diff --git a/docs/guide/migration.md b/docs/guide/migration.md
index 45b19e634..a9632f368 100644
--- a/docs/guide/migration.md
+++ b/docs/guide/migration.md
@@ -34,6 +34,13 @@ test('example', { sequential: true }, async () => { /* ... */ }) // [!code --]
 test('example', { concurrent: false }, async () => { /* ... */ }) // [!code ++]
 ```
 
+### Narrower Inference for `test.each` and `describe.each`
+
+`test.each` and `describe.each` now preserve literal types by default for array cases.
+This means callback parameters can be inferred as literal unions (for example `1 | 2`) instead of widened types (for example `number`) without needing `as const`.
+
+If your callback annotations intentionally reject literal values and relied on wider inference, update those annotations to accept the inferred literal unions.
+
 ### Locators in Commands are Serialized as Objects
 
 Locators forwarded to [browser commands](/api/browser/commands) are now serialized as a `SerializedLocator` object instead of a bare selector string. The object exposes two fields:
diff --git a/packages/runner/src/types/tasks.ts b/packages/runner/src/types/tasks.ts
index 35ee6d841..a62112cdc 100644
--- a/packages/runner/src/types/tasks.ts
+++ b/packages/runner/src/types/tasks.ts
@@ -397,11 +397,11 @@ interface EachFunctionReturn<T extends any[]> {
 }
 
 interface TestEachFunction {
-  <T extends any[] | [any]>(cases: ReadonlyArray<T>): EachFunctionReturn<T>
-  <T extends ReadonlyArray<any>>(cases: ReadonlyArray<T>): EachFunctionReturn<
+  <const T extends any[] | [any]>(cases: ReadonlyArray<T>): EachFunctionReturn<T>
+  <const T extends ReadonlyArray<any>>(cases: ReadonlyArray<T>): EachFunctionReturn<
     ExtractEachCallbackArgs<T>
   >
-  <T>(cases: ReadonlyArray<T>): EachFunctionReturn<T[]>
+  <const T>(cases: ReadonlyArray<T>): EachFunctionReturn<T[]>
   (...args: [TemplateStringsArray, ...any]): EachFunctionReturn<any[]>
 }
 
diff --git a/test/typescript/fixtures/dynamic-title/test/dynamic-title.test-d.ts b/test/typescript/fixtures/dynamic-title/test/dynamic-title.test-d.ts
index 19d62fbd2..71095e238 100644
--- a/test/typescript/fixtures/dynamic-title/test/dynamic-title.test-d.ts
+++ b/test/typescript/fixtures/dynamic-title/test/dynamic-title.test-d.ts
@@ -1,9 +1,19 @@
-import { expectTypeOf, test } from 'vitest'
+import { describe, expectTypeOf, test } from 'vitest'
 
 test.each(['some-value'])('each: %s', () => {
   expectTypeOf(1).toEqualTypeOf(2)
 })
 
+test.each([1, 2])('each literal number: %s', (num) => {
+  expectTypeOf(num).toEqualTypeOf<1 | 2>()
+})
+
+describe.each([1, 2])('describe.each literal number: %s', (num) => {
+  test('keeps literal union', () => {
+    expectTypeOf(num).toEqualTypeOf<1 | 2>()
+  })
+})
+
 test.for(['some-value'])('for: %s', () => {
   expectTypeOf(1).toEqualTypeOf(2)
 })
diff --git a/test/unit/test/each.test.ts b/test/unit/test/each.test.ts
index 6592edcd3..675d97140 100644
--- a/test/unit/test/each.test.ts
+++ b/test/unit/test/each.test.ts
@@ -1,4 +1,4 @@
-import { afterAll, describe, expect, test } from 'vitest'
+import { afterAll, describe, expect, expectTypeOf, test } from 'vitest'
 
 test.each([
   [1, 1, 2],
@@ -19,6 +19,10 @@ test.each([
   expect(typedB).toBeDefined()
 })
 
+test.each([1, 2])('preserves literal unions for test.each', (num) => {
+  expectTypeOf(num).toEqualTypeOf<1 | 2>()
+})
+
 describe.each([
   [1, 1, 2],
   [1, 2, 3],
@@ -37,6 +41,12 @@ describe.each([
   })
 })
 
+describe.each([1, 2])('preserves literal unions for describe.each', (num) => {
+  test('literal union type', () => {
+    expectTypeOf(num).toEqualTypeOf<1 | 2>()
+  })
+})
+
 describe.each([
   [1, 'a', '1a'],
   [1, 'b', '1b'],