chore: add docs/ai.md about document generation

Signed-off-by: Julien Veyssier <julien-nc@posteo.net>

README.md

@@ -37,7 +37,9 @@ Collaborative editing of federated documents requires richdocuments version 3.4
 
 **Note:** Due to our content security policy we cannot open a document on a remote instance without reloading the page to allow Nextcloud embedding the remote Collabora Online instance in a frame.
 
+### AI document generation
 
+This app is able to generate office documents from a prompt using AI. See the [AI doc](./docs/ai.md).
 
 ## Development setup
 

docs/ai.md

@@ -0,0 +1,31 @@
+<!--
+  - SPDX-FileCopyrightText: 2025 Nextcloud GmbH and Nextcloud contributors
+  - SPDX-License-Identifier: AGPL-3.0-or-later
+-->
+# AI document generation
+
+This app implements task processing providers to generate office documents from a user prompt. You can disable these providers
+in the "Artificial intelligence" admin settings section.
+
+This feature is accessible in the Assistant app.
+These providers require to setup multiple background job workers because each task schedules an extra one
+to actually generate the document content with a TextToText provider.
+
+You need a provider for the TextToText task type for this document generation feature to work.
+You can find the apps that implement such provider in
+[the overview of AI features](https://docs.nextcloud.com/server/latest/admin_manual/ai/overview.html#overview-of-ai-features).
+Look for the "Text processing using LLMs" feature in the app table.
+
+See how to set up background job workers in the
+[related page of the Nextcloud admin documentation](https://docs.nextcloud.com/server/latest/admin_manual/ai/overview.html#ai-overview-improve-ai-task-pickup-speed).
+
+## Office text document generation
+
+You can generate docx/odt/pdf documents from a prompt with the "Generate Office text document" task type in the Assistant.
+This feature actually first generates markdown from the prompt, then converts it to HTML and then asks Collabora
+to convert it into a document.
+
+## Spreadsheet document generation
+
+You can generate xlsx/ods documents from a prompt with the "Generate Office spreadsheet document" task type in the Assistant.
+This feature first generates CSV content from the prompt and asks Collabora to convert it into a document.

lib/Service/DocumentGenerationService.php

@@ -105,15 +105,6 @@ EOF;
 		$stream = fopen('php://memory', 'r+');
 		fwrite($stream, $text);
 		rewind($stream);
-
-		// This also works fine
-		//$tmpFilePath = $this->tempManager->getTemporaryFile();
-		//file_put_contents($tmpFilePath, $text);
-		//$stream = fopen($tmpFilePath, 'r');
-		//if ($stream === false) {
-		//	throw new RuntimeException('Failed to generate stream from string');
-		//}
-
 		return $stream;
 	}
 }