@@ -3,8 +3,11 @@ import { describe, expect, it } from "vitest";
 import {
   DEFAULT_TIMESTAMP_FORMAT,
   getAppModelOptions,
+  getFavoriteModel,
   normalizeCustomModelSlugs,
   resolveAppModelSelection,
+  toggleFavoriteModel,
+  type AppSettings,
 } from "./appSettings";
 
 describe("normalizeCustomModelSlugs", () => {
@@ -64,3 +67,102 @@ describe("timestamp format defaults", () => {
     expect(DEFAULT_TIMESTAMP_FORMAT).toBe("locale");
   });
 });
+
+function makeSettings(overrides?: Partial<AppSettings>): AppSettings {
+  return {
+    codexBinaryPath: "",
+    codexHomePath: "",
+    defaultThreadEnvMode: "local",
+    confirmThreadDelete: true,
+    enableAssistantStreaming: false,
+    timestampFormat: "locale",
+    customCodexModels: [],
+    customClaudeModels: [],
+    customCursorModels: [],
+    favoriteModel: undefined,
+    ...overrides,
+  };
+}
+
+describe("getFavoriteModel", () => {
+  it("returns null when no favorite is set", () => {
+    expect(getFavoriteModel(makeSettings())).toBeNull();
+  });
+
+  it("returns the favorite with provider and model when set", () => {
+    const settings = makeSettings({
+      favoriteModel: { provider: "codex", model: "gpt-5.4" },
+    });
+    const fav = getFavoriteModel(settings);
+    expect(fav).toEqual({ provider: "codex", model: "gpt-5.4" });
+  });
+
+  it("normalizes aliases to canonical slugs", () => {
+    const settings = makeSettings({
+      favoriteModel: { provider: "claudeCode", model: "opus" },
+    });
+    const fav = getFavoriteModel(settings);
+    expect(fav).toEqual({ provider: "claudeCode", model: "claude-opus-4-6" });
+  });
+
+  it("returns null for invalid provider values", () => {
+    const settings = makeSettings({
+      favoriteModel: { provider: "invalid" as any, model: "gpt-5.4" },
+    });
+    expect(getFavoriteModel(settings)).toBeNull();
+  });
+
+  it("returns null for empty model values", () => {
+    const settings = makeSettings({
+      favoriteModel: { provider: "codex", model: "" },
+    });
+    expect(getFavoriteModel(settings)).toBeNull();
+  });
+
+  it("returns a single global favorite regardless of provider", () => {
+    const settings = makeSettings({
+      favoriteModel: { provider: "claudeCode", model: "claude-opus-4-6" },
+    });
+    const fav = getFavoriteModel(settings);
+    expect(fav?.provider).toBe("claudeCode");
+    expect(fav?.model).toBe("claude-opus-4-6");
+  });
+});
+
+describe("toggleFavoriteModel", () => {
+  it("sets a favorite model when none is set", () => {
+    const settings = makeSettings();
+    const patch = toggleFavoriteModel(settings, "codex", "gpt-5.4");
+    expect(patch.favoriteModel).toEqual({ provider: "codex", model: "gpt-5.4" });
+  });
+
+  it("removes the favorite when toggling the same model", () => {
+    const settings = makeSettings({
+      favoriteModel: { provider: "codex", model: "gpt-5.4" },
+    });
+    const patch = toggleFavoriteModel(settings, "codex", "gpt-5.4");
+    expect(patch.favoriteModel).toBeUndefined();
+  });
+
+  it("switches the favorite to a different model in the same provider", () => {
+    const settings = makeSettings({
+      favoriteModel: { provider: "codex", model: "gpt-5.4" },
+    });
+    const patch = toggleFavoriteModel(settings, "codex", "gpt-5.3-codex");
+    expect(patch.favoriteModel).toEqual({ provider: "codex", model: "gpt-5.3-codex" });
+  });
+
+  it("switches the favorite to a different provider entirely", () => {
+    const settings = makeSettings({
+      favoriteModel: { provider: "codex", model: "gpt-5.4" },
+    });
+    const patch = toggleFavoriteModel(settings, "claudeCode", "claude-opus-4-6");
+    expect(patch.favoriteModel).toEqual({ provider: "claudeCode", model: "claude-opus-4-6" });
+  });
+
+  it("normalizes aliases when toggling", () => {
+    const settings = makeSettings();
+    const patch = toggleFavoriteModel(settings, "claudeCode", "opus");
+    expect(patch.favoriteModel).toEqual({ provider: "claudeCode", model: "claude-opus-4-6" });
+  });
+});
@@ -16,6 +16,12 @@ const BUILT_IN_MODEL_SLUGS_BY_PROVIDER: Record<ProviderKind, ReadonlySet<string>
   cursor: new Set(getModelOptions("cursor").map((option) => option.slug)),
 };
 
+const FavoriteModelSchema = Schema.Struct({
+  provider: Schema.Literals(["codex", "claudeCode", "cursor"]),
+  model: Schema.String,
+});
+export type FavoriteModel = typeof FavoriteModelSchema.Type;
+
 const AppSettingsSchema = Schema.Struct({
   codexBinaryPath: Schema.String.check(Schema.isMaxLength(4096)).pipe(
     Schema.withConstructorDefault(() => Option.some("")),
@@ -42,6 +48,7 @@ const AppSettingsSchema = Schema.Struct({
   customCursorModels: Schema.Array(Schema.String).pipe(
     Schema.withConstructorDefault(() => Option.some([])),
   ),
+  favoriteModel: Schema.optional(FavoriteModelSchema),
 });
 export type AppSettings = typeof AppSettingsSchema.Type;
 export interface AppModelOption {
@@ -159,6 +166,39 @@ export function resolveAppModelSelection(
   );
 }
 
+/**
+ * Returns the global favorite model, or `null` if none is set.
+ */
+export function getFavoriteModel(
+  settings: AppSettings,
+): FavoriteModel | null {
+  const fav = settings.favoriteModel;
+  if (!fav || !fav.provider || !fav.model) return null;
+  const provider = fav.provider;
+  if (!(provider in BUILT_IN_MODEL_SLUGS_BY_PROVIDER)) return null;
+  const normalized = normalizeModelSlug(fav.model, provider);
+  if (!normalized) return null;
+  return { provider, model: normalized };
+}
+
+/**
+ * Returns a partial `AppSettings` patch that toggles the global favorite model.
+ * If the model is already the favorite, it removes it. Otherwise, it sets it as the new favorite.
+ */
+export function toggleFavoriteModel(
+  settings: AppSettings,
+  provider: ProviderKind,
+  modelSlug: string,
+): Partial<AppSettings> {
+  const current = getFavoriteModel(settings);
+  const normalized = normalizeModelSlug(modelSlug, provider);
+  if (!normalized) return {};
+  const isSameFavorite = current?.provider === provider && current?.model === normalized;
+  return {
+    favoriteModel: isSameFavorite ? undefined : { provider, model: normalized },
+  };
+}
+
 export function useAppSettings() {
   const [settings, setSettings] = useLocalStorage(
     APP_SETTINGS_STORAGE_KEY,
 
@@ -122,7 +122,12 @@ import {
 import { SidebarTrigger } from "./ui/sidebar";
 import { newCommandId, newMessageId, newThreadId } from "~/lib/utils";
 import { readNativeApi } from "~/nativeApi";
-import { resolveAppModelSelection, useAppSettings } from "../appSettings";
+import {
+  getFavoriteModel,
+  resolveAppModelSelection,
+  toggleFavoriteModel,
+  useAppSettings,
+} from "../appSettings";
 import { isTerminalFocused } from "../lib/terminalFocus";
 import {
   type ComposerImageAttachment,
@@ -203,7 +208,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
   const syncServerReadModel = useStore((store) => store.syncServerReadModel);
   const setStoreThreadError = useStore((store) => store.setError);
   const setStoreThreadBranch = useStore((store) => store.setThreadBranch);
-  const { settings } = useAppSettings();
+  const { settings, updateSettings } = useAppSettings();
   const timestampFormat = settings.timestampFormat;
   const navigate = useNavigate();
   const rawSearch = useSearch({
@@ -367,17 +372,14 @@ export default function ChatView({ threadId }: ChatViewProps) {
   const serverThread = threads.find((t) => t.id === threadId);
   const fallbackDraftProject = projects.find((project) => project.id === draftThread?.projectId);
   const localDraftError = serverThread ? null : (localDraftErrorsByThreadId[threadId] ?? null);
+  const draftFallbackModel =
+    fallbackDraftProject?.model ?? DEFAULT_MODEL_BY_PROVIDER.codex;
   const localDraftThread = useMemo(
     () =>
       draftThread
-        ? buildLocalDraftThread(
-            threadId,
-            draftThread,
-            fallbackDraftProject?.model ?? DEFAULT_MODEL_BY_PROVIDER.codex,
-            localDraftError,
-          )
+        ? buildLocalDraftThread(threadId, draftThread, draftFallbackModel, localDraftError)
         : undefined,
-    [draftThread, fallbackDraftProject?.model, localDraftError, threadId],
+    [draftThread, draftFallbackModel, localDraftError, threadId],
   );
   const activeThread = serverThread ?? localDraftThread;
   const runtimeMode =
@@ -503,11 +505,17 @@ export default function ChatView({ threadId }: ChatViewProps) {
     ? (sessionProvider ?? selectedProviderByThreadId ?? null)
     : null;
   const inferredProviderFromDraftModel = inferProviderFromModel(composerDraft.model);
+  const globalFavorite = getFavoriteModel(settings);
+  const favoriteProvider = isLocalDraftThread && globalFavorite
+    ? globalFavorite.provider
+    : null;
   const selectedProvider: ProviderKind =
-    lockedProvider ?? selectedProviderByThreadId ?? inferredProviderFromDraftModel ?? "codex";
+    lockedProvider ?? selectedProviderByThreadId ?? inferredProviderFromDraftModel ?? favoriteProvider ?? "codex";
   const baseThreadModel = resolveModelSlugForProvider(
     selectedProvider,
-    activeThread?.model ?? activeProject?.model ?? getDefaultModel(selectedProvider),
+    isLocalDraftThread && globalFavorite && globalFavorite.provider === selectedProvider
+      ? globalFavorite.model
+      : (activeThread?.model ?? activeProject?.model ?? getDefaultModel(selectedProvider)),
   );
   const customModelsForSelectedProvider = settings.customCodexModels;
   const selectedModel = useMemo(() => {
@@ -3052,6 +3060,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
       selectedModel ||
       (activeThread.model as ModelSlug) ||
       (activeProject.model as ModelSlug) ||
+      (globalFavorite?.model as ModelSlug) ||
       DEFAULT_MODEL_BY_PROVIDER.codex;
 
     sendInFlightRef.current = true;
@@ -3081,6 +3090,7 @@ export default function ChatView({ threadId }: ChatViewProps) {
     activeProposedPlan,
     activeThread,
     beginSendPhase,
+    globalFavorite,
     isConnecting,
     isSendBusy,
     isServerThread,
@@ -3112,6 +3122,24 @@ export default function ChatView({ threadId }: ChatViewProps) {
       settings.customCodexModels,
     ],
   );
+  const onToggleFavorite = useCallback(
+    (provider: ProviderKind, model: ModelSlug) => {
+      const patch = toggleFavoriteModel(settings, provider, model);
+      updateSettings(patch);
+      const isFavoriting = patch.favoriteModel !== undefined;
+      const modelOptions = modelOptionsByProvider[provider];
+      const modelName = modelOptions.find((opt) => opt.slug === model)?.name ?? model;
+      toastManager.add({
+        type: isFavoriting ? "success" : "info",
+        title: isFavoriting ? "Set as default model" : "Default model removed",
+        description: isFavoriting
+          ? `New chats will use ${modelName}`
+          : "New chats will use the system default",
+        data: { dismissAfterVisibleMs: 2000 },
+      });
+    },
+    [settings, updateSettings, modelOptionsByProvider],
+  );
   const onEffortSelect = useCallback(
     (effort: CodexReasoningEffort) => {
       setComposerDraftEffort(threadId, effort);
@@ -3783,7 +3811,9 @@ export default function ChatView({ threadId }: ChatViewProps) {
                         model={selectedModelForPickerWithCustomFallback}
                         lockedProvider={lockedProvider}
                         modelOptionsByProvider={modelOptionsByProvider}
+                        favoriteModel={globalFavorite}
                         onProviderModelChange={onProviderModelSelect}
+                        onToggleFavorite={onToggleFavorite}
                       />
 
                       {isComposerFooterCompact ? (
 
@@ -2,7 +2,8 @@ import { type ModelSlug, type ProviderKind } from "@t3tools/contracts";
 import { normalizeModelSlug } from "@t3tools/shared/model";
 import { memo, useState } from "react";
 import { type ProviderPickerKind, PROVIDER_OPTIONS } from "../../session-logic";
-import { ChevronDownIcon } from "lucide-react";
+import { ChevronDownIcon, StarIcon } from "lucide-react";
+import type { FavoriteModel } from "../../appSettings";
 import { Button } from "../ui/button";
 import {
   Menu,
@@ -81,7 +82,9 @@ export const ProviderModelPicker = memo(function ProviderModelPicker(props: {
   modelOptionsByProvider: Record<ProviderKind, ReadonlyArray<{ slug: string; name: string }>>;
   compact?: boolean;
   disabled?: boolean;
+  favoriteModel?: FavoriteModel | null;
   onProviderModelChange: (provider: ProviderKind, model: ModelSlug) => void;
+  onToggleFavorite?: (provider: ProviderKind, model: ModelSlug) => void;
 }) {
   const [isMenuOpen, setIsMenuOpen] = useState(false);
   const selectedProviderOptions = props.modelOptionsByProvider[props.provider];
@@ -153,15 +156,53 @@ export const ProviderModelPicker = memo(function ProviderModelPicker(props: {
                       setIsMenuOpen(false);
                     }}
                   >
-                    {props.modelOptionsByProvider[option.value].map((modelOption) => (
-                      <MenuRadioItem
-                        key={`${option.value}:${modelOption.slug}`}
-                        value={modelOption.slug}
-                        onClick={() => setIsMenuOpen(false)}
-                      >
-                        {modelOption.name}
-                      </MenuRadioItem>
-                    ))}
+                    {props.modelOptionsByProvider[option.value].map((modelOption) => {
+                      const isFavorite =
+                        props.favoriteModel?.provider === option.value &&
+                        props.favoriteModel?.model === modelOption.slug;
+                      return (
+                        <MenuRadioItem
+                          key={`${option.value}:${modelOption.slug}`}
+                          value={modelOption.slug}
+                          onClick={() => setIsMenuOpen(false)}
+                        >
+                          <span className="inline-flex w-full items-center gap-2">
+                            <span className="flex-1 truncate">{modelOption.name}</span>
+                            {props.onToggleFavorite && (
+                              <button
+                                type="button"
+                                aria-label={
+                                  isFavorite
+                                    ? `Remove ${modelOption.name} as default`
+                                    : `Set ${modelOption.name} as default`
+                                }
+                                className={cn(
+                                  "shrink-0 rounded-sm p-0.5 transition-colors pointer-events-auto",
+                                  isFavorite
+                                    ? "text-amber-400"
+                                    : "text-muted-foreground/30 hover:text-amber-400/70",
+                                )}
+                                onPointerDown={(e) => {
+                                  e.stopPropagation();
+                                  e.preventDefault();
+                                }}
+                                onClick={(e) => {
+                                  e.stopPropagation();
+                                  e.preventDefault();
+                                  props.onToggleFavorite?.(option.value, modelOption.slug);
+                                }}
+                              >
+                                <StarIcon
+                                  aria-hidden="true"
+                                  className="size-3.5 shrink-0 pointer-events-none"
+                                  {...(isFavorite ? { fill: "currentColor" } : {})}
+                                />
+                              </button>
+                            )}
+                          </span>
+                        </MenuRadioItem>
+                      );
+                    })}
                   </MenuRadioGroup>
                 </MenuGroup>
               </MenuSubPopup>