diff --git a/src/components/budget/BudgetTable.wiring.test.ts b/src/components/budget/BudgetTable.wiring.test.ts
index 567ac0c..b16be6b 100644
--- a/src/components/budget/BudgetTable.wiring.test.ts
+++ b/src/components/budget/BudgetTable.wiring.test.ts
@@ -1,8 +1,7 @@
-// BudgetTable — how the grid tells the page its target (#400).
+// BudgetTable — how the grid tells the page its target (#400, #409).
 //
 // renderToStaticMarkup runs no effect, so the report would stay unguarded.
-// React's `useState`, `useRef` and `useEffect` are stubbed (technique of
-// OnboardingStepCard.test.tsx and useOnboardingChecklist.wiring.test.ts): the
+// React's hooks come from the shared harness (src/test/hookHarness.ts): the
 // grid runs as a plain function, its state and refs survive from one call to
 // the next as between two renders of a mounted component, and `commit()` runs
 // the effects as React does, an effect only when one of its dependencies
@@ -12,42 +11,11 @@ import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
 import type { BudgetYearRow } from "../../shared/types";
 import type { CollapseAccessors } from "../../utils/collapsibleRows";
 
-type Effect = { fn: () => void | (() => void); deps: readonly unknown[] | undefined };
-
-const harness = vi.hoisted(() => ({
-  slots: [] as unknown[],
-  setters: [] as Array<(next: unknown) => void>,
-  cursor: 0,
-  effects: [] as Effect[],
-  /** Dependencies of each effect at its last run. */
-  ran: new Map<number, readonly unknown[] | undefined>(),
+vi.mock("react", async (orig) => (await import("../../test/hookHarness")).fakeReact(await orig()));
+const ctx = vi.hoisted(() => ({
   /** Keys of the open groups (`p:<category id>`): the grid opens collapsed. */
   expanded: new Set<string>(),
 }));
-
-vi.mock("react", async (importOriginal) => {
-  const actual = await importOriginal<typeof import("react")>();
-  const slot = (init: () => unknown) => {
-    const index = harness.cursor++;
-    if (!(index in harness.slots)) harness.slots[index] = init();
-    return index;
-  };
-  return {
-    ...actual,
-    useState: (init: unknown) => {
-      const index = slot(() => (typeof init === "function" ? (init as () => unknown)() : init));
-      harness.setters[index] ??= (next: unknown) => {
-        harness.slots[index] =
-          typeof next === "function" ? (next as (previous: unknown) => unknown)(harness.slots[index]) : next;
-      };
-      return [harness.slots[index], harness.setters[index]];
-    },
-    useRef: (init: unknown) => harness.slots[slot(() => ({ current: init }))],
-    useEffect: (fn: Effect["fn"], deps?: readonly unknown[]) => {
-      harness.effects.push({ fn, deps });
-    },
-  };
-});
 vi.mock("react-i18next", () => ({
   useTranslation: () => ({ t: (k: string) => `t(${k})`, i18n: { language: "fr" } }),
 }));
@@ -55,7 +23,7 @@ vi.mock("../../hooks/useCollapsibleGroups", async () => {
   const { collapsibleKeys, isCollapsedFor, visibleRows } = await import("../../utils/collapsibleRows");
   return {
     useCollapsibleGroups: <T,>(_key: string | null, acc: CollapseAccessors<T>) => {
-      const isCollapsed = (row: T) => isCollapsedFor(harness.expanded, acc.keyOf(row), false);
+      const isCollapsed = (row: T) => isCollapsedFor(ctx.expanded, acc.keyOf(row), false);
       return {
         visible: (rows: T[]) => visibleRows(rows, acc, isCollapsed),
         isCollapsed,
@@ -64,7 +32,7 @@ vi.mock("../../hooks/useCollapsibleGroups", async () => {
         collapseAll: () => undefined,
         allExpanded: (rows: T[]) => {
           const keys = collapsibleKeys(rows, acc);
-          return keys.length > 0 && keys.every((key) => harness.expanded.has(key));
+          return keys.length > 0 && keys.every((key) => ctx.expanded.has(key));
         },
         groupCount: (rows: T[]) => collapsibleKeys(rows, acc).length,
       };
@@ -72,6 +40,7 @@ vi.mock("../../hooks/useCollapsibleGroups", async () => {
   };
 });
 
+import { hookHarness } from "../../test/hookHarness";
 import BudgetTable from "./BudgetTable";
 import type { BudgetOnboardingTargetKind } from "../../shared/types";
 
@@ -89,43 +58,31 @@ const leaf = (category_id: number, parent_id: number | null = null): BudgetYearR
 });
 const GROUPED: BudgetYearRow[] = [{ ...leaf(10), is_parent: true }, leaf(11, 10), leaf(12, 10)];
 
+const harness = hookHarness();
+
 /** One render of the mounted grid: its hooks are called in the same order each time. */
 function render(
   rows: BudgetYearRow[],
   onChange: (kind: BudgetOnboardingTargetKind | null) => void,
   onboardingTarget?: boolean,
 ) {
-  harness.cursor = 0;
-  harness.effects = [];
-  BudgetTable({
-    rows,
-    onUpdatePlanned: () => undefined,
-    onSplitEvenly: () => undefined,
-    onboardingTarget,
-    onOnboardingTargetChange: onChange,
-  });
+  harness.render(() =>
+    BudgetTable({
+      rows,
+      onUpdatePlanned: () => undefined,
+      onSplitEvenly: () => undefined,
+      onboardingTarget,
+      onOnboardingTargetChange: onChange,
+    }),
+  );
 }
 
 /** After a render: run each effect whose dependencies changed since its last run, as React does. */
-function commit() {
-  harness.effects.forEach((effect, index) => {
-    const previous = harness.ran.get(index);
-    const changed =
-      !harness.ran.has(index) ||
-      effect.deps === undefined ||
-      previous === undefined ||
-      effect.deps.some((dep, k) => !Object.is(dep, previous[k]));
-    harness.ran.set(index, effect.deps);
-    if (changed) effect.fn();
-  });
-}
+const commit = () => harness.commit();
 
 beforeEach(() => {
-  harness.slots = [];
-  harness.setters = [];
-  harness.effects = [];
-  harness.ran = new Map();
-  harness.expanded = new Set();
+  harness.clear();
+  ctx.expanded = new Set();
   vi.stubGlobal("localStorage", { getItem: () => null, setItem: () => undefined });
 });
 
@@ -146,7 +103,7 @@ describe("BudgetTable — the target told to the page (#400)", () => {
     expect(onChange).toHaveBeenCalledTimes(1);
 
     // The user opens the group: an editable row shows.
-    harness.expanded = new Set(["p:10"]);
+    ctx.expanded = new Set(["p:10"]);
     render(GROUPED, onChange, true);
     commit();
     render(GROUPED, onChange, true);
diff --git a/src/components/layout/AppShell.slot.test.tsx b/src/components/layout/AppShell.slot.test.tsx
index 6b184a8..1c54adf 100644
--- a/src/components/layout/AppShell.slot.test.tsx
+++ b/src/components/layout/AppShell.slot.test.tsx
@@ -1,53 +1,37 @@
-// OnboardingBannerSlot — the list's fold state and the path's wiring (#397).
+// OnboardingBannerSlot — the list's fold state and the path's wiring (#397, #409).
 //
-// renderToStaticMarkup runs no click, so React's `useState` is stubbed (same
-// technique as useOnboardingChecklist.wiring.test.ts): the slot runs as a
-// plain function, and its state survives from one call to the next as it
-// would between two renders of a mounted component.
+// renderToStaticMarkup runs no click, so React's hooks come from the shared
+// harness (src/test/hookHarness.ts): the slot runs as a plain function, and
+// its state survives from one call to the next as it would between two
+// renders of a mounted component.
 import { describe, it, expect, vi, beforeEach } from "vitest";
 import { isValidElement, type ReactElement, type ReactNode } from "react";
 import { Outlet } from "react-router-dom";
 
-const harness = vi.hoisted(() => ({
-  slots: [] as unknown[],
-  cursor: 0,
+vi.mock("react", async (orig) => (await import("../../test/hookHarness")).fakeReact(await orig()));
+const ctx = vi.hoisted(() => ({
   pathname: "/reports",
   onboarding: null as unknown,
 }));
-
-vi.mock("react", async (importOriginal) => {
-  const actual = await importOriginal<typeof import("react")>();
-  return {
-    ...actual,
-    useState: (init: unknown) => {
-      const index = harness.cursor++;
-      if (!(index in harness.slots)) {
-        harness.slots[index] = typeof init === "function" ? (init as () => unknown)() : init;
-      }
-      const set = (next: unknown) => {
-        harness.slots[index] =
-          typeof next === "function" ? (next as (previous: unknown) => unknown)(harness.slots[index]) : next;
-      };
-      return [harness.slots[index], set];
-    },
-  };
-});
 vi.mock("react-router-dom", async (importOriginal) => ({
   ...(await importOriginal<typeof import("react-router-dom")>()),
-  useLocation: () => ({ pathname: harness.pathname }),
+  useLocation: () => ({ pathname: ctx.pathname }),
 }));
 vi.mock("../../contexts/OnboardingContext", () => ({
   OnboardingProvider: ({ children }: { children: ReactNode }) => children,
-  useOnboarding: () => harness.onboarding,
+  useOnboarding: () => ctx.onboarding,
 }));
 vi.mock("./Sidebar", () => ({ default: () => null }));
 
+import { hookHarness } from "../../test/hookHarness";
 import AppShell, { OnboardingBannerSlot } from "./AppShell";
 import OnboardingBanner, { type OnboardingBannerProps } from "../onboarding/OnboardingBanner";
 import { computeChecklist } from "../../utils/onboardingChecklist";
 import { nextStep } from "../../utils/onboardingPath";
 import type { OnboardingValue } from "../../hooks/useOnboardingChecklist";
 
+const harness = hookHarness();
+
 type AnyElement = ReactElement<Record<string, unknown> & { children?: ReactNode }>;
 
 function find(node: ReactNode, pred: (el: AnyElement) => boolean): AnyElement[] {
@@ -79,21 +63,20 @@ function onboardingValue(): OnboardingValue {
 
 /** One render of the mounted slot: its hooks are read in the same order each time. */
 function renderSlot(): OnboardingBannerProps {
-  harness.cursor = 0;
-  const element = OnboardingBannerSlot() as ReactElement<OnboardingBannerProps>;
+  const element = harness.render(() => OnboardingBannerSlot() as ReactElement<OnboardingBannerProps>);
   expect(element.type).toBe(OnboardingBanner);
   return element.props;
 }
 
 beforeEach(() => {
-  harness.slots = [];
-  harness.pathname = "/reports";
-  harness.onboarding = onboardingValue();
+  harness.clear();
+  ctx.pathname = "/reports";
+  ctx.onboarding = onboardingValue();
 });
 
 describe("OnboardingBannerSlot (#397)", () => {
   it("hands the shared path to the banner, the list folded", () => {
-    const value = harness.onboarding as OnboardingValue;
+    const value = ctx.onboarding as OnboardingValue;
     const props = renderSlot();
     expect(props.mode).toBe("banner");
     expect(props.checklist).toBe(value.checklist);
@@ -105,7 +88,7 @@ describe("OnboardingBannerSlot (#397)", () => {
   });
 
   it("passes the mode and the entitlement as they come: the banner decides what to show", () => {
-    harness.onboarding = { ...onboardingValue(), mode: "none", budgetReady: false };
+    ctx.onboarding = { ...onboardingValue(), mode: "none", budgetReady: false };
     const props = renderSlot();
     expect(props.mode).toBe("none");
     expect(props.budgetReady).toBe(false);
@@ -121,19 +104,19 @@ describe("OnboardingBannerSlot (#397)", () => {
   });
 
   it("AppShell mounts one slot per route, so each page starts with the list folded", () => {
-    harness.pathname = "/import";
-    const shell = AppShell() as ReactNode;
+    ctx.pathname = "/import";
+    const shell = harness.render(() => AppShell() as ReactNode);
     const [slot] = find(shell, (e) => e.type === OnboardingBannerSlot);
     expect(slot).toBeDefined();
     expect(slot.key).toBe("/import");
 
-    harness.pathname = "/transactions";
-    const [next] = find(AppShell() as ReactNode, (e) => e.type === OnboardingBannerSlot);
+    ctx.pathname = "/transactions";
+    const [next] = find(harness.render(() => AppShell() as ReactNode), (e) => e.type === OnboardingBannerSlot);
     expect(next.key).toBe("/transactions");
   });
 
   it("AppShell puts the slot before the routed page, inside the provider, inside main", () => {
-    const shell = AppShell() as ReactNode;
+    const shell = harness.render(() => AppShell() as ReactNode);
     const [main] = find(shell, (e) => e.type === "main");
     expect(main).toBeDefined();
     const [provider] = find(main.props.children, (e) => typeof e.type === "function");
diff --git a/src/components/onboarding/OnboardingStepCard.test.tsx b/src/components/onboarding/OnboardingStepCard.test.tsx
index 75a8d4e..7a07aff 100644
--- a/src/components/onboarding/OnboardingStepCard.test.tsx
+++ b/src/components/onboarding/OnboardingStepCard.test.tsx
@@ -1,46 +1,28 @@
-// OnboardingStepCard — the connected card's wiring (#398).
+// OnboardingStepCard — the connected card's wiring (#398, #409).
 //
 // renderToStaticMarkup runs no effect, so the focus move would stay unguarded.
-// React's `useRef` and `useEffect` are stubbed (technique of
-// useOnboardingChecklist.wiring.test.ts and AppShell.slot.test.tsx): the card
-// runs as a plain function, its refs survive from one call to the next as they
-// would between two renders of a mounted component, and its effects are
-// captured and run by hand. The router and the path are faked.
+// React's hooks come from the shared harness (src/test/hookHarness.ts): the
+// card runs as a plain function, its refs survive from one call to the next as
+// they would between two renders of a mounted component, and `commit()` runs
+// its effect when one of its dependencies changed, as React does. The router
+// and the path are faked.
 import { describe, it, expect, vi, beforeEach } from "vitest";
 import type { ReactElement } from "react";
 
-type Effect = { fn: () => void | (() => void); deps: readonly unknown[] | undefined };
-
-const harness = vi.hoisted(() => ({
-  refs: [] as Array<{ current: unknown }>,
-  cursor: 0,
-  effects: [] as Effect[],
+vi.mock("react", async (orig) => (await import("../../test/hookHarness")).fakeReact(await orig()));
+const ctx = vi.hoisted(() => ({
   location: { pathname: "/import", state: null as unknown, key: "arrival-1" },
   navigate: vi.fn(),
   onboarding: null as unknown,
 }));
-
-vi.mock("react", async (importOriginal) => {
-  const actual = await importOriginal<typeof import("react")>();
-  return {
-    ...actual,
-    useRef: (init: unknown) => {
-      const index = harness.cursor++;
-      if (!(index in harness.refs)) harness.refs[index] = { current: init };
-      return harness.refs[index];
-    },
-    useEffect: (fn: Effect["fn"], deps?: readonly unknown[]) => {
-      harness.effects.push({ fn, deps });
-    },
-  };
-});
 vi.mock("react-router-dom", async (importOriginal) => ({
   ...(await importOriginal<typeof import("react-router-dom")>()),
-  useLocation: () => harness.location,
-  useNavigate: () => harness.navigate,
+  useLocation: () => ctx.location,
+  useNavigate: () => ctx.navigate,
 }));
-vi.mock("../../contexts/OnboardingContext", () => ({ useOnboarding: () => harness.onboarding }));
+vi.mock("../../contexts/OnboardingContext", () => ({ useOnboarding: () => ctx.onboarding }));
 
+import { hookHarness } from "../../test/hookHarness";
 import OnboardingStepCard from "./OnboardingStepCard";
 import StepCard, { type StepCardProps } from "./StepCard";
 import { computeChecklist } from "../../utils/onboardingChecklist";
@@ -48,6 +30,8 @@ import { nextStep, type StepCardModel } from "../../utils/onboardingPath";
 import type { OnboardingValue } from "../../hooks/useOnboardingChecklist";
 import type { OnboardingCounters } from "../../shared/types";
 
+const harness = hookHarness();
+
 const ZERO: OnboardingCounters = {
   sources: 0,
   imports: 0,
@@ -86,28 +70,27 @@ const DONE: StepCardModel = { text: null, done: true };
 
 /** One render of the mounted card: its hooks are called in the same order each time. */
 function render(model: StepCardModel | null = SOURCE_LIST): ReactElement<StepCardProps> | null {
-  harness.cursor = 0;
-  harness.effects = [];
-  return OnboardingStepCard({ model }) as ReactElement<StepCardProps> | null;
+  return harness.render(() => OnboardingStepCard({ model }) as ReactElement<StepCardProps> | null);
 }
 
+/** The card's title ref: its first hook. */
+const titleRef = () => harness.slots[0] as { current: unknown };
+
 /** The title the card's ref points at, once React would have attached it. */
 function attachTitle(): { focus: ReturnType<typeof vi.fn> } {
   const title = { focus: vi.fn() };
-  harness.refs[0].current = title;
+  titleRef().current = title;
   return title;
 }
 
-const runEffects = () => {
-  for (const effect of harness.effects) effect.fn();
-};
+/** The commit of the last render: its effect runs if one of its dependencies changed. */
+const commit = () => harness.commit();
 
 beforeEach(() => {
-  harness.refs = [];
-  harness.effects = [];
-  harness.location = { pathname: "/import", state: null, key: "arrival-1" };
-  harness.navigate.mockReset();
-  harness.onboarding = path(FOLDER_SET);
+  harness.clear();
+  ctx.location = { pathname: "/import", state: null, key: "arrival-1" };
+  ctx.navigate.mockReset();
+  ctx.onboarding = path(FOLDER_SET);
 });
 
 describe("OnboardingStepCard — when it shows (#398)", () => {
@@ -119,18 +102,18 @@ describe("OnboardingStepCard — when it shows (#398)", () => {
 
   it("renders nothing in another mode, on a route that is not the latched one, or without a model", () => {
     for (const mode of ["none", "banner", "complete"] as const) {
-      harness.onboarding = path(FOLDER_SET, { mode });
+      ctx.onboarding = path(FOLDER_SET, { mode });
       expect(render(), mode).toBeNull();
     }
-    harness.onboarding = path(FOLDER_SET, { cardPage: "/transactions" });
+    ctx.onboarding = path(FOLDER_SET, { cardPage: "/transactions" });
     expect(render()).toBeNull();
-    harness.onboarding = path(FOLDER_SET);
+    ctx.onboarding = path(FOLDER_SET);
     expect(render(null)).toBeNull();
   });
 
   it("stays once the page's steps are done: the latch keeps it, not the next step", () => {
-    harness.onboarding = path(IMPORTED);
-    const value = harness.onboarding as OnboardingValue;
+    ctx.onboarding = path(IMPORTED);
+    const value = ctx.onboarding as OnboardingValue;
     expect(value.nextStep?.to).toBe("/transactions");
     const card = render(DONE);
     expect(card).not.toBeNull();
@@ -145,27 +128,27 @@ describe("OnboardingStepCard — what it hands the card (#398)", () => {
     expect(props.position).toEqual({ n: 3, total: 6 });
     expect(props.text).toBe(SOURCE_LIST.text);
     expect(props.done).toBe(false);
-    expect(props.titleRef).toBe(harness.refs[0]);
+    expect(props.titleRef).toBe(titleRef());
   });
 
   it("the next step once done, and a wait while the next step is still on this page", () => {
-    harness.onboarding = path(IMPORTED);
+    ctx.onboarding = path(IMPORTED);
     expect(render(DONE)!.props.next).toEqual({
       kind: "step",
-      step: (harness.onboarding as OnboardingValue).nextStep,
+      step: (ctx.onboarding as OnboardingValue).nextStep,
     });
     // Before the re-read, the next step is still the source step, on /import.
-    harness.onboarding = path(FOLDER_SET);
+    ctx.onboarding = path(FOLDER_SET);
     expect(render(DONE)!.props.next).toEqual({ kind: "wait" });
   });
 
   it("no 'Step n of N' until the Budget entitlement is known", () => {
-    harness.onboarding = path(FOLDER_SET, { budgetReady: false });
+    ctx.onboarding = path(FOLDER_SET, { budgetReady: false });
     expect(render()!.props.position).toBeNull();
   });
 
   it("'Skip this step' skips the step the card shows; 'Close' hides the path", () => {
-    const value = harness.onboarding as OnboardingValue;
+    const value = ctx.onboarding as OnboardingValue;
     const props = render()!.props;
     props.onSkip();
     expect(value.skip).toHaveBeenCalledWith("source");
@@ -179,58 +162,60 @@ describe("OnboardingStepCard — the focus after 'Next step' (#398)", () => {
   const ARRIVAL = { onboarding: { focus: true } };
 
   it("moves the focus to the title, then consumes the navigation state", () => {
-    harness.location = { ...harness.location, state: ARRIVAL };
+    ctx.location = { ...ctx.location, state: ARRIVAL };
     render();
     const title = attachTitle();
-    runEffects();
+    commit();
     expect(title.focus).toHaveBeenCalledTimes(1);
-    expect(harness.navigate).toHaveBeenCalledTimes(1);
-    expect(harness.navigate).toHaveBeenCalledWith("/import", { replace: true, state: null });
-    expect(vi.mocked(harness.navigate).mock.invocationCallOrder[0]).toBeGreaterThan(
+    expect(ctx.navigate).toHaveBeenCalledTimes(1);
+    expect(ctx.navigate).toHaveBeenCalledWith("/import", { replace: true, state: null });
+    expect(vi.mocked(ctx.navigate).mock.invocationCallOrder[0]).toBeGreaterThan(
       title.focus.mock.invocationCallOrder[0],
     );
   });
 
   it("does it once per arrival: StrictMode's second run and later renders do nothing", () => {
-    harness.location = { ...harness.location, state: ARRIVAL };
+    ctx.location = { ...ctx.location, state: ARRIVAL };
     render();
     const title = attachTitle();
-    runEffects();
-    runEffects();
+    commit();
+    harness.replayEffects();
     render();
-    runEffects();
+    commit();
     expect(title.focus).toHaveBeenCalledTimes(1);
-    expect(harness.navigate).toHaveBeenCalledTimes(1);
+    expect(ctx.navigate).toHaveBeenCalledTimes(1);
 
     // A new arrival on the same mounted page asks again.
-    harness.location = { ...harness.location, key: "arrival-2" };
+    ctx.location = { ...ctx.location, key: "arrival-2" };
     render();
-    runEffects();
+    commit();
     expect(title.focus).toHaveBeenCalledTimes(2);
-    expect(harness.navigate).toHaveBeenCalledTimes(2);
+    expect(ctx.navigate).toHaveBeenCalledTimes(2);
   });
 
   it("waits for the card to show before focusing and consuming", () => {
-    harness.location = { ...harness.location, state: ARRIVAL };
+    ctx.location = { ...ctx.location, state: ARRIVAL };
     expect(render(null)).toBeNull();
-    runEffects();
-    expect(harness.navigate).not.toHaveBeenCalled();
+    commit();
+    expect(ctx.navigate).not.toHaveBeenCalled();
 
     render();
     const title = attachTitle();
-    runEffects();
+    commit();
     expect(title.focus).toHaveBeenCalledTimes(1);
-    expect(harness.navigate).toHaveBeenCalledTimes(1);
+    expect(ctx.navigate).toHaveBeenCalledTimes(1);
   });
 
   it("an ordinary visit, without navigation state or with a malformed one, does nothing and does not fail", () => {
     for (const state of [null, undefined, "focus", { onboarding: "focus" }, { onboarding: { focus: "yes" } }]) {
-      harness.location = { ...harness.location, state };
+      // A fresh mount per visit: its effect runs at its first commit.
+      harness.clear();
+      ctx.location = { ...ctx.location, state };
       render();
       const title = attachTitle();
-      expect(() => runEffects()).not.toThrow();
+      expect(() => commit()).not.toThrow();
       expect(title.focus).not.toHaveBeenCalled();
     }
-    expect(harness.navigate).not.toHaveBeenCalled();
+    expect(ctx.navigate).not.toHaveBeenCalled();
   });
 });
diff --git a/src/hooks/useOnboardingChecklist.wiring.test.ts b/src/hooks/useOnboardingChecklist.wiring.test.ts
index 10a4bc0..5655053 100644
--- a/src/hooks/useOnboardingChecklist.wiring.test.ts
+++ b/src/hooks/useOnboardingChecklist.wiring.test.ts
@@ -1,37 +1,18 @@
-// useOnboardingChecklist — the hook's own wiring (#396).
+// useOnboardingChecklist — the hook's own wiring (#396, #409).
 //
 // The reducer, the loader, the follower and the derivation are tested in
 // useOnboardingChecklist.test.ts; renderToStaticMarkup runs no effect, so what
-// the hook does with React would stay unguarded. Here React's hooks are
-// stubbed (same technique as useImportWizard.executeImport.test.ts): the hook
-// runs as a plain function on a prepared state, its effects are captured and
-// run by hand, and the onboarding service is mocked.
+// the hook does with React would stay unguarded. Here React's hooks come from
+// the shared harness (src/test/hookHarness.ts): the hook runs as a plain
+// function, its state, memos and callbacks survive from one render to the
+// next as in a mounted provider, its reducer is applied, and `commit()` runs
+// its effects as React does. The onboarding service is mocked.
 
 import { describe, it, expect, vi, beforeEach, afterEach } from "vitest";
 
-type Effect = { fn: () => void | (() => void); deps: readonly unknown[] | undefined };
-
-const harness = vi.hoisted(() => ({
-  state: null as unknown,
-  dispatch: vi.fn(),
-  effects: [] as Effect[],
-  pathname: "/",
-}));
-
-vi.mock("react", async (importOriginal) => {
-  const actual = await importOriginal<typeof import("react")>();
-  return {
-    ...actual,
-    useReducer: () => [harness.state, harness.dispatch],
-    useState: (init: unknown) => [typeof init === "function" ? (init as () => unknown)() : init, () => undefined],
-    useCallback: (fn: unknown) => fn,
-    useMemo: (fn: () => unknown) => fn(),
-    useEffect: (fn: Effect["fn"], deps?: readonly unknown[]) => {
-      harness.effects.push({ fn, deps });
-    },
-  };
-});
-vi.mock("react-router-dom", () => ({ useLocation: () => ({ pathname: harness.pathname }) }));
+vi.mock("react", async (orig) => (await import("../test/hookHarness")).fakeReact(await orig()));
+const ctx = vi.hoisted(() => ({ pathname: "/" }));
+vi.mock("react-router-dom", () => ({ useLocation: () => ({ pathname: ctx.pathname }) }));
 vi.mock("./useEntitlement", () => ({ useEntitlement: () => ({ allowed: true, ready: true }) }));
 vi.mock("../services/logService", () => ({ logInfo: vi.fn(), logWarn: vi.fn(), logError: vi.fn() }));
 vi.mock("../services/onboardingService", () => ({
@@ -43,6 +24,7 @@ vi.mock("../services/onboardingService", () => ({
   resumeStep: vi.fn(),
 }));
 
+import { hookHarness } from "../test/hookHarness";
 import {
   useOnboardingChecklist,
   initialOnboardingChecklistState,
@@ -61,6 +43,8 @@ import {
   type OnboardingSnapshot,
 } from "../services/onboardingService";
 
+const harness = hookHarness();
+
 const snapshot: OnboardingSnapshot = {
   counters: { sources: 1, imports: 1, manualCategorized: 0, budgetEntries: 0, transactions: 12 },
   importFolderSet: true,
@@ -73,19 +57,25 @@ const ready: OnboardingChecklistState = [
   { type: "LOAD_DONE", seq: 1, snapshot } as const,
 ].reduce(onboardingChecklistReducer, initialOnboardingChecklistState);
 
+/** One render of the mounted provider. */
+const render = () => harness.render(useOnboardingChecklist);
+
+/** The state the provider mounts with: its `useReducer` is its first React hook. */
+const mountWith = (state: OnboardingChecklistState) => {
+  harness.slots[0] = state;
+};
+
 /** Lets the loader's promises settle. */
 const flush = async () => {
   for (let i = 0; i < 10; i++) await Promise.resolve();
 };
 
 const actionsOfType = (type: string) =>
-  harness.dispatch.mock.calls.map((c) => c[0]).filter((a) => a.type === type);
+  harness.dispatch.mock.calls.map((c) => c[0] as { type: string }).filter((a) => a.type === type);
 
 beforeEach(() => {
-  harness.state = initialOnboardingChecklistState;
-  harness.pathname = "/";
-  harness.effects = [];
-  harness.dispatch.mockReset();
+  harness.clear();
+  ctx.pathname = "/";
   vi.mocked(getOnboardingSnapshot).mockReset().mockResolvedValue(snapshot);
   vi.mocked(initializeGuidedPath).mockReset().mockResolvedValue({ hidden: false });
   for (const write of [hideChecklist, showChecklist, skipStep, resumeStep]) {
@@ -95,18 +85,15 @@ beforeEach(() => {
 });
 
 afterEach(() => {
+  harness.unmount();
   vi.useRealTimers();
 });
 
 describe("useOnboardingChecklist — wiring (#396)", () => {
   it("reads at mount, through rule D9, and again whenever the route changes", async () => {
-    harness.pathname = "/import";
-    useOnboardingChecklist();
-    const [reread] = harness.effects;
-    // The route is a dependency: React runs the read again on every new pathname.
-    expect(reread.deps).toContain("/import");
-
-    reread.fn();
+    ctx.pathname = "/import";
+    render();
+    harness.commit();
     await flush();
     expect(initializeGuidedPath).toHaveBeenCalledTimes(1);
     expect(getOnboardingSnapshot).toHaveBeenCalledTimes(1);
@@ -114,15 +101,37 @@ describe("useOnboardingChecklist — wiring (#396)", () => {
       { type: "LOAD_START", seq: 1 },
       { type: "LOAD_DONE", seq: 1, snapshot },
     ]);
+
+    // The loaded state renders: same route, no new read.
+    const loaded = render();
+    harness.commit();
+    await flush();
+    expect(loaded.status).toBe("ready");
+    expect(getOnboardingSnapshot).toHaveBeenCalledTimes(1);
+
+    // A new route: React runs the read again.
+    ctx.pathname = "/transactions";
+    render();
+    harness.commit();
+    await flush();
+    expect(getOnboardingSnapshot).toHaveBeenCalledTimes(2);
+    expect(initializeGuidedPath).toHaveBeenCalledTimes(1);
   });
 
   it("re-reads 150 ms after a burst of data events, and its cleanup unsubscribes", async () => {
+    render();
+    harness.commit();
+    await flush();
     vi.useFakeTimers();
-    useOnboardingChecklist();
-    const follow = harness.effects[1];
-    expect(follow.deps).not.toContain(harness.pathname);
+    harness.dispatch.mockReset();
+
+    // A route change re-runs the read, not the follower: one subscription only.
+    ctx.pathname = "/reports";
+    render();
+    harness.commit();
+    await flush();
+    harness.dispatch.mockReset();
 
-    const cleanup = follow.fn() as () => void;
     notifyDataChanged();
     notifyDataChanged();
     vi.advanceTimersByTime(149);
@@ -131,28 +140,28 @@ describe("useOnboardingChecklist — wiring (#396)", () => {
     expect(actionsOfType("LOAD_START")).toHaveLength(1);
     await flush();
 
-    cleanup();
+    harness.unmount();
     notifyDataChanged();
     vi.advanceTimersByTime(300);
     expect(actionsOfType("LOAD_START")).toHaveLength(1);
   });
 
   it("stores a card latch that changed during render, and only then", () => {
-    harness.state = { ...ready, cardPage: "/import" };
-    harness.pathname = "/reports";
-    useOnboardingChecklist();
-    expect(harness.dispatch).toHaveBeenCalledWith({ type: "SET_CARD_PAGE", cardPage: null });
+    mountWith({ ...ready, cardPage: "/import" });
+    ctx.pathname = "/reports";
+    render();
+    expect(harness.dispatch.mock.calls).toEqual([[{ type: "SET_CARD_PAGE", cardPage: null }]]);
 
+    // The reducer applied it: the next render finds the latch stored.
     harness.dispatch.mockReset();
-    harness.state = ready;
-    useOnboardingChecklist();
+    expect(render().cardPage).toBeNull();
     expect(harness.dispatch).not.toHaveBeenCalled();
   });
 
   it("shares the derived next step and mode with the state", () => {
-    harness.state = ready;
-    harness.pathname = "/reports";
-    const value = useOnboardingChecklist();
+    mountWith(ready);
+    ctx.pathname = "/reports";
+    const value = render();
     expect(value.status).toBe("ready");
     expect(value.nextStep?.key).toBe("manualCategory");
     expect(value.mode).toBe("banner");
@@ -161,8 +170,8 @@ describe("useOnboardingChecklist — wiring (#396)", () => {
   });
 
   it("each action writes its preference first, then updates the state", async () => {
-    harness.state = ready;
-    const value = useOnboardingChecklist();
+    mountWith(ready);
+    const value = render();
     await value.hide();
     await value.show();
     await value.skip("budget");
@@ -183,20 +192,68 @@ describe("useOnboardingChecklist — wiring (#396)", () => {
   });
 
   it("an action whose write fails leaves the state alone and logs", async () => {
-    harness.state = ready;
-    const value = useOnboardingChecklist();
+    mountWith(ready);
+    const value = render();
     vi.mocked(hideChecklist).mockRejectedValueOnce(new Error("database is locked"));
     vi.mocked(skipStep).mockRejectedValueOnce(new Error("database is locked"));
     await value.hide();
     await value.skip("source");
     expect(harness.dispatch).not.toHaveBeenCalled();
     expect(logError).toHaveBeenCalledTimes(2);
+    expect(render().hidden).toBe(false);
   });
 
   it("refresh is the loader itself", async () => {
-    const value = useOnboardingChecklist();
+    const value = render();
     await value.refresh();
     expect(getOnboardingSnapshot).toHaveBeenCalledTimes(1);
     expect(actionsOfType("LOAD_DONE")).toHaveLength(1);
   });
 });
+
+describe("useOnboardingChecklist — what survives a render (#409)", () => {
+  it("keeps one loader for the provider's life: refresh, the value and the reads stay put", async () => {
+    mountWith(ready);
+    ctx.pathname = "/reports";
+    const first = render();
+    harness.commit();
+    await flush();
+    const reads = vi.mocked(getOnboardingSnapshot).mock.calls.length;
+
+    const second = render();
+    harness.commit();
+    await flush();
+    expect(second.refresh).toBe(first.refresh);
+    // Nothing changed: the shared value keeps its identity, so no consumer re-renders.
+    expect(second).toBe(first);
+    // A new loader would re-run the read effect at every render: a loop of reads.
+    expect(getOnboardingSnapshot).toHaveBeenCalledTimes(reads);
+  });
+
+  it("'Skip' moves the next step on the next render, without a re-read", async () => {
+    mountWith(ready);
+    ctx.pathname = "/reports";
+    const before = render();
+    expect(before.nextStep?.key).toBe("manualCategory");
+
+    await before.skip("manualCategory");
+    const after = render();
+    expect(getOnboardingSnapshot).not.toHaveBeenCalled();
+    expect(after.checklist).not.toBe(before.checklist);
+    expect(after.nextStep?.key).toBe("budget");
+  });
+
+  it("a change of mode alone reaches the consumers", () => {
+    // An empty profile: the dashboard shows its own empty state, other pages the banner.
+    mountWith({ ...ready, counters: { ...snapshot.counters, transactions: 0 } });
+    ctx.pathname = "/";
+    const dashboard = render();
+    ctx.pathname = "/reports";
+    const reports = render();
+    expect(reports.checklist).toBe(dashboard.checklist);
+    expect(reports.nextStep).toBe(dashboard.nextStep);
+    expect(reports.cardPage).toBe(dashboard.cardPage);
+    expect(reports.mode).not.toBe(dashboard.mode);
+    expect(reports.mode).toBe("banner");
+  });
+});
diff --git a/src/pages/BudgetPage.wiring.test.ts b/src/pages/BudgetPage.wiring.test.ts
index fd3b1e3..9791db7 100644
--- a/src/pages/BudgetPage.wiring.test.ts
+++ b/src/pages/BudgetPage.wiring.test.ts
@@ -1,7 +1,7 @@
-// BudgetPage — what the page does with the grid's target (#400).
+// BudgetPage — what the page does with the grid's target (#400, #409).
 //
 // A static render runs no effect, so the grid never reports there. React's
-// `useState` is stubbed (technique of AppShell.slot.test.tsx): the page runs
+// hooks come from the shared harness (src/test/hookHarness.ts): the page runs
 // as a plain function, its state survives from one call to the next as
 // between two renders of a mounted component, and its setters keep their
 // identity as React's do. The test plays the grid by calling the callback the
@@ -9,50 +9,31 @@
 import { describe, it, expect, vi, beforeEach } from "vitest";
 import { isValidElement, type ReactElement, type ReactNode } from "react";
 
-const harness = vi.hoisted(() => ({
-  slots: [] as unknown[],
-  setters: [] as Array<(next: unknown) => void>,
-  cursor: 0,
+vi.mock("react", async (orig) => (await import("../test/hookHarness")).fakeReact(await orig()));
+const ctx = vi.hoisted(() => ({
   pathname: "/budget",
   onboarding: null as unknown,
   budget: null as unknown,
 }));
-
-vi.mock("react", async (importOriginal) => {
-  const actual = await importOriginal<typeof import("react")>();
-  return {
-    ...actual,
-    useState: (init: unknown) => {
-      const index = harness.cursor++;
-      if (!(index in harness.slots)) {
-        harness.slots[index] = typeof init === "function" ? (init as () => unknown)() : init;
-      }
-      harness.setters[index] ??= (next: unknown) => {
-        harness.slots[index] =
-          typeof next === "function" ? (next as (previous: unknown) => unknown)(harness.slots[index]) : next;
-      };
-      return [harness.slots[index], harness.setters[index]];
-    },
-  };
-});
 vi.mock("react-router-dom", async (importOriginal) => ({
   ...(await importOriginal<typeof import("react-router-dom")>()),
-  useLocation: () => ({ pathname: harness.pathname }),
+  useLocation: () => ({ pathname: ctx.pathname }),
 }));
 vi.mock("react-i18next", () => ({
   useTranslation: () => ({ t: (k: string) => `t(${k})`, i18n: { language: "fr" } }),
 }));
 // The page's modules pull the database: stub the connection.
 vi.mock("../services/db", () => ({ getDb: vi.fn(), withTransaction: vi.fn() }));
-vi.mock("../contexts/OnboardingContext", () => ({ useOnboarding: () => harness.onboarding }));
+vi.mock("../contexts/OnboardingContext", () => ({ useOnboarding: () => ctx.onboarding }));
 vi.mock("../hooks/useReportsPeriod", () => ({
   useReportsPeriod: () => ({ accountIds: [], setAccountIds: () => undefined }),
 }));
 vi.mock("../hooks/useBudget", async (importOriginal) => ({
   ...(await importOriginal<typeof import("../hooks/useBudget")>()),
-  useBudget: () => harness.budget,
+  useBudget: () => ctx.budget,
 }));
 
+import { hookHarness } from "../test/hookHarness";
 import BudgetPage from "./BudgetPage";
 import BudgetTable from "../components/budget/BudgetTable";
 import OnboardingStepCard from "../components/onboarding/OnboardingStepCard";
@@ -62,6 +43,8 @@ import { computeChecklist } from "../utils/onboardingChecklist";
 import { budgetCardModel, nextStep, type BudgetCardModel } from "../utils/onboardingPath";
 import type { BudgetOnboardingTargetKind, OnboardingCounters } from "../shared/types";
 
+const harness = hookHarness();
+
 type AnyElement = ReactElement<Record<string, unknown> & { children?: ReactNode }>;
 
 function find(node: ReactNode, pred: (el: AnyElement) => boolean): AnyElement[] {
@@ -103,8 +86,7 @@ function path(counters: OnboardingCounters, overrides: Partial<OnboardingValue>
 
 /** One render of the mounted page: its hooks are read in the same order each time. */
 function render() {
-  harness.cursor = 0;
-  const page = BudgetPage() as AnyElement;
+  const page = harness.render(() => BudgetPage() as AnyElement);
   const [card] = find(page, (el) => el.type === OnboardingStepCard);
   const [grid] = find(page, (el) => el.type === BudgetTable);
   return {
@@ -116,12 +98,11 @@ function render() {
 }
 
 beforeEach(() => {
-  harness.slots = [];
-  harness.setters = [];
-  harness.pathname = "/budget";
-  harness.onboarding = path(BUDGET_LEFT);
+  harness.clear();
+  ctx.pathname = "/budget";
+  ctx.onboarding = path(BUDGET_LEFT);
   const state: BudgetState = { ...initialBudgetState(), totalInDb: 41 };
-  harness.budget = new Proxy({ state } as Record<string, unknown>, {
+  ctx.budget = new Proxy({ state } as Record<string, unknown>, {
     get: (target, key) => (key in target ? target[key as string] : vi.fn()),
   });
 });
@@ -136,7 +117,7 @@ describe("BudgetPage — the grid's target and the card (#400)", () => {
   });
 
   it("follows what the grid reports: its sentence, and the ring once a target is known", () => {
-    const checklist = (harness.onboarding as OnboardingValue).checklist;
+    const checklist = (ctx.onboarding as OnboardingValue).checklist;
     let view = render();
     expect(view.model).toEqual(budgetCardModel({ target: null }, checklist));
     expect(view.highlight).toBe(false);
@@ -164,16 +145,15 @@ describe("BudgetPage — the grid's target and the card (#400)", () => {
       { mode: "complete" as const, cardPage: null },
       { mode: "card" as const, cardPage: "/transactions" },
     ]) {
-      harness.slots = [];
-      harness.setters = [];
-      harness.onboarding = path(BUDGET_LEFT, overrides);
+      harness.clear();
+      ctx.onboarding = path(BUDGET_LEFT, overrides);
       render().report("cell");
       expect(render().highlight, JSON.stringify(overrides)).toBe(false);
     }
   });
 
   it("asks for no ring once the step is checked: the card says 'Done.'", () => {
-    harness.onboarding = path({ ...BUDGET_LEFT, budgetEntries: 1 });
+    ctx.onboarding = path({ ...BUDGET_LEFT, budgetEntries: 1 });
     render().report("cell");
     const view = render();
     expect(view.model).toEqual({ text: null, done: true, target: null });
@@ -195,15 +175,14 @@ describe("BudgetPage — the grid's target and the card (#400)", () => {
       budgetAllowed: true,
       skipped: ["source", "import", "manualCategory"],
     });
-    harness.onboarding = path(counters, { checklist, nextStep: nextStep(checklist) });
-    const budget = harness.budget as { state: BudgetState };
+    ctx.onboarding = path(counters, { checklist, nextStep: nextStep(checklist) });
+    const budget = ctx.budget as { state: BudgetState };
     budget.state = { ...budget.state, totalInDb: null };
     render().report("expandAll");
     expect(render().model.text?.key).toBe("onboarding.card.budget.collapsed");
 
     budget.state = { ...budget.state, totalInDb: 0 };
-    harness.cursor = 0;
-    const page = BudgetPage() as AnyElement;
+    const page = harness.render(() => BudgetPage() as AnyElement);
     expect(find(page, (el) => el.type === BudgetTable)).toHaveLength(0);
     const [card] = find(page, (el) => el.type === OnboardingStepCard);
     expect(card.props.model).toEqual({ text: null, done: false, target: null });
diff --git a/src/pages/settings/UsersSettingsPage.test.tsx b/src/pages/settings/UsersSettingsPage.test.tsx
index 947cb7d..953b3a0 100644
--- a/src/pages/settings/UsersSettingsPage.test.tsx
+++ b/src/pages/settings/UsersSettingsPage.test.tsx
@@ -1,41 +1,21 @@
-// UsersSettingsPage — the re-show button reads the shared path (#397).
+// UsersSettingsPage — the re-show button reads the shared path (#397, #409).
 //
-// React's `useState` is stubbed (same technique as
-// useOnboardingChecklist.wiring.test.ts): the page runs as a plain function
-// and its state survives from one call to the next, as between two renders of
-// the mounted page. So "the path got hidden by the banner of this very page"
-// is a new `useOnboarding()` value on the next render, without remounting.
+// React's hooks come from the shared harness (src/test/hookHarness.ts): the
+// page runs as a plain function, its state survives from one call to the
+// next, as between two renders of the mounted page, and `commit()` runs its
+// effects as React would. So "the path got hidden by the banner of this very
+// page" is a new `useOnboarding()` value on the next render, without
+// remounting, and an effect of the page that read the preference would run.
 import { describe, it, expect, vi, beforeEach } from "vitest";
 import { isValidElement, type ReactElement, type ReactNode } from "react";
 
-const harness = vi.hoisted(() => ({
-  slots: [] as unknown[],
-  cursor: 0,
-  onboarding: null as unknown,
-}));
-
-vi.mock("react", async (importOriginal) => {
-  const actual = await importOriginal<typeof import("react")>();
-  return {
-    ...actual,
-    useState: (init: unknown) => {
-      const index = harness.cursor++;
-      if (!(index in harness.slots)) {
-        harness.slots[index] = typeof init === "function" ? (init as () => unknown)() : init;
-      }
-      const set = (next: unknown) => {
-        harness.slots[index] =
-          typeof next === "function" ? (next as (previous: unknown) => unknown)(harness.slots[index]) : next;
-      };
-      return [harness.slots[index], set];
-    },
-  };
-});
+vi.mock("react", async (orig) => (await import("../../test/hookHarness")).fakeReact(await orig()));
+const ctx = vi.hoisted(() => ({ onboarding: null as unknown }));
 vi.mock("react-i18next", () => ({
   useTranslation: () => ({ t: (k: string) => `t(${k})`, i18n: { language: "fr" } }),
 }));
 vi.mock("../../contexts/OnboardingContext", () => ({
-  useOnboarding: () => harness.onboarding,
+  useOnboarding: () => ctx.onboarding,
 }));
 // The page's cards are not under test, and they reach tauri.
 vi.mock("../../components/settings/AccountCard", () => ({ default: () => null }));
@@ -46,10 +26,13 @@ vi.mock("../../components/settings/DocsContent", () => ({ default: () => null })
 vi.mock("../../services/userPreferenceService", () => ({ getPreference: vi.fn() }));
 vi.mock("../../services/onboardingService", () => ({ showChecklist: vi.fn() }));
 
+import { hookHarness } from "../../test/hookHarness";
 import UsersSettingsPage from "./UsersSettingsPage";
 import { getPreference } from "../../services/userPreferenceService";
 import { showChecklist } from "../../services/onboardingService";
 
+const harness = hookHarness();
+
 type AnyElement = ReactElement<Record<string, unknown> & { children?: ReactNode }>;
 
 function find(node: ReactNode, pred: (el: AnyElement) => boolean): AnyElement[] {
@@ -71,10 +54,11 @@ function path(hidden: boolean) {
   return { hidden, show: vi.fn(async () => undefined) };
 }
 
-/** One render of the mounted page. */
+/** One render of the mounted page, then its commit. */
 function renderPage(): ReactNode {
-  harness.cursor = 0;
-  return UsersSettingsPage() as ReactNode;
+  const page = harness.render(() => UsersSettingsPage() as ReactNode);
+  harness.commit();
+  return page;
 }
 
 const showButton = (page: ReactNode) =>
@@ -83,8 +67,8 @@ const confirmation = (page: ReactNode) =>
   find(page, (e) => e.props.role === "status" && texts(e.props.children).includes("t(settings.users.onboarding.confirmation)"));
 
 beforeEach(() => {
-  harness.slots = [];
-  harness.onboarding = path(false);
+  harness.clear();
+  ctx.onboarding = path(false);
   vi.mocked(getPreference).mockReset();
   vi.mocked(showChecklist).mockReset();
 });
@@ -99,7 +83,7 @@ describe("UsersSettingsPage — showing the path again (#397)", () => {
 
   it("offers the button as soon as the path is hidden from the banner of this page, without remounting", () => {
     expect(showButton(renderPage())).toHaveLength(0);
-    harness.onboarding = path(true);
+    ctx.onboarding = path(true);
     const page = renderPage();
     expect(texts(page)).toContain("t(settings.users.onboarding.label)");
     expect(showButton(page)).toHaveLength(1);
@@ -108,14 +92,14 @@ describe("UsersSettingsPage — showing the path again (#397)", () => {
 
   it("the button shows the path through the provider, then confirms in place", async () => {
     const hiddenPath = path(true);
-    harness.onboarding = hiddenPath;
+    ctx.onboarding = hiddenPath;
     const [button] = showButton(renderPage());
     await (button.props.onClick as () => Promise<void>)();
     expect(hiddenPath.show).toHaveBeenCalledTimes(1);
     expect(showChecklist).not.toHaveBeenCalled();
 
     // The provider applied SHOW: the next render reads the path shown.
-    harness.onboarding = path(false);
+    ctx.onboarding = path(false);
     const page = renderPage();
     expect(showButton(page)).toHaveLength(0);
     expect(confirmation(page)).toHaveLength(1);
@@ -123,13 +107,13 @@ describe("UsersSettingsPage — showing the path again (#397)", () => {
   });
 
   it("hidden again after a restore, it offers the button again", async () => {
-    harness.onboarding = path(true);
+    ctx.onboarding = path(true);
     const [button] = showButton(renderPage());
     await (button.props.onClick as () => Promise<void>)();
-    harness.onboarding = path(false);
+    ctx.onboarding = path(false);
     expect(confirmation(renderPage())).toHaveLength(1);
 
-    harness.onboarding = path(true);
+    ctx.onboarding = path(true);
     const page = renderPage();
     expect(showButton(page)).toHaveLength(1);
     expect(confirmation(page)).toHaveLength(0);
@@ -137,7 +121,7 @@ describe("UsersSettingsPage — showing the path again (#397)", () => {
 
   it("keeps the button when showing failed: the provider left the path hidden", async () => {
     const hiddenPath = path(true);
-    harness.onboarding = hiddenPath;
+    ctx.onboarding = hiddenPath;
     const [button] = showButton(renderPage());
     await (button.props.onClick as () => Promise<void>)();
     const page = renderPage();
@@ -145,8 +129,10 @@ describe("UsersSettingsPage — showing the path again (#397)", () => {
     expect(confirmation(page)).toHaveLength(0);
   });
 
-  it("never reads the preference itself", () => {
-    harness.onboarding = path(true);
+  it("never reads the preference itself, neither while rendering nor in an effect", () => {
+    ctx.onboarding = path(true);
+    renderPage();
+    ctx.onboarding = path(false);
     renderPage();
     expect(getPreference).not.toHaveBeenCalled();
   });