✨ Use a session to store key id

package.json

@@ -38,6 +38,7 @@
 		"@dicebear/collection": "^6.0.2",
 		"@dicebear/core": "^6.0.2",
 		"lodash": "^4.17.21",
-		"mongodb": "^5.1.0"
+		"mongodb": "^5.1.0",
+		"svelte-kit-cookie-session": "^3.4.1"
 	}
 }

src/app.d.ts

@@ -1,7 +1,21 @@
 // See https://kit.svelte.dev/docs/types#app
 // for information about these interfaces
+
+import type { KeyId } from '$lib/crypto';
+
+interface SessionData {
+	keyId?: KeyId;
+}
+
 declare global {
 	namespace App {
+		interface Locals {
+			session: import('svelte-kit-cookie-session').Session<SessionData>;
+		}
+
+		interface PageData {
+			session: SessionData;
+		}
 		// interface Error {}
 		// interface Locals {}
 		// interface PageData {}

src/hooks.server.ts

@@ -0,0 +1,5 @@
+import { handleSession } from 'svelte-kit-cookie-session';
+
+export const handle = handleSession({
+	secret: 'SOME_COMPLEX_SECRET_AT_LEAST_32_CHARS'
+});

src/routes/+page.server.ts

@@ -3,16 +3,28 @@ import client from '$lib/server/db';
 import type { KeyId } from '$lib/crypto';
 
 export const actions = {
-	default: async ({ request }) => {
+	default: async ({ request, locals }) => {
 		const formData = await request.formData();
-		const keyId = formData.get('key_id');
+		const keyId = formData.get('key_id') as KeyId | undefined;
 		const content = formData.get('encrypted_journal');
 		if (!keyId) {
 			throw new Error("No 'key_id' field in form data");
 		}
 		if (!content) {
 			throw new Error("No 'encrypted_journal' field in form data");
 		}
+		await locals.session.set({ keyId });
 		await client.store(keyId as KeyId, content.toString());
 	}
 } satisfies Actions;
+
+export const load = async ({ locals }) => {
+	const keyId = locals.session.data.keyId;
+	if (!keyId) {
+		return {};
+	}
+	const encryptedJournal = await client.get(keyId);
+	return {
+		encryptedJournal
+	};
+};

src/routes/+page.svelte

@@ -2,8 +2,14 @@
 	import { browser } from '$app/environment';
 	import keyPair from '$lib/stores/key-pair';
 	import { arrayBufferToBase64 } from '$lib/array-buffer';
-	import { journal, encryptedJournal } from '$lib/stores/journal';
+	import { journal, encryptedJournal, initJournalFromEncryptedContent } from '$lib/stores/journal';
 	import KeyPair from '../lib/key-pair.svelte';
+	import type { PageData } from './$types';
+
+	export let data: PageData;
+	$: if ($keyPair && data.encryptedJournal) {
+		initJournalFromEncryptedContent(data.encryptedJournal, $keyPair.privateKey);
+	}
 
 	$: base64EncodedJournal = browser
 		? arrayBufferToBase64($encryptedJournal.value || new ArrayBuffer(0))