feat(ui): add model thinking selector

packages/ui/src/lib/hooks/use-app-lifecycle.ts

@@ -69,6 +69,11 @@ export function useAppLifecycle(options: UseAppLifecycleOptions) {
         if (!instance) return
         emitSessionSidebarRequest({ instanceId: instance.id, action: "focus-agent-selector" })
       },
+      () => {
+        const instance = options.getActiveInstance()
+        if (!instance) return
+        emitSessionSidebarRequest({ instanceId: instance.id, action: "focus-variant-selector" })
+      },
     )
 
     registerEscapeShortcut(

packages/ui/src/lib/hooks/use-commands.ts

@@ -374,6 +374,20 @@ export function useCommands(options: UseCommandsOptions) {
       },
     })
 
+    commandRegistry.register({
+      id: "open-variant-selector",
+      label: "Select Model Variant",
+      description: "Choose a thinking effort for the current model",
+      category: "Agent & Model",
+      keywords: ["variant", "thinking", "reasoning", "effort"],
+      shortcut: { key: "T", meta: true, shift: true },
+      action: () => {
+        const instance = activeInstance()
+        if (!instance) return
+        emitSessionSidebarRequest({ instanceId: instance.id, action: "focus-variant-selector" })
+      },
+    })
+
     commandRegistry.register({
       id: "open-agent-selector",
       label: "Open Agent Selector",

packages/ui/src/lib/session-sidebar-events.ts

@@ -1,4 +1,8 @@
-export type SessionSidebarRequestAction = "focus-agent-selector" | "focus-model-selector" | "show-session-list"
+export type SessionSidebarRequestAction =
+  | "focus-agent-selector"
+  | "focus-model-selector"
+  | "focus-variant-selector"
+  | "show-session-list"
 
 export interface SessionSidebarRequestDetail {
   instanceId: string

packages/ui/src/lib/shortcuts/agent.ts

@@ -1,6 +1,10 @@
 import { keyboardRegistry } from "../keyboard-registry"
 
-export function registerAgentShortcuts(focusModelSelector: () => void, openAgentSelector: () => void) {
+export function registerAgentShortcuts(
+  focusModelSelector: () => void,
+  openAgentSelector: () => void,
+  focusVariantSelector: () => void,
+) {
   const isMac = () => navigator.platform.toLowerCase().includes("mac")
 
   keyboardRegistry.register({
@@ -20,4 +24,13 @@ export function registerAgentShortcuts(focusModelSelector: () => void, openAgent
     description: "open agent",
     context: "global",
   })
+
+  keyboardRegistry.register({
+    id: "focus-variant",
+    key: "T",
+    modifiers: { ctrl: !isMac(), meta: isMac(), shift: true },
+    handler: focusVariantSelector,
+    description: "focus thinking",
+    context: "global",
+  })
 }