Personal Catalogue: React & Firebase — Chapter 8, Exercise 2
=====================================================================

TASK
Build the naive useDuplicateCheckNaive hook (no debounce, no staleness
guard) and reproduce the race condition described in the chapter —
with a real "Dune" book already saved, type "Dune Messiah" and observe
a false "Dune already exists" warning appearing after the full title
has been typed.

SOLUTION

import { useState, useEffect } from 'react';
import { searchItems } from '../search';

function useDuplicateCheckNaive(title) {
  const [match, setMatch] = useState(null);

  useEffect(() => {
    const trimmed = title.trim();
    if (trimmed.length < 3) {
      setMatch(null);
      return;
    }

    searchItems(trimmed).then((results) => {
      const exact = results.find((r) => r.title.toLowerCase() === trimmed.toLowerCase());
      setMatch(exact || null);
    });
  }, [title]);

  return match;
}

Setup: a real Book titled exactly "Dune" already exists in the
catalogue.

Reproduction: type "Dune Messiah" into the title field at a normal
typing pace (not pausing between "Dune" and " Messiah").

Observed sequence:
1. After "Dune" is typed, a call fires for "Dune".
2. Typing continues to "Dune Messiah" — a second, independent call
   fires for "Dune Messiah".
3. The "Dune Messiah" call resolves first (no exact match, since no
   book is titled exactly that): no warning shown. Correct, for the
   moment.
4. The earlier "Dune" call resolves late, after the field already
   reads "Dune Messiah": the warning "Dune already exists" appears,
   even though the field no longer says "Dune" at all.

The warning is genuinely wrong at the moment it appears — there is no
book titled "Dune Messiah," yet the UI claims a duplicate exists, purely
because an earlier network response happened to arrive after a later
one.

WHY THIS WORKS AS AN ANSWER
----------------------------
It builds the exact naive hook the chapter describes, reproduces the
real timing sequence rather than only describing it abstractly, and
correctly identifies the observed warning as genuinely incorrect given
the actual state of the catalogue at the moment it appears.