diff --git a/backend/api/v1/modules/a76/classes/service.py b/backend/api/v1/modules/a76/classes/service.py
index 49c06bcb..acd7e717 100644
--- a/backend/api/v1/modules/a76/classes/service.py
+++ b/backend/api/v1/modules/a76/classes/service.py
@@ -48,27 +48,30 @@ class ClassService:
             query = query.filter(Class.company_id == company_id)
 
         if filters:
-            if filters.get("q"):
-                search = f"%{filters['q']}%"
+            # Búsqueda libre: OR en clave y descripciones (selectores / listados)
+            search_raw = filters.get("search") or filters.get("q")
+            if search_raw and str(search_raw).strip():
+                pattern = f"%{str(search_raw).strip()}%"
                 query = query.filter(
                     or_(
-                        Class.class_code.ilike(search),
-                        Class.description_es.ilike(search),
-                        Class.description_en.ilike(search)
+                        Class.class_code.ilike(pattern),
+                        Class.description_es.ilike(pattern),
+                        Class.description_en.ilike(pattern),
                     )
                 )
-            if filters.get("class_code"):
-                query = query.filter(
-                    Class.class_code.ilike(f"%{filters['class_code']}%")
-                )
-            if filters.get("description"):
-                description_pattern = f"%{filters['description']}%"
-                query = query.filter(
-                    or_(
-                        Class.description_es.ilike(description_pattern),
-                        Class.description_en.ilike(description_pattern),
+            else:
+                if filters.get("class_code"):
+                    query = query.filter(
+                        Class.class_code.ilike(f"%{filters['class_code']}%")
+                    )
+                if filters.get("description"):
+                    description_pattern = f"%{filters['description']}%"
+                    query = query.filter(
+                        or_(
+                            Class.description_es.ilike(description_pattern),
+                            Class.description_en.ilike(description_pattern),
+                        )
                     )
-                )
             if filters.get("material_key"):
                 query = query.filter(
                     Class.material_key.ilike(f"%{filters['material_key']}%")
diff --git a/frontend/src/lib/api/dashboard/a76/classes.ts b/frontend/src/lib/api/dashboard/a76/classes.ts
index 00c1cc4a..6f0eb86b 100644
--- a/frontend/src/lib/api/dashboard/a76/classes.ts
+++ b/frontend/src/lib/api/dashboard/a76/classes.ts
@@ -58,7 +58,9 @@ export interface A76ClassListParams {
     page_size?: number;
     class_code?: string;
     description?: string;
-    q?: string; // Agregado por si usas búsqueda general
+    /** Búsqueda OR en class_code, description_es y description_en (backend ClassService) */
+    search?: string;
+    q?: string;
     sort_by?: string;
     sort_order?: 'asc' | 'desc';
 }
diff --git a/frontend/src/lib/components/dashboard/goods/parts/class-selector-dialog.svelte b/frontend/src/lib/components/dashboard/goods/parts/class-selector-dialog.svelte
index 7a954a0a..cfa9e69c 100644
--- a/frontend/src/lib/components/dashboard/goods/parts/class-selector-dialog.svelte
+++ b/frontend/src/lib/components/dashboard/goods/parts/class-selector-dialog.svelte
@@ -1,156 +1,220 @@
 <script lang="ts">
-    import { Button } from "$lib/components/ui/button";
-    import { Input } from "$lib/components/ui/input";
-    import * as Dialog from "$lib/components/ui/dialog";
-    import { Search, Loader2, Tag, Ruler } from "lucide-svelte";
-    import { classesApi, type A76Class } from "$lib/api/dashboard/a76/classes"; // Ajusta ruta
-    import { companyStore } from "$lib/stores/company.svelte";
+	import { Button } from '$lib/components/ui/button';
+	import { Input } from '$lib/components/ui/input';
+	import * as Dialog from '$lib/components/ui/dialog';
+	import { Search, Loader2, Tag, Ruler } from 'lucide-svelte';
+	import { classesApi, type A76Class } from '$lib/api/dashboard/a76/classes';
+	import { companyStore } from '$lib/stores/company.svelte';
 
-    // --- PROPS ---
-    let { 
-        open = $bindable(false), 
-        onSelect 
-    }: { 
-        open: boolean, 
-        onSelect: (item: A76Class) => void 
-    } = $props();
+	let {
+		open = $bindable(false),
+		onSelect
+	}: {
+		open: boolean;
+		onSelect: (item: A76Class) => void;
+	} = $props();
 
-    // --- ESTADO ---
-    let items = $state<A76Class[]>([]);
-    let loading = $state(false);
-    let searchTerm = $state("");
-    let loaded = $state(false);
+	let items = $state<A76Class[]>([]);
+	let total = $state(0);
+	let currentPage = $state(1);
+	let loading = $state(false);
+	let loadingMore = $state(false);
+	let searchTerm = $state('');
 
-    // Filtro local: Busca por Clave (class_code) o Descripción (description_es)
-    let filteredItems = $derived(
-        items.filter(i => 
-            (i.class_code || "").toLowerCase().includes(searchTerm.toLowerCase()) || 
-            (i.description_es || "").toLowerCase().includes(searchTerm.toLowerCase())
-        )
-    );
+	const PAGE_SIZE = 100;
 
-    // Cargar datos al abrir
-    $effect(() => {
-        if (open && !loaded && companyStore.activeCompany?.id) {
-            loadClasses();
-        }
-    });
+	const hasMore = $derived(items.length < total && total > 0);
 
-    async function loadClasses() {
-        if (!companyStore.activeCompany?.id) return;
-        
-        loading = true;
-        try {
-            
-            const res = await classesApi.list({ 
-                company_id: companyStore.activeCompany.id,
-                page: 1,
-                page_size: 100
-            });
-            
-           
-            const data = (res as any).data || res;
-            
-            
-            const list = data.items || data.classes || [];
-            
-            if (Array.isArray(list)) {
-                items = list;
-                loaded = true;
-            } else {
-                console.warn("No encontré lista de clases en la respuesta:", data);
-            }
+	async function loadPage(trimmed: string, page: number, append: boolean) {
+		const companyId = companyStore.activeCompany?.id;
+		if (!companyId) return;
 
-        } catch (e) {
-            console.error("Error cargando clases:", e);
-        } finally {
-            loading = false;
-        }
-    }
+		if (append) {
+			if (loadingMore || loading || !hasMore) return;
+		} else if (loading) {
+			return;
+		}
 
-    function handleSelect(item: A76Class) {
-        if (onSelect) onSelect(item);
-        open = false;
-    }
+		if (page === 1) {
+			loading = true;
+		} else {
+			loadingMore = true;
+		}
+
+		try {
+			const res = await classesApi.list({
+				company_id: companyId,
+				page,
+				page_size: PAGE_SIZE,
+				...(trimmed ? { search: trimmed } : {})
+			});
+
+			const data = (res as { data?: { items?: A76Class[]; total?: number } }).data ?? res;
+			const raw = (data as { items?: A76Class[] }).items ?? [];
+			const newItems = Array.isArray(raw) ? raw : [];
+
+			if (append && newItems.length === 0) {
+				total = items.length;
+				return;
+			}
+
+			const t =
+				typeof (data as { total?: number }).total === 'number'
+					? (data as { total: number }).total
+					: append
+						? items.length + newItems.length
+						: newItems.length;
+
+			if (append) {
+				items = [...items, ...newItems];
+			} else {
+				items = newItems;
+			}
+			total = t;
+			currentPage = page;
+		} catch (e) {
+			console.error('Error cargando clases:', e);
+			if (!append) {
+				items = [];
+				total = 0;
+			}
+		} finally {
+			loading = false;
+			loadingMore = false;
+		}
+	}
+
+	function handleScroll(e: Event) {
+		const target = e.currentTarget as HTMLDivElement;
+		const threshold = 80;
+		if (target.scrollHeight - target.scrollTop - target.clientHeight > threshold) return;
+		if (!hasMore || loading || loadingMore) return;
+		const term = searchTerm.trim();
+		loadPage(term, currentPage + 1, true);
+	}
+
+	$effect(() => {
+		if (!open) {
+			searchTerm = '';
+			items = [];
+			total = 0;
+			currentPage = 1;
+		}
+	});
+
+	$effect(() => {
+		if (!open) return;
+		const companyId = companyStore.activeCompany?.id;
+		if (!companyId) return;
+
+		const term = searchTerm.trim();
+		const delayMs = term === '' ? 0 : 300;
+		const handle = setTimeout(() => {
+			loadPage(term, 1, false);
+		}, delayMs);
+		return () => clearTimeout(handle);
+	});
+
+	function handleSelect(item: A76Class) {
+		if (onSelect) onSelect(item);
+		open = false;
+	}
 </script>
 
 <Dialog.Root bind:open={open}>
-    <Dialog.Content class="sm:max-w-[700px] max-h-[80vh] flex flex-col z-[300]">
-        <Dialog.Header>
-            <Dialog.Title>Seleccionar Clase (Anexo 24)</Dialog.Title>
-            <Dialog.Description>
-                Seleccione la clasificación del material.
-            </Dialog.Description>
-        </Dialog.Header>
+	<Dialog.Content class="sm:max-w-[700px] max-h-[80vh] flex flex-col z-[300]">
+		<Dialog.Header>
+			<Dialog.Title>Seleccionar Clase (Anexo 24)</Dialog.Title>
+			<Dialog.Description>
+				Seleccione la clasificación del material. Desplace hacia abajo para cargar más resultados.
+			</Dialog.Description>
+		</Dialog.Header>
 
-        <div class="relative w-full my-2">
-            <Search class="absolute left-2.5 top-2.5 h-4 w-4 text-muted-foreground" />
-            <Input 
-                type="search" 
-                placeholder="Buscar por Clave o Descripción..." 
-                class="pl-9" 
-                bind:value={searchTerm}
-            />
-        </div>
+		<div class="relative w-full my-2">
+			<Search class="absolute left-2.5 top-2.5 h-4 w-4 text-muted-foreground" />
+			<Input
+				type="search"
+				placeholder="Buscar por Clave o Descripción..."
+				class="pl-9"
+				bind:value={searchTerm}
+			/>
+		</div>
 
-        <div class="flex-1 overflow-y-auto border rounded-md min-h-[300px]">
-            {#if loading}
-                <div class="flex flex-col items-center justify-center h-48 gap-2 text-muted-foreground">
-                    <Loader2 class="h-8 w-8 animate-spin text-primary" />
-                    <p>Cargando catálogo...</p>
-                </div>
-            {:else if filteredItems.length === 0}
-                <div class="flex flex-col items-center justify-center h-48 text-muted-foreground">
-                    <p>No se encontraron clases.</p>
-                </div>
-            {:else}
-                <table class="w-full text-sm">
-                    <thead class="bg-muted/50 sticky top-0 backdrop-blur-sm">
-                        <tr class="text-left border-b">
-                            <th class="p-3 font-medium text-muted-foreground w-[100px]">Clave</th>
-                            <th class="p-3 font-medium text-muted-foreground">Descripción</th>
-                            <th class="p-3 font-medium text-muted-foreground w-[80px]">UM</th>
-                        </tr>
-                    </thead>
-                    <tbody>
-                        {#each filteredItems as item}
-                            <tr 
-                                class="border-b hover:bg-accent/50 transition-colors cursor-pointer"
-                                onclick={() => handleSelect(item)}
-                            >
-                                <td class="p-3">
-                                    <span class="font-mono font-bold text-primary bg-primary/10 px-2 py-1 rounded text-xs">
-                                        {item.class_code}
-                                    </span>
-                                </td>
-                                
-                                <td class="p-3">
-                                    <div class="flex items-center gap-2">
-                                        <Tag class="h-3 w-3 text-muted-foreground shrink-0" />
-                                        <span class="truncate max-w-[300px]" title={item.description_es || ''}>
-                                            {item.description_es || 'Sin descripción'}
-                                        </span>
-                                    </div>
-                                </td>
+		<div
+			class="flex-1 overflow-y-auto border rounded-md min-h-[300px]"
+			onscroll={handleScroll}
+		>
+			{#if loading}
+				<div class="flex flex-col items-center justify-center h-48 gap-2 text-muted-foreground">
+					<Loader2 class="h-8 w-8 animate-spin text-primary" />
+					<p>Cargando catálogo...</p>
+				</div>
+			{:else if items.length === 0}
+				<div class="flex flex-col items-center justify-center h-48 text-muted-foreground">
+					<p>No se encontraron clases.</p>
+				</div>
+			{:else}
+				<table class="w-full text-sm">
+					<thead class="bg-muted/50 sticky top-0 backdrop-blur-sm">
+						<tr class="text-left border-b">
+							<th class="p-3 font-medium text-muted-foreground w-[100px]">Clave</th>
+							<th class="p-3 font-medium text-muted-foreground">Descripción</th>
+							<th class="p-3 font-medium text-muted-foreground w-[80px]">UM</th>
+						</tr>
+					</thead>
+					<tbody>
+						{#each items as item}
+							<tr
+								class="border-b hover:bg-accent/50 transition-colors cursor-pointer"
+								onclick={() => handleSelect(item)}
+							>
+								<td class="p-3">
+									<span
+										class="font-mono font-bold text-primary bg-primary/10 px-2 py-1 rounded text-xs"
+									>
+										{item.class_code}
+									</span>
+								</td>
 
-                                <td class="p-3">
-                                    <div class="flex items-center gap-1 text-xs text-muted-foreground">
-                                        <Ruler class="h-3 w-3" />
-                                        {item.unit_of_measure || '-'}
-                                    </div>
-                                </td>
-                            </tr>
-                        {/each}
-                    </tbody>
-                </table>
-            {/if}
-        </div>
+								<td class="p-3">
+									<div class="flex items-center gap-2">
+										<Tag class="h-3 w-3 text-muted-foreground shrink-0" />
+										<span
+											class="truncate max-w-[300px]"
+											title={item.description_es || item.description_en || ''}
+										>
+											{item.description_es || item.description_en || 'Sin descripción'}
+										</span>
+									</div>
+								</td>
 
-        <Dialog.Footer>
-            <div class="text-xs text-muted-foreground self-center mr-auto">
-                {filteredItems.length} registros encontrados
-            </div>
-            <Button variant="outline" onclick={() => open = false}>Cancelar</Button>
-        </Dialog.Footer>
-    </Dialog.Content>
-</Dialog.Root>
\ No newline at end of file
+								<td class="p-3">
+									<div class="flex items-center gap-1 text-xs text-muted-foreground">
+										<Ruler class="h-3 w-3" />
+										{item.unit_of_measure || '-'}
+									</div>
+								</td>
+							</tr>
+						{/each}
+					</tbody>
+				</table>
+				{#if loadingMore}
+					<div class="flex justify-center py-3 text-muted-foreground">
+						<Loader2 class="h-6 w-6 animate-spin" />
+					</div>
+				{/if}
+			{/if}
+		</div>
+
+		<Dialog.Footer>
+			<div class="text-xs text-muted-foreground self-center mr-auto">
+				{#if loading}
+					…
+				{:else}
+					Mostrando {items.length} de {total} registros
+				{/if}
+			</div>
+			<Button variant="outline" onclick={() => (open = false)}>Cancelar</Button>
+		</Dialog.Footer>
+	</Dialog.Content>
+</Dialog.Root>
diff --git a/frontend/src/lib/components/dashboard/invoices/edit/items/fa/class-dialog.svelte b/frontend/src/lib/components/dashboard/invoices/edit/items/fa/class-dialog.svelte
index 71a07c9e..3d091ec5 100644
--- a/frontend/src/lib/components/dashboard/invoices/edit/items/fa/class-dialog.svelte
+++ b/frontend/src/lib/components/dashboard/invoices/edit/items/fa/class-dialog.svelte
@@ -7,6 +7,7 @@
 	import { toast } from 'svelte-sonner';
 	import { companyStore } from '$lib/stores/company.svelte';
 	import { onMount } from 'svelte';
+	import { classesApi } from '$lib/api/dashboard/a76/classes';
 
 	let {
 		open = $bindable(false),
@@ -22,9 +23,9 @@
 	let isLoadingMore = $state(false);
 	let classes = $state<any[]>([]);
 	let currentPage = $state(1);
-	let hasMore = $state(true);
 	let totalItems = $state(0);
-	const itemsPerPage = 25;
+	const itemsPerPage = 50;
+	const hasMore = $derived(classes.length < totalItems && totalItems > 0);
 
 	async function fetchClasses(page: number = 1, search: string = '') {
 		const activeCompanyId = companyStore?.activeCompany?.id;
@@ -34,26 +35,17 @@
 		else isLoadingMore = true;
 
 		try {
-			// Construct query params
-			const params = new URLSearchParams({
-				company_id: activeCompanyId.toString(),
-				page: page.toString(),
-				page_size: itemsPerPage.toString(),
-				sort_by: 'class_code',
-				sort_order: 'asc'
+			const res: any = await classesApi.list({
+				company_id: activeCompanyId,
+				page,
+				page_size: itemsPerPage,
+				...(search ? { search } : {})
 			});
-
-			if (search) {
-				// Most TenantCRUDRoutes support 'q' for general search or field-specific filters
-				params.append('q', search);
-			}
-
-			const response = await fetch(`/api-sveltekit/classes?${params.toString()}`);
-
-			if (!response.ok) throw new Error('Error al buscar clases');
-
-			const data = await response.json();
-			const newItems = data.items || [];
+			
+			// Manejar diferentes formatos de respuesta
+			const data = res.data ?? res;
+			const newItems = Array.isArray(data.items) ? data.items : [];
+			const total = data.total ?? (page === 1 ? newItems.length : classes.length + newItems.length);
 			
 			if (page === 1) {
 				classes = newItems;
@@ -61,12 +53,15 @@
 				classes = [...classes, ...newItems];
 			}
 
-			totalItems = data.total || 0;
-			hasMore = newItems.length === itemsPerPage;
+			totalItems = total;
 			currentPage = page;
 		} catch (error) {
 			console.error('Error fetching classes:', error);
 			toast.error('Error al cargar clases');
+			if (page === 1) {
+				classes = [];
+				totalItems = 0;
+			}
 		} finally {
 			isSearching = false;
 			isLoadingMore = false;
@@ -75,9 +70,7 @@
 
 	// Debounce effect
 	$effect(() => {
-		// Accedemos a searchQuery para que el efecto dependa de él
 		const query = searchQuery;
-		
 		const timeout = setTimeout(() => {
 			if (debouncedSearch !== query) {
 				debouncedSearch = query;
@@ -85,10 +78,20 @@
 				fetchClasses(1, query);
 			}
 		}, 400);
-		
 		return () => clearTimeout(timeout);
 	});
 
+	$effect(() => {
+		if (!open) {
+			searchQuery = '';
+			classes = [];
+			totalItems = 0;
+			currentPage = 1;
+		}
+	});
+
+
+
 	function handleSelect(classItem: any) {
 		if (onSelect) onSelect(classItem);
 		open = false;
@@ -158,7 +161,7 @@
 						</Table.Row>
 					</Table.Header>
 					<Table.Body>
-						{#each classes as classItem (classItem.id)}
+						{#each classes as classItem (classItem.id || classItem.class_code)}
 							<Table.Row
 								class="group cursor-pointer border-zinc-100 dark:border-zinc-800/50 hover:bg-blue-50/50 dark:hover:bg-blue-900/10 transition-colors"
 								onclick={() => handleSelect(classItem)}
@@ -197,7 +200,6 @@
 								</Table.Row>
 							{/if}
 						{/each}
-
 						<!-- Infinite Scroll Trigger -->
 						{#if hasMore}
 							<Table.Row class="border-none hover:bg-transparent">