diff --git a/src/lib/stores/debate-context-store.ts b/src/lib/stores/debate-context-store.ts
index ea743827d..874216127 100644
--- a/src/lib/stores/debate-context-store.ts
+++ b/src/lib/stores/debate-context-store.ts
@@ -1,5 +1,6 @@
 import { create } from 'zustand';
 import { supabase } from '@/lib/supabase/client';
+import { currentUserId } from '@/lib/supabase/current-user';
 import type {
   DebateContextFeature,
   DebateContextOutputKind,
@@ -118,8 +119,7 @@ export const useDebateContextStore = create<DebateContextState>()((set, get) =>
     set((state) => ({ pins: { ...state.pins, [debateId]: withPin(state.pins[debateId] ?? [], ref, !pinned) } }));
     const save = async (): Promise<{ error: { message?: string; code?: string } | null }> => {
       if (generation !== pinGeneration) return { error: null };
-      const { data } = await supabase.auth.getUser();
-      const userId = data.user?.id;
+      const userId = await currentUserId();
       if (generation !== pinGeneration) return { error: null };
       if (!userId) return { error: { message: 'Sign in to pin results' } };
       return pinned
diff --git a/src/lib/stores/debate-store.ts b/src/lib/stores/debate-store.ts
index ea536e501..ae608af02 100644
--- a/src/lib/stores/debate-store.ts
+++ b/src/lib/stores/debate-store.ts
@@ -1,6 +1,7 @@
 import { create } from 'zustand';
 import { createJSONStorage, persist } from 'zustand/middleware';
 import { supabase } from '@/lib/supabase/client';
+import { currentUserId } from '@/lib/supabase/current-user';
 
 /** A favor, En contra, both sides, or not side-specific. */
 export type DebateSide = 'pro' | 'con' | 'both' | 'neutral';
@@ -95,8 +96,7 @@ function sortDebates(debates: Debate[]): Debate[] {
 }
 
 async function requireUserId(): Promise<string> {
-  const { data } = await supabase.auth.getUser();
-  const userId = data.user?.id;
+  const userId = await currentUserId();
   if (!userId) throw new Error('Sign in to manage debates');
   return userId;
 }
@@ -126,10 +126,10 @@ export const useDebateStore = create<DebateState>()(
 
       hydrate: async () => {
         const epoch = hydrationEpoch;
-        const { data: { user } } = await supabase.auth.getUser();
-        if (epoch !== hydrationEpoch || !user) return;
-        if (get().ownerUserId !== user.id) {
-          set({ ownerUserId: user.id, debates: [], currentDebateId: null, oneOff: false, hydrated: false });
+        const userId = await currentUserId();
+        if (epoch !== hydrationEpoch || !userId) return;
+        if (get().ownerUserId !== userId) {
+          set({ ownerUserId: userId, debates: [], currentDebateId: null, oneOff: false, hydrated: false });
         }
         const writesBefore = debateWrites;
         const [debatesResult, currentResult] = await Promise.all([
diff --git a/src/lib/stores/session-store.ts b/src/lib/stores/session-store.ts
index 51539f496..fe8f7db79 100644
--- a/src/lib/stores/session-store.ts
+++ b/src/lib/stores/session-store.ts
@@ -7,6 +7,7 @@ import type { BrainstormOutput, BrainstormInput } from '../ai/schemas/brainstorm
 import type { FactoidsOutput, FactoidsInput } from '../ai/schemas/factoids';
 import type { AskOutput } from '../ai/schemas/ask';
 import { supabase } from '@/lib/supabase/client';
+import { currentUserId } from '@/lib/supabase/current-user';
 import i18n from '@/i18n';
 import { activeDebateId, useDebateStore, type DebateSide } from './debate-store';
 
@@ -350,8 +351,11 @@ function mergeSourceFolders(currentFolders: string[], sources: Source[] = []) {
 }
 
 async function getUserId() {
-  const { data } = await supabase.auth.getUser();
-  return data.user?.id || null;
+  return await currentUserId();
+}
+
+function signInRequired(action: string): Error {
+  return new Error(`Sign in to ${action}`);
 }
 
 type EqQuery = {
@@ -574,13 +578,7 @@ export const useSessionStore = create<SessionState>()(
         const place = (list: Source[], item: Source) =>
           restoredId ? [...list, item].sort((x, y) => y.createdAt - x.createdAt) : [item, ...list];
         const userId = await getUserId();
-        if (!userId) {
-          set((state) => ({
-            sourceFolders: mergeSourceFolders(state.sourceFolders, [localItem]),
-            sourceLibrary: place(state.sourceLibrary, localItem),
-          }));
-          return;
-        }
+        if (!userId) throw signInRequired('save this source');
 
         const folderResult = await supabase
           .from('source_folders')
@@ -625,14 +623,17 @@ export const useSessionStore = create<SessionState>()(
       },
       createSourceFolder: async (folder) => {
         const normalized = normalizeFolder(folder);
+        const userId = await getUserId();
+        if (!userId) throw signInRequired('save this folder');
+        throwOnWriteError(
+          await supabase
+            .from('source_folders')
+            .upsert({ user_id: userId, name: normalized }, { onConflict: 'user_id,name' }),
+          'save source folder',
+        );
         set((state) => ({
           sourceFolders: mergeSourceFolders([...state.sourceFolders, normalized], state.sourceLibrary),
         }));
-        const userId = await getUserId();
-        if (!userId) return;
-        await supabase
-          .from('source_folders')
-          .upsert({ user_id: userId, name: normalized }, { onConflict: 'user_id,name' });
       },
       updateSource: async (id, patch) => {
         const current = get().sourceLibrary.find((s) => s.id === id);
@@ -660,7 +661,7 @@ export const useSessionStore = create<SessionState>()(
 
         try {
           const userId = await getUserId();
-          if (!userId) return;
+          if (!userId) throw signInRequired('save this source');
           if (nextSource.folder) {
             const folderResult = await supabase
               .from('source_folders')
@@ -725,7 +726,7 @@ export const useSessionStore = create<SessionState>()(
         set((state) => ({ sourceLibrary: state.sourceLibrary.map((source) => updates.get(source.id) ?? source) }));
         try {
           const userId = await getUserId();
-          if (!userId) return;
+          if (!userId) throw signInRequired('save this source');
           await Promise.all(Array.from(updates.values()).map(async (source) => {
             const result = await applyUserScopedIdFilter(
               supabase.from('sources').update({ metadata: source.metadata ?? null }),
@@ -761,7 +762,7 @@ export const useSessionStore = create<SessionState>()(
         };
 
         const userId = await getUserId();
-        if (!userId) return applyRename();
+        if (!userId) throw signInRequired('rename this folder');
         const folderResult = await supabase
           .from('source_folders')
           .upsert({ user_id: userId, name: to }, { onConflict: 'user_id,name' });
@@ -802,7 +803,7 @@ export const useSessionStore = create<SessionState>()(
         };
 
         const userId = await getUserId();
-        if (!userId) return applyDelete();
+        if (!userId) throw signInRequired('delete this folder');
         if (affected.length > 0) {
           throwOnWriteError(
             await supabase.from('sources').update({ folder: 'General' }).eq('user_id', userId).eq('debate_id', debateId).eq('folder', folder),
@@ -822,13 +823,12 @@ export const useSessionStore = create<SessionState>()(
         const debateId = useDebateStore.getState().currentDebateId;
         if (!debateId) throw new DebateRequiredError();
         const userId = await getUserId();
-        if (userId) {
-          throwOnWriteError(
-            await supabase.from('sources').update({ is_active: isActive })
-              .eq('user_id', userId).eq('debate_id', debateId).eq('folder', normalized),
-            'update source folder activity',
-          );
-        }
+        if (!userId) throw signInRequired('update this folder');
+        throwOnWriteError(
+          await supabase.from('sources').update({ is_active: isActive })
+            .eq('user_id', userId).eq('debate_id', debateId).eq('folder', normalized),
+          'update source folder activity',
+        );
         set((state) => ({
           sourceLibrary: state.sourceLibrary.map((source) =>
             source.debateId === debateId && normalizeFolder(source.folder) === normalized ? { ...source, isActive } : source
@@ -837,10 +837,9 @@ export const useSessionStore = create<SessionState>()(
       },
       removeSource: async (id) => {
         const userId = await getUserId();
-        if (userId) {
-          const result = await applyUserScopedIdFilter(supabase.from('sources').delete(), userId, id);
-          throwOnWriteError(result, 'delete source');
-        }
+        if (!userId) throw signInRequired('delete this source');
+        const result = await applyUserScopedIdFilter(supabase.from('sources').delete(), userId, id);
+        throwOnWriteError(result, 'delete source');
         set((state) => ({ sourceLibrary: state.sourceLibrary.filter((source) => source.id !== id) }));
       },
       toggleSource: async (id) => {
@@ -848,12 +847,11 @@ export const useSessionStore = create<SessionState>()(
         if (!current) return;
         const nextValue = !current.isActive;
         const userId = await getUserId();
-        if (userId) {
-          throwOnWriteError(
-            await applyUserScopedIdFilter(supabase.from('sources').update({ is_active: nextValue }), userId, id),
-            'toggle source activity',
-          );
-        }
+        if (!userId) throw signInRequired('update this source');
+        throwOnWriteError(
+          await applyUserScopedIdFilter(supabase.from('sources').update({ is_active: nextValue }), userId, id),
+          'toggle source activity',
+        );
         set((state) => ({
           sourceLibrary: state.sourceLibrary.map((source) => source.id === id ? { ...source, isActive: nextValue } : source),
         }));
@@ -887,12 +885,8 @@ export const useSessionStore = create<SessionState>()(
       saveCurrentCase: async (title) => {
         const current = get().generateResult;
         if (!current) return;
-        const localItem = { id: generateId(), data: current, createdAt: Date.now(), title };
         const userId = await getUserId();
-        if (!userId) {
-          set((state) => ({ savedCases: [localItem, ...state.savedCases] }));
-          return;
-        }
+        if (!userId) throw signInRequired('save this case');
         const { data, error } = await supabase
           .from('cases')
           .insert({ user_id: userId, title, input: {}, output: current })
@@ -948,12 +942,8 @@ export const useSessionStore = create<SessionState>()(
       saveCurrentAttack: async (title) => {
         const current = get().attackResult;
         if (!current) return;
-        const localItem = { id: generateId(), data: current, createdAt: Date.now(), title };
         const userId = await getUserId();
-        if (!userId) {
-          set((state) => ({ savedAttacks: [localItem, ...state.savedAttacks] }));
-          return;
-        }
+        if (!userId) throw signInRequired('save this attack');
         const { data, error } = await supabase
           .from('attacks')
           .insert({ user_id: userId, title, input: {}, output: current })
@@ -980,12 +970,8 @@ export const useSessionStore = create<SessionState>()(
       saveCurrentBrainstorm: async (title) => {
         const current = get().brainstormResult;
         if (!current) return;
-        const localItem = { id: generateId(), data: current, createdAt: Date.now(), title };
         const userId = await getUserId();
-        if (!userId) {
-          set((state) => ({ savedBrainstorms: [localItem, ...state.savedBrainstorms] }));
-          return;
-        }
+        if (!userId) throw signInRequired('save this brainstorm');
         const { data, error } = await supabase
           .from('brainstorms')
           .insert({ user_id: userId, title, input: {}, output: current })
@@ -1012,12 +998,8 @@ export const useSessionStore = create<SessionState>()(
       saveCurrentFactoids: async (title) => {
         const current = get().factoidsResult;
         if (!current) return;
-        const localItem = { id: generateId(), data: current, createdAt: Date.now(), title };
         const userId = await getUserId();
-        if (!userId) {
-          set((state) => ({ savedFactoids: [localItem, ...state.savedFactoids] }));
-          return;
-        }
+        if (!userId) throw signInRequired('save these factoids');
         const { data, error } = await supabase
           .from('factoids')
           .insert({ user_id: userId, title, input: {}, output: current })
@@ -1050,12 +1032,8 @@ export const useSessionStore = create<SessionState>()(
       saveCurrentChat: async (title) => {
         const current = get().askMessages;
         if (current.length === 0) return;
-        const localItem = { id: generateId(), data: current, createdAt: Date.now(), title };
         const userId = await getUserId();
-        if (!userId) {
-          set((state) => ({ savedChats: [localItem, ...state.savedChats] }));
-          return;
-        }
+        if (!userId) throw signInRequired('save this chat');
         const { data: chat, error } = await supabase
           .from('chats')
           .insert({ user_id: userId, title })
@@ -1084,12 +1062,8 @@ export const useSessionStore = create<SessionState>()(
       },
 
       saveFlowchart: async (title, data, debateId = activeDebateId()) => {
-        const localItem = { id: generateId(), data, createdAt: Date.now(), title, debateId, side: 'neutral' as const };
         const userId = await getUserId();
-        if (!userId) {
-          set((state) => ({ savedFlowcharts: [localItem, ...state.savedFlowcharts] }));
-          return;
-        }
+        if (!userId) throw signInRequired('save this flowchart');
         const { data: saved, error } = await supabase
           .from('flowcharts')
           .insert({
@@ -1118,7 +1092,7 @@ export const useSessionStore = create<SessionState>()(
 
       recordResult: async (kind, { title, input, output, debateId, side }) => {
         const userId = await getUserId();
-        if (!userId) throw new Error('[SessionStore] Sign in to save results to a debate');
+        if (!userId) throw signInRequired('save results to a debate');
         const { data, error } = await supabase
           .from(RESULT_TABLES[kind])
           .insert({ user_id: userId, debate_id: debateId, side, title: title.slice(0, 300) || 'Untitled', input: input ?? {}, output })
@@ -1135,7 +1109,7 @@ export const useSessionStore = create<SessionState>()(
 
       updateRecordedResult: async (kind, id, output) => {
         const userId = await getUserId();
-        if (!userId) return;
+        if (!userId) throw signInRequired('update this result');
         throwOnWriteError(
           await applyUserScopedIdFilter(supabase.from(RESULT_TABLES[kind]).update({ output }), userId, id),
           `update ${kind}`,
@@ -1389,7 +1363,7 @@ async function syncAskChatNow(debateId: string | null): Promise<void> {
   if (askMessages.length === 0 || askPersistedCount >= askMessages.length) return;
   if (!askChatId && !debateId) return;
   const userId = await getUserId();
-  if (!userId) return;
+  if (!userId) throw signInRequired('save this chat');
   // Clearing or replacing the conversation while a write is in flight must not
   // hand this chat or its count to the next conversation.
   const sameConversation = () => {
diff --git a/src/lib/stores/settings-store.ts b/src/lib/stores/settings-store.ts
index 15f53330d..f254bcad1 100644
--- a/src/lib/stores/settings-store.ts
+++ b/src/lib/stores/settings-store.ts
@@ -14,6 +14,7 @@ import {
 } from '../../../supabase/functions/_shared/model-catalog';
 import type { ProviderConfig } from '../ai/providers/types';
 import { supabase } from '@/lib/supabase/client';
+import { currentUserId } from '@/lib/supabase/current-user';
 
 export type FeatureTab = 'generate' | 'attack' | 'brainstorm' | 'factoids' | 'ask' | 'sparring';
 type CoreFeatureTab = Exclude<FeatureTab, 'sparring'>;
@@ -164,8 +165,7 @@ async function canAccessProModels(settings: Record<string, unknown>): Promise<bo
 }
 
 async function getUserId() {
-  const { data } = await supabase.auth.getUser();
-  return data.user?.id || null;
+  return await currentUserId();
 }
 
 // The auth trigger provisions every settings row, and clients may only UPDATE
diff --git a/src/lib/stores/sparring-store.ts b/src/lib/stores/sparring-store.ts
index 46956d125..c47ecd78f 100644
--- a/src/lib/stores/sparring-store.ts
+++ b/src/lib/stores/sparring-store.ts
@@ -2,6 +2,7 @@ import { create } from 'zustand';
 import { createJSONStorage, persist } from 'zustand/middleware';
 import { z } from 'zod';
 import { supabase } from '@/lib/supabase/client';
+import { currentUserId } from '@/lib/supabase/current-user';
 import {
   SparringScorecardSchema,
   SparringSpeakerSchema,
@@ -478,9 +479,9 @@ export const useSparringStore = create<SparringStoreState>()(
       hydrateSavedSessions: async () => {
         if (get().hydrated) return;
         const epoch = hydrationEpoch;
-        const { data: { user } } = await supabase.auth.getUser();
+        const userId = await currentUserId();
         if (epoch !== hydrationEpoch) return;
-        if (!user) {
+        if (!userId) {
           set({ hydrated: true });
           return;
         }
@@ -505,8 +506,8 @@ export const useSparringStore = create<SparringStoreState>()(
       deleteSavedSession: async (id) => {
         const previous = get().savedSessions;
         set({ savedSessions: previous.filter((session) => session.id !== id) });
-        const { data: { user } } = await supabase.auth.getUser();
-        if (!user) return;
+        const userId = await currentUserId();
+        if (!userId) return;
         const { error } = await supabase.from('sparring_sessions').delete().eq('id', id);
         if (error) {
           set({ savedSessions: previous });
diff --git a/src/lib/supabase/current-user.ts b/src/lib/supabase/current-user.ts
new file mode 100644
index 000000000..19897d1e6
--- /dev/null
+++ b/src/lib/supabase/current-user.ts
@@ -0,0 +1,40 @@
+import { getActiveUserId, supabase } from './client';
+
+/**
+ * Who is signed in, without treating an Auth-server failure as signed out.
+ *
+ * `auth.getUser()` asks the server. When that call fails, the old stores saved
+ * only in this browser and told the student the save worked. The id AuthProvider
+ * already has, then the local session, still name the user so the write can go
+ * to the database (or fail in the open).
+ */
+function rememberedUserId(): string | null {
+  // Some unit tests replace the client module and omit this export. Reading a
+  // missing mock export throws; that is the same as "nothing remembered".
+  try {
+    if (typeof getActiveUserId !== 'function') return null;
+    return getActiveUserId();
+  } catch {
+    return null;
+  }
+}
+
+export async function currentUserId(): Promise<string | null> {
+  const active = rememberedUserId();
+  if (active) return active;
+
+  const auth = supabase.auth;
+  if (typeof auth?.getUser === 'function') {
+    try {
+      const { data, error } = await auth.getUser();
+      if (!error && data.user?.id) return data.user.id;
+    } catch {
+      // The Auth server did not answer. Fall through to the local session.
+    }
+  }
+
+  if (typeof auth?.getSession !== 'function') return null;
+  const { data, error } = await auth.getSession();
+  if (error) return null;
+  return data.session?.user?.id ?? null;
+}
diff --git a/src/locales/en.json b/src/locales/en.json
index 7a2b4ac96..9243559a7 100644
--- a/src/locales/en.json
+++ b/src/locales/en.json
@@ -1601,6 +1601,7 @@
     "newFolderPlaceholder": "Folder name...",
     "newFolderHint": "Need a new folder? Use the \"New folder\" button up top.",
     "createFolder": "Create folder",
+    "saveFailed": "Could not save this source.",
     "sortBy": "Sort by",
     "sortSmart": "Smart",
     "sortMostUsed": "Most used",
diff --git a/src/locales/es.json b/src/locales/es.json
index e03254f8e..cc3e613de 100644
--- a/src/locales/es.json
+++ b/src/locales/es.json
@@ -1599,6 +1599,7 @@
     "newFolderPlaceholder": "Nombre de carpeta...",
     "newFolderHint": "¿Necesitas una carpeta nueva? Usa el botón \"Nueva carpeta\" arriba.",
     "createFolder": "Crear carpeta",
+    "saveFailed": "No se pudo guardar esta fuente.",
     "sortBy": "Ordenar por",
     "sortSmart": "Inteligente",
     "sortMostUsed": "Más usadas",
diff --git a/src/locales/hu.json b/src/locales/hu.json
index 46a0e4953..9f3486986 100644
--- a/src/locales/hu.json
+++ b/src/locales/hu.json
@@ -1599,6 +1599,7 @@
     "newFolderPlaceholder": "Mappa neve...",
     "newFolderHint": "Új mappára van szükség? Használd a felső „Új mappa” gombot.",
     "createFolder": "Mappa létrehozása",
+    "saveFailed": "Ezt a forrást nem sikerült menteni.",
     "sortBy": "Rendezés",
     "sortSmart": "Intelligens",
     "sortMostUsed": "Legtöbbet használt",
diff --git a/src/pages/LibraryPage.tsx b/src/pages/LibraryPage.tsx
index 9853279c4..27357364d 100644
--- a/src/pages/LibraryPage.tsx
+++ b/src/pages/LibraryPage.tsx
@@ -1,6 +1,6 @@
 import { useEffect, useRef, useState } from 'react';
 import { useTranslation } from 'react-i18next';
-import { useSessionStore, type Source } from '@/lib/stores/session-store';
+import { DebateRequiredError, useSessionStore, type Source } from '@/lib/stores/session-store';
 import { Card, CardContent, CardHeader, CardTitle } from '@/components/ui/card';
 import { Button, buttonVariants } from '@/components/ui/button';
 import { Input } from '@/components/ui/input';
@@ -243,7 +243,18 @@ export default function LibraryPage() {
     if (errors.title) return addTitleRef.current?.focus();
     if (errors.content) return addContentRef.current?.focus();
     // The Library always shows the Current Debate, even while tools run one-off.
-    await addSource({ ...newSource, debateId: currentDebate?.id ?? null });
+    try {
+      await addSource({ ...newSource, debateId: currentDebate?.id ?? null });
+    } catch (error) {
+      toast({
+        title: t('libraryPage.saveFailed', 'Could not save this source.'),
+        description: error instanceof DebateRequiredError
+          ? t('debate.sourceNeedsDebate', 'Start or select a debate before saving sources.')
+          : undefined,
+        variant: 'destructive',
+      });
+      return;
+    }
     setNewSource({ title: '', content: '', type: 'text', origin: '', folder: newSource.folder });
     setIsAdding(false);
   };
diff --git a/src/test/stores/session-save-auth.test.ts b/src/test/stores/session-save-auth.test.ts
new file mode 100644
index 000000000..fd53ab74d
--- /dev/null
+++ b/src/test/stores/session-save-auth.test.ts
@@ -0,0 +1,87 @@
+import { afterEach, describe, expect, it, vi } from 'vitest';
+import { setActiveAccessToken, supabase } from '@/lib/supabase/client';
+import { currentUserId } from '@/lib/supabase/current-user';
+import { useSessionStore } from '@/lib/stores/session-store';
+import { resetDebates, seedCurrentDebate, TEST_DEBATE_ID } from '@/test/helpers/debate';
+
+const DEBATE_ID = TEST_DEBATE_ID;
+
+function sourceRow() {
+  return {
+    id: '22222222-2222-4222-8222-222222222222',
+    title: 'School wifi notes',
+    content: 'The packet was lost.',
+    type: 'text',
+    origin: null as string | null,
+    folder: 'General',
+    metadata: null as null,
+    debate_id: DEBATE_ID,
+    is_active: true,
+    created_at: '2026-10-22T00:00:00.000Z',
+  };
+}
+
+describe('saves when the Auth server is down', () => {
+  afterEach(() => {
+    vi.restoreAllMocks();
+    setActiveAccessToken(null, null);
+    resetDebates();
+    useSessionStore.setState({ sourceLibrary: [], sourceFolders: ['General'], savedCases: [] });
+  });
+
+  it('uses the local session when getUser fails', async () => {
+    setActiveAccessToken(null, null);
+    vi.spyOn(supabase.auth, 'getUser').mockResolvedValue({
+      data: { user: null },
+      error: { message: 'Auth unavailable', name: 'AuthRetryableFetchError', status: 503 },
+    } as never);
+    vi.spyOn(supabase.auth, 'getSession').mockResolvedValue({
+      data: { session: { user: { id: 'user-1' } } },
+      error: null,
+    } as never);
+
+    await expect(currentUserId()).resolves.toBe('user-1');
+    expect(supabase.auth.getUser).toHaveBeenCalled();
+  });
+
+  it('writes a source to the database instead of pretending a local copy was saved', async () => {
+    setActiveAccessToken('token', 'user-1');
+    seedCurrentDebate();
+    const getUser = vi.spyOn(supabase.auth, 'getUser').mockRejectedValue(new Error('503'));
+    const insert = vi.fn(() => ({
+      select: () => ({
+        single: async (): Promise<{ data: ReturnType<typeof sourceRow>; error: null }> => ({ data: sourceRow(), error: null }),
+      }),
+    }));
+    vi.spyOn(supabase, 'from').mockImplementation((table: string) => {
+      if (table === 'source_folders') {
+        return { upsert: async (): Promise<{ error: null }> => ({ error: null }) } as never;
+      }
+      if (table === 'sources') return { insert } as never;
+      throw new Error(`unexpected table ${table}`);
+    });
+
+    await useSessionStore.getState().addSource({ title: 'School wifi notes', content: 'The packet was lost.', type: 'text' });
+
+    expect(getUser).not.toHaveBeenCalled();
+    expect(insert).toHaveBeenCalledOnce();
+    expect(useSessionStore.getState().sourceLibrary.map((source) => source.id)).toEqual([sourceRow().id]);
+  });
+
+  it('reports failure instead of keeping a source that only exists in the browser', async () => {
+    setActiveAccessToken(null, null);
+    seedCurrentDebate();
+    vi.spyOn(supabase.auth, 'getUser').mockResolvedValue({ data: { user: null }, error: null } as never);
+    vi.spyOn(supabase.auth, 'getSession').mockResolvedValue({ data: { session: null }, error: null } as never);
+    const from = vi.spyOn(supabase, 'from');
+
+    await expect(useSessionStore.getState().addSource({
+      title: 'School wifi notes',
+      content: 'The packet was lost.',
+      type: 'text',
+    })).rejects.toThrow(/Sign in to save this source/);
+
+    expect(from).not.toHaveBeenCalled();
+    expect(useSessionStore.getState().sourceLibrary).toEqual([]);
+  });
+});