fix(web): Cursor threads keep a stored model the catalog doesn't list

apps/web/src/components/chat/ModelPickerContent.tsx

@@ -113,7 +113,9 @@ function shouldIncludeModelPickerOption(input: {
   if (isProviderInstancePickerReady(input.entry)) return true;
   return (
     input.entry.enabled &&
-    (input.entry.driverKind === "opencode" || input.entry.driverKind === "antigravity") &&
+    (input.entry.driverKind === "opencode" ||
+      input.entry.driverKind === "antigravity" ||
+      input.entry.driverKind === "cursor") &&
     input.entry.instanceId === input.activeInstanceId &&
     input.option.slug === input.activeModel &&
     input.option.isUnavailable === true

apps/web/src/components/chat/TraitsPicker.tsx

@@ -122,7 +122,7 @@ function getSelectedTraits(
 ) {
   const caps = getProviderModelCapabilities(models, model, provider, includePlanAgent);
   const modelIsUnavailable =
-    provider === "opencode" &&
+    (provider === "opencode" || provider === "cursor") &&
     !models.some((candidate) => candidate.slug === normalizeModelSlug(model, provider));
   const descriptors = modelIsUnavailable
     ? buildUnavailableModelOptionDescriptors(

apps/web/src/components/chat/composerProviderState.tsx

@@ -86,7 +86,7 @@ export function getComposerProviderState(input: ComposerProviderStateInput): Com
     promptInjectionState = "none",
     includePlanAgent,
   } = input;
-  if (provider === "opencode") {
+  if (provider === "opencode" || provider === "cursor") {
     const normalizedModel = normalizeModelSlug(model, provider);
     const modelIsInCatalog = models.some((candidate) => candidate.slug === normalizedModel);
     if (!modelIsInCatalog) {

apps/web/src/components/chat/useComposerSelection.browser.test.tsx

@@ -0,0 +1,177 @@
+import { scopeThreadRef } from "@t3tools/client-runtime/environment";
+import type { AtomCommandResult } from "@t3tools/client-runtime/state/runtime";
+import type { EnvironmentThreadShell } from "@t3tools/client-runtime/state/shell";
+import {
+  EnvironmentId,
+  ProviderDriverKind,
+  ProviderInstanceId,
+  ThreadId,
+  type ServerProvider,
+} from "@t3tools/contracts";
+import { DEFAULT_UNIFIED_SETTINGS } from "@t3tools/contracts/settings";
+import { createModelSelection } from "@t3tools/shared/model";
+import * as Cause from "effect/Cause";
+import { AsyncResult, Atom } from "effect/reactivity";
+import { expect, it, vi } from "vite-plus/test";
+import { page } from "vite-plus/test/browser";
+
+const mocks = vi.hoisted(() => ({
+  setModelSelection: null as ((value: unknown) => Promise<AtomCommandResult<void, unknown>>) | null,
+}));
+
+vi.mock(import("../../state/use-orchestration-command"), async (importOriginal) => ({
+  ...(await importOriginal()),
+  useOrchestrationCommand: (() => (value: unknown) => mocks.setModelSelection?.(value)) as never,
+}));
+
+vi.mock(import("../../state/threads"), async (original) => {
+  const actual = await original();
+  return {
+    ...actual,
+    environmentThreadShells: {
+      ...actual.environmentThreadShells,
+      threadShellAtom: ((ref: { threadId: string }) => shellAtom(ref.threadId)) as never,
+    },
+  };
+});
+
+import { render } from "../../../test/render";
+import { deriveEffectiveComposerModelState, useComposerDraftStore } from "../../composerDraftStore";
+import { AppAtomRegistryProvider, appAtomRegistry } from "../../rpc/atomRegistry";
+import { useComposerSelection } from "./useComposerSelection";
+
+// Kept alive so a shell set before the hook mounts is still there when it saves a pick.
+const shellAtom = Atom.family((_threadId: string) => Atom.make<unknown>(null).pipe(Atom.keepAlive));
+
+function setup() {
+  const setModelSelection = vi.fn<(value: unknown) => Promise<AtomCommandResult<void, unknown>>>();
+  mocks.setModelSelection = setModelSelection;
+  return { setModelSelection };
+}
+
+const environmentId = EnvironmentId.make("environment-local");
+const cursor = ProviderInstanceId.make("cursor");
+const stored = createModelSelection(cursor, "claude-opus-5-5", [{ id: "effort", value: "medium" }]);
+
+const providers: ReadonlyArray<ServerProvider> = [
+  {
+    instanceId: cursor,
+    driver: ProviderDriverKind.make("cursor"),
+    enabled: true,
+    installed: true,
+    version: null,
+    status: "ready",
+    auth: { status: "authenticated" },
+    checkedAt: "2026-01-01T00:00:00.000Z",
+    models: [{ slug: "auto-smart", name: "Auto", isCustom: false, capabilities: {} }],
+    slashCommands: [],
+    skills: [],
+  },
+];
+
+// The hook reads only the thread's identity and stored selection.
+function cursorThread(id: string) {
+  return { environmentId, id: ThreadId.make(id), modelSelection: stored } as EnvironmentThreadShell;
+}
+
+function Picker(props: {
+  thread: EnvironmentThreadShell;
+  runtime: Parameters<typeof useComposerSelection>[0]["activeRuntime"];
+  model?: string;
+}) {
+  const { onProviderModelSelectStable } = useComposerSelection({
+    environmentId,
+    composerDraftTarget: scopeThreadRef(environmentId, props.thread.id),
+    draftThread: null,
+    activeThread: props.thread,
+    activeRuntime: props.runtime,
+    activeProjectSettings: { settings: { newWorktreesStartFromOrigin: false } },
+    settings: DEFAULT_UNIFIED_SETTINGS,
+    providerStatuses: providers,
+    lockedProvider: null,
+    supportsProviderSwitchingViaHandoff: true,
+    multipleModelSelections: null,
+    runtimeMode: "full-access",
+    isLocalDraftThread: false,
+    canOverrideServerThreadEnvMode: false,
+    setPendingServerThreadEnvModeEntry: () => {},
+    setPendingServerThreadStartFromOriginByThreadId: () => {},
+    scheduleComposerFocus: () => {},
+  });
+  return (
+    <button
+      type="button"
+      onClick={() => onProviderModelSelectStable(cursor, props.model ?? stored.model)}
+    >
+      Pick the model
+    </button>
+  );
+}
+
+it("keeps a Cursor thread's stored model and options when the user re-picks its unavailable row", async () => {
+  setup();
+  const thread = cursorThread("thread-cursor");
+  await using _screen = await render(<Picker thread={thread} runtime={null} />);
+  await page.getByRole("button", { name: "Pick the model" }).click();
+
+  await vi.waitFor(() => {
+    const draft = useComposerDraftStore
+      .getState()
+      .getComposerDraft(scopeThreadRef(environmentId, thread.id));
+    expect(draft?.modelSelectionByProvider[cursor] ?? thread.modelSelection).toEqual(stored);
+  });
+});
+
+it("switches back to the thread's stored model while the session runs on another instance", async () => {
+  setup();
+  const thread = cursorThread("thread-cursor-handoff");
+  const runtime = { providerInstanceId: ProviderInstanceId.make("codex") } as Parameters<
+    typeof useComposerSelection
+  >[0]["activeRuntime"];
+  await using _screen = await render(<Picker thread={thread} runtime={runtime} />);
+  await page.getByRole("button", { name: "Pick the model" }).click();
+
+  await vi.waitFor(() => {
+    const draft = useComposerDraftStore
+      .getState()
+      .getComposerDraft(scopeThreadRef(environmentId, thread.id));
+    expect(draft?.activeProvider).toBe(cursor);
+    expect(
+      deriveEffectiveComposerModelState({
+        draft,
+        providers,
+        selectedProvider: ProviderDriverKind.make("cursor"),
+        selectedInstanceId: cursor,
+        threadModelSelection: thread.modelSelection,
+        projectModelSelection: null,
+        settings: DEFAULT_UNIFIED_SETTINGS,
+      }),
+    ).toEqual({ selectedModel: stored.model, modelOptions: { [cursor]: stored.options } });
+  });
+});
+
+it("saves a re-picked model again when its first save failed", async () => {
+  const { setModelSelection } = setup();
+  setModelSelection
+    .mockResolvedValueOnce(AsyncResult.failure(Cause.fail(new Error("offline"))))
+    .mockResolvedValue(AsyncResult.success(undefined));
+  const thread = cursorThread("thread-cursor-retry");
+  appAtomRegistry.set(shellAtom(thread.id), thread);
+  await using _screen = await render(
+    <AppAtomRegistryProvider>
+      <Picker thread={thread} runtime={null} model="auto-smart" />
+    </AppAtomRegistryProvider>,
+  );
+  const pick = page.getByRole("button", { name: "Pick the model" });
+  await pick.click();
+  await vi.waitFor(() => expect(setModelSelection).toHaveBeenCalledTimes(1));
+  await pick.click();
+
+  const autoSave = expect.objectContaining({
+    input: {
+      threadId: thread.id,
+      modelSelection: expect.objectContaining({ instanceId: cursor, model: "auto-smart" }),
+    },
+  });
+  await vi.waitFor(() => expect(setModelSelection.mock.calls).toEqual([[autoSave], [autoSave]]));
+});

apps/web/src/components/chat/useComposerSelection.ts

@@ -152,13 +152,30 @@ export function useComposerSelection(input: ComposerSelectionInput) {
         return;
       }
     }
+    // The picker lists an unavailable model only as the active selection, so re-picking keeps it.
     const resolvedModel = resolveAppModelSelectionForInstance(
       instanceId,
       settings,
       providerStatuses,
       model,
+      { preserveUnavailableSelection: true },
     );
-    if (!resolvedModel) {
+    const threadRef = scopeThreadRef(activeThread.environmentId, activeThread.id);
+    const draft = useComposerDraftStore.getState().getComposerDraft(threadRef);
+    const shownInstanceId =
+      draft?.activeProvider ??
+      activeRuntime?.providerInstanceId ??
+      activeThread.modelSelection.instanceId;
+    const shownSelection =
+      draft?.modelSelectionByProvider[shownInstanceId] ?? activeThread.modelSelection;
+    if (
+      !resolvedModel ||
+      (instanceId === shownInstanceId &&
+        shownSelection.instanceId === instanceId &&
+        shownSelection.model === resolvedModel)
+    ) {
+      // Re-picking the shown model keeps its options and saves it again if that save failed.
+      if (resolvedModel && !isLocalDraftThread) applyThreadModelPick(threadRef);
       if (options?.focusComposer !== false) scheduleComposerFocus();
       return;
     }
@@ -184,7 +201,6 @@ export function useComposerSelection(input: ComposerSelectionInput) {
       if (options?.focusComposer !== false) scheduleComposerFocus();
       return;
     }
-    const threadRef = scopeThreadRef(activeThread.environmentId, activeThread.id);
     setComposerDraftModelSelection(threadRef, nextModelSelection, {
       explicit: true,
       replaceOptions: true,

apps/web/src/modelSelection.test.ts

@@ -402,6 +402,11 @@ describe("instance-scoped model selection", () => {
       availableModel: "gemini-3.1-pro",
       missingModel: "gemini-3.1-pro-high",
     },
+    {
+      driverName: "cursor",
+      availableModel: "auto-smart",
+      missingModel: "claude-opus-5-5",
+    },
   ])("$driverName catalog gaps", ({ driverName, availableModel, missingModel }) => {
     it("preserves a selected model when a catalog refresh no longer contains it", () => {
       const providers = [
@@ -508,6 +513,34 @@ describe("instance-scoped model selection", () => {
     expect(dispatch.modelOptionsForDispatch).toBeUndefined();
   });
 
+  it("sends a Cursor thread's stored model and options when the catalog lacks them", () => {
+    const instanceId = ProviderInstanceId.make("cursor");
+    const driver = ProviderDriverKind.make("cursor");
+    const stored = createModelSelection(instanceId, "claude-opus-5-5", [
+      { id: "effort", value: "medium" },
+    ]);
+    const providers = [provider({ provider: driver, instanceId, models: ["auto-smart"] })];
+    const state = deriveEffectiveComposerModelState({
+      draft: null,
+      providers,
+      selectedProvider: driver,
+      selectedInstanceId: instanceId,
+      threadModelSelection: stored,
+      projectModelSelection: null,
+      settings: settingsWithProviderInstances(),
+    });
+    const dispatch = getComposerProviderState({
+      provider: driver,
+      model: state.selectedModel,
+      models: providers[0]!.models,
+      modelOptions: state.modelOptions?.[instanceId],
+    });
+
+    expect(
+      createModelSelection(instanceId, state.selectedModel, dispatch.modelOptionsForDispatch),
+    ).toEqual(stored);
+  });
+
   it("preserves an explicit draft OpenCode selection while the catalog is empty", () => {
     const instanceId = ProviderInstanceId.make("opencode_work");
     const driver = ProviderDriverKind.make("opencode");

apps/web/src/modelSelection.ts

@@ -80,7 +80,9 @@ function appendUnavailableDynamicModelSelection(
   selectedModel: string | null | undefined,
   hiddenModels: ReadonlyArray<string>,
 ): AppModelOption[] {
-  if (provider !== "opencode" && provider !== "antigravity") return options;
+  if (provider !== "opencode" && provider !== "antigravity" && provider !== "cursor") {
+    return options;
+  }
   const slug = normalizeCustomModelSlug(selectedModel);
   if (!slug) return options;
   if (provider === "antigravity" && slug === ANTIGRAVITY_DEFAULT_MODEL) return options;
@@ -282,7 +284,9 @@ export function resolveAppModelSelectionForInstance(
   }
   if (
     resolutionOptions?.preserveUnavailableSelection &&
-    (entry.driverKind === "opencode" || entry.driverKind === "antigravity")
+    (entry.driverKind === "opencode" ||
+      entry.driverKind === "antigravity" ||
+      entry.driverKind === "cursor")
   ) {
     const unavailableSelection = normalizeCustomModelSlug(selectedModel);
     const hiddenModels = readInstanceModelPreferences(settings, entry.instanceId).hiddenModels;