feat: offer a merge that keeps the first book, without the workbench

frontend/src/lib/components/forms/merge-books/merge-books.svelte

@@ -1,7 +1,5 @@
 <script lang="ts">
 	import { untrack } from 'svelte';
-	import { toast } from 'svelte-sonner';
-	import { invalidate } from '$app/navigation';
 	import { ArrowRight, GitMerge, Plus, Undo2 } from '@lucide/svelte';
 
 	import * as Dialog from '$lib/components/ui/dialog/index.js';
@@ -11,9 +9,10 @@
 	import { Badge } from '$lib/components/ui/badge/index.js';
 	import BookImage from '$lib/components/view/book-image.svelte';
 	import GeneratedCover from '$lib/components/view/generated-cover.svelte';
-	import { mergeBooks } from '$lib/api/book.remote';
 	import type { Book } from '$lib/schema';
 
+	import { mergeInto } from './merge';
+
 	import {
 		MERGE_FIELDS,
 		applyAction,
@@ -105,26 +104,13 @@
 		if (busy) return;
 		busy = true;
 
-		try {
-			await mergeBooks({
-				library_id: libraryId,
-				survivor_id: survivor.id,
-				merged_ids: candidates.map((book) => book.id),
-				metadata: changed.length ? draft : undefined
-			});
+		const merged = await mergeInto(libraryId, survivor, folded, changed.length ? draft : undefined);
 
-			// Both, because this dialog is opened from the duplicates review and from
-			// the library's selection toolbar, and each page depends on a different one.
-			await Promise.all([invalidate('app:books'), invalidate('app:duplicate-books')]);
+		busy = false;
 
-			toast.success(`Merged into “${survivor.title}”`);
+		if (merged) {
 			open = false;
 			onmerged?.(survivor, folded);
-		} catch (error) {
-			console.error('Failed to merge books', error);
-			toast.error(error instanceof Error ? error.message : 'Could not merge these books');
-		} finally {
-			busy = false;
 		}
 	}
 </script>

frontend/src/lib/components/forms/merge-books/merge.ts

@@ -0,0 +1,44 @@
+import { invalidate } from '$app/navigation';
+import { toast } from 'svelte-sonner';
+
+import { mergeBooks } from '$lib/api/book.remote';
+import type { Book } from '$lib/schema';
+import type { FieldValue } from './field-spec';
+
+/**
+ * Fold `folded` into `survivor`, and tell the reader how it went.
+ *
+ * Shared because a merge is reachable two ways — the workbench, where the reader
+ * resolved the metadata field by field, and the quick action beside it, which
+ * takes the survivor's metadata as it stands. Only the `metadata` argument
+ * differs, and the invalidation and the wording should not.
+ *
+ * @returns whether the merge went through; the caller decides what to close or
+ * clear, and has no toast of its own to write either way.
+ */
+export async function mergeInto(
+	libraryId: number | string,
+	survivor: Book,
+	folded: Book[],
+	metadata?: Record<string, FieldValue>
+): Promise<boolean> {
+	try {
+		await mergeBooks({
+			library_id: libraryId,
+			survivor_id: survivor.id,
+			merged_ids: folded.map((book) => book.id),
+			metadata
+		});
+
+		// Both, because a merge is started from the duplicates review and from the
+		// library's selection toolbar, and each page depends on a different one.
+		await Promise.all([invalidate('app:books'), invalidate('app:duplicate-books')]);
+
+		toast.success(`Merged into “${survivor.title}”`);
+		return true;
+	} catch (error) {
+		console.error('Failed to merge books', error);
+		toast.error(error instanceof Error ? error.message : 'Could not merge these books');
+		return false;
+	}
+}

frontend/src/lib/components/view/batch-operations-toolbar.svelte

@@ -7,6 +7,7 @@
 		GitMerge,
 		Trash2,
 		SquareCheckBig,
+		SlidersHorizontal,
 		X,
 		Album,
 		PlusIcon
@@ -19,6 +20,7 @@
 	import { getBookshelfState } from '$lib/state/bookshelf.svelte';
 	import ShelfCreateDialog from '../forms/shelf-create-dialog.svelte';
 	import MergeBooks from '../forms/merge-books/merge-books.svelte';
+	import { mergeInto } from '../forms/merge-books/merge';
 	import type { Book } from '$lib/schema';
 
 	const libraryState = getLibraryState();
@@ -35,6 +37,42 @@
 	// the selection, so clearing the selection on success cannot empty the dialog
 	// underneath itself.
 	let mergingBooks = $state<Book[] | null>(null);
+
+	// A quick merge has no dialog to disable, so the flag is what stops a slow
+	// round trip being started twice.
+	let quickMerging = $state(false);
+
+	/** Put the library back in step with a merge that went through. */
+	function afterMerge(folded: Book[]) {
+		// Only the folded records are gone; the survivor is still in the library.
+		libraryState.activeLibrary!.total! -= folded.length;
+		bookshelfState.deletedBooks(folded);
+		selectionState.deselectAll();
+	}
+
+	/**
+	 * Merge without opening the workbench, keeping the book selected first.
+	 *
+	 * Selection is held in insertion order, so the first record is the one the
+	 * reader started from — the one they were looking at when they decided the
+	 * rest were copies of it.
+	 */
+	async function quickMerge() {
+		if (quickMerging) return;
+
+		// Read once: the merge clears the selection, and the bookkeeping afterwards
+		// still needs the records that went away.
+		const [survivor, ...folded] = selectedBooks;
+		if (!survivor || folded.length === 0) return;
+
+		quickMerging = true;
+
+		const merged = await mergeInto(libraryState.activeLibrary!.id, survivor, folded);
+
+		quickMerging = false;
+
+		if (merged) afterMerge(folded);
+	}
 </script>
 
 <!-- Mark selected as finished button -->
@@ -148,11 +186,44 @@
 {#if selectedBooks.length > 1}
 	<Tooltip.Provider>
 		<Tooltip.Root ignoreNonKeyboardFocus>
-			<Tooltip.Trigger
-				onclick={() => (mergingBooks = selectedBooks)}
-				class={buttonVariants({ variant: 'ghost', size: 'icon' })}
-			>
-				<GitMerge />
+			<Tooltip.Trigger>
+				{#snippet child({ props })}
+					<!-- A choice rather than a jump straight into the workbench: two
+					     copies of one book have nothing to resolve, and the dialog is a
+					     step in the way of saying so. -->
+					<DropdownMenu.Root>
+						<DropdownMenu.Trigger
+							{...props}
+							disabled={quickMerging}
+							class={buttonVariants({ variant: 'ghost', size: 'icon' })}
+						>
+							<GitMerge />
+						</DropdownMenu.Trigger>
+						<DropdownMenu.Content class="w-72">
+							<DropdownMenu.Item class="flex-col items-start gap-0.5" onclick={quickMerge}>
+								<span class="flex w-full min-w-0 items-center gap-2">
+									<GitMerge class="size-4 shrink-0" />
+									<span class="truncate">Keep “{selectedBooks[0].title}”</span>
+								</span>
+								<span class="pl-6 text-xs text-wrap text-muted-foreground">
+									Files move onto the book you selected first, which keeps its own metadata.
+								</span>
+							</DropdownMenu.Item>
+							<DropdownMenu.Item
+								class="flex-col items-start gap-0.5"
+								onclick={() => (mergingBooks = selectedBooks)}
+							>
+								<span class="flex items-center gap-2">
+									<SlidersHorizontal class="size-4 shrink-0" />
+									Choose what to keep…
+								</span>
+								<span class="pl-6 text-xs text-wrap text-muted-foreground">
+									Pick the record that survives and resolve the metadata field by field.
+								</span>
+							</DropdownMenu.Item>
+						</DropdownMenu.Content>
+					</DropdownMenu.Root>
+				{/snippet}
 			</Tooltip.Trigger>
 			<Tooltip.Content>
 				<p>Merge {selectedBooks.length} books</p>
@@ -247,16 +318,13 @@
 				(value) => {
 					// Bound, not passed as a bare `true`: the dialog closes itself on an
 					// outside click or Escape, and if that never reaches `mergingBooks`
-					// the snapshot stays set — the button then re-assigns the same
+					// the snapshot stays set — the menu item then re-assigns the same
 					// selection, nothing changes, and the dialog never reopens.
 					if (!value) mergingBooks = null;
 				}
 			}
 			onmerged={(_survivor, folded) => {
-				// Only the folded records are gone; the survivor is still in the library.
-				libraryState.activeLibrary!.total! -= folded.length;
-				bookshelfState.deletedBooks(folded);
-				selectionState.deselectAll();
+				afterMerge(folded);
 				mergingBooks = null;
 			}}
 		/>