style: drop redundant comments and apply formatting

Frontend now uses double quotes and semicolons. No behaviour change.

backend/app.py

@@ -21,8 +21,6 @@ def create_app() -> Flask:
         level=logging.INFO, format="%(asctime)s %(levelname)s %(name)s: %(message)s"
     )
     app = Flask(__name__)
-    # Werkzeug buffers and parses the whole body before our validation runs, so unauthenticated
-    # callers could exhaust memory; 1 MiB is far above the largest legitimate payload (10,000-char note).
     app.config["MAX_CONTENT_LENGTH"] = 1024 * 1024
     db.init_app(app)
     auth.init_app(app)
@@ -35,8 +33,6 @@ def create_app() -> Flask:
 
     @app.before_request
     def require_json_for_mutations():
-        # CSRF defense (ADR-0002): cross-site requests can only send this content type after a
-        # CORS preflight, and this API never grants CORS.
         if request.method in MUTATING_METHODS and not request.is_json:
             raise ApiError(
                 400, "Request body must be JSON with Content-Type: application/json"

backend/auth.py

@@ -30,7 +30,7 @@ INVALID_LOGIN = "Invalid username or password"
 
 def init_app(app: Flask) -> None:
     app.extensions["password_pepper"] = load_pepper(Path(app.root_path) / ".pepper")
-    _dummy_hash()  # pay the one-time cost now so the first unknown-user login isn't measurably slower
+    _dummy_hash()
     app.register_blueprint(bp)
 
 

backend/books.py

@@ -13,7 +13,7 @@ bp = Blueprint("books", __name__, url_prefix="/api")
 
 MAX_TEXT = 500
 MAX_PAGES = 100_000
-MAX_GENRE_ID = 32_767  # SMALLINT
+MAX_GENRE_ID = 32_767
 GENRE_ID_PATTERN = re.compile(r"[0-9]{1,5}")
 REQUIRED_FIELDS = ("title", "author", "genre_id", "total_pages")
 FIELDS = set(REQUIRED_FIELDS) | {"current_page"}
@@ -56,7 +56,6 @@ def to_json(row: dict) -> dict:
 
 
 def escape_like(term: str) -> str:
-    # Backslash is Postgres's default LIKE escape character.
     return term.replace("\\", "\\\\").replace("%", "\\%").replace("_", "\\_")
 
 
@@ -147,7 +146,6 @@ def create_book():
     return jsonify(to_json(owned_book(row["id"]))), 201
 
 
-# int(max=...) keeps ids within Postgres INT range: larger values 404 instead of erroring in SQL.
 @bp.get("/books/<int(max=2147483647):book_id>")
 @login_required
 def get_book(book_id: int):

backend/db.py

@@ -44,7 +44,6 @@ def _connection():
 
 
 def _finish_transaction(response):
-    # Commit only successful responses so a 4xx/5xx never leaves partial writes behind.
     conn = g.get("db")
     if conn is not None:
         if response.status_code < 400:
@@ -57,5 +56,5 @@ def _finish_transaction(response):
 def _release_connection(_exc):
     conn = g.pop("db", None)
     if conn is not None:
-        conn.rollback()  # no-op after commit; discards work if after_request never ran
+        conn.rollback()
         current_app.extensions["db_pool"].putconn(conn)

backend/schema.sql

@@ -19,8 +19,6 @@ CREATE TABLE IF NOT EXISTS genres (
     name TEXT NOT NULL UNIQUE
 );
 
--- WHERE NOT EXISTS instead of ON CONFLICT: ON CONFLICT consumes a sequence value per row
--- on every startup, which would eventually overflow SMALLSERIAL.
 INSERT INTO genres (name)
 SELECT seed.name
   FROM (VALUES ('Fiction'), ('Non-Fiction'), ('Mystery'), ('Thriller'), ('Science Fiction'),

backend/tests/__init__.py

@@ -13,7 +13,7 @@ TEST_DATABASE = "books_test"
 
 def _ensure_test_database() -> None:
     conn = psycopg2.connect(ADMIN_URL)
-    conn.autocommit = True  # CREATE DATABASE cannot run inside a transaction
+    conn.autocommit = True
     try:
         with conn.cursor() as cur:
             cur.execute(
@@ -28,6 +28,5 @@ def _ensure_test_database() -> None:
 
 
 _ensure_test_database()
-# Assigned, never defaulted: tests TRUNCATE tables, so they must not inherit a real DATABASE_URL.
 os.environ["DATABASE_URL"] = ADMIN_URL.rsplit("/", 1)[0] + "/" + TEST_DATABASE
 os.environ["PASSWORD_PEPPER"] = "test-pepper-0123456789abcdef0123456789abcdef"

backend/tests/support.py

@@ -5,7 +5,7 @@ import psycopg2
 
 from app import app
 
-HTTPS = "https://localhost"  # the session cookie is Secure
+HTTPS = "https://localhost"
 
 
 def db_execute(sql: str, params: tuple = ()) -> list[tuple]:

backend/tests/test_auth.py

@@ -70,7 +70,7 @@ class AuthTests(ApiTestCase):
 
     def test_login_is_case_insensitive_on_username(self):
         self.register("Alice")
-        self.client = app.test_client()  # fresh cookie jar: signed out
+        self.client = app.test_client()
         response = self.call(
             "POST",
             "/api/auth/login",
@@ -116,9 +116,7 @@ class AuthTests(ApiTestCase):
         self.register()
         token = self.session_token()
         self.assertEqual(self.call("POST", "/api/auth/logout").status_code, 204)
-        self.client.set_cookie(
+        self.client.set_cookie("sid", token, domain="localhost", path="/api")
-            "sid", token, domain="localhost", path="/api"
-        )  # replay the stolen cookie
         self.assertEqual(self.call("GET", "/api/auth/me").status_code, 401)
 
     def test_idle_session_expires(self):

backend/tests/test_books.py

@@ -17,7 +17,7 @@ class BookTests(ApiTestCase):
             (book["current_page"], book["total_pages"], book["status"]),
             (0, 412, "not_started"),
         )
-        self.assertIn("T", book["created_at"])  # ISO 8601
+        self.assertIn("T", book["created_at"])
 
     def test_create_trims_text(self):
         book = self.create_book(title="  Dune  ")

backend/tests/test_search.py

@@ -24,12 +24,10 @@ class SearchTests(ApiTestCase):
         self.assertEqual(self.titles("q=tolkien"), ["The Hobbit"])
 
     def test_wildcards_match_literally(self):
-        self.assertEqual(self.titles("q=100%25"), ["100% Pure"])  # %25 is "%"
+        self.assertEqual(self.titles("q=100%25"), ["100% Pure"])
-        self.assertEqual(self.titles("q=e_D"), ["100% Pure"])  # literal "_" in Jane_Doe
+        self.assertEqual(self.titles("q=e_D"), ["100% Pure"])
-        self.assertEqual(
+        self.assertEqual(self.titles("q=k_s"), [])
-            self.titles("q=k_s"), []
+        self.assertEqual(self.titles("q=k%5Cs"), ["1000 Pages"])
-        )  # unescaped "_" would match "Back\\slash"
-        self.assertEqual(self.titles("q=k%5Cs"), ["1000 Pages"])  # %5C is "\"
 
     def test_genre_filter_and_combination(self):
         self.assertEqual(

backend/validation.py

@@ -51,7 +51,6 @@ def text(body: dict, field: str, max_len: int) -> str:
 
 def integer(body: dict, field: str, low: int, high: int) -> int:
     value = body.get(field)
-    # bool is a subclass of int in Python; JSON true must not count as 1.
     if isinstance(value, bool) or not isinstance(value, int):
         raise ApiError(400, f"{field} must be a whole number", field)
     if not low <= value <= high:

src/App.tsx

@@ -1,13 +1,20 @@
-import { useState } from 'react'
+import { useState } from "react";
-import { BrowserRouter, Link, Navigate, Outlet, Route, Routes } from 'react-router'
+import {
-import { errorMessage } from './api'
+  BrowserRouter,
-import { AuthProvider, useAuth } from './auth/AuthContext'
+  Link,
-import { LoginForm } from './auth/LoginForm'
+  Navigate,
-import { RequireAuth } from './auth/RequireAuth'
+  Outlet,
-import { BookList } from './books/BookList'
+  Route,
-import { BookDetail } from './books/BookDetail'
+  Routes,
-import { BookForm } from './books/BookForm'
+} from "react-router";
-import { secondaryButton } from './ui'
+import { errorMessage } from "./api";
+import { AuthProvider, useAuth } from "./auth/AuthContext";
+import { LoginForm } from "./auth/LoginForm";
+import { RequireAuth } from "./auth/RequireAuth";
+import { BookList } from "./books/BookList";
+import { BookDetail } from "./books/BookDetail";
+import { BookForm } from "./books/BookForm";
+import { secondaryButton } from "./ui";
 
 export function App() {
   return (
@@ -16,7 +23,7 @@ export function App() {
         <AppRoutes />
       </AuthProvider>
     </BrowserRouter>
-  )
+  );
 }
 
 export function AppRoutes() {
@@ -33,12 +40,12 @@ export function AppRoutes() {
       </Route>
       <Route path="*" element={<Navigate to="/books" replace />} />
     </Routes>
-  )
+  );
 }
 
 function Shell() {
-  const { user, logout } = useAuth()
+  const { user, logout } = useAuth();
-  const [error, setError] = useState<string | null>(null)
+  const [error, setError] = useState<string | null>(null);
   return (
     <div className="min-h-screen bg-slate-50 text-slate-900">
       <header className="border-b border-slate-200 bg-white">
@@ -51,14 +58,19 @@ function Shell() {
             <button
               type="button"
               className={secondaryButton}
-              onClick={() => logout().catch((err) => setError(errorMessage(err)))}
+              onClick={() =>
+                logout().catch((err) => setError(errorMessage(err)))
+              }
             >
               Log out
             </button>
           </div>
         </div>
         {error && (
-          <p role="alert" className="mx-auto max-w-4xl px-4 pb-2 text-sm text-red-700">
+          <p
+            role="alert"
+            className="mx-auto max-w-4xl px-4 pb-2 text-sm text-red-700"
+          >
             {error}
           </p>
         )}
@@ -67,5 +79,5 @@ function Shell() {
         <Outlet />
       </main>
     </div>
-  )
+  );
 }

src/api.ts

@@ -1,54 +1,69 @@
-export type User = { id: number; username: string }
+export type User = { id: number; username: string };
-export type Genre = { id: number; name: string }
+export type Genre = { id: number; name: string };
-export type ReadingStatus = 'not_started' | 'reading' | 'finished'
+export type ReadingStatus = "not_started" | "reading" | "finished";
 export type Book = {
-  id: number
+  id: number;
-  title: string
+  title: string;
-  author: string
+  author: string;
-  genre: Genre
+  genre: Genre;
-  total_pages: number
+  total_pages: number;
-  current_page: number
+  current_page: number;
-  status: ReadingStatus
+  status: ReadingStatus;
-  created_at: string
+  created_at: string;
-  updated_at: string
+  updated_at: string;
-}
+};
-export type Note = { id: number; book_id: number; body: string; created_at: string; updated_at: string }
+export type Note = {
+  id: number;
+  book_id: number;
+  body: string;
+  created_at: string;
+  updated_at: string;
+};
 
 export class ApiError extends Error {
-  readonly status: number
+  readonly status: number;
-  readonly field?: string
+  readonly field?: string;
 
   constructor(status: number, message: string, field?: string) {
-    super(message)
+    super(message);
-    this.status = status
+    this.status = status;
-    this.field = field
+    this.field = field;
   }
 }
 
-let handleUnauthorized: () => void = () => {}
+let handleUnauthorized: () => void = () => {};
 
 export function setUnauthorizedHandler(handler: () => void) {
-  handleUnauthorized = handler
+  handleUnauthorized = handler;
 }
 
-export async function api<T>(method: 'GET' | 'POST' | 'PATCH' | 'DELETE', path: string, body?: unknown): Promise<T> {
+export async function api<T>(
+  method: "GET" | "POST" | "PATCH" | "DELETE",
+  path: string,
+  body?: unknown,
+): Promise<T> {
   const response = await fetch(`/api${path}`, {
     method,
-    credentials: 'same-origin',
+    credentials: "same-origin",
-    // Always JSON: the server rejects mutations without it (CSRF defense, ADR-0002).
+    headers: { "Content-Type": "application/json" },
-    headers: { 'Content-Type': 'application/json' },
     body: body === undefined ? undefined : JSON.stringify(body),
-  })
+  });
-  if (response.status === 204) return undefined as T
+  if (response.status === 204) return undefined as T;
-  const data = await response.json().catch(() => null)
+  const data = await response.json().catch(() => null);
   if (!response.ok) {
-    // 401s from /auth/* are expected answers (bad login, not signed in yet), not an expired session.
+    if (response.status === 401 && !path.startsWith("/auth/"))
-    if (response.status === 401 && !path.startsWith('/auth/')) handleUnauthorized()
+      handleUnauthorized();
-    throw new ApiError(response.status, data?.error ?? `Request failed with status ${response.status}`, data?.field)
+    throw new ApiError(
+      response.status,
+      data?.error ?? `Request failed with status ${response.status}`,
+      data?.field,
+    );
   }
-  return data as T
+  return data as T;
 }
 
 export function errorMessage(error: unknown): string {
-  return error instanceof ApiError ? error.message : 'Could not reach the server; check your connection and try again'
+  return error instanceof ApiError
+    ? error.message
+    : "Could not reach the server; check your connection and try again";
 }

src/auth/AuthContext.tsx

@@ -1,42 +1,52 @@
-import { createContext, useContext, useEffect, useState, type ReactNode } from 'react'
+import {
-import { api, setUnauthorizedHandler, type User } from '../api'
+  createContext,
+  useContext,
+  useEffect,
+  useState,
+  type ReactNode,
+} from "react";
+import { api, setUnauthorizedHandler, type User } from "../api";
 
 type AuthValue = {
-  user: User | null
+  user: User | null;
-  loading: boolean
+  loading: boolean;
-  login: (username: string, password: string) => Promise<void>
+  login: (username: string, password: string) => Promise<void>;
-  register: (username: string, password: string) => Promise<void>
+  register: (username: string, password: string) => Promise<void>;
-  logout: () => Promise<void>
+  logout: () => Promise<void>;
-}
+};
 
-const AuthContext = createContext<AuthValue | null>(null)
+const AuthContext = createContext<AuthValue | null>(null);
 
 export function AuthProvider({ children }: { children: ReactNode }) {
-  const [user, setUser] = useState<User | null>(null)
+  const [user, setUser] = useState<User | null>(null);
-  const [loading, setLoading] = useState(true)
+  const [loading, setLoading] = useState(true);
 
   useEffect(() => {
-    setUnauthorizedHandler(() => setUser(null))
+    setUnauthorizedHandler(() => setUser(null));
-    api<User>('GET', '/auth/me')
+    api<User>("GET", "/auth/me")
       .then(setUser, () => setUser(null))
-      .finally(() => setLoading(false))
+      .finally(() => setLoading(false));
-  }, [])
+  }, []);
 
   const value: AuthValue = {
     user,
     loading,
-    login: async (username, password) => setUser(await api<User>('POST', '/auth/login', { username, password })),
+    login: async (username, password) =>
-    register: async (username, password) => setUser(await api<User>('POST', '/auth/register', { username, password })),
+      setUser(await api<User>("POST", "/auth/login", { username, password })),
+    register: async (username, password) =>
+      setUser(
+        await api<User>("POST", "/auth/register", { username, password }),
+      ),
     logout: async () => {
-      await api('POST', '/auth/logout')
+      await api("POST", "/auth/logout");
-      setUser(null)
+      setUser(null);
     },
-  }
+  };
-  return <AuthContext value={value}>{children}</AuthContext>
+  return <AuthContext value={value}>{children}</AuthContext>;
 }
 
 export function useAuth(): AuthValue {
-  const value = useContext(AuthContext)
+  const value = useContext(AuthContext);
-  if (!value) throw new Error('useAuth must be used inside <AuthProvider>')
+  if (!value) throw new Error("useAuth must be used inside <AuthProvider>");
-  return value
+  return value;
 }

src/auth/LoginForm.tsx

@@ -1,42 +1,46 @@
-import { useState, type FormEvent } from 'react'
+import { useState, type FormEvent } from "react";
-import { Navigate, useLocation, type Location } from 'react-router'
+import { Navigate, useLocation, type Location } from "react-router";
-import { errorMessage } from '../api'
+import { errorMessage } from "../api";
-import { card, inputClass, labelText, primaryButton } from '../ui'
+import { card, inputClass, labelText, primaryButton } from "../ui";
-import { useAuth } from './AuthContext'
+import { useAuth } from "./AuthContext";
 
 export function LoginForm() {
-  const { user, login, register } = useAuth()
+  const { user, login, register } = useAuth();
-  const location = useLocation()
+  const location = useLocation();
-  const [mode, setMode] = useState<'login' | 'register'>('login')
+  const [mode, setMode] = useState<"login" | "register">("login");
-  const [username, setUsername] = useState('')
+  const [username, setUsername] = useState("");
-  const [password, setPassword] = useState('')
+  const [password, setPassword] = useState("");
-  const [error, setError] = useState<string | null>(null)
+  const [error, setError] = useState<string | null>(null);
-  const [busy, setBusy] = useState(false)
+  const [busy, setBusy] = useState(false);
 
   if (user) {
-    const from = (location.state as { from?: Location } | null)?.from
+    const from = (location.state as { from?: Location } | null)?.from;
-    return <Navigate to={from ? from.pathname + from.search : '/books'} replace />
+    return (
+      <Navigate to={from ? from.pathname + from.search : "/books"} replace />
+    );
   }
 
-  const isLogin = mode === 'login'
+  const isLogin = mode === "login";
 
   async function submit(event: FormEvent) {
-    event.preventDefault()
+    event.preventDefault();
-    setError(null)
+    setError(null);
-    setBusy(true)
+    setBusy(true);
     try {
-      await (isLogin ? login : register)(username, password)
+      await (isLogin ? login : register)(username, password);
     } catch (err) {
-      setError(errorMessage(err))
+      setError(errorMessage(err));
     } finally {
-      setBusy(false)
+      setBusy(false);
     }
   }
 
   return (
     <div className="min-h-screen bg-slate-50 px-4 pt-16">
       <main className={`mx-auto max-w-sm ${card}`}>
-        <h1 className="mb-4 text-2xl font-semibold">{isLogin ? 'Sign in' : 'Create account'}</h1>
+        <h1 className="mb-4 text-2xl font-semibold">
+          {isLogin ? "Sign in" : "Create account"}
+        </h1>
         <form onSubmit={submit} className="space-y-4">
           <label className="block">
             <span className={labelText}>Username</span>
@@ -46,7 +50,7 @@ export function LoginForm() {
               onChange={(e) => setUsername(e.target.value)}
               autoComplete="username"
               aria-invalid={error ? true : undefined}
-              aria-describedby={error ? 'login-error' : undefined}
+              aria-describedby={error ? "login-error" : undefined}
               required
             />
           </label>
@@ -57,10 +61,10 @@ export function LoginForm() {
               type="password"
               value={password}
               onChange={(e) => setPassword(e.target.value)}
-              autoComplete={isLogin ? 'current-password' : 'new-password'}
+              autoComplete={isLogin ? "current-password" : "new-password"}
               minLength={isLogin ? undefined : 12}
               aria-invalid={error ? true : undefined}
-              aria-describedby={error ? 'login-error' : undefined}
+              aria-describedby={error ? "login-error" : undefined}
               required
             />
           </label>
@@ -69,21 +73,25 @@ export function LoginForm() {
               {error}
             </p>
           )}
-          <button type="submit" disabled={busy} className={`${primaryButton} w-full`}>
+          <button
-            {isLogin ? 'Sign in' : 'Create account'}
+            type="submit"
+            disabled={busy}
+            className={`${primaryButton} w-full`}
+          >
+            {isLogin ? "Sign in" : "Create account"}
           </button>
         </form>
         <button
           type="button"
           className="mt-4 text-sm text-indigo-700 underline"
           onClick={() => {
-            setMode(isLogin ? 'register' : 'login')
+            setMode(isLogin ? "register" : "login");
-            setError(null)
+            setError(null);
           }}
         >
-          {isLogin ? 'Need an account? Register' : 'Have an account? Sign in'}
+          {isLogin ? "Need an account? Register" : "Have an account? Sign in"}
         </button>
       </main>
     </div>
-  )
+  );
 }

src/auth/RequireAuth.tsx

@@ -1,10 +1,10 @@
-import { Navigate, Outlet, useLocation } from 'react-router'
+import { Navigate, Outlet, useLocation } from "react-router";
-import { useAuth } from './AuthContext'
+import { useAuth } from "./AuthContext";
 
 export function RequireAuth() {
-  const { user, loading } = useAuth()
+  const { user, loading } = useAuth();
-  const location = useLocation()
+  const location = useLocation();
-  if (loading) return <p className="p-6 text-slate-500">Loading…</p>
+  if (loading) return <p className="p-6 text-slate-500">Loading…</p>;
-  if (!user) return <Navigate to="/login" replace state={{ from: location }} />
+  if (!user) return <Navigate to="/login" replace state={{ from: location }} />;
-  return <Outlet />
+  return <Outlet />;
 }

src/auth/auth.test.tsx

@@ -1,70 +1,110 @@
-import { screen } from '@testing-library/react'
+import { screen } from "@testing-library/react";
-import { describe, expect, it } from 'vitest'
+import { describe, expect, it } from "vitest";
-import { alice, dune, genres, mockApi, renderApp, signedIn } from '../test/helpers'
+import {
+  alice,
+  dune,
+  genres,
+  mockApi,
+  renderApp,
+  signedIn,
+} from "../test/helpers";
 
-describe('auth flow', () => {
+describe("auth flow", () => {
-  it('sends signed-out users to sign in, then back to the page they wanted', async () => {
+  it("sends signed-out users to sign in, then back to the page they wanted", async () => {
     const calls = mockApi({
-      'GET /api/auth/me': () => [401, { error: 'Not signed in or session expired; log in again' }],
+      "GET /api/auth/me": () => [
-      'POST /api/auth/login': () => [200, alice],
+        401,
-      'GET /api/genres': () => [200, genres],
+        { error: "Not signed in or session expired; log in again" },
-      'GET /api/books': () => [200, [dune]],
+      ],
-    })
+      "POST /api/auth/login": () => [200, alice],
-    const user = renderApp('/books?q=dune')
+      "GET /api/genres": () => [200, genres],
+      "GET /api/books": () => [200, [dune]],
+    });
+    const user = renderApp("/books?q=dune");
 
-    await screen.findByRole('heading', { name: 'Sign in' })
+    await screen.findByRole("heading", { name: "Sign in" });
-    await user.type(screen.getByLabelText('Username'), 'alice')
+    await user.type(screen.getByLabelText("Username"), "alice");
-    await user.type(screen.getByLabelText('Password'), 'correct horse battery')
+    await user.type(screen.getByLabelText("Password"), "correct horse battery");
-    await user.click(screen.getByRole('button', { name: 'Sign in' }))
+    await user.click(screen.getByRole("button", { name: "Sign in" }));
 
-    expect(await screen.findByLabelText('Search title or author')).toHaveValue('dune')
+    expect(await screen.findByLabelText("Search title or author")).toHaveValue(
+      "dune",
+    );
     expect(calls).toContainEqual({
-      method: 'POST',
+      method: "POST",
-      path: '/api/auth/login',
+      path: "/api/auth/login",
-      body: { username: 'alice', password: 'correct horse battery' },
+      body: { username: "alice", password: "correct horse battery" },
-    })
+    });
-  })
+  });
 
-  it('shows the server error for a bad login', async () => {
+  it("shows the server error for a bad login", async () => {
     mockApi({
-      'GET /api/auth/me': () => [401, { error: 'Not signed in' }],
+      "GET /api/auth/me": () => [401, { error: "Not signed in" }],
-      'POST /api/auth/login': () => [401, { error: 'Invalid username or password' }],
+      "POST /api/auth/login": () => [
-    })
+        401,
-    const user = renderApp('/login')
+        { error: "Invalid username or password" },
-    await user.type(await screen.findByLabelText('Username'), 'alice')
+      ],
-    await user.type(screen.getByLabelText('Password'), 'wrong password!')
+    });
-    await user.click(screen.getByRole('button', { name: 'Sign in' }))
+    const user = renderApp("/login");
-    expect(await screen.findByRole('alert')).toHaveTextContent('Invalid username or password')
+    await user.type(await screen.findByLabelText("Username"), "alice");
-    expect(screen.getByLabelText('Password')).toHaveAttribute('aria-describedby', 'login-error')
+    await user.type(screen.getByLabelText("Password"), "wrong password!");
-  })
+    await user.click(screen.getByRole("button", { name: "Sign in" }));
+    expect(await screen.findByRole("alert")).toHaveTextContent(
+      "Invalid username or password",
+    );
+    expect(screen.getByLabelText("Password")).toHaveAttribute(
+      "aria-describedby",
+      "login-error",
+    );
+  });
 
-  it('registers a new account', async () => {
+  it("registers a new account", async () => {
     const calls = mockApi({
-      'GET /api/auth/me': () => [401, { error: 'Not signed in' }],
+      "GET /api/auth/me": () => [401, { error: "Not signed in" }],
-      'POST /api/auth/register': () => [201, alice],
+      "POST /api/auth/register": () => [201, alice],
-      'GET /api/genres': () => [200, genres],
+      "GET /api/genres": () => [200, genres],
-      'GET /api/books': () => [200, []],
+      "GET /api/books": () => [200, []],
-    })
+    });
-    const user = renderApp('/login')
+    const user = renderApp("/login");
-    await user.click(await screen.findByRole('button', { name: 'Need an account? Register' }))
+    await user.click(
-    await user.type(screen.getByLabelText('Username'), 'alice')
+      await screen.findByRole("button", { name: "Need an account? Register" }),
-    await user.type(screen.getByLabelText('Password'), 'correct horse battery')
+    );
-    await user.click(screen.getByRole('button', { name: 'Create account' }))
+    await user.type(screen.getByLabelText("Username"), "alice");
-    expect(await screen.findByText('No books yet. Add your first one.')).toBeInTheDocument()
+    await user.type(screen.getByLabelText("Password"), "correct horse battery");
-    expect(calls.some((c) => c.method === 'POST' && c.path === '/api/auth/register')).toBe(true)
+    await user.click(screen.getByRole("button", { name: "Create account" }));
-  })
+    expect(
+      await screen.findByText("No books yet. Add your first one."),
+    ).toBeInTheDocument();
+    expect(
+      calls.some((c) => c.method === "POST" && c.path === "/api/auth/register"),
+    ).toBe(true);
+  });
 
-  it('returns to sign in when the session expires mid-use', async () => {
+  it("returns to sign in when the session expires mid-use", async () => {
-    signedIn({ 'GET /api/books': () => [401, { error: 'Not signed in or session expired; log in again' }] })
+    signedIn({
-    renderApp('/books')
+      "GET /api/books": () => [
-    expect(await screen.findByRole('heading', { name: 'Sign in' })).toBeInTheDocument()
+        401,
-  })
+        { error: "Not signed in or session expired; log in again" },
+      ],
+    });
+    renderApp("/books");
+    expect(
+      await screen.findByRole("heading", { name: "Sign in" }),
+    ).toBeInTheDocument();
+  });
 
-  it('logs out', async () => {
+  it("logs out", async () => {
-    const calls = signedIn({ 'GET /api/books': () => [200, []], 'POST /api/auth/logout': () => [204] })
+    const calls = signedIn({
-    const user = renderApp('/books')
+      "GET /api/books": () => [200, []],
-    await user.click(await screen.findByRole('button', { name: 'Log out' }))
+      "POST /api/auth/logout": () => [204],
-    expect(await screen.findByRole('heading', { name: 'Sign in' })).toBeInTheDocument()
+    });
-    expect(calls.some((c) => c.method === 'POST' && c.path === '/api/auth/logout')).toBe(true)
+    const user = renderApp("/books");
-  })
+    await user.click(await screen.findByRole("button", { name: "Log out" }));
-})
+    expect(
+      await screen.findByRole("heading", { name: "Sign in" }),
+    ).toBeInTheDocument();
+    expect(
+      calls.some((c) => c.method === "POST" && c.path === "/api/auth/logout"),
+    ).toBe(true);
+  });
+});

src/books/BookDetail.test.tsx

@@ -1,72 +1,112 @@
-import { screen, waitFor } from '@testing-library/react'
+import { screen, waitFor } from "@testing-library/react";
-import { describe, expect, it } from 'vitest'
+import { describe, expect, it } from "vitest";
-import type { Book } from '../api'
+import type { Book } from "../api";
-import { dune, renderApp, signedIn } from '../test/helpers'
+import { dune, renderApp, signedIn } from "../test/helpers";
 
 function withProgress(current_page: number): Book {
-  const status = current_page === 0 ? 'not_started' : current_page === dune.total_pages ? 'finished' : 'reading'
+  const status =
-  return { ...dune, current_page, status }
+    current_page === 0
+      ? "not_started"
+      : current_page === dune.total_pages
+        ? "finished"
+        : "reading";
+  return { ...dune, current_page, status };
 }
 
-describe('BookDetail', () => {
+describe("BookDetail", () => {
-  it('updates progress and reflects it in the bar', async () => {
+  it("updates progress and reflects it in the bar", async () => {
     const calls = signedIn({
-      'GET /api/books/7': () => [200, dune],
+      "GET /api/books/7": () => [200, dune],
-      'PATCH /api/books/7': ({ body }) => [200, withProgress((body as { current_page: number }).current_page)],
+      "PATCH /api/books/7": ({ body }) => [
-    })
+        200,
-    const user = renderApp('/books/7')
+        withProgress((body as { current_page: number }).current_page),
-    expect(await screen.findByText('142 / 380 (37%)')).toBeInTheDocument()
+      ],
+    });
+    const user = renderApp("/books/7");
+    expect(await screen.findByText("142 / 380 (37%)")).toBeInTheDocument();
 
-    const input = screen.getByLabelText('Current page')
+    const input = screen.getByLabelText("Current page");
-    await user.clear(input)
+    await user.clear(input);
-    await user.type(input, '200')
+    await user.type(input, "200");
-    await user.click(screen.getByRole('button', { name: 'Save progress' }))
+    await user.click(screen.getByRole("button", { name: "Save progress" }));
 
-    expect(await screen.findByText('200 / 380 (53%)')).toBeInTheDocument()
+    expect(await screen.findByText("200 / 380 (53%)")).toBeInTheDocument();
-    expect(calls).toContainEqual({ method: 'PATCH', path: '/api/books/7', body: { current_page: 200 } })
+    expect(calls).toContainEqual({
-  })
+      method: "PATCH",
+      path: "/api/books/7",
+      body: { current_page: 200 },
+    });
+  });
 
-  it('marks a book finished', async () => {
+  it("marks a book finished", async () => {
     signedIn({
-      'GET /api/books/7': () => [200, dune],
+      "GET /api/books/7": () => [200, dune],
-      'PATCH /api/books/7': () => [200, withProgress(380)],
+      "PATCH /api/books/7": () => [200, withProgress(380)],
-    })
+    });
-    const user = renderApp('/books/7')
+    const user = renderApp("/books/7");
-    await user.click(await screen.findByRole('button', { name: 'Mark finished' }))
+    await user.click(
-    expect(await screen.findByText('380 / 380 (100%)')).toBeInTheDocument()
+      await screen.findByRole("button", { name: "Mark finished" }),
-    expect(screen.getByText('Finished')).toBeInTheDocument()
+    );
-  })
+    expect(await screen.findByText("380 / 380 (100%)")).toBeInTheDocument();
+    expect(screen.getByText("Finished")).toBeInTheDocument();
+  });
 
-  it('shows the server message when a progress update is rejected', async () => {
+  it("shows the server message when a progress update is rejected", async () => {
     signedIn({
-      'GET /api/books/7': () => [200, dune],
+      "GET /api/books/7": () => [200, dune],
-      'PATCH /api/books/7': () => [400, { error: 'current_page must be between 0 and 100000', field: 'current_page' }],
+      "PATCH /api/books/7": () => [
-    })
+        400,
-    const user = renderApp('/books/7')
+        {
-    await user.click(await screen.findByRole('button', { name: 'Save progress' }))
+          error: "current_page must be between 0 and 100000",
-    // findByText, not findByRole('alert'): once Task 11 mounts the journal, the page may show more than one alert.
+          field: "current_page",
-    expect(await screen.findByText('current_page must be between 0 and 100000')).toHaveAttribute('role', 'alert')
+        },
-    expect(screen.getByLabelText('Current page')).toHaveAttribute('aria-invalid', 'true')
+      ],
-  })
+    });
+    const user = renderApp("/books/7");
+    await user.click(
+      await screen.findByRole("button", { name: "Save progress" }),
+    );
+    expect(
+      await screen.findByText("current_page must be between 0 and 100000"),
+    ).toHaveAttribute("role", "alert");
+    expect(screen.getByLabelText("Current page")).toHaveAttribute(
+      "aria-invalid",
+      "true",
+    );
+  });
 
-  it('shows not found for a missing or foreign book', async () => {
+  it("shows not found for a missing or foreign book", async () => {
-    signedIn({ 'GET /api/books/999': () => [404, { error: 'Book not found' }] })
+    signedIn({
-    renderApp('/books/999')
+      "GET /api/books/999": () => [404, { error: "Book not found" }],
-    expect(await screen.findByRole('heading', { name: 'Book not found' })).toBeInTheDocument()
+    });
-    expect(screen.getByRole('link', { name: /back to library/i })).toHaveAttribute('href', '/books')
+    renderApp("/books/999");
-  })
+    expect(
+      await screen.findByRole("heading", { name: "Book not found" }),
+    ).toBeInTheDocument();
+    expect(
+      screen.getByRole("link", { name: /back to library/i }),
+    ).toHaveAttribute("href", "/books");
+  });
 
-  it('deletes after confirmation and returns to the list', async () => {
+  it("deletes after confirmation and returns to the list", async () => {
     const calls = signedIn({
-      'GET /api/books/7': () => [200, dune],
+      "GET /api/books/7": () => [200, dune],
-      'DELETE /api/books/7': () => [204],
+      "DELETE /api/books/7": () => [204],
-      'GET /api/books': () => [200, []],
+      "GET /api/books": () => [200, []],
-    })
+    });
-    const user = renderApp('/books/7')
+    const user = renderApp("/books/7");
-    await user.click(await screen.findByRole('button', { name: 'Delete book' }))
+    await user.click(
-    expect(screen.getByRole('dialog')).toHaveTextContent('Delete “Dune”?')
+      await screen.findByRole("button", { name: "Delete book" }),
-    await user.click(screen.getByRole('button', { name: 'Yes, delete' }))
+    );
-    expect(await screen.findByText('No books yet. Add your first one.')).toBeInTheDocument()
+    expect(screen.getByRole("dialog")).toHaveTextContent("Delete “Dune”?");
-    await waitFor(() => expect(calls.some((c) => c.method === 'DELETE' && c.path === '/api/books/7')).toBe(true))
+    await user.click(screen.getByRole("button", { name: "Yes, delete" }));
-  })
+    expect(
-})
+      await screen.findByText("No books yet. Add your first one."),
+    ).toBeInTheDocument();
+    await waitFor(() =>
+      expect(
+        calls.some((c) => c.method === "DELETE" && c.path === "/api/books/7"),
+      ).toBe(true),
+    );
+  });
+});

src/books/BookDetail.tsx

@@ -1,86 +1,109 @@
-import { useEffect, useState, type FormEvent } from 'react'
+import { useEffect, useState, type FormEvent } from "react";
-import { Link, useNavigate, useParams } from 'react-router'
+import { Link, useNavigate, useParams } from "react-router";
-import { api, ApiError, errorMessage, type Book } from '../api'
+import { api, ApiError, errorMessage, type Book } from "../api";
-import { card, dangerButton, inputClass, labelText, primaryButton, secondaryButton } from '../ui'
+import {
-import { NotesJournal } from '../notes/NotesJournal'
+  card,
-import { ProgressBar, StatusBadge } from './Progress'
+  dangerButton,
+  inputClass,
+  labelText,
+  primaryButton,
+  secondaryButton,
+} from "../ui";
+import { NotesJournal } from "../notes/NotesJournal";
+import { ProgressBar, StatusBadge } from "./Progress";
 
 export function BookDetail() {
-  const { id } = useParams()
+  const { id } = useParams();
-  const navigate = useNavigate()
+  const navigate = useNavigate();
-  const [book, setBook] = useState<Book | null>(null)
+  const [book, setBook] = useState<Book | null>(null);
-  const [loadError, setLoadError] = useState<{ notFound: boolean; message: string } | null>(null)
+  const [loadError, setLoadError] = useState<{
-  const [attempt, setAttempt] = useState(0)
+    notFound: boolean;
-  const [page, setPage] = useState('')
+    message: string;
-  const [progressError, setProgressError] = useState<string | null>(null)
+  } | null>(null);
-  const [confirmingDelete, setConfirmingDelete] = useState(false)
+  const [attempt, setAttempt] = useState(0);
-  const [deleteError, setDeleteError] = useState<string | null>(null)
+  const [page, setPage] = useState("");
+  const [progressError, setProgressError] = useState<string | null>(null);
+  const [confirmingDelete, setConfirmingDelete] = useState(false);
+  const [deleteError, setDeleteError] = useState<string | null>(null);
 
   useEffect(() => {
-    let cancelled = false
+    let cancelled = false;
-    setLoadError(null)
+    setLoadError(null);
-    api<Book>('GET', `/books/${id}`).then(
+    api<Book>("GET", `/books/${id}`).then(
       (found) => {
-        if (cancelled) return
+        if (cancelled) return;
-        setBook(found)
+        setBook(found);
-        setPage(String(found.current_page))
+        setPage(String(found.current_page));
       },
       (err) => {
-        if (!cancelled) setLoadError({ notFound: err instanceof ApiError && err.status === 404, message: errorMessage(err) })
+        if (!cancelled)
+          setLoadError({
+            notFound: err instanceof ApiError && err.status === 404,
+            message: errorMessage(err),
+          });
       },
-    )
+    );
     return () => {
-      cancelled = true
+      cancelled = true;
-    }
+    };
-  }, [id, attempt])
+  }, [id, attempt]);
 
   if (loadError?.notFound) {
     return (
       <div className={card}>
         <h1 className="text-xl font-semibold">Book not found</h1>
-        <Link to="/books" className="mt-2 inline-block text-indigo-700 underline">
+        <Link
+          to="/books"
+          className="mt-2 inline-block text-indigo-700 underline"
+        >
           ← Back to library
         </Link>
       </div>
-    )
+    );
   }
   if (loadError) {
     return (
       <div role="alert" className="flex items-center gap-3 text-red-700">
         <span>{loadError.message}</span>
-        <button type="button" className={secondaryButton} onClick={() => setAttempt((n) => n + 1)}>
+        <button
+          type="button"
+          className={secondaryButton}
+          onClick={() => setAttempt((n) => n + 1)}
+        >
           Retry
         </button>
       </div>
-    )
+    );
   }
-  if (!book) return <p className="text-slate-500">Loading…</p>
+  if (!book) return <p className="text-slate-500">Loading…</p>;
-  const current = book
+  const current = book;
 
   async function saveProgress(currentPage: number) {
-    setProgressError(null)
+    setProgressError(null);
     try {
-      const updated = await api<Book>('PATCH', `/books/${current.id}`, { current_page: currentPage })
+      const updated = await api<Book>("PATCH", `/books/${current.id}`, {
-      setBook(updated)
+        current_page: currentPage,
-      setPage(String(updated.current_page))
+      });
+      setBook(updated);
+      setPage(String(updated.current_page));
     } catch (err) {
-      setProgressError(errorMessage(err))
+      setProgressError(errorMessage(err));
     }
   }
 
   async function deleteBook() {
-    setDeleteError(null)
+    setDeleteError(null);
     try {
-      await api('DELETE', `/books/${current.id}`)
+      await api("DELETE", `/books/${current.id}`);
-      navigate('/books', { replace: true })
+      navigate("/books", { replace: true });
     } catch (err) {
-      setDeleteError(errorMessage(err))
+      setDeleteError(errorMessage(err));
     }
   }
 
   function submitProgress(event: FormEvent) {
-    event.preventDefault()
+    event.preventDefault();
-    void saveProgress(Number(page))
+    void saveProgress(Number(page));
   }
 
   return (
@@ -97,7 +120,10 @@ export function BookDetail() {
           <StatusBadge status={book.status} />
         </div>
         <ProgressBar book={book} />
-        <form onSubmit={submitProgress} className="mt-4 flex flex-wrap items-end gap-2">
+        <form
+          onSubmit={submitProgress}
+          className="mt-4 flex flex-wrap items-end gap-2"
+        >
           <label>
             <span className={labelText}>Current page</span>
             <input
@@ -109,7 +135,7 @@ export function BookDetail() {
               onChange={(e) => setPage(e.target.value)}
               required
               aria-invalid={progressError ? true : undefined}
-              aria-describedby={progressError ? 'progress-error' : undefined}
+              aria-describedby={progressError ? "progress-error" : undefined}
             />
           </label>
           <button type="submit" className={primaryButton}>
@@ -125,7 +151,11 @@ export function BookDetail() {
           </button>
         </form>
         {progressError && (
-          <p id="progress-error" role="alert" className="mt-2 text-sm text-red-700">
+          <p
+            id="progress-error"
+            role="alert"
+            className="mt-2 text-sm text-red-700"
+          >
             {progressError}
           </p>
         )}
@@ -133,18 +163,34 @@ export function BookDetail() {
           <Link to={`/books/${book.id}/edit`} className={secondaryButton}>
             Edit
           </Link>
-          <button type="button" className={dangerButton} onClick={() => setConfirmingDelete(true)}>
+          <button
+            type="button"
+            className={dangerButton}
+            onClick={() => setConfirmingDelete(true)}
+          >
             Delete book
           </button>
         </div>
         {confirmingDelete && (
-          <dialog open aria-labelledby="delete-prompt" className={`relative mt-4 ${card} ring-2 ring-red-200`}>
+          <dialog
+            open
+            aria-labelledby="delete-prompt"
+            className={`relative mt-4 ${card} ring-2 ring-red-200`}
+          >
             <p id="delete-prompt">{`Delete “${book.title}”? This also deletes its reading journal.`}</p>
             <div className="mt-3 flex gap-2">
-              <button type="button" className={dangerButton} onClick={() => void deleteBook()}>
+              <button
+                type="button"
+                className={dangerButton}
+                onClick={() => void deleteBook()}
+              >
                 Yes, delete
               </button>
-              <button type="button" className={secondaryButton} onClick={() => setConfirmingDelete(false)}>
+              <button
+                type="button"
+                className={secondaryButton}
+                onClick={() => setConfirmingDelete(false)}
+              >
                 Cancel
               </button>
             </div>
@@ -158,5 +204,5 @@ export function BookDetail() {
       </header>
       <NotesJournal bookId={book.id} />
     </article>
-  )
+  );
 }

src/books/BookForm.test.tsx

@@ -1,76 +1,107 @@
-import { screen } from '@testing-library/react'
+import { screen } from "@testing-library/react";
-import { describe, expect, it } from 'vitest'
+import { describe, expect, it } from "vitest";
-import { dune, renderApp, signedIn } from '../test/helpers'
+import { dune, renderApp, signedIn } from "../test/helpers";
 
-const fresh = { ...dune, current_page: 0, status: 'not_started' as const }
+const fresh = { ...dune, current_page: 0, status: "not_started" as const };
 
-describe('BookForm', () => {
+describe("BookForm", () => {
-  it('adds a book and opens it', async () => {
+  it("adds a book and opens it", async () => {
     const calls = signedIn({
-      'POST /api/books': () => [201, fresh],
+      "POST /api/books": () => [201, fresh],
-      'GET /api/books/7': () => [200, fresh],
+      "GET /api/books/7": () => [200, fresh],
-    })
+    });
-    const user = renderApp('/books/new')
+    const user = renderApp("/books/new");
-    await screen.findByRole('option', { name: 'Science Fiction' })
+    await screen.findByRole("option", { name: "Science Fiction" });
-    await user.type(screen.getByLabelText('Title'), 'Dune')
+    await user.type(screen.getByLabelText("Title"), "Dune");
-    await user.type(screen.getByLabelText('Author'), 'Frank Herbert')
+    await user.type(screen.getByLabelText("Author"), "Frank Herbert");
-    await user.selectOptions(screen.getByLabelText('Genre'), 'Science Fiction')
+    await user.selectOptions(screen.getByLabelText("Genre"), "Science Fiction");
-    await user.type(screen.getByLabelText('Total pages'), '380')
+    await user.type(screen.getByLabelText("Total pages"), "380");
-    await user.click(screen.getByRole('button', { name: 'Add book' }))
+    await user.click(screen.getByRole("button", { name: "Add book" }));
 
-    expect(await screen.findByRole('heading', { name: 'Dune', level: 1 })).toBeInTheDocument()
+    expect(
+      await screen.findByRole("heading", { name: "Dune", level: 1 }),
+    ).toBeInTheDocument();
     expect(calls).toContainEqual({
-      method: 'POST',
+      method: "POST",
-      path: '/api/books',
+      path: "/api/books",
-      body: { title: 'Dune', author: 'Frank Herbert', genre_id: 5, total_pages: 380, current_page: 0 },
+      body: {
-    })
+        title: "Dune",
-  })
+        author: "Frank Herbert",
-
+        genre_id: 5,
-  it('shows a server validation error against the field', async () => {
+        total_pages: 380,
-    signedIn({ 'POST /api/books': () => [400, { error: 'Unknown genre_id; see GET /api/genres', field: 'genre_id' }] })
+        current_page: 0,
-    const user = renderApp('/books/new')
-    await screen.findByRole('option', { name: 'Science Fiction' })
-    await user.type(screen.getByLabelText('Title'), 'Dune')
-    await user.type(screen.getByLabelText('Author'), 'Frank Herbert')
-    await user.selectOptions(screen.getByLabelText('Genre'), 'Science Fiction')
-    await user.type(screen.getByLabelText('Total pages'), '380')
-    await user.click(screen.getByRole('button', { name: 'Add book' }))
-
-    expect(await screen.findByRole('alert')).toHaveTextContent('Unknown genre_id')
-    expect(screen.getByLabelText('Genre')).toHaveAttribute('aria-invalid', 'true')
-  })
-
-  it('edits an existing book', async () => {
-    let saved = dune
-    const calls = signedIn({
-      'GET /api/books/7': () => [200, saved],
-      'PATCH /api/books/7': ({ body }) => {
-        saved = { ...saved, ...(body as object) }
-        return [200, saved]
       },
-    })
+    });
-    const user = renderApp('/books/7/edit')
+  });
-    const title = await screen.findByDisplayValue('Dune')
-    await user.clear(title)
-    await user.type(title, 'Dune Messiah')
-    await user.click(screen.getByRole('button', { name: 'Save changes' }))
 
-    expect(await screen.findByRole('heading', { name: 'Dune Messiah', level: 1 })).toBeInTheDocument()
+  it("shows a server validation error against the field", async () => {
-    expect(calls).toContainEqual({
-      method: 'PATCH',
-      path: '/api/books/7',
-      body: { title: 'Dune Messiah', author: 'Frank Herbert', genre_id: 5, total_pages: 380, current_page: 142 },
-    })
-  })
-
-  it('retries a failed load and shows the prefilled form', async () => {
-    let attempts = 0
     signedIn({
-      'GET /api/books/7': () => (++attempts === 1 ? [500, { error: 'Database unavailable' }] : [200, dune]),
+      "POST /api/books": () => [
-    })
+        400,
-    const user = renderApp('/books/7/edit')
+        { error: "Unknown genre_id; see GET /api/genres", field: "genre_id" },
-    expect(await screen.findByRole('alert')).toHaveTextContent('Database unavailable')
+      ],
-    await user.click(screen.getByRole('button', { name: 'Retry' }))
+    });
-    expect(await screen.findByLabelText('Title')).toHaveValue('Dune')
+    const user = renderApp("/books/new");
-  })
+    await screen.findByRole("option", { name: "Science Fiction" });
-})
+    await user.type(screen.getByLabelText("Title"), "Dune");
+    await user.type(screen.getByLabelText("Author"), "Frank Herbert");
+    await user.selectOptions(screen.getByLabelText("Genre"), "Science Fiction");
+    await user.type(screen.getByLabelText("Total pages"), "380");
+    await user.click(screen.getByRole("button", { name: "Add book" }));
+
+    expect(await screen.findByRole("alert")).toHaveTextContent(
+      "Unknown genre_id",
+    );
+    expect(screen.getByLabelText("Genre")).toHaveAttribute(
+      "aria-invalid",
+      "true",
+    );
+  });
+
+  it("edits an existing book", async () => {
+    let saved = dune;
+    const calls = signedIn({
+      "GET /api/books/7": () => [200, saved],
+      "PATCH /api/books/7": ({ body }) => {
+        saved = { ...saved, ...(body as object) };
+        return [200, saved];
+      },
+    });
+    const user = renderApp("/books/7/edit");
+    const title = await screen.findByDisplayValue("Dune");
+    await user.clear(title);
+    await user.type(title, "Dune Messiah");
+    await user.click(screen.getByRole("button", { name: "Save changes" }));
+
+    expect(
+      await screen.findByRole("heading", { name: "Dune Messiah", level: 1 }),
+    ).toBeInTheDocument();
+    expect(calls).toContainEqual({
+      method: "PATCH",
+      path: "/api/books/7",
+      body: {
+        title: "Dune Messiah",
+        author: "Frank Herbert",
+        genre_id: 5,
+        total_pages: 380,
+        current_page: 142,
+      },
+    });
+  });
+
+  it("retries a failed load and shows the prefilled form", async () => {
+    let attempts = 0;
+    signedIn({
+      "GET /api/books/7": () =>
+        ++attempts === 1
+          ? [500, { error: "Database unavailable" }]
+          : [200, dune],
+    });
+    const user = renderApp("/books/7/edit");
+    expect(await screen.findByRole("alert")).toHaveTextContent(
+      "Database unavailable",
+    );
+    await user.click(screen.getByRole("button", { name: "Retry" }));
+    expect(await screen.findByLabelText("Title")).toHaveValue("Dune");
+  });
+});

src/books/BookForm.tsx

@@ -1,81 +1,105 @@
-import { useEffect, useState, type FormEvent } from 'react'
+import { useEffect, useState, type FormEvent } from "react";
-import { Link, useNavigate, useParams } from 'react-router'
+import { Link, useNavigate, useParams } from "react-router";
-import { api, ApiError, errorMessage, type Book } from '../api'
+import { api, ApiError, errorMessage, type Book } from "../api";
-import { card, inputClass, labelText, primaryButton, secondaryButton } from '../ui'
+import {
-import { useGenres } from './useGenres'
+  card,
+  inputClass,
+  labelText,
+  primaryButton,
+  secondaryButton,
+} from "../ui";
+import { useGenres } from "./useGenres";
 
-type Fields = { title: string; author: string; genre_id: string; total_pages: string; current_page: string }
+type Fields = {
-type FormError = { message: string; field?: string }
+  title: string;
+  author: string;
+  genre_id: string;
+  total_pages: string;
+  current_page: string;
+};
+type FormError = { message: string; field?: string };
 
-const EMPTY: Fields = { title: '', author: '', genre_id: '', total_pages: '', current_page: '0' }
+const EMPTY: Fields = {
+  title: "",
+  author: "",
+  genre_id: "",
+  total_pages: "",
+  current_page: "0",
+};
 
 export function BookForm() {
-  const { id } = useParams()
+  const { id } = useParams();
-  const editing = id !== undefined
+  const editing = id !== undefined;
-  const navigate = useNavigate()
+  const navigate = useNavigate();
-  const { genres, error: genresError } = useGenres()
+  const { genres, error: genresError } = useGenres();
-  const [fields, setFields] = useState<Fields>(EMPTY)
+  const [fields, setFields] = useState<Fields>(EMPTY);
-  const [loading, setLoading] = useState(editing)
+  const [loading, setLoading] = useState(editing);
-  const [loadError, setLoadError] = useState<string | null>(null)
+  const [loadError, setLoadError] = useState<string | null>(null);
-  const [error, setError] = useState<FormError | null>(null)
+  const [error, setError] = useState<FormError | null>(null);
-  const [busy, setBusy] = useState(false)
+  const [busy, setBusy] = useState(false);
-  const [attempt, setAttempt] = useState(0)
+  const [attempt, setAttempt] = useState(0);
 
   useEffect(() => {
-    if (!editing) return
+    if (!editing) return;
-    let cancelled = false
+    let cancelled = false;
-    setLoadError(null)
+    setLoadError(null);
-    setLoading(true)
+    setLoading(true);
-    api<Book>('GET', `/books/${id}`).then(
+    api<Book>("GET", `/books/${id}`).then(
       (book) => {
-        if (cancelled) return
+        if (cancelled) return;
         setFields({
           title: book.title,
           author: book.author,
           genre_id: String(book.genre.id),
           total_pages: String(book.total_pages),
           current_page: String(book.current_page),
-        })
+        });
-        setLoading(false)
+        setLoading(false);
       },
       (err) => {
-        if (cancelled) return
+        if (cancelled) return;
-        setLoadError(errorMessage(err))
+        setLoadError(errorMessage(err));
-        setLoading(false)
+        setLoading(false);
       },
-    )
+    );
     return () => {
-      cancelled = true
+      cancelled = true;
-    }
+    };
-  }, [editing, id, attempt])
+  }, [editing, id, attempt]);
 
   function set(name: keyof Fields) {
-    return (event: { target: { value: string } }) => setFields((prev) => ({ ...prev, [name]: event.target.value }))
+    return (event: { target: { value: string } }) =>
+      setFields((prev) => ({ ...prev, [name]: event.target.value }));
   }
 
   function invalid(name: keyof Fields) {
-    return error?.field === name ? { 'aria-invalid': true, 'aria-describedby': 'form-error' } : {}
+    return error?.field === name
+      ? { "aria-invalid": true, "aria-describedby": "form-error" }
+      : {};
   }
 
   async function submit(event: FormEvent) {
-    event.preventDefault()
+    event.preventDefault();
-    setError(null)
+    setError(null);
-    setBusy(true)
+    setBusy(true);
     const payload = {
       title: fields.title,
       author: fields.author,
       genre_id: Number(fields.genre_id),
       total_pages: Number(fields.total_pages),
       current_page: Number(fields.current_page),
-    }
+    };
     try {
       const saved = editing
-        ? await api<Book>('PATCH', `/books/${id}`, payload)
+        ? await api<Book>("PATCH", `/books/${id}`, payload)
-        : await api<Book>('POST', '/books', payload)
+        : await api<Book>("POST", "/books", payload);
-      navigate(`/books/${saved.id}`)
+      navigate(`/books/${saved.id}`);
     } catch (err) {
-      setError({ message: errorMessage(err), field: err instanceof ApiError ? err.field : undefined })
+      setError({
-      setBusy(false)
+        message: errorMessage(err),
+        field: err instanceof ApiError ? err.field : undefined,
+      });
+      setBusy(false);
     }
   }
 
@@ -84,7 +108,11 @@ export function BookForm() {
       <div role="alert" className={card}>
         <p className="text-red-700">{loadError}</p>
         <div className="mt-2 flex items-center gap-3">
-          <button type="button" className={secondaryButton} onClick={() => setAttempt((n) => n + 1)}>
+          <button
+            type="button"
+            className={secondaryButton}
+            onClick={() => setAttempt((n) => n + 1)}
+          >
             Retry
           </button>
           <Link to="/books" className="text-indigo-700 underline">
@@ -92,24 +120,46 @@ export function BookForm() {
           </Link>
         </div>
       </div>
-    )
+    );
   }
-  if (loading) return <p className="text-slate-500">Loading…</p>
+  if (loading) return <p className="text-slate-500">Loading…</p>;
 
   return (
     <form onSubmit={submit} className={`space-y-4 ${card}`}>
-      <h1 className="text-2xl font-semibold">{editing ? 'Edit book' : 'Add a book'}</h1>
+      <h1 className="text-2xl font-semibold">
+        {editing ? "Edit book" : "Add a book"}
+      </h1>
       <label className="block">
         <span className={labelText}>Title</span>
-        <input className={inputClass} value={fields.title} onChange={set('title')} maxLength={500} required {...invalid('title')} />
+        <input
+          className={inputClass}
+          value={fields.title}
+          onChange={set("title")}
+          maxLength={500}
+          required
+          {...invalid("title")}
+        />
       </label>
       <label className="block">
         <span className={labelText}>Author</span>
-        <input className={inputClass} value={fields.author} onChange={set('author')} maxLength={500} required {...invalid('author')} />
+        <input
+          className={inputClass}
+          value={fields.author}
+          onChange={set("author")}
+          maxLength={500}
+          required
+          {...invalid("author")}
+        />
       </label>
       <label className="block">
         <span className={labelText}>Genre</span>
-        <select className={inputClass} value={fields.genre_id} onChange={set('genre_id')} required {...invalid('genre_id')}>
+        <select
+          className={inputClass}
+          value={fields.genre_id}
+          onChange={set("genre_id")}
+          required
+          {...invalid("genre_id")}
+        >
           <option value="">Choose a genre</option>
           {genres.map((g) => (
             <option key={g.id} value={String(g.id)}>
@@ -118,7 +168,12 @@ export function BookForm() {
           ))}
         </select>
       </label>
-      {genresError && <p role="alert" className="text-sm text-red-700">{`Could not load genres: ${genresError}`}</p>}
+      {genresError && (
+        <p
+          role="alert"
+          className="text-sm text-red-700"
+        >{`Could not load genres: ${genresError}`}</p>
+      )}
       <div className="flex gap-4">
         <label className="block">
           <span className={labelText}>Total pages</span>
@@ -128,9 +183,9 @@ export function BookForm() {
             min={1}
             max={100000}
             value={fields.total_pages}
-            onChange={set('total_pages')}
+            onChange={set("total_pages")}
             required
-            {...invalid('total_pages')}
+            {...invalid("total_pages")}
           />
         </label>
         <label className="block">
@@ -141,9 +196,9 @@ export function BookForm() {
             min={0}
             max={fields.total_pages || undefined}
             value={fields.current_page}
-            onChange={set('current_page')}
+            onChange={set("current_page")}
             required
-            {...invalid('current_page')}
+            {...invalid("current_page")}
           />
         </label>
       </div>
@@ -154,12 +209,15 @@ export function BookForm() {
       )}
       <div className="flex gap-2">
         <button type="submit" disabled={busy} className={primaryButton}>
-          {editing ? 'Save changes' : 'Add book'}
+          {editing ? "Save changes" : "Add book"}
         </button>
-        <Link to={editing ? `/books/${id}` : '/books'} className={secondaryButton}>
+        <Link
+          to={editing ? `/books/${id}` : "/books"}
+          className={secondaryButton}
+        >
           Cancel
         </Link>
       </div>
     </form>
-  )
+  );
 }

src/books/BookList.test.tsx

@@ -1,58 +1,86 @@
-import { screen, waitFor } from '@testing-library/react'
+import { screen, waitFor } from "@testing-library/react";
-import { describe, expect, it } from 'vitest'
+import { describe, expect, it } from "vitest";
-import { dune, renderApp, signedIn } from '../test/helpers'
+import { dune, renderApp, signedIn } from "../test/helpers";
 
-describe('BookList', () => {
+describe("BookList", () => {
-  it('shows each book with author, genre, status, and progress', async () => {
+  it("shows each book with author, genre, status, and progress", async () => {
-    signedIn({ 'GET /api/books': () => [200, [dune]] })
+    signedIn({ "GET /api/books": () => [200, [dune]] });
-    renderApp('/books')
+    renderApp("/books");
-    expect(await screen.findByRole('heading', { name: 'Dune' })).toBeInTheDocument()
+    expect(
-    expect(screen.getByText('Frank Herbert · Science Fiction')).toBeInTheDocument()
+      await screen.findByRole("heading", { name: "Dune" }),
-    expect(screen.getByText('Reading')).toBeInTheDocument()
+    ).toBeInTheDocument();
-    expect(screen.getByText('142 / 380 (37%)')).toBeInTheDocument()
+    expect(
-    expect(screen.getByRole('link', { name: /Dune/ })).toHaveAttribute('href', '/books/7')
+      screen.getByText("Frank Herbert · Science Fiction"),
-  })
+    ).toBeInTheDocument();
+    expect(screen.getByText("Reading")).toBeInTheDocument();
+    expect(screen.getByText("142 / 380 (37%)")).toBeInTheDocument();
+    expect(screen.getByRole("link", { name: /Dune/ })).toHaveAttribute(
+      "href",
+      "/books/7",
+    );
+  });
 
-  it('distinguishes an empty library from no matches', async () => {
+  it("distinguishes an empty library from no matches", async () => {
-    signedIn({ 'GET /api/books': () => [200, []] })
+    signedIn({ "GET /api/books": () => [200, []] });
-    const user = renderApp('/books')
+    const user = renderApp("/books");
-    expect(await screen.findByText('No books yet. Add your first one.')).toBeInTheDocument()
+    expect(
-    await user.type(screen.getByLabelText('Search title or author'), 'zzz')
+      await screen.findByText("No books yet. Add your first one."),
-    expect(await screen.findByText('No matches. Try a different search or genre.')).toBeInTheDocument()
+    ).toBeInTheDocument();
-  })
+    await user.type(screen.getByLabelText("Search title or author"), "zzz");
+    expect(
+      await screen.findByText("No matches. Try a different search or genre."),
+    ).toBeInTheDocument();
+  });
 
-  it('debounces search into the URL and the request', async () => {
+  it("debounces search into the URL and the request", async () => {
-    const calls = signedIn({ 'GET /api/books': () => [200, [dune]] })
+    const calls = signedIn({ "GET /api/books": () => [200, [dune]] });
-    const user = renderApp('/books')
+    const user = renderApp("/books");
-    await screen.findByRole('heading', { name: 'Dune' })
+    await screen.findByRole("heading", { name: "Dune" });
-    await user.type(screen.getByLabelText('Search title or author'), 'herbert')
+    await user.type(screen.getByLabelText("Search title or author"), "herbert");
-    await waitFor(() => expect(calls.map((c) => c.path)).toContain('/api/books?q=herbert'))
+    await waitFor(() =>
-    expect(calls.filter((c) => c.path.startsWith('/api/books?q=h')).map((c) => c.path)).toEqual(['/api/books?q=herbert'])
+      expect(calls.map((c) => c.path)).toContain("/api/books?q=herbert"),
-  })
+    );
+    expect(
+      calls
+        .filter((c) => c.path.startsWith("/api/books?q=h"))
+        .map((c) => c.path),
+    ).toEqual(["/api/books?q=herbert"]);
+  });
 
-  it('filters by genre', async () => {
+  it("filters by genre", async () => {
-    const calls = signedIn({ 'GET /api/books': () => [200, [dune]] })
+    const calls = signedIn({ "GET /api/books": () => [200, [dune]] });
-    const user = renderApp('/books')
+    const user = renderApp("/books");
-    await screen.findByRole('option', { name: 'Science Fiction' })
+    await screen.findByRole("option", { name: "Science Fiction" });
-    await user.selectOptions(screen.getByLabelText('Genre'), 'Science Fiction')
+    await user.selectOptions(screen.getByLabelText("Genre"), "Science Fiction");
-    await waitFor(() => expect(calls.map((c) => c.path)).toContain('/api/books?genre_id=5'))
+    await waitFor(() =>
-  })
+      expect(calls.map((c) => c.path)).toContain("/api/books?genre_id=5"),
+    );
+  });
 
-  it('restores search and genre from the URL', async () => {
+  it("restores search and genre from the URL", async () => {
-    const calls = signedIn({ 'GET /api/books': () => [200, [dune]] })
+    const calls = signedIn({ "GET /api/books": () => [200, [dune]] });
-    renderApp('/books?q=dune&genre=5')
+    renderApp("/books?q=dune&genre=5");
-    await screen.findByRole('option', { name: 'Science Fiction' })
+    await screen.findByRole("option", { name: "Science Fiction" });
-    expect(screen.getByLabelText('Search title or author')).toHaveValue('dune')
+    expect(screen.getByLabelText("Search title or author")).toHaveValue("dune");
-    expect(screen.getByLabelText('Genre')).toHaveValue('5')
+    expect(screen.getByLabelText("Genre")).toHaveValue("5");
-    expect(calls.map((c) => c.path)).toContain('/api/books?q=dune&genre_id=5')
+    expect(calls.map((c) => c.path)).toContain("/api/books?q=dune&genre_id=5");
-  })
+  });
 
-  it('offers retry when loading fails', async () => {
+  it("offers retry when loading fails", async () => {
-    let attempts = 0
+    let attempts = 0;
-    signedIn({ 'GET /api/books': () => (++attempts === 1 ? [500, { error: 'Unexpected server error' }] : [200, [dune]]) })
+    signedIn({
-    const user = renderApp('/books')
+      "GET /api/books": () =>
-    expect(await screen.findByRole('alert')).toHaveTextContent('Unexpected server error')
+        ++attempts === 1
-    await user.click(screen.getByRole('button', { name: 'Retry' }))
+          ? [500, { error: "Unexpected server error" }]
-    expect(await screen.findByRole('heading', { name: 'Dune' })).toBeInTheDocument()
+          : [200, [dune]],
-  })
+    });
-})
+    const user = renderApp("/books");
+    expect(await screen.findByRole("alert")).toHaveTextContent(
+      "Unexpected server error",
+    );
+    await user.click(screen.getByRole("button", { name: "Retry" }));
+    expect(
+      await screen.findByRole("heading", { name: "Dune" }),
+    ).toBeInTheDocument();
+  });
+});

src/books/BookList.tsx

@@ -1,73 +1,90 @@
-import { useEffect, useState } from 'react'
+import { useEffect, useState } from "react";
-import { Link, useSearchParams } from 'react-router'
+import { Link, useSearchParams } from "react-router";
-import { api, errorMessage, type Book } from '../api'
+import { api, errorMessage, type Book } from "../api";
-import { card, inputClass, labelText, primaryButton, secondaryButton } from '../ui'
+import {
-import { ProgressBar, StatusBadge } from './Progress'
+  card,
-import { useGenres } from './useGenres'
+  inputClass,
+  labelText,
+  primaryButton,
+  secondaryButton,
+} from "../ui";
+import { ProgressBar, StatusBadge } from "./Progress";
+import { useGenres } from "./useGenres";
 
-const SEARCH_DEBOUNCE_MS = 250
+const SEARCH_DEBOUNCE_MS = 250;
 
 export function BookList() {
-  const [params, setParams] = useSearchParams()
+  const [params, setParams] = useSearchParams();
-  const q = params.get('q') ?? ''
+  const q = params.get("q") ?? "";
-  const genre = params.get('genre') ?? ''
+  const genre = params.get("genre") ?? "";
-  const [search, setSearch] = useState(q)
+  const [search, setSearch] = useState(q);
-  const [books, setBooks] = useState<Book[] | null>(null)
+  const [books, setBooks] = useState<Book[] | null>(null);
-  const [error, setError] = useState<string | null>(null)
+  const [error, setError] = useState<string | null>(null);
-  const [attempt, setAttempt] = useState(0)
+  const [attempt, setAttempt] = useState(0);
-  const { genres, error: genresError } = useGenres()
+  const { genres, error: genresError } = useGenres();
 
   function updateParam(key: string, value: string) {
     setParams(
       (prev) => {
-        const next = new URLSearchParams(prev)
+        const next = new URLSearchParams(prev);
-        if (value) next.set(key, value)
+        if (value) next.set(key, value);
-        else next.delete(key)
+        else next.delete(key);
-        return next
+        return next;
       },
       { replace: true },
-    )
+    );
   }
 
-  // Keep the input in sync when the URL changes from outside (back/forward navigation).
+  useEffect(() => setSearch(q), [q]);
-  useEffect(() => setSearch(q), [q])
 
   useEffect(() => {
-    if (search === q) return
+    if (search === q) return;
-    const timer = setTimeout(() => updateParam('q', search), SEARCH_DEBOUNCE_MS)
+    const timer = setTimeout(
-    return () => clearTimeout(timer)
+      () => updateParam("q", search),
-  }, [search, q])
+      SEARCH_DEBOUNCE_MS,
+    );
+    return () => clearTimeout(timer);
+  }, [search, q]);
 
   useEffect(() => {
-    let cancelled = false
+    let cancelled = false;
-    const query = new URLSearchParams()
+    const query = new URLSearchParams();
-    if (q.trim()) query.set('q', q.trim())
+    if (q.trim()) query.set("q", q.trim());
-    if (genre) query.set('genre_id', genre)
+    if (genre) query.set("genre_id", genre);
-    api<Book[]>('GET', `/books?${query}`).then(
+    api<Book[]>("GET", `/books?${query}`).then(
       (found) => {
-        if (cancelled) return
+        if (cancelled) return;
-        setBooks(found)
+        setBooks(found);
-        setError(null)
+        setError(null);
       },
       (err) => {
-        if (!cancelled) setError(errorMessage(err))
+        if (!cancelled) setError(errorMessage(err));
       },
-    )
+    );
     return () => {
-      cancelled = true
+      cancelled = true;
-    }
+    };
-  }, [q, genre, attempt])
+  }, [q, genre, attempt]);
 
   return (
     <section>
       <div className="mb-4 flex flex-wrap items-end gap-3">
         <label className="min-w-48 grow">
           <span className={labelText}>Search title or author</span>
-          <input type="search" className={inputClass} value={search} onChange={(e) => setSearch(e.target.value)} />
+          <input
+            type="search"
+            className={inputClass}
+            value={search}
+            onChange={(e) => setSearch(e.target.value)}
+          />
         </label>
         <label>
           <span className={labelText}>Genre</span>
-          <select className={inputClass} value={genre} onChange={(e) => updateParam('genre', e.target.value)}>
+          <select
+            className={inputClass}
+            value={genre}
+            onChange={(e) => updateParam("genre", e.target.value)}
+          >
             <option value="">All genres</option>
             {genres.map((g) => (
               <option key={g.id} value={String(g.id)}>
@@ -88,7 +105,11 @@ export function BookList() {
       {error ? (
         <div role="alert" className="flex items-center gap-3 text-red-700">
           <span>{error}</span>
-          <button type="button" className={secondaryButton} onClick={() => setAttempt((n) => n + 1)}>
+          <button
+            type="button"
+            className={secondaryButton}
+            onClick={() => setAttempt((n) => n + 1)}
+          >
             Retry
           </button>
         </div>
@@ -96,7 +117,9 @@ export function BookList() {
         <p className="text-slate-500">Loading…</p>
       ) : books.length === 0 ? (
         <p className="text-slate-600">
-          {q.trim() || genre ? 'No matches. Try a different search or genre.' : 'No books yet. Add your first one.'}
+          {q.trim() || genre
+            ? "No matches. Try a different search or genre."
+            : "No books yet. Add your first one."}
         </p>
       ) : (
         <ul className="grid gap-3 sm:grid-cols-2">
@@ -118,5 +141,5 @@ export function BookList() {
         </ul>
       )}
     </section>
-  )
+  );
 }

src/books/Progress.tsx

@@ -1,21 +1,23 @@
-import type { Book, ReadingStatus } from '../api'
+import type { Book, ReadingStatus } from "../api";
 
 const STATUS: Record<ReadingStatus, { label: string; style: string }> = {
-  not_started: { label: 'Not started', style: 'bg-slate-100 text-slate-700' },
+  not_started: { label: "Not started", style: "bg-slate-100 text-slate-700" },
-  reading: { label: 'Reading', style: 'bg-amber-100 text-amber-800' },
+  reading: { label: "Reading", style: "bg-amber-100 text-amber-800" },
-  finished: { label: 'Finished', style: 'bg-emerald-100 text-emerald-800' },
+  finished: { label: "Finished", style: "bg-emerald-100 text-emerald-800" },
-}
+};
 
 export function StatusBadge({ status }: { status: ReadingStatus }) {
   return (
-    <span className={`rounded-full px-2 py-0.5 text-xs font-medium whitespace-nowrap ${STATUS[status].style}`}>
+    <span
+      className={`rounded-full px-2 py-0.5 text-xs font-medium whitespace-nowrap ${STATUS[status].style}`}
+    >
       {STATUS[status].label}
     </span>
-  )
+  );
 }
 
 export function ProgressBar({ book }: { book: Book }) {
-  const percent = Math.round((book.current_page / book.total_pages) * 100)
+  const percent = Math.round((book.current_page / book.total_pages) * 100);
   return (
     <div className="mt-3">
       <progress
@@ -26,5 +28,5 @@ export function ProgressBar({ book }: { book: Book }) {
       />
       <p className="text-sm text-slate-600">{`${book.current_page} / ${book.total_pages} (${percent}%)`}</p>
     </div>
-  )
+  );
 }

src/books/useGenres.ts

@@ -1,11 +1,13 @@
-import { useEffect, useState } from 'react'
+import { useEffect, useState } from "react";
-import { api, errorMessage, type Genre } from '../api'
+import { api, errorMessage, type Genre } from "../api";
 
 export function useGenres(): { genres: Genre[]; error: string | null } {
-  const [genres, setGenres] = useState<Genre[]>([])
+  const [genres, setGenres] = useState<Genre[]>([]);
-  const [error, setError] = useState<string | null>(null)
+  const [error, setError] = useState<string | null>(null);
   useEffect(() => {
-    api<Genre[]>('GET', '/genres').then(setGenres, (err) => setError(errorMessage(err)))
+    api<Genre[]>("GET", "/genres").then(setGenres, (err) =>
-  }, [])
+      setError(errorMessage(err)),
-  return { genres, error }
+    );
+  }, []);
+  return { genres, error };
 }

src/main.tsx

@@ -1,10 +1,10 @@
-import { StrictMode } from 'react'
+import { StrictMode } from "react";
-import { createRoot } from 'react-dom/client'
+import { createRoot } from "react-dom/client";
-import { App } from './App'
+import { App } from "./App";
-import './index.css'
+import "./index.css";
 
-createRoot(document.getElementById('root')!).render(
+createRoot(document.getElementById("root")!).render(
   <StrictMode>
     <App />
   </StrictMode>,
-)
+);

src/notes/NotesJournal.test.tsx

@@ -1,98 +1,126 @@
-import { fireEvent, screen, within } from '@testing-library/react'
+import { fireEvent, screen, within } from "@testing-library/react";
-import { describe, expect, it } from 'vitest'
+import { describe, expect, it } from "vitest";
-import type { Note } from '../api'
+import type { Note } from "../api";
-import { dune, renderApp, signedIn } from '../test/helpers'
+import { dune, renderApp, signedIn } from "../test/helpers";
 
 const older: Note = {
   id: 11,
   book_id: 7,
-  body: 'Started reading',
+  body: "Started reading",
-  created_at: '2026-10-01T10:00:00+00:00',
+  created_at: "2026-10-01T10:00:00+00:00",
-  updated_at: '2026-10-01T10:00:00+00:00',
+  updated_at: "2026-10-01T10:00:00+00:00",
-}
+};
 
-describe('NotesJournal', () => {
+describe("NotesJournal", () => {
-  it('lists entries and adds a new one at the top', async () => {
+  it("lists entries and adds a new one at the top", async () => {
     const calls = signedIn({
-      'GET /api/books/7': () => [200, dune],
+      "GET /api/books/7": () => [200, dune],
-      'GET /api/books/7/notes': () => [200, [older]],
+      "GET /api/books/7/notes": () => [200, [older]],
-      'POST /api/books/7/notes': ({ body }) => [
+      "POST /api/books/7/notes": ({ body }) => [
         201,
-        { ...older, id: 12, body: (body as { body: string }).body, created_at: '2026-10-02T10:00:00+00:00', updated_at: '2026-10-02T10:00:00+00:00' },
+        {
+          ...older,
+          id: 12,
+          body: (body as { body: string }).body,
+          created_at: "2026-10-02T10:00:00+00:00",
+          updated_at: "2026-10-02T10:00:00+00:00",
+        },
       ],
-    })
+    });
-    const user = renderApp('/books/7')
+    const user = renderApp("/books/7");
-    expect(await screen.findByText('Started reading')).toBeInTheDocument()
+    expect(await screen.findByText("Started reading")).toBeInTheDocument();
-    await user.type(screen.getByLabelText('New journal entry'), 'Loved chapter 3')
+    await user.type(
-    await user.click(screen.getByRole('button', { name: 'Add entry' }))
+      screen.getByLabelText("New journal entry"),
+      "Loved chapter 3",
+    );
+    await user.click(screen.getByRole("button", { name: "Add entry" }));
 
-    await screen.findByText('Loved chapter 3')
+    await screen.findByText("Loved chapter 3");
-    const items = screen.getAllByRole('listitem')
+    const items = screen.getAllByRole("listitem");
-    expect(items[0]).toHaveTextContent('Loved chapter 3')
+    expect(items[0]).toHaveTextContent("Loved chapter 3");
-    expect(items[1]).toHaveTextContent('Started reading')
+    expect(items[1]).toHaveTextContent("Started reading");
-    expect(screen.getByLabelText('New journal entry')).toHaveValue('')
+    expect(screen.getByLabelText("New journal entry")).toHaveValue("");
-    expect(calls).toContainEqual({ method: 'POST', path: '/api/books/7/notes', body: { body: 'Loved chapter 3' } })
+    expect(calls).toContainEqual({
-  })
+      method: "POST",
+      path: "/api/books/7/notes",
+      body: { body: "Loved chapter 3" },
+    });
+  });
 
-  it('edits an entry and marks it edited', async () => {
+  it("edits an entry and marks it edited", async () => {
     signedIn({
-      'GET /api/books/7': () => [200, dune],
+      "GET /api/books/7": () => [200, dune],
-      'GET /api/books/7/notes': () => [200, [older]],
+      "GET /api/books/7/notes": () => [200, [older]],
-      'PATCH /api/notes/11': ({ body }) => [
+      "PATCH /api/notes/11": ({ body }) => [
         200,
-        { ...older, body: (body as { body: string }).body, updated_at: '2026-10-02T10:00:00+00:00' },
+        {
+          ...older,
+          body: (body as { body: string }).body,
+          updated_at: "2026-10-02T10:00:00+00:00",
+        },
       ],
-    })
+    });
-    const user = renderApp('/books/7')
+    const user = renderApp("/books/7");
-    const item = (await screen.findByText('Started reading')).closest('li')!
+    const item = (await screen.findByText("Started reading")).closest("li")!;
-    await user.click(within(item).getByRole('button', { name: 'Edit entry' }))
+    await user.click(within(item).getByRole("button", { name: "Edit entry" }));
-    const editor = within(item).getByLabelText('Edit entry')
+    const editor = within(item).getByLabelText("Edit entry");
-    await user.clear(editor)
+    await user.clear(editor);
-    await user.type(editor, 'Finished part one')
+    await user.type(editor, "Finished part one");
-    await user.click(within(item).getByRole('button', { name: 'Save' }))
+    await user.click(within(item).getByRole("button", { name: "Save" }));
 
-    expect(await within(item).findByText('Finished part one')).toBeInTheDocument()
+    expect(
-    expect(within(item).getByText(/edited/)).toBeInTheDocument()
+      await within(item).findByText("Finished part one"),
-  })
+    ).toBeInTheDocument();
+    expect(within(item).getByText(/edited/)).toBeInTheDocument();
+  });
 
-  it('deletes an entry', async () => {
+  it("deletes an entry", async () => {
     signedIn({
-      'GET /api/books/7': () => [200, dune],
+      "GET /api/books/7": () => [200, dune],
-      'GET /api/books/7/notes': () => [200, [older]],
+      "GET /api/books/7/notes": () => [200, [older]],
-      'DELETE /api/notes/11': () => [204],
+      "DELETE /api/notes/11": () => [204],
-    })
+    });
-    const user = renderApp('/books/7')
+    const user = renderApp("/books/7");
-    await user.click(await screen.findByRole('button', { name: 'Delete entry' }))
+    await user.click(
-    expect(await screen.findByText('No entries yet.')).toBeInTheDocument()
+      await screen.findByRole("button", { name: "Delete entry" }),
-  })
+    );
+    expect(await screen.findByText("No entries yet.")).toBeInTheDocument();
+  });
 
-  it('shows the server error when adding fails', async () => {
+  it("shows the server error when adding fails", async () => {
     signedIn({
-      'GET /api/books/7': () => [200, dune],
+      "GET /api/books/7": () => [200, dune],
-      'GET /api/books/7/notes': () => [200, []],
+      "GET /api/books/7/notes": () => [200, []],
-      'POST /api/books/7/notes': () => [400, { error: 'body must be at most 10000 characters', field: 'body' }],
+      "POST /api/books/7/notes": () => [
-    })
+        400,
-    const user = renderApp('/books/7')
+        { error: "body must be at most 10000 characters", field: "body" },
-    await user.type(await screen.findByLabelText('New journal entry'), 'x')
+      ],
-    await user.click(screen.getByRole('button', { name: 'Add entry' }))
+    });
-    expect(await screen.findByRole('alert')).toHaveTextContent('body must be at most 10000 characters')
+    const user = renderApp("/books/7");
-  })
+    await user.type(await screen.findByLabelText("New journal entry"), "x");
+    await user.click(screen.getByRole("button", { name: "Add entry" }));
+    expect(await screen.findByRole("alert")).toHaveTextContent(
+      "body must be at most 10000 characters",
+    );
+  });
 
-  it('posts a double-clicked entry only once', async () => {
+  it("posts a double-clicked entry only once", async () => {
     const calls = signedIn({
-      'GET /api/books/7': () => [200, dune],
+      "GET /api/books/7": () => [200, dune],
-      'GET /api/books/7/notes': () => [200, []],
+      "GET /api/books/7/notes": () => [200, []],
-      'POST /api/books/7/notes': ({ body }) => [201, { ...older, id: 12, body: (body as { body: string }).body }],
+      "POST /api/books/7/notes": ({ body }) => [
-    })
+        201,
-    const user = renderApp('/books/7')
+        { ...older, id: 12, body: (body as { body: string }).body },
-    await screen.findByText('No entries yet.')
+      ],
-    await user.type(screen.getByLabelText('New journal entry'), 'Once only')
+    });
-    const add = screen.getByRole('button', { name: 'Add entry' })
+    const user = renderApp("/books/7");
-    // Two clicks before the pending POST settles; user.dblClick would wait for it and mask the bug.
+    await screen.findByText("No entries yet.");
-    fireEvent.click(add)
+    await user.type(screen.getByLabelText("New journal entry"), "Once only");
-    fireEvent.click(add)
+    const add = screen.getByRole("button", { name: "Add entry" });
+    fireEvent.click(add);
+    fireEvent.click(add);
 
-    await screen.findByText('Once only')
+    await screen.findByText("Once only");
-    expect(calls.filter((c) => c.method === 'POST')).toHaveLength(1)
+    expect(calls.filter((c) => c.method === "POST")).toHaveLength(1);
-  })
+  });
-})
+});

src/test/helpers.tsx

@@ -1,65 +1,71 @@
-import { render } from '@testing-library/react'
+import { render } from "@testing-library/react";
-import userEvent from '@testing-library/user-event'
+import userEvent from "@testing-library/user-event";
-import { MemoryRouter } from 'react-router'
+import { MemoryRouter } from "react-router";
-import { vi } from 'vitest'
+import { vi } from "vitest";
-import type { Book, Genre, User } from '../api'
+import type { Book, Genre, User } from "../api";
-import { AppRoutes } from '../App'
+import { AppRoutes } from "../App";
-import { AuthProvider } from '../auth/AuthContext'
+import { AuthProvider } from "../auth/AuthContext";
 
-export const alice: User = { id: 1, username: 'alice' }
+export const alice: User = { id: 1, username: "alice" };
 export const genres: Genre[] = [
-  { id: 3, name: 'Fantasy' },
+  { id: 3, name: "Fantasy" },
-  { id: 5, name: 'Science Fiction' },
+  { id: 5, name: "Science Fiction" },
-]
+];
 export const dune: Book = {
   id: 7,
-  title: 'Dune',
+  title: "Dune",
-  author: 'Frank Herbert',
+  author: "Frank Herbert",
-  genre: { id: 5, name: 'Science Fiction' },
+  genre: { id: 5, name: "Science Fiction" },
   total_pages: 380,
   current_page: 142,
-  status: 'reading',
+  status: "reading",
-  created_at: '2026-10-01T10:00:00+00:00',
+  created_at: "2026-10-01T10:00:00+00:00",
-  updated_at: '2026-10-01T10:00:00+00:00',
+  updated_at: "2026-10-01T10:00:00+00:00",
-}
+};
 
-type Reply = [status: number, body?: unknown]
+type Reply = [status: number, body?: unknown];
-type Handler = (request: { body: unknown; url: URL }) => Reply
+type Handler = (request: { body: unknown; url: URL }) => Reply;
-export type Call = { method: string; path: string; body: unknown }
+export type Call = { method: string; path: string; body: unknown };
 
-/** Replaces fetch (the network boundary) with route handlers keyed by "METHOD /api/path". */
 export function mockApi(routes: Record<string, Handler>): Call[] {
-  const calls: Call[] = []
+  const calls: Call[] = [];
   vi.stubGlobal(
-    'fetch',
+    "fetch",
     vi.fn(async (input: string, init: RequestInit = {}) => {
-      const url = new URL(input, 'http://localhost')
+      const url = new URL(input, "http://localhost");
-      const method = init.method ?? 'GET'
+      const method = init.method ?? "GET";
-      const body = typeof init.body === 'string' ? JSON.parse(init.body) : undefined
+      const body =
-      calls.push({ method, path: url.pathname + url.search, body })
+        typeof init.body === "string" ? JSON.parse(init.body) : undefined;
-      const handler = routes[`${method} ${url.pathname}`]
+      calls.push({ method, path: url.pathname + url.search, body });
-      const [status, data] = handler ? handler({ body, url }) : [500, { error: `No mock for ${method} ${url.pathname}` }]
+      const handler = routes[`${method} ${url.pathname}`];
+      const [status, data] = handler
+        ? handler({ body, url })
+        : [500, { error: `No mock for ${method} ${url.pathname}` }];
       return new Response(status === 204 ? null : JSON.stringify(data), {
         status,
-        headers: { 'Content-Type': 'application/json' },
+        headers: { "Content-Type": "application/json" },
-      })
+      });
     }),
-  )
+  );
-  return calls
+  return calls;
 }
 
 export function signedIn(routes: Record<string, Handler> = {}): Call[] {
-  return mockApi({ 'GET /api/auth/me': () => [200, alice], 'GET /api/genres': () => [200, genres], ...routes })
+  return mockApi({
+    "GET /api/auth/me": () => [200, alice],
+    "GET /api/genres": () => [200, genres],
+    ...routes,
+  });
 }
 
 export function renderApp(url: string) {
-  const user = userEvent.setup()
+  const user = userEvent.setup();
   render(
     <MemoryRouter initialEntries={[url]}>
       <AuthProvider>
         <AppRoutes />
       </AuthProvider>
     </MemoryRouter>,
-  )
+  );
-  return user
+  return user;
 }

src/test/setup.ts

@@ -1,6 +1,5 @@
-import '@testing-library/jest-dom/vitest'
+import "@testing-library/jest-dom/vitest";
-import { cleanup } from '@testing-library/react'
+import { cleanup } from "@testing-library/react";
-import { afterEach } from 'vitest'
+import { afterEach } from "vitest";
 
-// Vitest globals are off, so Testing Library cannot register its own cleanup.
+afterEach(() => cleanup());
-afterEach(() => cleanup())

src/ui.ts

@@ -1,9 +1,9 @@
-export const card = 'rounded-lg bg-white p-4 shadow'
+export const card = "rounded-lg bg-white p-4 shadow";
-export const labelText = 'mb-1 block text-sm font-medium text-slate-700'
+export const labelText = "mb-1 block text-sm font-medium text-slate-700";
 export const inputClass =
-  'block w-full rounded-md border border-slate-300 px-3 py-2 focus-visible:outline-2 focus-visible:outline-indigo-600 aria-invalid:border-red-600'
+  "block w-full rounded-md border border-slate-300 px-3 py-2 focus-visible:outline-2 focus-visible:outline-indigo-600 aria-invalid:border-red-600";
 const button =
-  'inline-flex items-center justify-center rounded-md px-4 py-2 text-sm font-medium focus-visible:outline-2 focus-visible:outline-offset-2 disabled:opacity-50'
+  "inline-flex items-center justify-center rounded-md px-4 py-2 text-sm font-medium focus-visible:outline-2 focus-visible:outline-offset-2 disabled:opacity-50";
-export const primaryButton = `${button} bg-indigo-600 text-white hover:bg-indigo-700 focus-visible:outline-indigo-600`
+export const primaryButton = `${button} bg-indigo-600 text-white hover:bg-indigo-700 focus-visible:outline-indigo-600`;
-export const secondaryButton = `${button} border border-slate-300 bg-white text-slate-800 hover:bg-slate-100 focus-visible:outline-indigo-600`
+export const secondaryButton = `${button} border border-slate-300 bg-white text-slate-800 hover:bg-slate-100 focus-visible:outline-indigo-600`;
-export const dangerButton = `${button} bg-red-600 text-white hover:bg-red-700 focus-visible:outline-red-600`
+export const dangerButton = `${button} bg-red-600 text-white hover:bg-red-700 focus-visible:outline-red-600`;