Hi, thanks for your reply. I tried what you said, but it didn't work. I'll share my original code so you can review it; I probably missed something.

This is my code:
quantity_dialog.xml

<?xml version="1.0" encoding="UTF-8"?>

<t t-name="alx_barcode_psv.QuantityDialog">

<Dialog size="'md'" title="props.title || _('Ingrese cantidad')" footer="false" withCloseButton="false">

<t t-set="DialogHeader" t-value="''"/>

<div class="o_form_label mb-2">

<t t-esc="props.subtitle || ''"/>

</div>

<div class="mb-3">

<label class="form-label">

<t t-esc="props.label || _('Cantidad a agregar')"/>

</label>

<input type="number"

class="form-control"

t-model="state.qty"

min="0"

step="any"

t-att-autofocus="true"/>

<div class="d-flex justify-content-end mt-4">

<button style="margin-right: 8px;" type="button" class="btn btn-secondary" t-on-click="onCancel">

Cancelar

</button>

<button type="button" class="btn btn-primary" t-on-click="onConfirm">

Aceptar

</button>

</div>

</div>

</Dialog>

</t>

/** @odoo-module **/

import { _t } from "@web/core/l10n/translation";

import { patch } from "@web/core/utils/patch";

import BarcodePickingModel from "@stock_barcode/models/barcode_picking_model";

import { Component, useState } from "@odoo/owl";

import { Dialog } from "@web/core/dialog/dialog";

// COMPONENTE QuantityDialog embebido

class QuantityDialog extends Component {

static template = "alx_barcode_psv.QuantityDialog";

static components = { Dialog };

setup() {

const { defaultQty = 1 } = this.props;

this.state = useState({ qty: String(defaultQty) });

}

onConfirm() {

const value = parseFloat(this.state.qty);

if (isNaN(value) || value <= 0) return;

this.props.resolve(value);

this.props.close();

this._reactivateScanner();

}

onCancel() {

this.props.resolve(false);

this.props.close();

this._reactivateScanner();

}

_reactivateScanner() {

const model = this.props.model;

if (model && typeof model.startBarcodeScanner === "function") {

model.startBarcodeScanner();

model.trigger("playSound");

}

}

}

// Función de diálogo

function askQuantity(dialogService, product, model) {

return new Promise((resolve) => {

const title = _t("Cantidad para %s", product?.display_name || _t("Producto"));

const subtitle = product?.code ? `[${product.code}] ${product.display_name}` : (product?.display_name || "");

dialogService.add(QuantityDialog, {

title,

subtitle,

label: _t("Cantidad a agregar"),

defaultQty: 1,

resolve,

model,

closeOnOutsideClick: false,

closeOnEsc: false,

});

});

}

// Validación de producto no reservado

function denyNewLine(product) {

const name =

(product?.code ? `[${product.code}] ` : "") +

(product?.display_name || _t("Producto"));

this.trigger("playSound");

this.notification(

_t("No puedes escanear el producto %s porque no está reservado en esta operación.", name),

{ type: "danger" }

);

}

// Guardamos funciones originales

const ORIG = {

updateLine: BarcodePickingModel.prototype.updateLine,

setQtyDone: BarcodePickingModel.prototype.setQtyDone,

};

// Parcheo al modelo

patch(BarcodePickingModel.prototype, {

createNewLine(params) {

denyNewLine.call(this, params?.fieldsParams?.product_id);

return false;

},

async _createNewLine(params) {

denyNewLine.call(this, params?.fieldsParams?.product_id);

return false;

},

askBeforeNewLinesCreation(/* product */) {

return false;

},

async updateLine(line, fieldsParams = {}) {

if (fieldsParams.__skipQtyPopup || fieldsParams.package || fieldsParams.resultPackage) {

return await ORIG.updateLine.call(this, line, fieldsParams);

}

const product = fieldsParams.product || line?.product_id;

if (!product) {

return await ORIG.updateLine.call(this, line, fieldsParams);

}

this.trigger("playSound");

const qty = await askQuantity(this.dialogService, product, this);

if (!qty) {

this.notification(_t("Operación cancelada"), { type: "warning" });

return false;

}

const current = this.getQtyDone(line) || 0;

const newQty = current + qty;

fieldsParams.qty_done = newQty;

fieldsParams.__skipQtyPopup = true;

const res = await ORIG.updateLine.call(this, line, fieldsParams);

this.trigger("update");

return res;

},

});

{

"name": "Barcode Validations and entries",

"author": "ARCA Labs",

"depends": ["base","stock_barcode","barcodes"],

"data": [],

"assets": {

"web.assets_backend": [

"alx_barcode_psv/static/src/js/barcode_model_override.js",

"alx_barcode_psv/static/src/components/quantity_dialog/quantity_dialog.xml",

],

},

}