Composer model seat (ModelSelect) should reuse /model popup's search/filter for large catalogs

[merlinbr]

Add search/filter to the composer model dropdown

Problem

When I click the model selector in the composer bar (the trigger that shows "DeepSeek-V4-Flash" or whatever model is currently active), I get a dropdown with all provider groups and their models listed out. If a provider has a lot of models — which is common with OpenRouter or custom providers — this list gets really long and I have to scroll through everything to find what I want.

The weird thing is: if I type /model instead, the popup that opens already has a search box that filters models by name. So the search capability exists in the codebase (filterOptions in ui-commands/popup.ts), it's just not available in the composer trigger that a lot of people actually use.

I almost forgot that I could also use /model — I just click the model button like I do in other chat UIs. The current dropdown works fine when there are only a few models, but becomes painful at scale.

What I'd expect

Click the model trigger → the model pane opens → there's a small search input at the top where I can type "qwen" or "glm" and the list filters down in real time. Basically the same experience as the /model popup, but in the dropdown I already use.

Affected code

• packages/client/ui-model-selection/src/client/ModelSelect.tsx — the composer model seat
• packages/client/ui-commands/src/client/popup.ts — already has filterOptions() that could be reused

Possible solution

Add a compact search input to the pane === 'model' view in ModelSelect, wired to the same filterOptions logic the /model popup already uses. The search could sit at the top of the model list, filter the state.groups → models hierarchy by name, and disappear or collapse when not needed.

Not sure about the exact UI design... the team knows this better than I do but the core ask is just: let me search the model list from the composer trigger, not just from /model.

[sitechfromgeorgia]

Confirmed on Windows 11 with @deepseek-ai/dsh 0.1.1-rc.2 and the built-in OpenRouter route.

For one ordinary session, session.models currently returns 276 OpenRouter models. The composer ModelSelect has no search input, so switching to an exact model requires a long manual scroll. /model is a useful workaround, but it is not discoverable for users who naturally click the model button in the composer.

A few acceptance details that would make the composer search especially useful:

• Match case-insensitively against provider name/id and model display name/id (for example, openrouter, deepseek-v4, or openai/gpt-5.6).
• Preserve provider grouping while hiding groups with zero matches.
• Autofocus the search input when entering the model pane.
• Keep keyboard navigation predictable: ArrowUp/ArrowDown, Enter to select, and Escape to clear/close.
• Show an explicit no-results state and do not mutate the current selection until the user selects a result.
• Filter locally and immediately; a 276-row catalog does not need another network request.
• Clear the query when the menu closes so the next open is not unexpectedly filtered.

This is distinct from #3147, which adds filtering and bulk selection to the provider model-candidate picker in Settings. This request is specifically for the per-session composer component at packages/client/ui-model-selection/src/client/ModelSelect.tsx.

This small UX improvement would save substantial time for OpenRouter and other large catalogs. Thanks for raising it.