From 1839e6335205bf2e857b77973bd2904abf81c4b9 Mon Sep 17 00:00:00 2001
From: Alexander Johansson <alexander@n1s.se>
Date: Tue, 24 Jun 2025 13:49:25 +0200
Subject: [PATCH 01/11] add test

---
 .../src/__tests__/hydration.test.tsx          | 52 +++++++++++++++++++
 1 file changed, 52 insertions(+)

diff --git a/packages/query-core/src/__tests__/hydration.test.tsx b/packages/query-core/src/__tests__/hydration.test.tsx
index 5582e9da16..1581bbaaf2 100644
--- a/packages/query-core/src/__tests__/hydration.test.tsx
+++ b/packages/query-core/src/__tests__/hydration.test.tsx
@@ -5,6 +5,8 @@ import { QueryCache } from '../queryCache'
 import { dehydrate, hydrate } from '../hydration'
 import { MutationCache } from '../mutationCache'
 import { executeMutation, mockOnlineManagerIsOnline } from './utils'
+import superjson from 'superjson'
+import assert from 'assert'
 
 describe('dehydration and rehydration', () => {
   beforeEach(() => {
@@ -40,6 +42,7 @@ describe('dehydration and rehydration', () => {
     await vi.waitFor(() =>
       queryClient.prefetchQuery({
         queryKey: ['null'],
+
         queryFn: () => sleep(0).then(() => null),
       }),
     )
@@ -1402,4 +1405,53 @@ describe('dehydration and rehydration', () => {
     clientQueryClient.clear()
     serverQueryClient.clear()
   })
+
+  // https://github.com/TanStack/query/issues/6802
+  test('should serialize and deserialize query keys', async () => {
+    const createQueryClient = () =>
+      new QueryClient({
+        defaultOptions: {
+          dehydrate: {
+            serializeData: superjson.serialize,
+          },
+          hydrate: {
+            deserializeData: superjson.deserialize,
+          },
+        },
+      })
+
+    const getFirstEntry = (client: QueryClient) => {
+      const [entry] = client.getQueryCache().getAll()
+      assert(entry, 'cache should not be empty')
+      return entry
+    }
+
+    const serverClient = createQueryClient()
+
+    const date = new Date('2024-01-01T00:00:00.000Z')
+
+    serverClient.setQueryData(['date', date], {
+      date,
+    })
+
+    const serverEntry = getFirstEntry(serverClient)
+
+    // use JSON.parse(JSON.stringify()) to mock a http roundtrip
+    const dehydrated = JSON.parse(JSON.stringify(dehydrate(serverClient)))
+
+    const frontendClient = createQueryClient()
+
+    hydrate(frontendClient, dehydrated)
+
+    const clientEntry = getFirstEntry(frontendClient)
+    
+    
+
+    expect(clientEntry).toMatchObject(serverEntry)
+
+    
+    expect(clientEntry.queryKey).toEqual(serverEntry.queryKey)
+    expect(clientEntry.queryHash).toEqual(serverEntry.queryHash)
+    
+  })
 })

From b02a871c2588425a08729859e6b3ddfcaf98dda4 Mon Sep 17 00:00:00 2001
From: Alexander Johansson <alexander@n1s.se>
Date: Tue, 24 Jun 2025 13:51:15 +0200
Subject: [PATCH 02/11] meep

---
 packages/query-core/package.json                     | 3 ++-
 packages/query-core/src/__tests__/hydration.test.tsx | 5 -----
 packages/query-core/src/hydration.ts                 | 9 ++++++---
 pnpm-lock.yaml                                       | 4 ++++
 4 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/packages/query-core/package.json b/packages/query-core/package.json
index 0a588ee9ac..30d9ccf7e7 100644
--- a/packages/query-core/package.json
+++ b/packages/query-core/package.json
@@ -60,6 +60,7 @@
   ],
   "devDependencies": {
     "@tanstack/query-test-utils": "workspace:*",
-    "npm-run-all2": "^5.0.0"
+    "npm-run-all2": "^5.0.0",
+    "superjson": "^2.2.1"
   }
 }
diff --git a/packages/query-core/src/__tests__/hydration.test.tsx b/packages/query-core/src/__tests__/hydration.test.tsx
index 1581bbaaf2..f97c3f02a0 100644
--- a/packages/query-core/src/__tests__/hydration.test.tsx
+++ b/packages/query-core/src/__tests__/hydration.test.tsx
@@ -1406,7 +1406,6 @@ describe('dehydration and rehydration', () => {
     serverQueryClient.clear()
   })
 
-  // https://github.com/TanStack/query/issues/6802
   test('should serialize and deserialize query keys', async () => {
     const createQueryClient = () =>
       new QueryClient({
@@ -1444,14 +1443,10 @@ describe('dehydration and rehydration', () => {
     hydrate(frontendClient, dehydrated)
 
     const clientEntry = getFirstEntry(frontendClient)
-    
-    
 
     expect(clientEntry).toMatchObject(serverEntry)
 
-    
     expect(clientEntry.queryKey).toEqual(serverEntry.queryKey)
     expect(clientEntry.queryHash).toEqual(serverEntry.queryHash)
-    
   })
 })
diff --git a/packages/query-core/src/hydration.ts b/packages/query-core/src/hydration.ts
index 1361036d86..2bba1bd9a7 100644
--- a/packages/query-core/src/hydration.ts
+++ b/packages/query-core/src/hydration.ts
@@ -86,7 +86,7 @@ function dehydrateQuery(
         data: serializeData(query.state.data),
       }),
     },
-    queryKey: query.queryKey,
+    queryKey: serializeData(query.queryKey),
     queryHash: query.queryHash,
     ...(query.state.status === 'pending' && {
       promise: query.promise?.then(serializeData).catch((error) => {
@@ -196,10 +196,13 @@ export function hydrate(
   })
 
   queries.forEach(
-    ({ queryKey, state, queryHash, meta, promise, dehydratedAt }) => {
+    (nextQuery) => {
+      const { state, queryHash, meta, promise, dehydratedAt } = nextQuery
+      
       const syncData = promise ? tryResolveSync(promise) : undefined
       const rawData = state.data === undefined ? syncData?.data : state.data
       const data = rawData === undefined ? rawData : deserializeData(rawData)
+      const newQueryKey = deserializeData(nextQuery.queryKey)
 
       let query = queryCache.get(queryHash)
       const existingQueryIsPending = query?.state.status === 'pending'
@@ -232,7 +235,7 @@ export function hydrate(
           {
             ...client.getDefaultOptions().hydrate?.queries,
             ...options?.defaultOptions?.queries,
-            queryKey,
+            queryKey: newQueryKey,
             queryHash,
             meta,
           },
diff --git a/pnpm-lock.yaml b/pnpm-lock.yaml
index 839f124ba0..0f6a497ed5 100644
--- a/pnpm-lock.yaml
+++ b/pnpm-lock.yaml
@@ -2452,6 +2452,9 @@ importers:
       npm-run-all2:
         specifier: ^5.0.0
         version: 5.0.2
+      superjson:
+        specifier: ^2.2.1
+        version: 2.2.1
 
   packages/query-devtools:
     devDependencies:
@@ -7831,6 +7834,7 @@ packages:
 
   '@vercel/edge@1.2.1':
     resolution: {integrity: sha512-1++yncEyIAi68D3UEOlytYb1IUcIulMWdoSzX2h9LuSeeyR7JtaIgR8DcTQ6+DmYOQn+5MCh6LY+UmK6QBByNA==}
+    deprecated: This package is deprecated. You should to use `@vercel/functions` instead.
 
   '@vercel/nft@0.29.2':
     resolution: {integrity: sha512-A/Si4mrTkQqJ6EXJKv5EYCDQ3NL6nJXxG8VGXePsaiQigsomHYQC9xSpX8qGk7AEZk4b1ssbYIqJ0ISQQ7bfcA==}

From 76b1375d04ad96062d2e4f085e407765cd155f01 Mon Sep 17 00:00:00 2001
From: Alexander Johansson <alexander@n1s.se>
Date: Tue, 24 Jun 2025 13:56:29 +0200
Subject: [PATCH 03/11] tweak

---
 packages/query-core/src/hydration.ts | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/query-core/src/hydration.ts b/packages/query-core/src/hydration.ts
index 2bba1bd9a7..d81565f8d2 100644
--- a/packages/query-core/src/hydration.ts
+++ b/packages/query-core/src/hydration.ts
@@ -202,7 +202,7 @@ export function hydrate(
       const syncData = promise ? tryResolveSync(promise) : undefined
       const rawData = state.data === undefined ? syncData?.data : state.data
       const data = rawData === undefined ? rawData : deserializeData(rawData)
-      const newQueryKey = deserializeData(nextQuery.queryKey)
+      const queryKey = deserializeData(nextQuery.queryKey)
 
       let query = queryCache.get(queryHash)
       const existingQueryIsPending = query?.state.status === 'pending'
@@ -235,7 +235,7 @@ export function hydrate(
           {
             ...client.getDefaultOptions().hydrate?.queries,
             ...options?.defaultOptions?.queries,
-            queryKey: newQueryKey,
+            queryKey: queryKey,
             queryHash,
             meta,
           },

From af0efb275d52824dc1fa611a1b6ad87c753d862f Mon Sep 17 00:00:00 2001
From: Alexander Johansson <alexander@n1s.se>
Date: Tue, 24 Jun 2025 13:57:25 +0200
Subject: [PATCH 04/11] tweak

---
 packages/query-core/src/hydration.ts | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/packages/query-core/src/hydration.ts b/packages/query-core/src/hydration.ts
index d81565f8d2..e881d6c8c1 100644
--- a/packages/query-core/src/hydration.ts
+++ b/packages/query-core/src/hydration.ts
@@ -235,7 +235,7 @@ export function hydrate(
           {
             ...client.getDefaultOptions().hydrate?.queries,
             ...options?.defaultOptions?.queries,
-            queryKey: queryKey,
+            queryKey,
             queryHash,
             meta,
           },

From 448de0264ede5cd16a145940481bc78e3f558c7c Mon Sep 17 00:00:00 2001
From: "autofix-ci[bot]" <114827586+autofix-ci[bot]@users.noreply.github.com>
Date: Tue, 24 Jun 2025 11:58:50 +0000
Subject: [PATCH 05/11] ci: apply automated fixes

---
 packages/query-core/src/hydration.ts | 133 +++++++++++++--------------
 1 file changed, 64 insertions(+), 69 deletions(-)

diff --git a/packages/query-core/src/hydration.ts b/packages/query-core/src/hydration.ts
index e881d6c8c1..2ad2d22e1f 100644
--- a/packages/query-core/src/hydration.ts
+++ b/packages/query-core/src/hydration.ts
@@ -195,78 +195,73 @@ export function hydrate(
     )
   })
 
-  queries.forEach(
-    (nextQuery) => {
-      const { state, queryHash, meta, promise, dehydratedAt } = nextQuery
-      
-      const syncData = promise ? tryResolveSync(promise) : undefined
-      const rawData = state.data === undefined ? syncData?.data : state.data
-      const data = rawData === undefined ? rawData : deserializeData(rawData)
-      const queryKey = deserializeData(nextQuery.queryKey)
+  queries.forEach((nextQuery) => {
+    const { state, queryHash, meta, promise, dehydratedAt } = nextQuery
 
-      let query = queryCache.get(queryHash)
-      const existingQueryIsPending = query?.state.status === 'pending'
-      const existingQueryIsFetching = query?.state.fetchStatus === 'fetching'
+    const syncData = promise ? tryResolveSync(promise) : undefined
+    const rawData = state.data === undefined ? syncData?.data : state.data
+    const data = rawData === undefined ? rawData : deserializeData(rawData)
+    const queryKey = deserializeData(nextQuery.queryKey)
 
-      // Do not hydrate if an existing query exists with newer data
-      if (query) {
-        const hasNewerSyncData =
-          syncData &&
-          // We only need this undefined check to handle older dehydration
-          // payloads that might not have dehydratedAt
-          dehydratedAt !== undefined &&
-          dehydratedAt > query.state.dataUpdatedAt
-        if (
-          state.dataUpdatedAt > query.state.dataUpdatedAt ||
-          hasNewerSyncData
-        ) {
-          // omit fetchStatus from dehydrated state
-          // so that query stays in its current fetchStatus
-          const { fetchStatus: _ignored, ...serializedState } = state
-          query.setState({
-            ...serializedState,
-            data,
-          })
-        }
-      } else {
-        // Restore query
-        query = queryCache.build(
-          client,
-          {
-            ...client.getDefaultOptions().hydrate?.queries,
-            ...options?.defaultOptions?.queries,
-            queryKey,
-            queryHash,
-            meta,
-          },
-          // Reset fetch status to idle to avoid
-          // query being stuck in fetching state upon hydration
-          {
-            ...state,
-            data,
-            fetchStatus: 'idle',
-            status: data !== undefined ? 'success' : state.status,
-          },
-        )
-      }
+    let query = queryCache.get(queryHash)
+    const existingQueryIsPending = query?.state.status === 'pending'
+    const existingQueryIsFetching = query?.state.fetchStatus === 'fetching'
 
-      if (
-        promise &&
-        !existingQueryIsPending &&
-        !existingQueryIsFetching &&
-        // Only hydrate if dehydration is newer than any existing data,
-        // this is always true for new queries
-        (dehydratedAt === undefined || dehydratedAt > query.state.dataUpdatedAt)
-      ) {
-        // This doesn't actually fetch - it just creates a retryer
-        // which will re-use the passed `initialPromise`
-        // Note that we need to call these even when data was synchronously
-        // available, as we still need to set up the retryer
-        void query.fetch(undefined, {
-          // RSC transformed promises are not thenable
-          initialPromise: Promise.resolve(promise).then(deserializeData),
+    // Do not hydrate if an existing query exists with newer data
+    if (query) {
+      const hasNewerSyncData =
+        syncData &&
+        // We only need this undefined check to handle older dehydration
+        // payloads that might not have dehydratedAt
+        dehydratedAt !== undefined &&
+        dehydratedAt > query.state.dataUpdatedAt
+      if (state.dataUpdatedAt > query.state.dataUpdatedAt || hasNewerSyncData) {
+        // omit fetchStatus from dehydrated state
+        // so that query stays in its current fetchStatus
+        const { fetchStatus: _ignored, ...serializedState } = state
+        query.setState({
+          ...serializedState,
+          data,
         })
       }
-    },
-  )
+    } else {
+      // Restore query
+      query = queryCache.build(
+        client,
+        {
+          ...client.getDefaultOptions().hydrate?.queries,
+          ...options?.defaultOptions?.queries,
+          queryKey,
+          queryHash,
+          meta,
+        },
+        // Reset fetch status to idle to avoid
+        // query being stuck in fetching state upon hydration
+        {
+          ...state,
+          data,
+          fetchStatus: 'idle',
+          status: data !== undefined ? 'success' : state.status,
+        },
+      )
+    }
+
+    if (
+      promise &&
+      !existingQueryIsPending &&
+      !existingQueryIsFetching &&
+      // Only hydrate if dehydration is newer than any existing data,
+      // this is always true for new queries
+      (dehydratedAt === undefined || dehydratedAt > query.state.dataUpdatedAt)
+    ) {
+      // This doesn't actually fetch - it just creates a retryer
+      // which will re-use the passed `initialPromise`
+      // Note that we need to call these even when data was synchronously
+      // available, as we still need to set up the retryer
+      void query.fetch(undefined, {
+        // RSC transformed promises are not thenable
+        initialPromise: Promise.resolve(promise).then(deserializeData),
+      })
+    }
+  })
 }

From 01c17fa6bec97a59139a6ddaac362c42ce5f3737 Mon Sep 17 00:00:00 2001
From: Alexander Johansson <alexander@n1s.se>
Date: Tue, 24 Jun 2025 13:58:47 +0200
Subject: [PATCH 06/11] fmt

---
 packages/query-core/src/__tests__/hydration.test.tsx | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/packages/query-core/src/__tests__/hydration.test.tsx b/packages/query-core/src/__tests__/hydration.test.tsx
index f97c3f02a0..77727ae1e0 100644
--- a/packages/query-core/src/__tests__/hydration.test.tsx
+++ b/packages/query-core/src/__tests__/hydration.test.tsx
@@ -1444,9 +1444,9 @@ describe('dehydration and rehydration', () => {
 
     const clientEntry = getFirstEntry(frontendClient)
 
-    expect(clientEntry).toMatchObject(serverEntry)
-
     expect(clientEntry.queryKey).toEqual(serverEntry.queryKey)
     expect(clientEntry.queryHash).toEqual(serverEntry.queryHash)
+
+    expect(clientEntry).toMatchObject(serverEntry)
   })
 })

From ec4b11a81d1885f5bc83d4a59e1e7b4866bb9fe0 Mon Sep 17 00:00:00 2001
From: Alexander Johansson <alexander@n1s.se>
Date: Tue, 24 Jun 2025 14:25:28 +0200
Subject: [PATCH 07/11] lint

---
 packages/query-core/src/__tests__/hydration.test.tsx | 6 +++---
 1 file changed, 3 insertions(+), 3 deletions(-)

diff --git a/packages/query-core/src/__tests__/hydration.test.tsx b/packages/query-core/src/__tests__/hydration.test.tsx
index 77727ae1e0..3d2b12854e 100644
--- a/packages/query-core/src/__tests__/hydration.test.tsx
+++ b/packages/query-core/src/__tests__/hydration.test.tsx
@@ -1,12 +1,12 @@
+import assert from 'node:assert'
 import { afterEach, beforeEach, describe, expect, test, vi } from 'vitest'
 import { sleep } from '@tanstack/query-test-utils'
+import superjson from 'superjson'
 import { QueryClient } from '../queryClient'
 import { QueryCache } from '../queryCache'
 import { dehydrate, hydrate } from '../hydration'
 import { MutationCache } from '../mutationCache'
 import { executeMutation, mockOnlineManagerIsOnline } from './utils'
-import superjson from 'superjson'
-import assert from 'assert'
 
 describe('dehydration and rehydration', () => {
   beforeEach(() => {
@@ -1406,7 +1406,7 @@ describe('dehydration and rehydration', () => {
     serverQueryClient.clear()
   })
 
-  test('should serialize and deserialize query keys', async () => {
+  test('should serialize and deserialize query keys', () => {
     const createQueryClient = () =>
       new QueryClient({
         defaultOptions: {

From 99bdd0bdda98e36c0717a48e38da4980b54577fd Mon Sep 17 00:00:00 2001
From: Alexander Johansson <alexander@n1s.se>
Date: Tue, 24 Jun 2025 14:32:04 +0200
Subject: [PATCH 08/11] mkay

---
 .../src/__tests__/hydration.test.tsx          | 20 +++++++++----------
 1 file changed, 10 insertions(+), 10 deletions(-)

diff --git a/packages/query-core/src/__tests__/hydration.test.tsx b/packages/query-core/src/__tests__/hydration.test.tsx
index 3d2b12854e..ccc77bc9eb 100644
--- a/packages/query-core/src/__tests__/hydration.test.tsx
+++ b/packages/query-core/src/__tests__/hydration.test.tsx
@@ -973,7 +973,7 @@ describe('dehydration and rehydration', () => {
       defaultOptions: {
         dehydrate: {
           shouldDehydrateQuery: () => true,
-          serializeData: (data) => data.toISOString(),
+          serializeData: superjson.serialize,
         },
       },
     })
@@ -988,7 +988,7 @@ describe('dehydration and rehydration', () => {
     const hydrationClient = new QueryClient({
       defaultOptions: {
         hydrate: {
-          deserializeData: (data) => new Date(data),
+          deserializeData: superjson.deserialize,
         },
       },
     })
@@ -1009,7 +1009,7 @@ describe('dehydration and rehydration', () => {
       defaultOptions: {
         dehydrate: {
           shouldDehydrateQuery: () => true,
-          serializeData: (data) => data.toISOString(),
+          serializeData: superjson.serialize,
         },
       },
     })
@@ -1024,7 +1024,7 @@ describe('dehydration and rehydration', () => {
     const hydrationClient = new QueryClient({
       defaultOptions: {
         hydrate: {
-          deserializeData: (data) => new Date(data),
+          deserializeData: superjson.deserialize,
         },
       },
     })
@@ -1044,7 +1044,7 @@ describe('dehydration and rehydration', () => {
     const hydrationClient = new QueryClient({
       defaultOptions: {
         hydrate: {
-          deserializeData: (data) => new Date(data),
+          deserializeData: superjson.deserialize,
         },
       },
     })
@@ -1062,7 +1062,7 @@ describe('dehydration and rehydration', () => {
       defaultOptions: {
         dehydrate: {
           shouldDehydrateQuery: () => true,
-          serializeData: (data) => data.toISOString(),
+          serializeData: superjson.serialize,
         },
       },
     })
@@ -1223,10 +1223,10 @@ describe('dehydration and rehydration', () => {
       expect(clientQueryClient.getQueryData(query.queryKey)).toBe(0),
     )
 
-    expect(serializeDataMock).toHaveBeenCalledTimes(1)
+    expect(serializeDataMock).toHaveBeenCalledTimes(2) // once for data, once for queryKey
     expect(serializeDataMock).toHaveBeenCalledWith(0)
 
-    expect(deserializeDataMock).toHaveBeenCalledTimes(1)
+    expect(deserializeDataMock).toHaveBeenCalledTimes(2) // once for data, once for queryKey
     expect(deserializeDataMock).toHaveBeenCalledWith(0)
 
     // --- server ---
@@ -1245,10 +1245,10 @@ describe('dehydration and rehydration', () => {
       expect(clientQueryClient.getQueryData(query.queryKey)).toBe(1),
     )
 
-    expect(serializeDataMock).toHaveBeenCalledTimes(2)
+    expect(serializeDataMock).toHaveBeenCalledTimes(4) // twice for data, twice for queryKey
     expect(serializeDataMock).toHaveBeenCalledWith(1)
 
-    expect(deserializeDataMock).toHaveBeenCalledTimes(2)
+    expect(deserializeDataMock).toHaveBeenCalledTimes(4) // twice for data, twice for queryKey
     expect(deserializeDataMock).toHaveBeenCalledWith(1)
 
     clientQueryClient.clear()

From 561ad589487bfa8bbf77e00eb6f4f9196b4a2d91 Mon Sep 17 00:00:00 2001
From: Alexander Johansson <alexander@n1s.se>
Date: Tue, 24 Jun 2025 14:33:34 +0200
Subject: [PATCH 09/11] rm

---
 .../src/__tests__/hydration.test.tsx          | 22 +------------------
 1 file changed, 1 insertion(+), 21 deletions(-)

diff --git a/packages/query-core/src/__tests__/hydration.test.tsx b/packages/query-core/src/__tests__/hydration.test.tsx
index ccc77bc9eb..fee4d89629 100644
--- a/packages/query-core/src/__tests__/hydration.test.tsx
+++ b/packages/query-core/src/__tests__/hydration.test.tsx
@@ -1180,8 +1180,6 @@ describe('dehydration and rehydration', () => {
   })
 
   test('should overwrite data when a new promise is streamed in', async () => {
-    const serializeDataMock = vi.fn((data: any) => data)
-    const deserializeDataMock = vi.fn((data: any) => data)
 
     const countRef = { current: 0 }
     // --- server ---
@@ -1189,7 +1187,6 @@ describe('dehydration and rehydration', () => {
       defaultOptions: {
         dehydrate: {
           shouldDehydrateQuery: () => true,
-          serializeData: serializeDataMock,
         },
       },
     })
@@ -1208,13 +1205,7 @@ describe('dehydration and rehydration', () => {
 
     // --- client ---
 
-    const clientQueryClient = new QueryClient({
-      defaultOptions: {
-        hydrate: {
-          deserializeData: deserializeDataMock,
-        },
-      },
-    })
+    const clientQueryClient = new QueryClient()
 
     hydrate(clientQueryClient, dehydrated)
 
@@ -1223,12 +1214,6 @@ describe('dehydration and rehydration', () => {
       expect(clientQueryClient.getQueryData(query.queryKey)).toBe(0),
     )
 
-    expect(serializeDataMock).toHaveBeenCalledTimes(2) // once for data, once for queryKey
-    expect(serializeDataMock).toHaveBeenCalledWith(0)
-
-    expect(deserializeDataMock).toHaveBeenCalledTimes(2) // once for data, once for queryKey
-    expect(deserializeDataMock).toHaveBeenCalledWith(0)
-
     // --- server ---
     countRef.current++
     serverQueryClient.clear()
@@ -1245,11 +1230,6 @@ describe('dehydration and rehydration', () => {
       expect(clientQueryClient.getQueryData(query.queryKey)).toBe(1),
     )
 
-    expect(serializeDataMock).toHaveBeenCalledTimes(4) // twice for data, twice for queryKey
-    expect(serializeDataMock).toHaveBeenCalledWith(1)
-
-    expect(deserializeDataMock).toHaveBeenCalledTimes(4) // twice for data, twice for queryKey
-    expect(deserializeDataMock).toHaveBeenCalledWith(1)
 
     clientQueryClient.clear()
     serverQueryClient.clear()

From 569d3a6020984553ce8a776b10b905cbf8156117 Mon Sep 17 00:00:00 2001
From: "autofix-ci[bot]" <114827586+autofix-ci[bot]@users.noreply.github.com>
Date: Tue, 24 Jun 2025 12:34:49 +0000
Subject: [PATCH 10/11] ci: apply automated fixes

---
 packages/query-core/src/__tests__/hydration.test.tsx | 2 --
 1 file changed, 2 deletions(-)

diff --git a/packages/query-core/src/__tests__/hydration.test.tsx b/packages/query-core/src/__tests__/hydration.test.tsx
index fee4d89629..7cb1d3ff9d 100644
--- a/packages/query-core/src/__tests__/hydration.test.tsx
+++ b/packages/query-core/src/__tests__/hydration.test.tsx
@@ -1180,7 +1180,6 @@ describe('dehydration and rehydration', () => {
   })
 
   test('should overwrite data when a new promise is streamed in', async () => {
-
     const countRef = { current: 0 }
     // --- server ---
     const serverQueryClient = new QueryClient({
@@ -1230,7 +1229,6 @@ describe('dehydration and rehydration', () => {
       expect(clientQueryClient.getQueryData(query.queryKey)).toBe(1),
     )
 
-
     clientQueryClient.clear()
     serverQueryClient.clear()
   })

From 73c4f1ad5f26b6f3a4f42222e0909e5d6b7601f9 Mon Sep 17 00:00:00 2001
From: Alexander Johansson <alexander@n1s.se>
Date: Wed, 25 Jun 2025 12:32:00 +0200
Subject: [PATCH 11/11] explicit

---
 .../query-core/src/__tests__/hydration.test.tsx    | 14 ++++++++------
 1 file changed, 8 insertions(+), 6 deletions(-)

diff --git a/packages/query-core/src/__tests__/hydration.test.tsx b/packages/query-core/src/__tests__/hydration.test.tsx
index 7cb1d3ff9d..02f0683970 100644
--- a/packages/query-core/src/__tests__/hydration.test.tsx
+++ b/packages/query-core/src/__tests__/hydration.test.tsx
@@ -1,11 +1,11 @@
 import assert from 'node:assert'
-import { afterEach, beforeEach, describe, expect, test, vi } from 'vitest'
 import { sleep } from '@tanstack/query-test-utils'
 import superjson from 'superjson'
-import { QueryClient } from '../queryClient'
-import { QueryCache } from '../queryCache'
+import { afterEach, beforeEach, describe, expect, test, vi } from 'vitest'
 import { dehydrate, hydrate } from '../hydration'
 import { MutationCache } from '../mutationCache'
+import { QueryCache } from '../queryCache'
+import { QueryClient } from '../queryClient'
 import { executeMutation, mockOnlineManagerIsOnline } from './utils'
 
 describe('dehydration and rehydration', () => {
@@ -1405,10 +1405,11 @@ describe('dehydration and rehydration', () => {
 
     const serverClient = createQueryClient()
 
-    const date = new Date('2024-01-01T00:00:00.000Z')
+    // Make a query key that isn't plain javascript object
+    const queryKey = ['date', new Date('2024-01-01T00:00:00.000Z')] as const
 
-    serverClient.setQueryData(['date', date], {
-      date,
+    serverClient.setQueryData(queryKey, {
+      foo: 'bar',
     })
 
     const serverEntry = getFirstEntry(serverClient)
@@ -1422,6 +1423,7 @@ describe('dehydration and rehydration', () => {
 
     const clientEntry = getFirstEntry(frontendClient)
 
+    expect(clientEntry.queryKey).toEqual(queryKey)
     expect(clientEntry.queryKey).toEqual(serverEntry.queryKey)
     expect(clientEntry.queryHash).toEqual(serverEntry.queryHash)