improve session activity and model display

frontend/src/components/ModelSelector.tsx

@@ -20,12 +20,13 @@ export function ModelSelector() {
     <div className="relative" ref={ref}>
       <button
         onClick={() => setOpen((v) => !v)}
-        className="flex h-[34px] items-center gap-2 border-[3px] border-white bg-accent px-3 text-white shadow-accent-soft"
+        className="flex h-[34px] min-w-0 max-w-[260px] items-center gap-2 border-[3px] border-white bg-accent px-3 text-white shadow-accent-soft"
+        title={selectedModel || undefined}
         style={{ borderRadius: 7 }}
       >
         <span className="h-2.5 w-2.5 border-2 border-line bg-white" />
-        <span className="text-[14px] leading-none">{selectedModel || "—"}</span>
-        <ChevronDown size={12} />
+        <span className="min-w-0 truncate text-[14px] leading-none">{selectedModel || "—"}</span>
+        <ChevronDown size={12} className="flex-none" />
       </button>
 
       {open && (
@@ -51,7 +52,9 @@ export function ModelSelector() {
                   m.name === selectedModel ? "bg-accent" : "bg-card"
                 }`}
               />
-              <span className="flex-1 text-xs text-ink-2">{m.name}</span>
+              <span className="min-w-0 flex-1 truncate text-xs text-ink-2" title={m.name}>
+                {m.name}
+              </span>
               {m.size_go > 0 && (
                 <span className="text-[10px] text-muted-2">{m.size_go} Go</span>
               )}