chat: remember last model

web/src/App.tsx

@@ -37,6 +37,10 @@ type SidebarItem = SidebarSelection & {
   title: string;
   updatedAt: string;
   createdAt: string;
+  initiatedProvider: Provider | null;
+  initiatedModel: string | null;
+  lastUsedProvider: Provider | null;
+  lastUsedModel: string | null;
 };
 type ContextMenuState = {
   item: SidebarSelection;
@@ -89,11 +93,26 @@ function loadStoredModelPreferences() {
 }
 
 function pickProviderModel(options: string[], preferred: string | null, fallback: string | null = null) {
-  if (preferred && options.includes(preferred)) return preferred;
   if (fallback && options.includes(fallback)) return fallback;
+  if (preferred && options.includes(preferred)) return preferred;
   return options[0] ?? "";
 }
 
+function getProviderLabel(provider: Provider | null | undefined) {
+  if (provider === "openai") return "OpenAI";
+  if (provider === "anthropic") return "Anthropic";
+  if (provider === "xai") return "xAI";
+  return "";
+}
+
+function getChatModelSelection(chat: Pick<ChatSummary, "lastUsedProvider" | "lastUsedModel"> | Pick<ChatDetail, "lastUsedProvider" | "lastUsedModel"> | null) {
+  if (!chat?.lastUsedProvider || !chat.lastUsedModel?.trim()) return null;
+  return {
+    provider: chat.lastUsedProvider,
+    model: chat.lastUsedModel.trim(),
+  };
+}
+
 type ModelComboboxProps = {
   options: string[];
   value: string;
@@ -212,6 +231,10 @@ function buildSidebarItems(chats: ChatSummary[], searches: SearchSummary[]): Sid
       title: getChatTitle(chat),
       updatedAt: chat.updatedAt,
       createdAt: chat.createdAt,
+      initiatedProvider: chat.initiatedProvider,
+      initiatedModel: chat.initiatedModel,
+      lastUsedProvider: chat.lastUsedProvider,
+      lastUsedModel: chat.lastUsedModel,
     })),
     ...searches.map((search) => ({
       kind: "search" as const,
@@ -219,6 +242,10 @@ function buildSidebarItems(chats: ChatSummary[], searches: SearchSummary[]): Sid
       title: getSearchTitle(search),
       updatedAt: search.updatedAt,
       createdAt: search.createdAt,
+      initiatedProvider: null,
+      initiatedModel: null,
+      lastUsedProvider: null,
+      lastUsedModel: null,
     })),
   ];
 
@@ -473,6 +500,16 @@ export default function App() {
     return searches.find((search) => search.id === selectedItem.id) ?? null;
   }, [searches, selectedItem]);
 
+  useEffect(() => {
+    if (draftKind || selectedItem?.kind !== "chat") return;
+    const detailSelection = selectedChat?.id === selectedItem.id ? getChatModelSelection(selectedChat) : null;
+    const summarySelection = getChatModelSelection(selectedChatSummary);
+    const nextSelection = detailSelection ?? summarySelection;
+    if (!nextSelection) return;
+    setProvider(nextSelection.provider);
+    setModel(nextSelection.model);
+  }, [draftKind, selectedChat, selectedChatSummary, selectedItem]);
+
   const selectedTitle = useMemo(() => {
     if (draftKind === "chat") return "New chat";
     if (draftKind === "search") return "New search";
@@ -611,6 +648,10 @@ export default function App() {
         title: chat.title,
         createdAt: chat.createdAt,
         updatedAt: chat.updatedAt,
+        initiatedProvider: chat.initiatedProvider,
+        initiatedModel: chat.initiatedModel,
+        lastUsedProvider: chat.lastUsedProvider,
+        lastUsedModel: chat.lastUsedModel,
         messages: [],
       });
       setSelectedSearch(null);
@@ -937,6 +978,9 @@ export default function App() {
             ) : null}
             {sidebarItems.map((item) => {
               const active = selectedItem?.kind === item.kind && selectedItem.id === item.id;
+              const initiatedLabel = item.kind === "chat" && item.initiatedModel
+                ? `${getProviderLabel(item.initiatedProvider)}${item.initiatedProvider ? " · " : ""}${item.initiatedModel}`
+                : null;
               return (
                 <button
                   key={`${item.kind}-${item.id}`}
@@ -956,7 +1000,12 @@ export default function App() {
                     {item.kind === "chat" ? <MessageSquare className="h-3.5 w-3.5" /> : <Search className="h-3.5 w-3.5" />}
                     <p className="truncate text-sm font-medium">{item.title}</p>
                   </div>
-                  <p className={cn("mt-1 text-xs", active ? "text-violet-100/90" : "text-violet-300/60")}>{formatDate(item.updatedAt)}</p>
+                  <div className="mt-1 flex items-center gap-2 text-xs">
+                    <p className={cn("shrink-0", active ? "text-violet-100/90" : "text-violet-300/60")}>{formatDate(item.updatedAt)}</p>
+                    {initiatedLabel ? (
+                      <p className={cn("ml-auto truncate text-right", active ? "text-violet-200/65" : "text-violet-300/45")}>{initiatedLabel}</p>
+                    ) : null}
+                  </div>
                 </button>
               );
             })}

web/src/lib/api.ts

@@ -3,6 +3,10 @@ export type ChatSummary = {
   title: string | null;
   createdAt: string;
   updatedAt: string;
+  initiatedProvider: Provider | null;
+  initiatedModel: string | null;
+  lastUsedProvider: Provider | null;
+  lastUsedModel: string | null;
 };
 
 export type SearchSummary = {
@@ -26,6 +30,10 @@ export type ChatDetail = {
   title: string | null;
   createdAt: string;
   updatedAt: string;
+  initiatedProvider: Provider | null;
+  initiatedModel: string | null;
+  lastUsedProvider: Provider | null;
+  lastUsedModel: string | null;
   messages: Message[];
 };