give each app its own page, preloading and session stores, using context

runtime/src/app/app.ts

@@ -1,7 +1,6 @@
 import { writable } from 'svelte/store.mjs';
 import App from '@sapper/internal/App.svelte';
-import { stores } from '@sapper/internal/shared';
-import { Root, root_preload, ErrorComponent, ignore, components, routes } from '@sapper/internal/manifest-client';
+import { root_preload, ErrorComponent, ignore, components, routes } from '@sapper/internal/manifest-client';
 import {
 	Target,
 	ScrollPosition,
@@ -24,12 +23,16 @@ let current_token: {};
 let root_preloaded: Promise<any>;
 let current_branch = [];
 
-const session = writable(initial_data && initial_data.session);
+const stores = {
+	page: writable({}),
+	preloading: writable(null),
+	session: writable(initial_data && initial_data.session)
+};
 
 let $session;
 let session_dirty: boolean;
 
-session.subscribe(async value => {
+stores.session.subscribe(async value => {
 	$session = value;
 
 	if (!ready) return;
@@ -216,7 +219,11 @@ async function render(redirect: Redirect, branch: any[], props: any, page: Page)
 	if (root_component) {
 		root_component.$set(props);
 	} else {
-		props.session = session;
+		props.stores = {
+			page: { subscribe: stores.page.subscribe },
+			preloading: { subscribe: stores.preloading.subscribe },
+			session: stores.session
+		};
 		props.level0 = {
 			props: await root_preloaded
 		};

runtime/src/app/index.ts

@@ -1,10 +1,7 @@
 import { getContext } from 'svelte';
-import { CONTEXT_KEY, stores } from '@sapper/internal/shared';
+import { CONTEXT_KEY } from '@sapper/internal/shared';
 
-export const preloading = { subscribe: stores.preloading.subscribe };
-export const page = { subscribe: stores.page.subscribe };
-
-export const getSession = () => getContext(CONTEXT_KEY);
+export const stores = () => getContext(CONTEXT_KEY);
 
 export { default as start } from './start/index';
 export { default as goto } from './goto/index';

runtime/src/server/middleware/get_page_handler.ts

@@ -204,10 +204,22 @@ export function get_page_handler(
 			});
 
 			const props = {
+				stores: {
+					page: {
+						subscribe: writable({
+							path: req.path,
+							query: req.query,
+							params
+						}).subscribe
+					},
+					preloading: {
+						subscribe: writable(null).subscribe
+					},
+					session: writable(session)
+				},
 				segments: layout_segments,
 				status: error ? status : 200,
 				error: error ? error instanceof Error ? error : { message: error } : null,
-				session: writable(session),
 				level0: {
 					props: preloaded[0]
 				},
@@ -231,12 +243,6 @@ export function get_page_handler(
 				}
 			}
 
-			stores.page.set({
-				path: req.path,
-				query: req.query,
-				params: params
-			});
-
 			const { html, head, css } = App.render(props);
 
 			const serialized = {