fix(metadata): restore Hardcover title and author matching

Use Hardcover's default search configuration because custom fields currently return a payload-level error. Surface future search errors in logs so failures remain diagnosable.

Fixes #1123

server/src/modules/hardcover/hardcover-book-match.service.test.ts

@@ -1,4 +1,4 @@
-import { describe, it, expect, vi, beforeEach } from 'vitest';
+import { describe, it, expect, vi, beforeEach, afterEach } from 'vitest';
 
 import { EDITION_DISPLAY_LIMIT, HardcoverBookMatchService } from './hardcover-book-match.service';
 
@@ -37,6 +37,10 @@ describe('HardcoverBookMatchService', () => {
     mockRepo.upsertBookState.mockResolvedValue({});
   });
 
+  afterEach(() => {
+    vi.restoreAllMocks();
+  });
+
   it('returns cached match when state exists and no error', async () => {
     mockRepo.findBookState.mockResolvedValue({
       hardcoverBookId: 100,
@@ -189,6 +193,32 @@ describe('HardcoverBookMatchService', () => {
       expect.stringContaining('query SearchBooks'),
       expect.objectContaining({ query: 'Test Book Test Author' }),
     );
+    const searchQuery = mockClient.query.mock.calls[1]?.[2] as string;
+    expect(searchQuery).toContain('error');
+    expect(searchQuery).not.toContain('fields:');
+    expect(searchQuery).not.toContain('weights:');
+  });
+
+  it('logs payload-level errors returned by Hardcover search', async () => {
+    mockRepo.findBookState.mockResolvedValue(undefined);
+    mockClient.query.mockResolvedValueOnce({ books: [] }).mockResolvedValueOnce({
+      search: {
+        error: 'Number of values in `num_typos` does not match number of `query_by` fields.',
+        ids: null,
+      },
+    });
+    const service = makeService();
+    const logger = Reflect.get(service, 'logger') as { warn: (message: string) => void };
+    const warnSpy = vi.spyOn(logger, 'warn').mockImplementation(() => undefined);
+
+    await expect(service.matchBook(1, 'tok', baseBook)).resolves.toBeNull();
+
+    expect(mockClient.query).toHaveBeenCalledTimes(2);
+    expect(warnSpy).toHaveBeenCalledWith(
+      expect.stringMatching(
+        /^\[hardcover\.book_match\] \[fail\] userId=1 bookId=42 method=title_author durationMs=\d+ errorClass=SearchError error="Number of values in `num_typos` does not match number of `query_by` fields\." - title lookup failed$/,
+      ),
+    );
   });
 
   it('preserves Hardcover search ranking when hydrating title matches', async () => {

server/src/modules/hardcover/hardcover-book-match.service.ts

@@ -46,9 +46,8 @@ query SearchBooks($query: String!) {
     query_type: "Book"
     per_page: 5
     page: 1
-    fields: "title,author_names,alternative_titles"
-    weights: "5,2,1"
   ) {
+    error
     ids
   }
 }`;
@@ -200,7 +199,8 @@ function mapEditionForDisplay(edition: HardcoverEditionDisplayRow): HardcoverEdi
 
 interface SearchBooksResult {
   search?: {
-    ids?: number[];
+    error?: string | null;
+    ids?: number[] | null;
   } | null;
 }
 
@@ -354,10 +354,18 @@ export class HardcoverBookMatchService {
     author: string,
     book: BookSyncData,
   ): Promise<HardcoverBookMatch | null> {
+    const startedAt = Date.now();
     try {
       const searchData = await this.client.query<SearchBooksResult>(userId, token, SEARCH_BOOKS_QUERY, {
         query: `${title} ${author}`,
       });
+      if (searchData.search?.error) {
+        const error = sanitizeLogValue(searchData.search.error);
+        this.logger.warn(
+          `[hardcover.book_match] [fail] userId=${userId} bookId=${book.bookId} method=title_author durationMs=${Date.now() - startedAt} errorClass=SearchError error="${error}" - title lookup failed`,
+        );
+        return null;
+      }
       const ids = searchData.search?.ids?.filter((id) => Number.isInteger(id)).slice(0, 5) ?? [];
       if (ids.length === 0) return null;
 
@@ -374,9 +382,10 @@ export class HardcoverBookMatchService {
         matchMethod: 'title',
       };
     } catch (err) {
+      const errorClass = err instanceof Error ? err.constructor.name : 'Error';
       const error = sanitizeLogValue(err instanceof Error ? err.message : String(err));
       this.logger.warn(
-        `[hardcover.book_match] [fail] userId=${userId} bookId=${book.bookId} method=title_author error="${error}" - title lookup failed`,
+        `[hardcover.book_match] [fail] userId=${userId} bookId=${book.bookId} method=title_author durationMs=${Date.now() - startedAt} errorClass=${errorClass} error="${error}" - title lookup failed`,
       );
       return null;
     }