From 267637edd5d415c5065ee0d828031791f19e3d80 Mon Sep 17 00:00:00 2001
From: Valerii Strilets <valerii.strilets@gmail.com>
Date: Sun, 6 Sep 2026 09:54:22 +0300
Subject: [PATCH] fix: rehydrate Svelte PermixHydrate when state changes

PermixHydrate only hydrated once at init, so a new `state` prop (for
example after navigation) was ignored. React and Vue already re-hydrate
on prop change; Svelte now does the same via $effect.pre.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
---
 permix/src/svelte/PermixHydrate.svelte |  6 +++++-
 permix/src/svelte/components.test.ts   | 16 ++++++++++++++++
 2 files changed, 21 insertions(+), 1 deletion(-)

diff --git a/permix/src/svelte/PermixHydrate.svelte b/permix/src/svelte/PermixHydrate.svelte
index d98ac4bc..413c8579 100644
--- a/permix/src/svelte/PermixHydrate.svelte
+++ b/permix/src/svelte/PermixHydrate.svelte
@@ -8,7 +8,11 @@ const { state, children }: { state: DehydratedState<any>, children: Snippet } =
 
 const context = usePermixContext()
 
-untrack(() => context.permix.hydrate(state))
+// Hydrate before children render, and again whenever `state` changes.
+$effect.pre(() => {
+  const next = state
+  untrack(() => context.permix.hydrate(next))
+})
 </script>
 
 {@render children()}
diff --git a/permix/src/svelte/components.test.ts b/permix/src/svelte/components.test.ts
index a999f398..a7fe777d 100644
--- a/permix/src/svelte/components.test.ts
+++ b/permix/src/svelte/components.test.ts
@@ -35,6 +35,22 @@ describe('components', () => {
     expect(getByTestId('create')).toHaveTextContent('true')
   })
 
+  it('should rehydrate when state changes', async () => {
+    const permix = createPermix<{
+      post: ['create', 'read']
+    }>()
+
+    const { getByTestId, rerender } = render(HydrateApp, {
+      props: { permix, state: { post: { create: true, read: false } } },
+    })
+
+    expect(getByTestId('create')).toHaveTextContent('true')
+
+    await rerender({ permix, state: { post: { create: false, read: false } } })
+
+    expect(getByTestId('create')).toHaveTextContent('false')
+  })
+
   it('should work with Check component', () => {
     const permix = createPermix<{
       post: ['create']