docs(TSP-1101): document text selection context feature in Chat file viewer

get-started/chat/introduction.mdx

@@ -13,12 +13,12 @@
   Start chatting now at chat.relevanceai.com — works on desktop and mobile
 </Card>
 
 ## Using different LLMs in Chat
 
 You can select the LLM you want to use in Chat:
 
 <div style={{ width:"100%",position:"relative","padding-top":"56.75%"}}>
 <iframe src="https://app.supademo.com/embed/cmfgfi5x0bz4239ozw2fj4het" frameBorder="0" title="How to set up Google Drive as a source of Knowledge" allow="clipboard-write; fullscreen" webkitAllowFullscreen="true" mozAllowFullscreen="true" allowFullscreen style={{ position:"absolute",top:0,left:0,width:"100%",height:"100%",border:"3px solid #5E43CE",borderRadius:"10px" }} />
 </div>
 
 1. Click the name of the LLM you're currently on (or Auto if you've selected 'Auto' previously) in the top right of Chat
@@ -101,7 +101,7 @@
 Save any prompt from your Chat conversations to make it available to all users in your project through the @ menu.
 
 <div style={{ width:"100%",position:"relative","padding-top":"56.75%" }}>
 <iframe src="https://app.supademo.com/embed/cminu37g60bizgxadmuzniah7" frameBorder="0" title="How to save a prompt" allow="clipboard-write; fullscreen" webkitAllowFullscreen="true" mozAllowFullscreen="true" allowFullscreen style={{ position:"absolute",top:0,left:0,width:"100%",height:"100%",border:"3px solid #5E43CE",borderRadius:"10px" }} />
 </div>
 
 1. Start a new conversation and enter the prompt you want to save
@@ -150,6 +150,25 @@
 
 ---
 
+## Selecting text from files
+
+When viewing a file in the Chat file viewer, you can highlight specific text passages and attach them as context to your chat message. This lets you reference a precise excerpt rather than an entire document, giving the agent exactly the information it needs.
+
+### Attaching a text selection to a message
+
+1. Open a file in the Chat file viewer
+2. Click and drag to highlight the text passage you want to reference
+3. Optionally, add a note to your selection to provide additional context
+4. Click **Add to message** to attach the selection to your chat input
+5. The selected text appears as a dismissible pill in the chat input — click the **×** on the pill to remove it if needed
+6. Send your message as normal; the selection is included as structured context
+
+### When to use text selection
+
+Use text selection when you need to ask about or act on a specific part of a file rather than its entirety. For example, point an agent to a single clause in a contract, a specific function in a code file, or a particular paragraph in a report. Providing targeted context reduces ambiguity and typically produces more accurate, focused responses than attaching a whole document.
+
+---
+
 ## Providing Feedback on Responses
 
 Help improve your AI agents by rating their responses with thumbs up or thumbs down. Your feedback helps identify what's working well and what needs improvement, making agents more effective over time.
@@ -196,7 +215,7 @@
 
 ## Supported file types in Chat
 
 Chat empowers you to work with a wide range of file types, both for input and output. Upload documents, images, and data files to provide context to your conversations, and generate new files based on your Agent's responses or built-in Agent outputs. Whether you're analyzing spreadsheets, processing PDFs, or creating presentations, Chat seamlessly handles file operations across different model providers.
 
 Here's a comprehensive breakdown of supported file types by model provider:
 
@@ -330,7 +349,7 @@
         To monitor your Chat credit usage, navigate to **Settings > Plan & Billing** to see a detailed breakdown of your credit expenses. Learn more about [Plans and credits](/admin/subscriptions/plans).
         </Tip>
     </Accordion>
     <Accordion title="Can I use different LLMs in Chat?">
     Yes, you can select the LLM you want to use in Chat by following these steps:
 
     1. Click on the cog icon in the top right of your screen