 1) Attach a single image in the same turn
+$conversation->message(
+    $user,
+    new Message('What is shown here?'),
+    [new Message(file_get_contents(__DIR__.'/images/screenshot.png'))]
+);
+
+// 2) Attach multiple images in one turn
+$conversation->message(
+    $user,
+    new Message('Compare these two images and list differences.'),
+    [
+        new Message(file_get_contents(__DIR__.'/images/before.png')),
+        new Message(file_get_contents(__DIR__.'/images/after.png')),
+    ]
+);
+
+// 3) Build and reuse a message object with attachments
+$prompt = (new Message('Extract visible text from this receipt'))
+    ->addAttachment(new Message(file_get_contents(__DIR__.'/images/receipt.jpg')));
+
+$conversation->message($user, $prompt);
+```
+
+### Attachment Limits and Validation
+
+Attachment validation is enforced by default in `Conversation::message(...)`.
+Guardrail values come from the selected adapter (not from conversation-level user configuration).
+
+Default adapter guardrails:
+
+- Max attachments per message: `10`
+- Max binary size per attachment: `5_000_000` bytes (~5 MB)
+- Max total attachment payload per turn: `20_000_000` bytes (~20 MB)
+- MIME allowlist: `image/png`, `image/jpeg`, `image/webp`, `image/gif`
+- Reject empty or unreadable payloads
+- Adapter compatibility checks (attachment type must be supported by the selected adapter)
+
+To customize limits, create an adapter subclass and override limit methods:
+
+```php
+<?php
+
+use Utopia\Agents\Adapters\OpenAI;
+
+class StrictOpenAI extends OpenAI
+{
+    public function getMaxAttachmentsPerMessage(): ?int
+    {
+        return 3;
+    }
+
+    public function getMaxAttachmentBytes(): ?int
+    {
+        return 2_000_000;
+    }
+
+    public function getMaxTotalAttachmentBytes(): ?int
+    {
+        return 6_000_000;
+    }
+
+    /**
+     * @return list<string>|null
+     */
+    public function getAllowedAttachmentMimeTypes(): ?array
+    {
+        return ['image/png', 'image/jpeg'];
+    }
+}
 ```
 
 ## Schema and Schema Objects