diff --git a/packages/playwright-core/types/structs.d.ts b/packages/playwright-core/types/structs.d.ts
index 11f87a2ccebf4..3b671e99ac17b 100644
--- a/packages/playwright-core/types/structs.d.ts
+++ b/packages/playwright-core/types/structs.d.ts
@@ -25,12 +25,17 @@ export type Serializable = any;
  */
 export type EvaluationArgument = {};
 
-type CallbackResult<T> = T extends PromiseLike<infer U> ? Promise<Unboxed<U>> : Promise<Unboxed<T>>;
-export type NoHandles<Arg> = Arg extends JSHandle ? never : (Arg extends Function ? never : (Arg extends object ? { [Key in keyof Arg]: NoHandles<Arg[Key]> } : Arg));
+export type NoHandles<Arg> =
+  Arg extends JSHandle ? never :
+  Arg extends (...args: infer T) => PromiseLike<infer U> ? (...args: T) => Promise<NoHandles<U>> :
+  Arg extends (...args: infer T) => infer R ? (...args: T) => NoHandles<R> :
+  Arg extends object ? { [Key in keyof Arg]: NoHandles<Arg[Key]> } :
+  Arg;
 export type Unboxed<Arg> =
   Arg extends ElementHandle<infer T> ? T :
   Arg extends JSHandle<infer T> ? T :
-  Arg extends (...args: infer T) => infer R ? (...args: T) => CallbackResult<R> :
+  Arg extends (...args: infer T) => PromiseLike<infer U> ? (...args: T) => Promise<Unboxed<U>> :
+  Arg extends (...args: infer T) => infer R ? (...args: T) => Unboxed<R> :
   Arg extends NoHandles<Arg> ? Arg :
   Arg extends [infer A0] ? [Unboxed<A0>] :
   Arg extends [infer A0, infer A1] ? [Unboxed<A0>, Unboxed<A1>] :
diff --git a/utils/generate_types/test/test.ts b/utils/generate_types/test/test.ts
index 3e4d407f1c0c7..88d4d00665ea8 100644
--- a/utils/generate_types/test/test.ts
+++ b/utils/generate_types/test/test.ts
@@ -428,10 +428,12 @@ playwright.chromium.launch().then(async browser => {
   {
     await locator.evaluateAll((sel: HTMLSelectElement[]) => {})
   }
+  // Handles in callback results are unboxed, but the callback keeps its authored
+  // sync/async signature, even though the runtime always exposes it as async on the page side.
   {
     await locator.evaluate((e, cb) => {
       const value = cb(2);
-      const assertion: AssertType<Promise<number>, typeof value> = true;
+      const assertion: AssertType<number, typeof value> = true;
     }, (x: number) => 2 * x);
   }
   {
@@ -456,6 +458,54 @@ playwright.chromium.launch().then(async browser => {
       const assertion: AssertType<Promise<{ double: number, add: number }>, typeof value> = true;
     }, { cb: func });
   }
+  {
+    // Promises nested in the argument are not awaited, only callback results are.
+    const result = await page.evaluate(arg => {
+      const assertion: AssertType<Promise<number>, typeof arg.a> = true;
+      return arg;
+    }, { a: new Promise<number>(() => {}), b: 42 });
+    const assertion: AssertType<{ a: Promise<number>, b: number }, typeof result> = true;
+  }
+  await browser.close();
+})();
+
+// branded primitives in evaluate arguments — https://github.com/microsoft/playwright/issues/42000
+declare const __brand: unique symbol;
+type Branded<T, B> = T & { [__brand]: B };
+type IsoDate = Branded<string, 'IsoDate'>;
+declare function takesIsoDate(date: IsoDate): void;
+
+(async () => {
+  const browser = await playwright.chromium.launch();
+  const page = await browser.newPage();
+  const date = '2026-01-15' as IsoDate;
+  {
+    const result = await page.evaluate((d: IsoDate) => d, date);
+    const assertion: AssertType<IsoDate, typeof result> = true;
+  }
+  {
+    await page.evaluate(d => takesIsoDate(d), date);
+  }
+  {
+    await page.evaluate(({ d }) => takesIsoDate(d), { d: date });
+  }
+  {
+    const count = 42 as Branded<number, 'Count'>;
+    const result = await page.evaluate(c => c, count);
+    const assertion: AssertType<Branded<number, 'Count'>, typeof result> = true;
+  }
+  {
+    const result = await page.evaluate((arg: { d?: IsoDate }) => arg.d, { d: date } as { d?: IsoDate });
+    const assertion: AssertType<IsoDate | undefined, typeof result> = true;
+  }
+  {
+    const result = await page.evaluate((dates: readonly IsoDate[]) => dates[0], [date] as readonly IsoDate[]);
+    const assertion: AssertType<IsoDate, typeof result> = true;
+  }
+  {
+    const result = await page.evaluate((pair: [IsoDate, number]) => pair[0], [date, 42] as [IsoDate, number]);
+    const assertion: AssertType<IsoDate, typeof result> = true;
+  }
   await browser.close();
 })();