Core

@thermal-label/labelmanager-core is the shared protocol layer used by both the Node.js and Web packages. It contains the byte-stream encoder, the bitmap pipeline wiring, the device and media registries, the status parser, and the offline preview helper. It also re-exports the @thermal-label/contracts base types (PrinterAdapter, MediaDescriptor, PrinterStatus, …) for consumer convenience.

You rarely import *-core directly — use the Node.js or Web package for production code. Core is useful when you need the protocol encoder or offline preview without a live printer.

Looking for byte-level details?

The D1 tape protocol reference (in d1-core, shared with the LabelWriter Duo) documents the USB topology, exact byte sequences, status bits, mode-switch flow, and a porting checklist for other languages or runtimes.

Core API

Export	Description
DEVICES / findDevice	Device registry (VID, PID, family, supported tapes)
MEDIA / DEFAULT_MEDIA	Media registry and the 12 mm fallback for assumed previews
findMediaByTapeWidth(widthMm)	Lookup helper
STATUS_REQUEST	ESC A byte sequence
parseStatus(bytes)	Parse the status byte into PrinterStatus (contracts shape)
createPreviewOffline(image, media)	Render PreviewResult without a live printer connection
buildPrinterStream(bitmap, engine, opts, media)	Encode a full label job as a contiguous USB byte stream
LabelManagerDevice	Device descriptor type (extends contracts DeviceDescriptor)
LabelManagerMedia	Media descriptor type (extends contracts MediaDescriptor)
LabelManagerPrintOptions	Protocol options (copies, tapeWidth, rotate)
TapeWidth	6 | 9 | 12 | 19
PrinterAdapter, MediaDescriptor, PrinterStatus, Transport, …	Re-exported from @thermal-label/contracts

One encoder, transport's choice of interface

buildPrinterStream produces a single contiguous byte stream — the opcode order is fixed and bench-validated against the labelle Python prior art (see protocol reference). The transport layer is responsible for chunking that stream to the target endpoint's wMaxPacketSize (64 bytes) and for selecting which USB interface to write to.

The stream prints correctly on either of the two viable interfaces a LabelManager exposes after mode-switch:

• Printer class (Interface 0, bulk EP 0x05 OUT) — the default. Linux doesn't bind a kernel driver to it, so no detachKernelDriver step is needed and the udev story is conventional.
• HID (Interface 2, interrupt EP 0x01 OUT) — viable, but the Node driver needs to detach usbhid first; the browser would use WebHID instead of WebUSB. Not currently exposed by the Node or web packages, but the encoder output is interface-agnostic.

The byte stream is identical in either case. There is no separate "HID-style report" output shape — that was a misconception in earlier versions of this driver, drawn from generic ESC/POS receipt-printer conventions that don't apply to D1.