diff --git a/apps/webapp/app/components/primitives/Dialog.tsx b/apps/webapp/app/components/primitives/Dialog.tsx
index 3a7666eb80..b62bb01f22 100644
--- a/apps/webapp/app/components/primitives/Dialog.tsx
+++ b/apps/webapp/app/components/primitives/Dialog.tsx
@@ -3,8 +3,7 @@
 import * as React from "react";
 import * as DialogPrimitive from "@radix-ui/react-dialog";
 import { cn } from "~/utils/cn";
-import { XMarkIcon } from "@heroicons/react/24/solid";
-import { ShortcutKey } from "./ShortcutKey";
+import { ModalCloseButton } from "./ModalCloseButton";
 
 const Dialog = DialogPrimitive.Root;
 
@@ -56,18 +55,10 @@ const DialogContent = React.forwardRef<
     >
       <hr className="absolute left-0 top-11 w-full" />
       {children}
-      {showCloseButton && (
-        <DialogPrimitive.Close className="data-[state=open]:bg-accent data-[state=open]:text-muted-foreground group absolute right-2 top-2.25 flex items-center gap-1 rounded-sm p-1 py-1 pl-0 pr-1 opacity-70 transition focus-custom hover:bg-background-hover hover:opacity-100 focus-visible:focus-custom disabled:pointer-events-none">
-          <ShortcutKey
-            shortcut={{
-              key: "esc",
-            }}
-            variant="medium"
-          />
-          <XMarkIcon className="size-4 text-text-dimmed transition group-hover:text-text-bright" />
-          <span className="sr-only">Close</span>
-        </DialogPrimitive.Close>
-      )}
+      {/* The default size-7 is the height this button had when it rendered the esc key alongside the
+          icon, so the vertical geometry dialogs align against (the top-11 divider, absolutely
+          positioned titles) is unchanged — it only gets narrower. */}
+      {showCloseButton && <ModalCloseButton className="absolute right-2 top-2.25" />}
     </DialogPrimitive.Content>
   </DialogPortal>
 ));
diff --git a/apps/webapp/app/components/primitives/ModalCloseButton.tsx b/apps/webapp/app/components/primitives/ModalCloseButton.tsx
new file mode 100644
index 0000000000..8827a702e4
--- /dev/null
+++ b/apps/webapp/app/components/primitives/ModalCloseButton.tsx
@@ -0,0 +1,58 @@
+import * as DialogPrimitive from "@radix-ui/react-dialog";
+import * as React from "react";
+import { CrossIcon } from "~/assets/icons/CrossIcon";
+import { cn } from "~/utils/cn";
+import { ShortcutKey } from "./ShortcutKey";
+import { Tooltip, TooltipContent, TooltipProvider, TooltipTrigger } from "./Tooltip";
+
+const CLOSE_TOOLTIP_DELAY_MS = 500;
+
+/**
+ * The close button for modal surfaces — Dialog and Sheet, which are both Radix Dialog underneath.
+ * Pass `className` to position it, and to override the default `size-7` box where a surface needs
+ * to keep a tighter header height.
+ */
+export function ModalCloseButton({ className }: { className?: string }) {
+  const [open, setOpen] = React.useState(false);
+  const openTimeout = React.useRef<ReturnType<typeof setTimeout>>();
+
+  const cancelOpen = () => clearTimeout(openTimeout.current);
+  React.useEffect(() => cancelOpen, []);
+
+  const close = () => {
+    cancelOpen();
+    setOpen(false);
+  };
+
+  return (
+    <TooltipProvider>
+      {/* The tooltip is driven by our own hover timer rather than Radix's: Radix opens tooltips
+          instantly on focus, and these surfaces autofocus this button whenever they hold no other
+          tabbable content, which would pop the tooltip open on mount and leave it there.
+          Radix-initiated opens are ignored; its closes (pointer leave, blur, click) are honoured. */}
+      <Tooltip open={open} onOpenChange={(nextOpen) => !nextOpen && close()}>
+        <TooltipTrigger asChild>
+          <DialogPrimitive.Close
+            onPointerEnter={(event) => {
+              if (event.pointerType === "touch") return;
+              cancelOpen();
+              openTimeout.current = setTimeout(() => setOpen(true), CLOSE_TOOLTIP_DELAY_MS);
+            }}
+            onPointerLeave={close}
+            className={cn(
+              "group flex size-7 items-center justify-center rounded-sm opacity-70 transition focus-custom hover:bg-background-hover hover:opacity-100 focus-visible:focus-custom disabled:pointer-events-none",
+              className
+            )}
+          >
+            <CrossIcon className="size-4 text-text-dimmed transition group-hover:text-text-bright" />
+            <span className="sr-only">Close</span>
+          </DialogPrimitive.Close>
+        </TooltipTrigger>
+        <TooltipContent className="flex items-center py-1.5 pl-2.5 pr-2 text-xs text-text-bright">
+          Close
+          <ShortcutKey shortcut={{ key: "esc" }} variant="medium" />
+        </TooltipContent>
+      </Tooltip>
+    </TooltipProvider>
+  );
+}
diff --git a/apps/webapp/app/components/primitives/SheetV3.tsx b/apps/webapp/app/components/primitives/SheetV3.tsx
index 922f28d5ba..5bfc14285e 100644
--- a/apps/webapp/app/components/primitives/SheetV3.tsx
+++ b/apps/webapp/app/components/primitives/SheetV3.tsx
@@ -1,9 +1,8 @@
-import { XMarkIcon } from "@heroicons/react/20/solid";
 import * as SheetPrimitive from "@radix-ui/react-dialog";
 import { cva, type VariantProps } from "class-variance-authority";
 import * as React from "react";
 import { cn } from "~/utils/cn";
-import { ShortcutKey } from "./ShortcutKey";
+import { ModalCloseButton } from "./ModalCloseButton";
 
 const Sheet = SheetPrimitive.Root;
 
@@ -91,11 +90,9 @@ const SheetTitle = React.forwardRef<
     {...props}
   >
     {children}
-    <SheetPrimitive.Close className="flex items-center gap-1 rounded-sm p-1 pl-0 transition hover:bg-background-hover focus-visible:focus-custom disabled:pointer-events-none">
-      <ShortcutKey shortcut={{ key: "esc" }} variant="small" />
-      <XMarkIcon className="size-4 text-text-dimmed" />
-      <span className="sr-only">Close</span>
-    </SheetPrimitive.Close>
+    {/* size-6 rather than the default size-7 keeps this header row at the height it had when the
+        button rendered the esc key alongside the icon — it only gets narrower. */}
+    <ModalCloseButton className="size-6" />
   </SheetPrimitive.Title>
 ));
 SheetTitle.displayName = SheetPrimitive.Title.displayName;