From 041217ca3367e28ce7bdbfd8e3708a186c6efee8 Mon Sep 17 00:00:00 2001
From: Mats Bosson <mats.bosson@gmail.com>
Date: Sun, 29 Mar 2026 07:23:19 +0700
Subject: [PATCH] Fix Checkbox indeterminate state

---
 .../core/src/components/checkbox/checkbox.tsx | 23 ++++++++-----------
 .../primitives/create-controllable-signal.ts  |  2 +-
 2 files changed, 10 insertions(+), 15 deletions(-)

diff --git a/packages/core/src/components/checkbox/checkbox.tsx b/packages/core/src/components/checkbox/checkbox.tsx
index 9e46e39..d698fe8 100644
--- a/packages/core/src/components/checkbox/checkbox.tsx
+++ b/packages/core/src/components/checkbox/checkbox.tsx
@@ -1,5 +1,5 @@
 import type { JSX } from "solid-js";
-import { splitProps } from "solid-js";
+import { createEffect, splitProps } from "solid-js";
 import { createControllableSignal } from "../../primitives/create-controllable-signal";
 
 /** Represents all three states a checkbox can be in. */
@@ -37,18 +37,11 @@ export function Checkbox(props: CheckboxProps): JSX.Element {
     "children",
   ]);
 
-  const [isChecked, setChecked] = createControllableSignal<CheckedState>(
-    local.onCheckedChange
-      ? {
-          value: () => local.checked,
-          defaultValue: () => local.defaultChecked ?? false,
-          onChange: local.onCheckedChange,
-        }
-      : {
-          value: () => local.checked,
-          defaultValue: () => local.defaultChecked ?? false,
-        },
-  );
+  const [isChecked, setChecked] = createControllableSignal<CheckedState>({
+    value: () => local.checked,
+    defaultValue: () => local.defaultChecked ?? false,
+    onChange: local.onCheckedChange,
+  });
 
   const ariaChecked = (): boolean | "mixed" => {
     const c = isChecked();
@@ -87,7 +80,9 @@ export function Checkbox(props: CheckboxProps): JSX.Element {
           value={local.value ?? "on"}
           checked={isChecked() === true}
           ref={(el) => {
-            if (el) el.indeterminate = isChecked() === "indeterminate";
+            createEffect(() => {
+              el.indeterminate = isChecked() === "indeterminate";
+            });
           }}
           style={{ display: "none" }}
         />
diff --git a/packages/core/src/primitives/create-controllable-signal.ts b/packages/core/src/primitives/create-controllable-signal.ts
index 71fd9ab..a36b39f 100644
--- a/packages/core/src/primitives/create-controllable-signal.ts
+++ b/packages/core/src/primitives/create-controllable-signal.ts
@@ -6,7 +6,7 @@ export interface CreateControllableSignalOptions<T> {
   /** Default value used when uncontrolled. Only read once at creation time — not reactive after mount. */
   defaultValue: Accessor<T>;
   /** Called whenever the value changes (both modes). */
-  onChange?: (value: T) => void;
+  onChange?: ((value: T) => void) | undefined;
 }
 
 /**