fix(preact): reuse the parent context by default in HydrationProvider, as React does

packages/preact/src/hydration.spec.tsx

@@ -8,11 +8,13 @@ import {
   act
 } from '@testing-library/preact'
 import {
+  type InjectionContext,
   signal,
   hydratable
 } from '@nano_kit/store'
 import {
   InjectionContextProvider,
+  useInjectionContext,
   useInject,
   useSignal
 } from './core.js'
@@ -36,6 +38,12 @@ function Test() {
   )
 }
 
+function Context({ contexts }: { contexts: (InjectionContext | undefined)[] }) {
+  contexts.push(useInjectionContext())
+
+  return null
+}
+
 describe('preact', () => {
   describe('hydration', () => {
     describe('HydrationProvider', () => {
@@ -86,6 +94,40 @@ describe('preact', () => {
 
         expect(container.innerHTML).toBe('<div>empty</div>')
       })
+
+      it('should reuse the parent hydration context by default', () => {
+        const contexts: (InjectionContext | undefined)[] = []
+
+        render(
+          <InjectionContextProvider>
+            <HydrationProvider>
+              <Context contexts={contexts}/>
+              <HydrationProvider>
+                <Context contexts={contexts}/>
+              </HydrationProvider>
+            </HydrationProvider>
+          </InjectionContextProvider>
+        )
+
+        expect(contexts[1]).toBe(contexts[0])
+      })
+
+      it('should create a child context when reuse is disabled', () => {
+        const contexts: (InjectionContext | undefined)[] = []
+
+        render(
+          <InjectionContextProvider>
+            <HydrationProvider>
+              <Context contexts={contexts}/>
+              <HydrationProvider reuse={false}>
+                <Context contexts={contexts}/>
+              </HydrationProvider>
+            </HydrationProvider>
+          </InjectionContextProvider>
+        )
+
+        expect(contexts[1]).not.toBe(contexts[0])
+      })
     })
 
     describe('StaticHydrationProvider', () => {

packages/preact/src/hydration.tsx

@@ -25,6 +25,7 @@ export interface HydrationProviderProps extends InjectionContextProps {
   context?: InjectionProvider[]
   /**
    * Whether to reuse an existing InjectionContext or create a new one.
+   * `true` by default.
    */
   reuse?: boolean
 }
@@ -36,7 +37,7 @@ export interface HydrationProviderProps extends InjectionContextProps {
 export function HydrationProvider({
   dehydrated,
   context = [],
-  reuse,
+  reuse = true,
   children
 }: HydrationProviderProps) {
   const currentContext = useInjectionContext()

website/src/content/docs/store-integrations/preact.mdx

@@ -169,7 +169,7 @@ function App({ dehydrated }) {
 Props:
 - `dehydrated?` — dehydrated key-value pairs `[string, unknown][]`, or a falsy value to skip hydration
 - `context?` — additional injection providers
-- `reuse?` — reuse an existing `InjectionContext` instead of creating a new one; set to `true` if you want the hydration context to be shared with the rest of your app instead of isolated
+- `reuse?` — reuse an existing `InjectionContext` instead of creating a new one; `true` by default
 
 #### `StaticHydrationProvider`