diff --git a/docs/ai/context/ui-components.md b/docs/ai/context/ui-components.md
index 072481e8b..ae924f957 100644
--- a/docs/ai/context/ui-components.md
+++ b/docs/ai/context/ui-components.md
@@ -114,11 +114,15 @@ surface, border, shape, or color styling.
 | `label` | `string?` | — | Button text |
 | `disabled` | `boolean?` | `false` | Disabled state |
 | `loading` | `boolean?` | `false` | Loading state |
-| `size` | `'sm' \| 'md' \| 'lg'` | `'md'` | Size |
+| `size` | `'sm' \| 'md' \| 'lg' \| 'unset'` | `'md'` | Preset size; `unset` leaves sizing to the caller |
 | `block` | `boolean?` | `false` | Full width |
 
 **Slots**: `default` (fallback when no `label`)
 
+`size="unset"` omits the preset padding and text-size classes in `BasicButton`,
+`Button`, and `GhostButton`. Callers must supply any required sizing, including
+fixed dimensions for circular buttons.
+
 ### Button
 
 Solid general-purpose action. It has no border and shows offset outlines on
diff --git a/packages/ui/src/components/misc/button.vue b/packages/ui/src/components/misc/button.vue
index 35939ece4..d24d3125c 100644
--- a/packages/ui/src/components/misc/button.vue
+++ b/packages/ui/src/components/misc/button.vue
@@ -24,6 +24,7 @@ const circleSizeClasses: Record<ButtonSize, string> = {
   sm: 'h-8 w-8',
   md: 'h-10 w-10',
   lg: 'h-12 w-12',
+  unset: '',
 }
 
 const colorClasses: Record<ButtonColor, Record<ButtonVariant, string[]>> = {
diff --git a/packages/ui/src/components/misc/ghost-button.vue b/packages/ui/src/components/misc/ghost-button.vue
index a2695e351..abcbfe339 100644
--- a/packages/ui/src/components/misc/ghost-button.vue
+++ b/packages/ui/src/components/misc/ghost-button.vue
@@ -19,6 +19,7 @@ const sizeClasses: Record<ButtonSize, string> = {
   sm: 'min-h-7 px-2! py-1! text-xs',
   md: 'min-h-8 px-3! py-1.5! text-sm',
   lg: 'min-h-10 px-4! py-2! text-base',
+  unset: '',
 }
 
 const basicProps = computed(() => ({