fix(react): track owners separately, mutate updaters with dispatcher

packages/react/src/index.ts

@@ -91,11 +91,17 @@ Object.defineProperties(Signal.prototype, {
 });
 
 // Track the current owner (roughly equiv to current vnode)
-// let currentOwner: ReactOwner;
-// Object.defineProperty(internals.ReactCurrentOwner, "current", {
-// 	get() { return currentOwner; },
-// 	set(owner) { currentOwner = owner; },
-// });
+let lastOwner: ReactOwner | undefined;
+let currentOwner: ReactOwner | null = null;
+Object.defineProperty(internals.ReactCurrentOwner, "current", {
+	get() {
+		return currentOwner;
+	},
+	set(owner) {
+		currentOwner = owner;
+		if (currentOwner) lastOwner = currentOwner;
+	},
+});
 
 // Track the current dispatcher (roughly equiv to current component impl)
 let lock = false;
@@ -108,17 +114,19 @@ Object.defineProperty(internals.ReactCurrentDispatcher, "current", {
 	set(api) {
 		currentDispatcher = api;
 		if (lock) return;
-		if (api && !isInvalidHookAccessor(api)) {
+		if (lastOwner && api && !isInvalidHookAccessor(api)) {
 			// prevent re-injecting useReducer when the Dispatcher
 			// context changes to run the reducer callback:
 			lock = true;
 			const rerender = api.useReducer(UPDATE, {})[1];
 			lock = false;
-			const currentOwner = internals.ReactCurrentOwner.current;
-			let updater = updaterForComponent.get(currentOwner);
+
+			let updater = updaterForComponent.get(lastOwner);
 			if (!updater) {
 				updater = createUpdater(rerender);
-				updaterForComponent.set(currentOwner, updater);
+				updaterForComponent.set(lastOwner, updater);
+			} else {
+				updater._updater = rerender;
 			}
 			setCurrentUpdater(updater);
 		} else {

packages/react/test/index.test.tsx

@@ -2,7 +2,7 @@
 globalThis.IS_REACT_ACT_ENVIRONMENT = true;
 
 import { signal, useComputed } from "@preact/signals-react";
-import { createElement, useMemo } from "react";
+import { createElement, useMemo, memo, StrictMode } from "react";
 import { createRoot, Root } from "react-dom/client";
 import { act } from "react-dom/test-utils";
 
@@ -158,5 +158,26 @@ describe("@preact/signals-react", () => {
 			});
 			expect(scratch.textContent).to.equal("bar");
 		});
+
+		it("should consistently rerender in strict mode", async () => {
+			const sig = signal<string>(null!);
+
+			const Test = memo(() => <p>{sig.value}</p>);
+			const App = () => (
+				<StrictMode>
+					<Test />
+				</StrictMode>
+			);
+
+			for (let i = 0; i < 3; i++) {
+				const value = `${i}`;
+
+				act(() => {
+					sig.value = value;
+					render(<App />);
+				});
+				expect(scratch.textContent).to.equal(value);
+			}
+		});
 	});
 });