Implement Micro QR Code (M1-M4)

[productdevbook]

Context

Micro QR codes are increasingly requested for space-constrained applications (packaging labels, small components). While no single competitor issue tracks this, the demand comes from the broader barcode ecosystem and users of libraries like bwip-js that support it.

Description

Micro QR Code is a compact variant of QR Code defined in ISO/IEC 18004 Annex C. It uses a single finder pattern (vs. three in standard QR) and supports versions M1-M4 with sizes from 11x11 to 17x17 modules. It is ideal for very small labels where a full QR code would be too large.

Current Status in etiket

The types and stubs already exist in src/encoders/qr/micro.ts:

export function encodeMicroQR(_text: string, _options?: MicroQROptions): boolean[][] {
  throw new Error("Micro QR Code is not yet implemented");
}

The QRCodeOptions interface has a micro?: boolean field, but it is not wired up.

Proposed Solution

1. Implement the Micro QR encoding algorithm in src/encoders/qr/micro.ts:
   • M1: Numeric only, no EC
   • M2: Numeric + Alphanumeric, EC L/M
   • M3: Numeric + Alphanumeric + Byte + Kanji, EC L/M/Q
   • M4: All modes, EC L/M/Q
2. Single finder pattern placement (top-left only)
3. Micro QR specific format information encoding
4. Wire up the micro option in the main encodeQR function
5. Export encodeMicroQR from the public API
6. Add a dedicated microqr() convenience function or respect the micro: true option

[productdevbook]

Resolved in commit edc0677 — encodeMicroQR() for M1-M4 (11x11 to 17x17). Single finder, auto version/mode selection. 11 tests.