fix(ui): radio fields do not reliably trigger admin.condition re-evaluation on sibling fields (#16056)

Fixes #15929

Author: paulpopus

packages/ui/src/forms/Form/fieldReducer.ts

@@ -427,10 +427,13 @@ export function fieldReducer(state: FormState, action: FieldAction): FormState {
       }
 
       // reset `isModified` in all other fields
+      // Use destructuring instead of delete to avoid mutating field objects
+      // shared with the previous state (shallow copy shares references)
       if ('value' in action) {
         for (const [path, field] of Object.entries(newState)) {
           if (path !== action.path && 'isModified' in field) {
-            delete newState[path].isModified
+            const { isModified: _, ...fieldWithoutIsModified } = field
+            newState[path] = fieldWithoutIsModified as typeof field
           }
         }
       }

test/fields/collections/ConditionalLogic/e2e.spec.ts

@@ -2,22 +2,23 @@ import type { BrowserContext, Page } from '@playwright/test'
 
 import { expect, test } from '@playwright/test'
 import { addArrayRow } from '__helpers/e2e/fields/array/index.js'
+import { addBlock } from '__helpers/e2e/fields/blocks/index.js'
 import path from 'path'
 import { fileURLToPath } from 'url'
 
 import type { PayloadTestSDK } from '../../../__helpers/shared/sdk/index.js'
 import type { Config } from '../../payload-types.js'
 
+import { assertNetworkRequests } from '../../../__helpers/e2e/assertNetworkRequests.js'
 import {
   ensureCompilationIsDone,
   initPageConsoleErrorCatch,
   saveDocAndAssert,
   // throttleTest,
 } from '../../../__helpers/e2e/helpers.js'
 import { AdminUrlUtil } from '../../../__helpers/shared/adminUrlUtil.js'
-import { assertNetworkRequests } from '../../../__helpers/e2e/assertNetworkRequests.js'
-import { initPayloadE2ENoConfig } from '../../../__helpers/shared/initPayloadE2ENoConfig.js'
 import { reInitializeDB } from '../../../__helpers/shared/clearAndSeed/reInitializeDB.js'
+import { initPayloadE2ENoConfig } from '../../../__helpers/shared/initPayloadE2ENoConfig.js'
 import { RESTClient } from '../../../__helpers/shared/rest.js'
 import { TEST_TIMEOUT_LONG } from '../../../playwright.config.js'
 import { conditionalLogicSlug } from '../../slugs.js'
@@ -287,4 +288,36 @@ describe('Conditional Logic', () => {
 
     await expect(fieldWithOperationCondition).toBeHidden()
   })
+
+  test('should toggle conditional field when radio changes inside a block', async () => {
+    await page.goto(url.create)
+
+    await addBlock({
+      page,
+      fieldName: 'blocksWithRadioCondition',
+      blockToSelect: 'Block With Radio Condition',
+    })
+
+    // Conditional field should be hidden (defaultValue: 'hide')
+    const conditionalField = page.locator(
+      '#field-blocksWithRadioCondition__0__conditionalTextField',
+    )
+    await expect(conditionalField).toBeHidden()
+
+    // Click "Show" radio and wait for form state response
+    const showRadio = page.locator('label:has(input[id*="radioTrigger-show"])')
+    await showRadio.click()
+
+    await expect(async () => {
+      await expect(conditionalField).toBeVisible()
+    }).toPass()
+
+    // Click "Hide" radio
+    const hideRadio = page.locator('label:has(input[id*="radioTrigger-hide"])')
+    await hideRadio.click()
+
+    await expect(async () => {
+      await expect(conditionalField).toBeHidden()
+    }).toPass()
+  })
 })

test/fields/collections/ConditionalLogic/index.ts

@@ -202,6 +202,35 @@ const ConditionalLogic: CollectionConfig = {
         },
       ],
     },
+    {
+      name: 'blocksWithRadioCondition',
+      type: 'blocks',
+      blocks: [
+        {
+          slug: 'blockWithRadioCondition',
+          dbName: 'bRadioCon',
+          fields: [
+            {
+              dbName: 'rTrig',
+              name: 'radioTrigger',
+              type: 'radio',
+              defaultValue: 'hide',
+              options: [
+                { label: 'Show', value: 'show' },
+                { label: 'Hide', value: 'hide' },
+              ],
+            },
+            {
+              name: 'conditionalTextField',
+              type: 'text',
+              admin: {
+                condition: (_data, siblingData) => siblingData?.radioTrigger === 'show',
+              },
+            },
+          ],
+        },
+      ],
+    },
     {
       name: 'arrayOne',
       type: 'array',