Google Messages Web — Hide Sidebar by David F Dev

Google Messages Web — Hide Sidebar gives you back the full width of the chat window on messages.google.com/web/.
The conversation list and Start chat button are hidden by default. A small drawer-handle button on the left edge of the viewport lets you bring the sidebar back at any time and tuck it away again when you're done.

Features
- Hides the left sidebar: the conversation list and the Start chat header. The right-hand pane (your active conversation) gets the full width.
- Slim toggle button: a 16-pixel pill on the left edge. Click to reveal the sidebar, click again to hide it. Stays out of the way of Google's own UI.
- Remembers your last conversation: when you reload or reopen Google Messages, the addon takes you straight back to the last conversation you were viewing. No more landing on an empty welcome screen with the sidebar hidden.
- Works inside Firefox Taskbar Tabs: the conversation-restore logic is tuned for Taskbar Tabs / site-windows.
- Self-healing: if a stored conversation has been deleted, the addon detects the bounce and clears the stored id automatically.

Privacy
This addon stores exactly one piece of data in browser.storage.local: the id of your most recently viewed conversation. That data lives on your device, is scoped to this addon, and is never transmitted anywhere. There is no network code in the addon at all.

Requirements
Firefox 109 or later (Manifest V3).

Source
Source code, issues, and contributions: <https://github.com/DavidF-Dev/Google-Messages-Web-Hide-Sidebar>

Released under the MIT license.