diff --git a/packages/ui/src/features/task-detail/BranchMismatchDialog.test.tsx b/packages/ui/src/features/task-detail/BranchMismatchDialog.test.tsx
new file mode 100644
index 0000000000..6c2d317ec2
--- /dev/null
+++ b/packages/ui/src/features/task-detail/BranchMismatchDialog.test.tsx
@@ -0,0 +1,77 @@
+import { Theme } from "@radix-ui/themes";
+import { render, screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { describe, expect, it, vi } from "vitest";
+import { BranchMismatchDialog } from "./BranchMismatchDialog";
+
+function renderDialog(
+  overrides?: Partial<Parameters<typeof BranchMismatchDialog>[0]>,
+) {
+  const handlers = {
+    onSwitch: vi.fn(),
+    onContinue: vi.fn(),
+    onCancel: vi.fn(),
+  };
+  render(
+    <Theme>
+      <BranchMismatchDialog
+        open
+        linkedBranch="feat/foo"
+        currentBranch="main"
+        hasUncommittedChanges={false}
+        switchError={null}
+        {...handlers}
+        {...overrides}
+      />
+    </Theme>,
+  );
+  return handlers;
+}
+
+describe("BranchMismatchDialog", () => {
+  // The Switch case is the regression: the button was wrapped in
+  // AlertDialog.Action, whose auto-close fired onOpenChange -> onCancel,
+  // discarding the pending message so it was never sent after the checkout
+  // succeeded.
+  it.each([
+    { button: "Switch branch", fires: "onSwitch" },
+    { button: "Continue anyway", fires: "onContinue" },
+    { button: "Cancel", fires: "onCancel" },
+  ] as const)(
+    "clicking $button fires $fires only",
+    async ({ button, fires }) => {
+      const user = userEvent.setup();
+      const handlers = renderDialog();
+
+      await user.click(screen.getByRole("button", { name: button }));
+
+      for (const [name, handler] of Object.entries(handlers)) {
+        expect(handler, name).toHaveBeenCalledTimes(name === fires ? 1 : 0);
+      }
+    },
+  );
+
+  it("Escape closes and fires onCancel when idle", async () => {
+    const user = userEvent.setup();
+    const { onCancel } = renderDialog();
+
+    await user.keyboard("{Escape}");
+
+    expect(onCancel).toHaveBeenCalledTimes(1);
+  });
+
+  it("Escape does not fire onCancel while switching", async () => {
+    const user = userEvent.setup();
+    const { onCancel } = renderDialog({ isSwitching: true });
+
+    await user.keyboard("{Escape}");
+
+    expect(onCancel).not.toHaveBeenCalled();
+  });
+
+  it("shows the switch error", () => {
+    renderDialog({ switchError: "dirty worktree" });
+
+    expect(screen.getByText("dirty worktree")).toBeInTheDocument();
+  });
+});
diff --git a/packages/ui/src/features/task-detail/BranchMismatchDialog.tsx b/packages/ui/src/features/task-detail/BranchMismatchDialog.tsx
index 23c5cb5b78..04b343cae1 100644
--- a/packages/ui/src/features/task-detail/BranchMismatchDialog.tsx
+++ b/packages/ui/src/features/task-detail/BranchMismatchDialog.tsx
@@ -55,7 +55,9 @@ export function BranchMismatchDialog({
     <AlertDialog.Root
       open={open}
       onOpenChange={(isOpen) => {
-        if (!isOpen) onCancel();
+        // While the checkout runs the dialog must stay up: onCancel discards
+        // the pending message the switch handler sends on success.
+        if (!isOpen && !isSwitching) onCancel();
       }}
     >
       <AlertDialog.Content maxWidth="420px" size="2">
@@ -116,16 +118,18 @@ export function BranchMismatchDialog({
             Continue anyway
           </Button>
 
-          <AlertDialog.Action>
-            <Button
-              variant="solid"
-              size="1"
-              onClick={onSwitch}
-              loading={isSwitching}
-            >
-              Switch branch
-            </Button>
-          </AlertDialog.Action>
+          {/* Not an AlertDialog.Action: Action closes the dialog on click,
+              which fires onOpenChange -> onCancel and discards the pending
+              message before the checkout finishes. The dialog closes (or
+              shows the error) when the mutation settles. */}
+          <Button
+            variant="solid"
+            size="1"
+            onClick={onSwitch}
+            loading={isSwitching}
+          >
+            Switch branch
+          </Button>
         </Flex>
       </AlertDialog.Content>
     </AlertDialog.Root>