feat: display selected text from page in sidepanel (#496)

* feat: select text and pass to sidepanel

* fix: lint issues

* fix: persist selection across tabs

* fix: review comments

* fix: change when the selection is cleared

* feat: sanitize url

packages/browseros-agent/apps/server/src/agent/format-message.ts

@@ -38,10 +38,34 @@ export function formatBrowserContext(browserContext?: BrowserContext): string {
   return `${lines.join('\n')}\n\n---\n\n`
 }
 
+/** Strip XML-like tags that match our prompt delimiters to prevent injection. */
+function sanitizeForPrompt(s: string): string {
+  return s.replace(
+    /<\/?(?:selected_text|USER_QUERY|page_context|AGENT_PROMPT|soul|memory_and_identity|security|workspace)[^>]*>/gi,
+    '',
+  )
+}
+
 export function formatUserMessage(
   message: string,
   browserContext?: BrowserContext,
+  selectedText?: string,
+  selectedTextSource?: { url: string; title: string },
 ): string {
   const contextPrefix = formatBrowserContext(browserContext)
-  return `${contextPrefix}<USER_QUERY>\n${message}\n</USER_QUERY>`
+
+  let selectedTextBlock = ''
+  if (selectedText) {
+    const sanitizedText = sanitizeForPrompt(selectedText)
+    const title = selectedTextSource?.title
+      ? sanitizeForPrompt(selectedTextSource.title).replace(/"/g, "'")
+      : ''
+    const url = selectedTextSource?.url
+      ? sanitizeForPrompt(selectedTextSource.url)
+      : ''
+    const source = title ? ` (from "${title}"${url ? ` — ${url}` : ''})` : ''
+    selectedTextBlock = `<selected_text${source}>\n${sanitizedText}\n</selected_text>\n\n`
+  }
+
+  return `${contextPrefix}${selectedTextBlock}<USER_QUERY>\n${message}\n</USER_QUERY>`
 }

packages/browseros-agent/apps/server/src/api/services/chat-service.ts

@@ -171,6 +171,8 @@ export class ChatService {
     const userContent = formatUserMessage(
       request.message,
       resolvedMessageContext,
+      request.selectedText,
+      request.selectedTextSource,
     )
     session.agent.appendUserMessage(userContent)
 

packages/browseros-agent/apps/server/src/api/types.ts

@@ -47,6 +47,13 @@ export const ChatRequestSchema = AgentLLMConfigSchema.extend({
   supportsImages: z.boolean().optional().default(true),
   mode: z.enum(['chat', 'agent']).optional().default('agent'),
   declinedApps: z.array(z.string()).optional(),
+  selectedText: z.string().optional(),
+  selectedTextSource: z
+    .object({
+      url: z.string(),
+      title: z.string(),
+    })
+    .optional(),
   previousConversation: z
     .union([
       z.array(