diff --git a/apps/web/src/lib/workspace-state.test.ts b/apps/web/src/lib/workspace-state.test.ts
index 33154c9..6e3aaba 100644
--- a/apps/web/src/lib/workspace-state.test.ts
+++ b/apps/web/src/lib/workspace-state.test.ts
@@ -1,6 +1,6 @@
 import { beforeEach, describe, expect, it } from 'vitest';
 import {
-  loadEditorPercent, loadTreeOpen, storeEditorPercent, storeTreeOpen
+  loadEditorPercent, loadTreeOpen, loadWorkspaceSource, storeEditorPercent, storeTreeOpen, storeWorkspaceSource
 } from './workspace-state';
 
 const values = new Map<string, string>();
@@ -9,6 +9,41 @@ const storage = {
   setItem: (key: string, value: string) => { values.set(key, value); }
 };
 
+describe('workspace source persistence', () => {
+  beforeEach(() => values.clear());
+
+  it('defaults to no remembered source and stores both file and mode', () => {
+    expect(loadWorkspaceSource('writer', 'paper', storage)).toBeNull();
+    const source = { fileId: 'chapter', mode: 'files' as const };
+    storeWorkspaceSource('writer', 'paper', source, storage);
+    expect(loadWorkspaceSource('writer', 'paper', storage)).toEqual(source);
+  });
+
+  it('keeps accounts and projects separate', () => {
+    storeWorkspaceSource('writer', 'paper', { fileId: 'chapter', mode: 'files' }, storage);
+    storeWorkspaceSource('writer', 'other-paper', { fileId: 'appendix', mode: 'manuscript' }, storage);
+    storeWorkspaceSource('reader', 'paper', { fileId: 'intro', mode: 'manuscript' }, storage);
+    expect(loadWorkspaceSource('writer', 'paper', storage)).toEqual({ fileId: 'chapter', mode: 'files' });
+    expect(loadWorkspaceSource('writer', 'other-paper', storage)).toEqual({ fileId: 'appendix', mode: 'manuscript' });
+    expect(loadWorkspaceSource('reader', 'paper', storage)).toEqual({ fileId: 'intro', mode: 'manuscript' });
+  });
+
+  it.each(['{', 'null', '[]', '42', '{"fileId":"chapter","mode":"invalid"}', '{"fileId":5,"mode":"files"}', '{"fileId":"","mode":"files"}'])('ignores invalid saved data: %s', (value) => {
+    storeWorkspaceSource('writer', 'paper', { fileId: 'chapter', mode: 'files' }, storage);
+    storage.setItem([...values.keys()][0]!, value);
+    expect(loadWorkspaceSource('writer', 'paper', storage)).toBeNull();
+  });
+
+  it('allows navigation when browser storage is blocked or full', () => {
+    const blocked = {
+      getItem: () => { throw new DOMException('Blocked', 'SecurityError'); },
+      setItem: () => { throw new DOMException('Full', 'QuotaExceededError'); }
+    };
+    expect(loadWorkspaceSource('writer', 'paper', blocked)).toBeNull();
+    expect(() => storeWorkspaceSource('writer', 'paper', { fileId: 'chapter', mode: 'files' }, blocked)).not.toThrow();
+  });
+});
+
 describe('workspace layout persistence', () => {
   beforeEach(() => values.clear());
 
diff --git a/apps/web/src/lib/workspace-state.ts b/apps/web/src/lib/workspace-state.ts
index 5f4b7df..575cd72 100644
--- a/apps/web/src/lib/workspace-state.ts
+++ b/apps/web/src/lib/workspace-state.ts
@@ -2,6 +2,32 @@ const TREE_OPEN_KEY = 'overroot.fileTreeOpen';
 const EDITOR_PERCENT_KEY = 'overroot.editorSplit';
 type StateStorage = Pick<Storage, 'getItem' | 'setItem'>;
 
+export interface WorkspaceSource {
+  fileId: string;
+  mode: 'manuscript' | 'files';
+}
+
+export function loadWorkspaceSource(userId: string, projectHash: string, storage?: StateStorage): WorkspaceSource | null {
+  try {
+    const value: unknown = JSON.parse((storage ?? window.localStorage).getItem(workspaceSourceKey(userId, projectHash)) ?? 'null');
+    if (value && typeof value === 'object' && 'fileId' in value && typeof value.fileId === 'string' && value.fileId &&
+      'mode' in value && (value.mode === 'manuscript' || value.mode === 'files')) {
+      return { fileId: value.fileId, mode: value.mode };
+    }
+  } catch { /* Browser storage can be unavailable or contain invalid JSON. */ }
+  return null;
+}
+
+export function storeWorkspaceSource(userId: string, projectHash: string, source: WorkspaceSource, storage?: StateStorage): void {
+  try {
+    (storage ?? window.localStorage).setItem(workspaceSourceKey(userId, projectHash), JSON.stringify(source));
+  } catch { /* A blocked or full store must not prevent opening a file. */ }
+}
+
+function workspaceSourceKey(userId: string, projectHash: string): string {
+  return `overroot.workspaceSource.${JSON.stringify([userId, projectHash])}`;
+}
+
 export const MIN_EDITOR_PERCENT = 25;
 export const MAX_EDITOR_PERCENT = 75;
 
diff --git a/apps/web/src/pages/WorkspacePage.test.tsx b/apps/web/src/pages/WorkspacePage.test.tsx
index 981791b..29a24da 100644
--- a/apps/web/src/pages/WorkspacePage.test.tsx
+++ b/apps/web/src/pages/WorkspacePage.test.tsx
@@ -21,10 +21,10 @@ vi.mock('../components/WorkspaceDialogs', async (importOriginal) => {
 });
 vi.mock('../components/ManuscriptPane', async () => {
   const { useEffect } = await import('react');
-  return { ManuscriptPane: function Pane({ onFlushReady, onPresence }: { onFlushReady: (flush: (() => Promise<void>) | null) => void; onPresence: NonNullable<typeof harness.onPresence> }) {
+  return { ManuscriptPane: function Pane({ onFlushReady, onPresence, entryFile }: { onFlushReady: (flush: (() => Promise<void>) | null) => void; onPresence: NonNullable<typeof harness.onPresence>; entryFile: string }) {
     useEffect(() => { harness.onPresence = onPresence; }, [onPresence]);
     useEffect(() => { onFlushReady(() => harness.flush()); return () => onFlushReady(null); }, [onFlushReady]);
-    return <div>Manuscript test editor</div>;
+    return <div>Manuscript test editor<span data-testid="manuscript-entry">{entryFile}</span></div>;
   } };
 });
 vi.mock('../components/EditorPane', async () => {
@@ -45,6 +45,7 @@ function deferred<T>() {
 }
 beforeEach(() => {
   vi.resetAllMocks();
+  window.localStorage.clear();
   harness.flush.mockImplementation(async () => {});
   harness.api.getProject.mockResolvedValue({ project: { hash: 'project', name: 'Paper', entryFile: 'main.tex', role: 'owner', canWrite: true, canManage: true, memberCount: 1 } });
   harness.api.listFiles.mockResolvedValue({ files: [main, result] });
@@ -54,7 +55,7 @@ beforeEach(() => {
 afterEach(cleanup);
 async function openWorkspace() {
   render(<MemoryRouter initialEntries={['/project/project']}><Routes><Route path="/project/:hash" element={<WorkspacePage/>}/></Routes></MemoryRouter>);
-  await screen.findByText('Manuscript test editor');
+  await screen.findByText(/(?:Manuscript|File) test editor/);
 }
 function startFileMutation(operation: string, path: string, content: string, renamePath?: string) {
   if (operation === 'create') {
@@ -74,6 +75,65 @@ function startFileMutation(operation: string, path: string, content: string, ren
   }
 }
 
+describe('source view persistence', () => {
+  it.each(['files', 'manuscript'])('restores the last opened file and %s mode after a remount', async (mode) => {
+    await openWorkspace();
+    fireEvent.click(screen.getByRole('button', { name: 'result.tex' }));
+    await screen.findByText(result.content);
+    if (mode === 'manuscript') {
+      fireEvent.click(screen.getByRole('button', { name: 'Manuscript' }));
+      await screen.findByText('Manuscript test editor');
+    }
+    cleanup();
+    harness.api.getFile.mockClear();
+    await openWorkspace();
+    expect(harness.api.getFile).toHaveBeenCalledWith('project', result.id);
+    expect(screen.getByRole('button', { name: result.path }).closest('.tree-file')).toHaveClass('is-active');
+    expect(screen.getByRole('button', { name: mode === 'files' ? 'Files' : 'Manuscript' })).toHaveAttribute('aria-pressed', 'true');
+    if (mode === 'files') expect(screen.getByText(result.content)).toBeInTheDocument();
+    else expect(screen.getByTestId('manuscript-entry')).toHaveTextContent(result.path);
+  });
+
+  it('restores a renamed file by its stable ID', async () => {
+    await openWorkspace();
+    fireEvent.click(screen.getByRole('button', { name: result.path }));
+    await screen.findByText(result.content);
+    cleanup();
+    const renamed = { ...result, path: 'renamed.tex' };
+    harness.api.listFiles.mockResolvedValue({ files: [main, renamed] });
+    harness.api.getFile.mockResolvedValue({ file: renamed });
+    await openWorkspace();
+    expect(screen.getByRole('button', { name: renamed.path }).closest('.tree-file')).toHaveClass('is-active');
+  });
+
+  it('falls back to the project default if the remembered file was deleted', async () => {
+    await openWorkspace();
+    fireEvent.click(screen.getByRole('button', { name: result.path }));
+    await screen.findByText(result.content);
+    cleanup();
+    harness.api.listFiles.mockResolvedValue({ files: [main] });
+    await openWorkspace();
+    expect(screen.getByText(main.content)).toBeInTheDocument();
+    expect(screen.getByRole('button', { name: main.path }).closest('.tree-file')).toHaveClass('is-active');
+    cleanup();
+    harness.api.listFiles.mockResolvedValue({ files: [main, result] });
+    await openWorkspace();
+    expect(screen.getByText(main.content)).toBeInTheDocument();
+  });
+
+  it('keeps the last opened file when a newer selection fails', async () => {
+    await openWorkspace();
+    fireEvent.click(screen.getByRole('button', { name: result.path }));
+    await screen.findByText(result.content);
+    harness.api.getFile.mockRejectedValueOnce(new Error('Could not open file'));
+    fireEvent.click(screen.getByRole('button', { name: main.path }));
+    await screen.findByText('Could not open file');
+    cleanup();
+    await openWorkspace();
+    expect(screen.getByText(result.content)).toBeInTheDocument();
+  });
+});
+
 describe('online collaborators', () => {
   const people = ['Alice Smith', 'Alice Stone', 'Bo', 'Charlie', 'Dana', 'Eli'].map((name, clientId) => ({ clientId, name, color: '#2583e9' }));
 
diff --git a/apps/web/src/pages/WorkspacePage.tsx b/apps/web/src/pages/WorkspacePage.tsx
index 11ebefe..955150e 100644
--- a/apps/web/src/pages/WorkspacePage.tsx
+++ b/apps/web/src/pages/WorkspacePage.tsx
@@ -21,8 +21,8 @@ import { ApiError } from '../lib/api';
 import { initials, relativeTime } from '../lib/format';
 import { useSession } from '../lib/session';
 import {
-  loadEditorPercent, loadTreeOpen, MAX_EDITOR_PERCENT, MIN_EDITOR_PERCENT,
-  storeEditorPercent, storeTreeOpen
+  loadEditorPercent, loadTreeOpen, loadWorkspaceSource, MAX_EDITOR_PERCENT, MIN_EDITOR_PERCENT,
+  storeEditorPercent, storeTreeOpen, storeWorkspaceSource
 } from '../lib/workspace-state';
 import type { CompileJob, ProjectDetail, ProjectEvent, ProjectFile, SourceLocation } from '../types';
 
@@ -187,13 +187,17 @@ function ProjectWorkspace({ hash }: { hash: string }) {
       setProject(projectResponse.project);
       setFiles(fileResponse.files);
       const accepted = updateJob(compileResponse.job);
-      const initial = fileResponse.files.find((file) => file.path === projectResponse.project.entryFile) ?? fileResponse.files[0];
+      const savedSource = user?.id ? loadWorkspaceSource(user.id, hash) : null;
+      const initial = fileResponse.files.find((file) => file.id === savedSource?.fileId)
+        ?? fileResponse.files.find((file) => file.path === projectResponse.project.entryFile)
+        ?? fileResponse.files[0];
       if (initial) setSelected((await api.getFile(hash, initial.id)).file);
+      setEditorMode(savedSource?.mode ?? 'manuscript');
       const previewJob = compileResponse.job?.status === 'succeeded' ? compileResponse.job : compileResponse.lastSuccessfulJob;
       if (previewJob?.hasPdf && (accepted || !currentJob.current?.hasPdf)) await loadPdf(previewJob);
     } catch (reason) { setError(reason instanceof Error ? reason.message : 'Could not open project'); }
     finally { setLoading(false); }
-  }, [api, hash, loadPdf, updateJob]);
+  }, [api, hash, loadPdf, updateJob, user?.id]);
 
   const reconcile = useCallback(async () => {
     try {
@@ -212,6 +216,11 @@ function ProjectWorkspace({ hash }: { hash: string }) {
   }, [api, hash, loadFiles, loadPdf, navigate, updateJob]);
 
   useEffect(() => { void loadProject(); }, [loadProject]);
+  useEffect(() => {
+    if (!loading && user?.id && selected?.id) {
+      storeWorkspaceSource(user.id, hash, { fileId: selected.id, mode: editorMode });
+    }
+  }, [loading, user?.id, hash, selected?.id, editorMode]);
   useEffect(() => () => { if (activityTimer.current != null) clearTimeout(activityTimer.current); }, []);
 
   const handleEvent = useCallback((event: ProjectEvent) => {