See screenshots at the bottom

LMArena | Model Manager: Pin, Reorder & Persistent Auto-Select

Upgrades LMArena’s model picker so you can pin favorite models to the top, drag-reorder pinned models, and automatically re-select your last used model (persistently), with separate memory per Chat / Search / Image / Code modes.

Why You Need This

Switching models in LMArena gets annoying fast:

• Your go-to models get buried in a long dropdown.
• You keep re-selecting the same model every time you open a new chat or navigate.
• Different modalities need different “default” models (Chat vs Search vs Image vs Code).

This script makes the model picker feel like it has “favorites + a real default.”

Key Features

• Pin Models to the Top: One-click pin icon on each model to keep favorites always at the top.
• Drag to Reorder Pinned Models: Pinned models gain a subtle grip handle (on hover) for drag-and-drop reordering.
• Mode-Aware Memory (Chat/Search/Image/Code):
  • Pins are stored separately per modality.
  • “Last selected model” is also stored per modality, so each mode can have its own default.
• Persistent Auto-Select Last Model:
  • Adds an in-dropdown row: “Auto-select last chosen model” with a checkbox toggle.
  • When enabled, it automatically selects your saved model when appropriate.
• No Dropdown Flash During Auto-Restore:
  • Uses a temporary invisible “mask” while it opens/selects/closes the dropdown so you don’t see it flicker.
• Better Dropdown Usability:
  • Removes name truncation (so long model names stay readable).
  • Forces a high z-index and tall max-height so the menu is more usable.
• SPA-Safe Selection Enforcement:
  • After navigation, it can briefly “enforce” your saved model if LMArena tries to overwrite it a moment later.

How to Use

Action	Result
Open the model dropdown	You’ll see pin + (for pinned) reorder controls on items
Click the pin icon	Pin/unpin a model
Hover a pinned model, drag the grip	Reorder pinned models
Toggle Auto-select last chosen model checkbox	Enable/disable auto-restore for the current modality
Select a model normally	Saves it as the “last selected” for this modality

Behavior Details

• Pins are scoped by modality (e.g. Chat pins don’t affect Image pins).
• Auto-restore is scoped by modality and defaults to enabled unless you turn it off for that mode.
• If your saved model doesn’t exist in the current mode, auto-restore backs off instead of looping.

Performance Notes

• Only “enhances” the UI when the Radix/cmdk dropdown is present, using MutationObserver + small debouncing.
• Uses pointer-event drag (not HTML5 drag-and-drop) for a smoother reorder experience.
• Caches mode/modality detection and invalidates it on SPA navigation.

Installation

1. Install Violentmonkey / Tampermonkey.
2. Install this userscript.
3. Visit lmarena.ai and open the model picker.