Add POS shopify.printing API (getPrinters + printer selection)

[aaronschubert0]

What

Adds the POS shopify.printing API to the 2026-07 surface, per the approved TAG spec Shopify/ui-api-design#1413. This is the types layer of the cross-repo Printing API work.

const printers = await shopify.printing.getPrinters();
const receiptPrinter = printers.find((p) => p.connected);

if (receiptPrinter) {
  await shopify.printing.print('/print/receipt', {printer: receiptPrinter});
} else {
  await shopify.printing.print('/print/receipt'); // system print dialog
}

Changes

• api/printing-api/printing-api.ts (new):
  • PrintingApiContent — getPrinters(): Promise<Printer[]> and print(src, options?): Promise<void>
  • PrintOptions — { printer?: Printer }
  • Printer — { id: string; name: string; connected: boolean }
  • PrintingApi — { printing: PrintingApiContent } (the shopify.printing namespace)
  • JSDoc mirrors the committed spec; each interface carries @publicDocs for shopify.dev generation.
• standard-api.ts: add PrintingApi to StandardApi.
• api.ts: export the new public types.
• print-api.ts: @deprecate PrintApi / PrintApiContent in favor of shopify.printing. shopify.print stays as a deprecated alias.
• Changeset: minor.

Notes

• This PR is types only. Runtime behavior (version gating to >= 2026-07, getPrinters() returning the connected receipt printer, and routing print(src, {printer}) to it) lands in the extensibility plugin (PR A2) and the pos-mobile bridge (PR B2).
• Printer follows the committed spec exactly — { id, name, connected }, no type field.

Testing

• tsc --noEmit over @shopify/ui-extensions: 0 errors.

Related

• Spec (TAG-approved): Shopify/ui-api-design#1413
• Downstream — extensibility printingPlugin: Shopify/extensibility#1457
• Downstream — pos-mobile bridge (getPrinters + receipt routing): shop/world#837111
• Downstream — shopify-dev docs: shop/world#837232

🤖 Drafted with pi.