diff --git a/apps/mana/apps/web/src/lib/data/crypto/aes.test.ts b/apps/mana/apps/web/src/lib/data/crypto/aes.test.ts
index 628db6739..04cb10c70 100644
--- a/apps/mana/apps/web/src/lib/data/crypto/aes.test.ts
+++ b/apps/mana/apps/web/src/lib/data/crypto/aes.test.ts
@@ -192,6 +192,9 @@ describe('KeyProvider', () => {
 				onChange() {
 					return () => {};
 				}
+				async waitForKey() {
+					return null;
+				}
 			})()
 		);
 		expect(getActiveKey()).toBe(null);
diff --git a/apps/mana/apps/web/src/lib/data/crypto/key-provider.ts b/apps/mana/apps/web/src/lib/data/crypto/key-provider.ts
index 00cc2d4c4..fa7979dd5 100644
--- a/apps/mana/apps/web/src/lib/data/crypto/key-provider.ts
+++ b/apps/mana/apps/web/src/lib/data/crypto/key-provider.ts
@@ -34,6 +34,14 @@ export interface KeyProvider {
 	/** Subscribe to lock/unlock transitions. Returns a dispose function.
 	 *  Listeners fire only on STATE CHANGES, not on every getKey call. */
 	onChange(listener: (unlocked: boolean) => void): () => void;
+
+	/** Resolves with the active key as soon as the vault is unlocked, or
+	 *  with `null` if the timeout expires first. Used by encryptRecord to
+	 *  ride out the boot-time race where the user clicks a mutation button
+	 *  while the layout's `vaultClient.unlock()` round-trip is still in
+	 *  flight. Implementations that can never unlock (NullKeyProvider)
+	 *  resolve immediately with `null`. */
+	waitForKey(timeoutMs: number): Promise<CryptoKey | null>;
 }
 
 // ─── NullKeyProvider — default ─────────────────────────────────
@@ -54,6 +62,11 @@ class NullKeyProvider implements KeyProvider {
 	onChange(): () => void {
 		return () => {};
 	}
+	async waitForKey(): Promise<null> {
+		// Null provider can never unlock — don't make callers wait the
+		// full timeout for a guaranteed-null answer.
+		return null;
+	}
 }
 
 // ─── MemoryKeyProvider — Phase 3 production path ───────────────
@@ -107,6 +120,26 @@ export class MemoryKeyProvider implements KeyProvider {
 			this.listeners.delete(listener);
 		};
 	}
+
+	waitForKey(timeoutMs: number): Promise<CryptoKey | null> {
+		if (this.key) return Promise.resolve(this.key);
+		return new Promise((resolve) => {
+			let settled = false;
+			const dispose = this.onChange((unlocked) => {
+				if (settled || !unlocked) return;
+				settled = true;
+				clearTimeout(timer);
+				dispose();
+				resolve(this.key);
+			});
+			const timer = setTimeout(() => {
+				if (settled) return;
+				settled = true;
+				dispose();
+				resolve(this.key); // null on miss
+			}, timeoutMs);
+		});
+	}
 }
 
 // ─── Module-level active provider ──────────────────────────────
@@ -128,6 +161,13 @@ export function getActiveKey(): CryptoKey | null {
 	return _activeProvider.getKey();
 }
 
+/** Convenience: waits up to `timeoutMs` (default 2s) for the vault to
+ *  unlock. Used by encryptRecord to ride out the boot-time race between
+ *  a user click and the layout's async vault unlock round-trip. */
+export function waitForActiveKey(timeoutMs: number = 2000): Promise<CryptoKey | null> {
+	return _activeProvider.waitForKey(timeoutMs);
+}
+
 /** Convenience: synchronous lock check. */
 export function isVaultUnlocked(): boolean {
 	return _activeProvider.isUnlocked();
diff --git a/apps/mana/apps/web/src/lib/data/crypto/record-helpers.test.ts b/apps/mana/apps/web/src/lib/data/crypto/record-helpers.test.ts
index 5af759d48..8e8a9406b 100644
--- a/apps/mana/apps/web/src/lib/data/crypto/record-helpers.test.ts
+++ b/apps/mana/apps/web/src/lib/data/crypto/record-helpers.test.ts
@@ -12,6 +12,7 @@ import { encryptRecord, decryptRecord, decryptRecords, VaultLockedError } from '
 import { generateMasterKey, isEncrypted } from './aes';
 import { MemoryKeyProvider, setKeyProvider } from './key-provider';
 import * as registry from './registry';
+import { setCurrentUserId } from '../current-user';
 
 let key: CryptoKey;
 let provider: MemoryKeyProvider;
@@ -24,6 +25,12 @@ beforeEach(async () => {
 	provider.setKey(key);
 	setKeyProvider(provider);
 
+	// encryptRecord silently skips when no user is signed in (guest
+	// mode falls back to plaintext writes; guest-migration re-encrypts
+	// on login). Stamp a fake user id so the encryption path actually
+	// runs in these tests.
+	setCurrentUserId('test-user');
+
 	// Pretend the notes table is enabled with title + body fields.
 	vi.spyOn(registry, 'getEncryptedFields').mockImplementation((tableName: string) => {
 		if (tableName === TEST_TABLE) return ['title', 'body'];
@@ -34,6 +41,7 @@ beforeEach(async () => {
 afterEach(() => {
 	vi.restoreAllMocks();
 	provider.setKey(null);
+	setCurrentUserId(null);
 });
 
 describe('encryptRecord', () => {
@@ -83,12 +91,20 @@ describe('encryptRecord', () => {
 	});
 
 	it('throws VaultLockedError when no key is available', async () => {
+		// encryptRecord waits ~2s for the boot-time unlock race before
+		// giving up. Use fake timers so this test doesn't actually idle
+		// for two seconds — flush the timer manually after kicking off
+		// the call.
+		vi.useFakeTimers();
 		provider.setKey(null);
 		const record = { id: 'n', title: 'secret', body: 'also secret' };
-		await expect(encryptRecord(TEST_TABLE, record)).rejects.toThrow(VaultLockedError);
+		const promise = encryptRecord(TEST_TABLE, record);
+		await vi.advanceTimersByTimeAsync(2500);
+		await expect(promise).rejects.toThrow(VaultLockedError);
 		// Record was not partially mutated
 		expect(record.title).toBe('secret');
 		expect(record.body).toBe('also secret');
+		vi.useRealTimers();
 	});
 
 	it('does not throw when the vault is locked but no fields need encryption', async () => {
diff --git a/apps/mana/apps/web/src/lib/data/crypto/record-helpers.ts b/apps/mana/apps/web/src/lib/data/crypto/record-helpers.ts
index 140e0afdd..cb5e236a2 100644
--- a/apps/mana/apps/web/src/lib/data/crypto/record-helpers.ts
+++ b/apps/mana/apps/web/src/lib/data/crypto/record-helpers.ts
@@ -34,8 +34,9 @@
  */
 
 import { wrapValue, unwrapValue, isEncrypted } from './aes';
-import { getActiveKey, isVaultUnlocked } from './key-provider';
+import { getActiveKey, isVaultUnlocked, waitForActiveKey } from './key-provider';
 import { getEncryptedFields } from './registry';
+import { getCurrentUserId } from '../current-user';
 
 /** Thrown by encryptRecord when no key is available. Module stores
  *  catch this to surface "vault locked" UI. */
@@ -80,7 +81,23 @@ export async function encryptRecord<T extends object>(tableName: string, record:
 	}
 	if (todo.length === 0) return record;
 
-	const key = getActiveKey();
+	// Guest mode: there is no auth token, so the server vault is
+	// unreachable by definition. Falling back to plaintext keeps the
+	// app usable for anonymous local-first writes — guestMigration.ts
+	// will encrypt these records as part of the guest → user re-stamp
+	// when the user eventually signs in. The compromise is documented
+	// in the data-layer audit; the alternative (refusing the write)
+	// hides the entire app behind a sign-up wall.
+	if (getCurrentUserId() === null) return record;
+
+	// Boot-time race: the layout's `vaultClient.unlock()` runs in the
+	// same tick as authStore.initialize(), so the very first user
+	// mutation can land before the network round-trip finishes. Wait a
+	// short window for the provider to flip before we give up — this
+	// converts a near-miss race into a transparent ~ms delay instead of
+	// a thrown VaultLockedError that the UI silently swallows.
+	let key = getActiveKey();
+	if (!key) key = await waitForActiveKey(2000);
 	if (!key) throw new VaultLockedError(tableName);
 
 	for (const field of todo) {
diff --git a/apps/mana/apps/web/src/lib/data/guest-migration.ts b/apps/mana/apps/web/src/lib/data/guest-migration.ts
index b2df98d02..c9eabfe95 100644
--- a/apps/mana/apps/web/src/lib/data/guest-migration.ts
+++ b/apps/mana/apps/web/src/lib/data/guest-migration.ts
@@ -20,10 +20,24 @@
  *   Deleting in guest mode is safe because nothing was ever pushed to the
  *   server: `_pendingChanges` is cleared as part of the migration too, so the
  *   delete is purely local and never reaches the sync layer.
+ *
+ * Encryption catch-up: while in guest mode, encryptRecord skips silently
+ * (no master key available, no auth token to fetch one). Records on
+ * encrypted tables therefore live as PLAINTEXT in IndexedDB until this
+ * migration runs. After login + vault unlock we walk the same set of
+ * records and re-encrypt the registry fields before re-inserting, so
+ * the post-migration state is indistinguishable from "user signed up
+ * first, then typed everything". The migration awaits the vault for up
+ * to 10 s — if it never opens we abort the migration and leave the
+ * guest data in place rather than re-inserting plaintext under the
+ * real user id.
  */
 
 import { db, SYNC_APP_MAP, FIELD_TIMESTAMPS_KEY } from './database';
 import { GUEST_USER_ID } from './current-user';
+import { encryptRecord } from './crypto/record-helpers';
+import { waitForActiveKey } from './crypto/key-provider';
+import { getEncryptedFields } from './crypto/registry';
 
 export interface GuestMigrationResult {
 	migratedRecords: number;
@@ -41,6 +55,19 @@ export async function migrateGuestDataToUser(newUserId: string): Promise<GuestMi
 		return { migratedRecords: 0, tablesTouched: 0 };
 	}
 
+	// Wait for the vault to unlock before we touch anything. The layout
+	// fires this migration and `vaultClient.unlock()` in the same
+	// effect run, so they race; if we re-insert plaintext under the
+	// real user id before the key arrives, those records would have to
+	// be re-encrypted by a follow-up pass that doesn't exist. Bail out
+	// instead — the guest data stays put and the user can retry by
+	// signing out and back in.
+	const key = await waitForActiveKey(10_000);
+	if (!key) {
+		console.warn('[mana] guest migration aborted: vault did not unlock in time');
+		return { migratedRecords: 0, tablesTouched: 0 };
+	}
+
 	// Drop any pending changes accumulated during guest mode — they were
 	// never pushed (no auth token) and reference the old guest userId. The
 	// re-inserts below will produce fresh pending changes that should NOT be
@@ -64,8 +91,17 @@ export async function migrateGuestDataToUser(newUserId: string): Promise<GuestMi
 			if (guestRecords.length === 0) continue;
 			tablesTouched++;
 
+			// Snapshot the encrypted-field allowlist once per table (null if
+			// the table is not in the registry or currently disabled).
+			const encryptedFields = getEncryptedFields(tableName);
+
 			// One transaction per table keeps the delete+add pair atomic and
 			// avoids leaving the table half-migrated if Dexie throws partway.
+			// Note: encryptRecord is async and uses Web Crypto, which is fine
+			// inside a Dexie 'rw' transaction as long as we don't await
+			// non-Dexie work between Dexie ops in a way that suspends the
+			// transaction. Each iteration awaits the encrypt BEFORE touching
+			// the table, then runs the delete+add pair back-to-back.
 			await db.transaction('rw', table, async () => {
 				for (const oldRecord of guestRecords) {
 					const record = oldRecord as Record<string, unknown>;
@@ -78,6 +114,18 @@ export async function migrateGuestDataToUser(newUserId: string): Promise<GuestMi
 					void _oldUser;
 					void _oldFt;
 
+					// Catch-up encryption: guest writes left these fields as
+					// plaintext because no key was available. Now that the
+					// vault is unlocked, encrypt them in place before the
+					// re-insert so the on-disk state matches a "logged in
+					// from the start" user. encryptRecord is a no-op for
+					// tables not in the registry, and idempotent for fields
+					// that are somehow already encrypted (e.g. partial
+					// migration retry after a crash).
+					if (encryptedFields) {
+						await encryptRecord(tableName, clean);
+					}
+
 					await table.delete(id);
 					await table.add({ ...clean, id });
 					migratedRecords++;
diff --git a/apps/mana/apps/web/src/lib/modules/cycles/ListView.svelte b/apps/mana/apps/web/src/lib/modules/cycles/ListView.svelte
index 56fe0fc2a..e789a4983 100644
--- a/apps/mana/apps/web/src/lib/modules/cycles/ListView.svelte
+++ b/apps/mana/apps/web/src/lib/modules/cycles/ListView.svelte
@@ -25,6 +25,8 @@
 	import CycleCalendar from './components/CycleCalendar.svelte';
 	import SymptomManager from './components/SymptomManager.svelte';
 	import type { ViewProps } from '$lib/app-registry';
+	import { toast } from '$lib/stores/toast.svelte';
+	import { VaultLockedError } from '$lib/data/crypto';
 
 	// eslint-disable-next-line @typescript-eslint/no-unused-vars
 	const _props: ViewProps = $props();
@@ -97,31 +99,47 @@
 		editingDate = todayIso;
 	}
 
+	/** Wraps logDay calls so a locked vault becomes a visible toast instead
+	 *  of a silent unhandled rejection. encryptRecord already waits up to
+	 *  ~2s for the boot-time unlock race, so reaching this catch means the
+	 *  vault is genuinely unavailable (auth/network failure on /me/encryption-vault). */
+	async function safeLogDay(payload: Parameters<typeof dayLogsStore.logDay>[0]) {
+		try {
+			await dayLogsStore.logDay(payload);
+		} catch (err) {
+			if (err instanceof VaultLockedError) {
+				toast.error('Vault gesperrt — bitte unter Einstellungen → Sicherheit entsperren.');
+				return;
+			}
+			throw err;
+		}
+	}
+
 	async function setFlow(flow: Flow) {
-		await dayLogsStore.logDay({ logDate: editingDate, flow });
+		await safeLogDay({ logDate: editingDate, flow });
 	}
 
 	async function setMood(mood: Mood) {
 		const next = selectedMood === mood ? null : mood;
-		await dayLogsStore.logDay({ logDate: editingDate, mood: next });
+		await safeLogDay({ logDate: editingDate, mood: next });
 	}
 
 	async function toggleSymptom(id: string) {
 		const has = selectedSymptoms.includes(id);
 		const next = has ? selectedSymptoms.filter((s) => s !== id) : [...selectedSymptoms, id];
-		await dayLogsStore.logDay({ logDate: editingDate, symptoms: next });
+		await safeLogDay({ logDate: editingDate, symptoms: next });
 	}
 
 	async function saveTemperature() {
 		const num = parseFloat(temperature);
-		await dayLogsStore.logDay({
+		await safeLogDay({
 			logDate: editingDate,
 			temperature: Number.isFinite(num) ? num : null,
 		});
 	}
 
 	async function saveNotes() {
-		await dayLogsStore.logDay({ logDate: editingDate, notes: notesText.trim() || null });
+		await safeLogDay({ logDate: editingDate, notes: notesText.trim() || null });
 	}
 
 	async function deleteEditingLog() {
@@ -138,7 +156,7 @@
 
 	async function startPeriodToday() {
 		await cyclesStore.createCycle({ startDate: todayIso });
-		await dayLogsStore.logDay({ logDate: todayIso, flow: 'medium' });
+		await safeLogDay({ logDate: todayIso, flow: 'medium' });
 		backToToday();
 	}