diff --git a/ts/deck-options/index.ts b/ts/deck-options/index.ts
index ee406ead2..bb625b592 100644
--- a/ts/deck-options/index.ts
+++ b/ts/deck-options/index.ts
@@ -5,7 +5,7 @@
 @typescript-eslint/no-explicit-any: "off",
  */
 
-import "sveltelib/export-internal";
+import "sveltelib/export-runtime";
 
 import { getDeckOptionsInfo, DeckOptionsState } from "./lib";
 import { setupI18n, ModuleName } from "lib/i18n";
diff --git a/ts/editor/index.ts b/ts/editor/index.ts
index 7d39aad78..0e269d76b 100644
--- a/ts/editor/index.ts
+++ b/ts/editor/index.ts
@@ -6,7 +6,7 @@
 @typescript-eslint/no-explicit-any: "off",
  */
 
-import "sveltelib/export-internal";
+import "sveltelib/export-runtime";
 
 import { filterHTML } from "html-filter";
 import { updateActiveButtons } from "./toolbar";
diff --git a/ts/lib/runtime-require.ts b/ts/lib/runtime-require.ts
new file mode 100644
index 000000000..336b0270c
--- /dev/null
+++ b/ts/lib/runtime-require.ts
@@ -0,0 +1,19 @@
+// Copyright: Ankitects Pty Ltd and contributors
+// License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
+
+/* eslint
+@typescript-eslint/no-explicit-any: "off",
+ */
+
+/// This can be extended to allow require() calls at runtime, for libraries
+/// that are not included at bundling time.
+export const runtimeLibraries = {};
+
+// Export require() as a global.
+(globalThis as any).require = function (name: string): unknown {
+    const lib = runtimeLibraries[name];
+    if (lib === undefined) {
+        throw new Error(`Cannot require(${name}) at runtime.`);
+    }
+    return lib;
+};
diff --git a/ts/sveltelib/BUILD.bazel b/ts/sveltelib/BUILD.bazel
index 60cbfd715..0803416df 100644
--- a/ts/sveltelib/BUILD.bazel
+++ b/ts/sveltelib/BUILD.bazel
@@ -13,6 +13,7 @@ ts_library(
     tsconfig = "//:tsconfig.json",
     visibility = ["//visibility:public"],
     deps = [
+        "//ts/lib",
         "@npm//svelte",
         "@npm//tslib",
     ],
diff --git a/ts/sveltelib/export-internal.ts b/ts/sveltelib/export-internal.ts
deleted file mode 100644
index c83b80520..000000000
--- a/ts/sveltelib/export-internal.ts
+++ /dev/null
@@ -1,6 +0,0 @@
-// Copyright: Ankitects Pty Ltd and contributors
-// License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
-
-// allow Svelte add-ons
-import * as svelte_internal from "svelte/internal";
-window["svelte_internal"] = svelte_internal;
diff --git a/ts/sveltelib/export-runtime.ts b/ts/sveltelib/export-runtime.ts
new file mode 100644
index 000000000..f8ffeddcd
--- /dev/null
+++ b/ts/sveltelib/export-runtime.ts
@@ -0,0 +1,11 @@
+// Copyright: Ankitects Pty Ltd and contributors
+// License: GNU AGPL, version 3 or later; http://www.gnu.org/licenses/agpl.html
+//
+// Expose the Svelte runtime bundled with Anki, so that add-ons can require() it.
+// If they were to bundle their own runtime, things like bindings and contexts
+// would not work.
+
+import { runtimeLibraries } from "lib/runtime-require";
+import * as svelteRuntime from "svelte/internal";
+
+runtimeLibraries["svelte/internal"] = svelteRuntime;