diff --git a/apps/readest-app/src/__tests__/services/hardcover/HardcoverClient.test.ts b/apps/readest-app/src/__tests__/services/hardcover/HardcoverClient.test.ts
index 2e9eb8f8..fe3032b0 100644
--- a/apps/readest-app/src/__tests__/services/hardcover/HardcoverClient.test.ts
+++ b/apps/readest-app/src/__tests__/services/hardcover/HardcoverClient.test.ts
@@ -13,7 +13,7 @@ type MockFetchResponse = {
 type MockFetch = ReturnType<typeof vi.fn<(...args: unknown[]) => Promise<MockFetchResponse>>>;
 
 type TestBookContext = {
-  editionId: number;
+  editionId: number | null;
   pages: number | null;
   bookId: number;
   bookPages: number | null;
@@ -712,4 +712,90 @@ describe('HardcoverClient', () => {
       userBook: { id: 303 },
     });
   });
+
+  test('leaves the edition id unresolved when title search lacks a featured edition and the user has none selected', async () => {
+    const book = { title: 'Crime and Punishment', author: 'Fyodor Dostoevsky' } as Book;
+
+    // authenticate
+    fetchMock.mockResolvedValueOnce({
+      ok: true,
+      status: 200,
+      json: () => Promise.resolve({ data: { me: { id: 1 } } }),
+    });
+    // QUERY_SEARCH_BOOK — real Typesense hit shape, no featured_edition_id present
+    fetchMock.mockResolvedValueOnce({
+      ok: true,
+      status: 200,
+      json: () =>
+        Promise.resolve({
+          data: { search: { results: { hits: [{ document: { id: 713309, pages: 311 } }] } } },
+        }),
+    });
+    // QUERY_GET_BOOK_USER_DATA — currently-reading book, but no specific edition selected
+    fetchMock.mockResolvedValueOnce({
+      ok: true,
+      status: 200,
+      json: () =>
+        Promise.resolve({
+          data: {
+            editions: [
+              {
+                book: {
+                  id: 713309,
+                  pages: 311,
+                  user_books: [
+                    {
+                      id: 303,
+                      status_id: 2,
+                      edition: null,
+                      user_book_reads: [{ id: 505, started_at: '2026-06-25', edition: null }],
+                    },
+                  ],
+                },
+              },
+            ],
+          },
+        }),
+    });
+
+    const context = await clientApi.fetchBookContext(book);
+
+    expect(context?.bookId).toBe(713309);
+    // Regression #4792: the edition id must NOT fall back to the book id. Sending
+    // a book id as edition_id makes Hardcover's Action reject the read mutation
+    // with a parse-failed error. Leave it null when no real edition is known.
+    expect(context?.editionId).toBeNull();
+  });
+
+  test('forwards a null edition id to the read mutation when no edition is resolved (#4792)', async () => {
+    const book = {
+      createdAt: 1711737600000,
+      title: 'Crime and Punishment',
+      author: 'Test',
+    } as Book;
+    const config = { progress: [3, 311] } as BookConfig;
+
+    vi.spyOn(clientApi, 'ensureBookInLibrary').mockResolvedValue({
+      editionId: null,
+      pages: 311,
+      bookId: 713309,
+      bookPages: 311,
+      userBook: {
+        id: 303,
+        status_id: 2,
+        user_book_reads: [{ id: 505, started_at: '2026-06-25' }],
+      },
+    });
+    const requestSpy = vi.spyOn(clientApi, 'request').mockResolvedValue({});
+
+    await client.pushProgress(book, config);
+
+    const requestCalls = requestSpy.mock.calls as RequestSpyCall[];
+    const updateReadCall = requestCalls.find((call) =>
+      String(call[0]).includes('mutation UpdateRead'),
+    );
+    expect(updateReadCall).toBeDefined();
+    const variables = updateReadCall?.[1] as { edition_id?: unknown };
+    expect(variables.edition_id).toBeNull();
+  });
 });
diff --git a/apps/readest-app/src/services/hardcover/HardcoverClient.ts b/apps/readest-app/src/services/hardcover/HardcoverClient.ts
index e0c63699..3f0a5285 100644
--- a/apps/readest-app/src/services/hardcover/HardcoverClient.ts
+++ b/apps/readest-app/src/services/hardcover/HardcoverClient.ts
@@ -23,7 +23,10 @@ type HardcoverSettingsLike = {
 };
 
 type BookContext = {
-  editionId: number;
+  // Null when no real Hardcover edition is known (e.g. a title-search match with
+  // no featured edition and no user-selected edition). Never fall back to the
+  // book id here — Hardcover rejects a book id used as an edition_id (#4792).
+  editionId: number | null;
   pages: number | null;
   bookId: number;
   bookPages: number | null;
@@ -284,9 +287,10 @@ export class HardcoverClient {
     if (!rawBookId) return null;
 
     const bookId = Number(rawBookId);
-    const editionId = Number(
-      hit.featured_edition_id ?? hit.document?.featured_edition_id ?? bookId,
-    );
+    const rawEditionId = hit.featured_edition_id ?? hit.document?.featured_edition_id;
+    // Only the featured edition is a real edition id; never substitute the book
+    // id (Hardcover rejects a book id passed as edition_id, #4792).
+    const editionId = rawEditionId != null ? Number(rawEditionId) : null;
     const pages =
       hit.pages != null
         ? Number(hit.pages)
@@ -461,7 +465,7 @@ export class HardcoverClient {
     if (context.userBook) return context;
 
     const data = await this.request<
-      { object: { book_id: number; edition_id: number; status_id: number } },
+      { object: { book_id: number; edition_id?: number; status_id: number } },
       {
         insert_user_book: {
           error?: string | null;
@@ -474,7 +478,9 @@ export class HardcoverClient {
     >(MUTATION_INSERT_USER_BOOK, {
       object: {
         book_id: context.bookId,
-        edition_id: context.editionId,
+        // Omit edition_id entirely when unknown so Hardcover falls back to the
+        // book's default edition instead of rejecting an invalid one (#4792).
+        ...(context.editionId != null ? { edition_id: context.editionId } : {}),
         status_id: isReading ? 2 : 1,
       },
     });
diff --git a/apps/readest-app/src/services/hardcover/hardcover-graphql.ts b/apps/readest-app/src/services/hardcover/hardcover-graphql.ts
index a8d72f6d..2178d6ca 100644
--- a/apps/readest-app/src/services/hardcover/hardcover-graphql.ts
+++ b/apps/readest-app/src/services/hardcover/hardcover-graphql.ts
@@ -129,7 +129,7 @@ mutation UpdateUserBook($user_book_id: Int!, $object: UserBookUpdateInput!) {
 `;
 
 export const MUTATION_INSERT_READ = `
-mutation InsertRead($user_book_id: Int!, $edition_id: Int!, $progress_pages: Int!, $started_at: date!) {
+mutation InsertRead($user_book_id: Int!, $edition_id: Int, $progress_pages: Int!, $started_at: date!) {
   insert_user_book_read(
     user_book_id: $user_book_id
     user_book_read: {
@@ -142,7 +142,7 @@ mutation InsertRead($user_book_id: Int!, $edition_id: Int!, $progress_pages: Int
 `;
 
 export const MUTATION_UPDATE_READ = `
-mutation UpdateRead($id: Int!, $progress_pages: Int!, $edition_id: Int!, $started_at: date!) {
+mutation UpdateRead($id: Int!, $progress_pages: Int!, $edition_id: Int, $started_at: date!) {
   update_user_book_read(
     id: $id
     object: {
@@ -156,7 +156,7 @@ mutation UpdateRead($id: Int!, $progress_pages: Int!, $edition_id: Int!, $starte
 
 export const MUTATION_INSERT_JOURNAL = `
 mutation InsertReadingJournal(
-  $book_id: Int!, $edition_id: Int!, $event: String!, $entry: String!,
+  $book_id: Int!, $edition_id: Int, $event: String!, $entry: String!,
   $action_at: date, $page: Int!, $possible: Int!, $percent: Float!, $privacy_setting_id: Int!
 ) {
   insert_reading_journal(