Rewrite or hide loaded messages, brand the welcome screen, and discover tools from the composer

This release gives you control over how loaded chat history renders, lets you put your logo on the empty-thread welcome screen, and adds a tool-mention picker button so users can discover available tools without knowing to type @.

Features

Transform chat history before it renders #3240 - A new optional history.transformChatMessage hook on ElementsConfig runs against every message loaded from chat.load: return a rewritten message to render it, or null to omit it. Keep backend-specific transcript conventions — like stripping server-injected framing or hiding system events — out of your rendered chat without forking the library. (Author: @simplesagar)
Add a logo to the welcome screen #3222 - The new WelcomeConfig.logo option renders a logo image above the title on the empty-thread welcome screen, so a fresh chat opens with your branding. (Author: @simplesagar)
Tool-mention picker in the composer #3222 - A new button next to the attachment button opens a list of available tools and inserts an @mention for the chosen one — a discoverable counterpart to the existing type-@ autocomplete. It hides itself when tool mentions are disabled or there are no tools. (Author: @simplesagar)