diff --git a/apps/loopover-miner-ui/src/chat-rail.test.tsx b/apps/loopover-miner-ui/src/chat-rail.test.tsx
index 6290908b33..87b199a9e8 100644
--- a/apps/loopover-miner-ui/src/chat-rail.test.tsx
+++ b/apps/loopover-miner-ui/src/chat-rail.test.tsx
@@ -1,4 +1,5 @@
 import { fireEvent, render, screen } from "@testing-library/react";
+import * as React from "react";
 import { afterEach, describe, expect, it, vi } from "vitest";
 
 // The TanStack Router lib is not under test here — RootShell's own rail-state persistence is. Stub Link so the
@@ -14,6 +15,15 @@ vi.mock("@tanstack/react-router", async () => {
   };
 });
 
+// Stateful stub so the #7792 close/reopen test can assert in-rail React state survives the mobile sheet cycle
+// without standing up the real chat backend / streaming stack.
+vi.mock("./components/chat/conversation", () => ({
+  ChatConversation: () => {
+    const [draft, setDraft] = React.useState("");
+    return <input aria-label="chat draft" value={draft} onChange={(event) => setDraft(event.target.value)} />;
+  },
+}));
+
 import { ChatRail } from "./components/chat-rail";
 import { RootShell } from "./routes/__root";
 
@@ -81,6 +91,25 @@ describe("ChatRail (#6513)", () => {
     expect(screen.getByRole("dialog")).toBeTruthy(); // Sheet content
     expect(screen.queryByRole("complementary")).toBeNull(); // never the docked panel on mobile
   });
+
+  it("preserves chat draft state across a mobile sheet close/reopen cycle (#7792)", () => {
+    setViewport(400);
+    const onOpenChange = vi.fn();
+    const { rerender } = render(<ChatRail open onOpenChange={onOpenChange} />);
+
+    const draft = screen.getByRole("textbox", { name: /chat draft/i });
+    fireEvent.change(draft, { target: { value: "still typing…" } });
+    expect((draft as HTMLInputElement).value).toBe("still typing…");
+
+    // Close the sheet (same open=false transition accidental tap-outside / Escape / toggle would cause).
+    rerender(<ChatRail open={false} onOpenChange={onOpenChange} />);
+    // forceMount keeps the dialog content in the tree even while closed.
+    expect(screen.getByRole("dialog", { hidden: true })).toBeTruthy();
+
+    // Reopen — draft must still be there (RailBody never unmounted).
+    rerender(<ChatRail open onOpenChange={onOpenChange} />);
+    expect((screen.getByRole("textbox", { name: /chat draft/i }) as HTMLInputElement).value).toBe("still typing…");
+  });
 });
 
 describe("RootShell chat-rail integration (#6513)", () => {
diff --git a/apps/loopover-miner-ui/src/components/chat-rail.tsx b/apps/loopover-miner-ui/src/components/chat-rail.tsx
index 53e3b9494e..b92478c617 100644
--- a/apps/loopover-miner-ui/src/components/chat-rail.tsx
+++ b/apps/loopover-miner-ui/src/components/chat-rail.tsx
@@ -47,7 +47,10 @@ export function ChatRail({ open, onOpenChange }: ChatRailProps) {
           Chat
         </Button>
         <Sheet open={open} onOpenChange={onOpenChange}>
-          <SheetContent id={RAIL_PANEL_ID} side="right" className="w-[380px] p-0">
+          {/* forceMount: keep RailBody mounted when the sheet closes so chat state survives, matching the
+              desktop `<aside hidden={!open}>` contract (#7792). SheetContent already forwards unknown props
+              onto Radix Dialog.Content, which honors forceMount. */}
+          <SheetContent id={RAIL_PANEL_ID} side="right" className="w-[380px] p-0" forceMount>
             <SheetHeader className="sr-only">
               <SheetTitle>Chat</SheetTitle>
               <SheetDescription>Ask about this miner&rsquo;s local state.</SheetDescription>
diff --git a/packages/loopover-ui-kit/src/components/sheet.tsx b/packages/loopover-ui-kit/src/components/sheet.tsx
index 52b63177d9..bc8ed78c4b 100644
--- a/packages/loopover-ui-kit/src/components/sheet.tsx
+++ b/packages/loopover-ui-kit/src/components/sheet.tsx
@@ -57,10 +57,18 @@ interface SheetContentProps
 const SheetContent = React.forwardRef<
   React.ElementRef<typeof SheetPrimitive.Content>,
   SheetContentProps
->(({ side = "right", className, children, ...props }, ref) => (
-  <SheetPortal>
-    <SheetOverlay />
-    <SheetPrimitive.Content ref={ref} className={cn(sheetVariants({ side }), className)} {...props}>
+>(({ side = "right", className, children, forceMount, ...props }, ref) => (
+  // When callers pass forceMount (e.g. chat-rail mobile sheet, #7792), forward it to Portal + Overlay +
+  // Content together: Content-only forceMount is a no-op if Portal's Presence has already unmounted the
+  // subtree. Default (forceMount undefined) keeps the prior unmount-on-close behavior for every other sheet.
+  <SheetPortal forceMount={forceMount}>
+    <SheetOverlay forceMount={forceMount} />
+    <SheetPrimitive.Content
+      ref={ref}
+      forceMount={forceMount}
+      className={cn(sheetVariants({ side }), className)}
+      {...props}
+    >
       <SheetPrimitive.Close className="absolute right-4 top-4 rounded-sm opacity-70 ring-offset-background cursor-pointer transition-opacity hover:opacity-100 focus:outline-none focus:ring-2 focus:ring-ring focus:ring-offset-2 disabled:pointer-events-none data-[state=open]:bg-secondary">
         <X className="h-4 w-4" />
         <span className="sr-only">Close</span>
@@ -71,14 +79,29 @@ const SheetContent = React.forwardRef<
 ));
 SheetContent.displayName = SheetPrimitive.Content.displayName;
 
-const SheetHeader = ({ className, ...props }: React.HTMLAttributes<HTMLDivElement>) => (
-  <div className={cn("flex flex-col space-y-2 text-center sm:text-left", className)} {...props} />
+const SheetHeader = ({
+  className,
+  ...props
+}: React.HTMLAttributes<HTMLDivElement>) => (
+  <div
+    className={cn(
+      "flex flex-col space-y-2 text-center sm:text-left",
+      className,
+    )}
+    {...props}
+  />
 );
 SheetHeader.displayName = "SheetHeader";
 
-const SheetFooter = ({ className, ...props }: React.HTMLAttributes<HTMLDivElement>) => (
+const SheetFooter = ({
+  className,
+  ...props
+}: React.HTMLAttributes<HTMLDivElement>) => (
   <div
-    className={cn("flex flex-col-reverse sm:flex-row sm:justify-end sm:space-x-2", className)}
+    className={cn(
+      "flex flex-col-reverse sm:flex-row sm:justify-end sm:space-x-2",
+      className,
+    )}
     {...props}
   />
 );