Web guide

@thermal-label/marklife-web exposes:

• requestPrinters(opts) — the browser picker for one transport, returning a PrinterAdapterMap. This is the entry point.
• WebMarklifePrinter — the PrinterAdapter; construct it yourself when you already hold a Transport.
• MarklifeBleTransport, resolveProfile, MARKLIFE_BLE_PROFILES, OPTIONAL_SERVICES — the BLE pieces, for hosts that drive navigator.bluetooth themselves.
• devicesForTransport(type) — the registry entries that declare a transport; what DeviceIdentificationRequiredError.candidates is built from.
• requestPrinterSerial / fromSerialPort — deprecated single-transport factories, kept for one release.

requestPrinters

import { requestPrinters } from '@thermal-label/marklife-web';

const printers = await requestPrinters({ transport: 'bluetooth-gatt' });
const printer = printers.primary!;

transport	Picker	Identification
'bluetooth-gatt'	Web Bluetooth, filtered on every registry name prefix	From the advertised name by longest-prefix match: P12_ZA15B_BLE → P12. Unmatched → DeviceIdentificationRequiredError.
'usb'	WebUSB, filtered on the registry's vendor/product ids	From the vendor/product id. Unmatched → DeviceIdentificationRequiredError.
'serial', 'bluetooth-spp'	Web Serial (any port the page may see)	None available; deviceKey is required and the call rejects without it.

An explicit deviceKey always wins over identification.

DeviceIdentificationRequiredError carries candidates (the entries that declare the transport) and continueWith(key), which resumes with the already-picked device so the browser picker does not open twice.

BLE

The chassis advertise a vendor UUID rather than the service they host, and a single unit can host several GATT profiles. After the picker, requestPrinters connects, probes the four known profiles in preference order and opens MarklifeBleTransport on the first that resolves. Profile A's credit gate on ff03 is honoured automatically; see the hardware page for the profile table and the protocol index for the gate.

Chrome, Edge and Opera on desktop and Android; not Firefox or Safari.

USB

The P12 and P15 enumerate as USB Printer-class devices. WebUSB needs the OS to leave the interface unclaimed — on Linux, a udev rule granting access (MODE="0666", TAG+="uaccess") plus usblp unbound from the interface (an ACTION=="bind", DRIVER=="usblp" unbind rule keyed on the VID); on Windows, a WinUSB driver.

Serial

Web Serial lists every paired Bluetooth SPP device and every USB-serial bridge the page is permitted to see, and tells you nothing about which is which. Pass deviceKey. Pairing notes — PINs, the RFCOMM bind on Linux — are in the Node guide; the port it produces is what the picker lists.

Chrome, Edge and Opera on desktop only.

WebMarklifePrinter

class WebMarklifePrinter implements PrinterAdapter {
  constructor(device: DeviceEntry, transport: Transport, options?: WebMarklifePrinterOptions);
  readonly family: 'marklife';
  readonly device: DeviceEntry;
  get model(): string;
  get connected(): boolean;
  print(image: RawImageData, media?: MediaDescriptor, options?: MarklifePrintOptions): Promise<void>;
  createPreview(image: RawImageData, options?: PreviewOptions): Promise<PreviewResult>;
  getStatus(): Promise<MarklifeStatus>;
  onStatus(cb: (status: PrinterStatus) => void): () => void;
  close(): Promise<void>;
}

interface WebMarklifePrinterOptions {
  threshold?: number;          // dither threshold, 0..255; per-engine default
  interChunkDelayMs?: number;  // pause between packets; registry default
}

• print() encodes the job for the entry's engine and feeds it to the transport in registry-sized packets with a pause between them (the pacing every chassis needs). It throws MediaNotSpecifiedError without a media descriptor.
• getStatus() reports link state only; no chassis has a status query wired. onStatus() polls it.
• print() and getStatus() are serialised against each other, so a status poll during a print waits for the job to finish.

Bringing your own transport

WebMarklifePrinter takes any Transport. To skip the picker logic — a WebUSB device you already hold, say:

import { WebUsbTransport } from '@thermal-label/transport/web';
import { DEVICES } from '@thermal-label/marklife-core';
import { WebMarklifePrinter } from '@thermal-label/marklife-web';

const transport = await WebUsbTransport.fromDevice(usbDevice);
const printer = new WebMarklifePrinter(DEVICES.P12, transport);