cmd: `addinvoice --qr` to print invoice QR by hieblmi · Pull Request #10638 · lightningnetwork/lnd

hieblmi · 2026-03-09T13:05:22Z

Optionally print the QR code of an invoice, added with lncli addinvoice --amt 1010 --qr

gemini-code-assist · 2026-03-09T13:05:37Z

Summary of Changes

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This pull request enhances the lncli command-line tool by integrating a QR code generation feature for invoices. Users can now opt to display a scannable QR code for their payment requests directly in the terminal, significantly improving the ease of use for mobile wallet integration and streamlining the payment process.

Highlights

New Feature: QR Code Display: Introduced a new --qr flag to the addinvoice command, allowing users to display a QR code of the generated payment request directly in the terminal.
Dependency Update: Added a new Go module dependency, github.com/mdp/qrterminal/v3, to facilitate QR code generation and display.
Documentation: Updated the release notes for version 0.21.0 to reflect the addition of the --qr flag.

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Changelog

cmd/commands/cmd_invoice.go
- Added os and qrterminal imports.
- Introduced a new cli.BoolFlag named qr to the AddInvoiceCommand.
- Implemented logic to generate and print a half-block QR code of the PaymentRequest to os.Stdout if the qr flag is set.
docs/release-notes/release-notes-0.21.0.md
- Added a new entry documenting the --qr flag for the addinvoice command under the 'New Features' section.
go.mod
- Added github.com/mdp/qrterminal/v3 and rsc.io/qr as indirect dependencies.
go.sum
- Updated checksums for the newly added github.com/mdp/qrterminal/v3 and rsc.io/qr dependencies.

Activity

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Code Review

This pull request introduces a useful feature to display a QR code for an invoice via the --qr flag in the addinvoice command. The implementation is straightforward and correct. I have one suggestion to add a comment to the new code block to align with the repository's style guide regarding code documentation.

cmd/commands/cmd_invoice.go

ziggie1984

Have you tested this with a bigger invoice including blinded paths ? I wonder what is the information limit for this QR code representation ?

ziggie1984 · 2026-03-09T18:56:57Z

go.mod

 )

+require (
+	github.com/mdp/qrterminal/v3 v3.2.1 // indirect


why are these in a separarte required block ?

moved them, fixed.

hieblmi · 2026-03-10T08:41:06Z

Have you tested this with a bigger invoice including blinded paths ? I wonder what is the information limit for this QR code representation ?

You really have to dial down the font size of your terminal to make the QR code fit onto the screen, but it works.

On the limits:

QR code max: 4,296 alphanumeric characters (version 40, error correction L). Since bech32 invoices are alphanumeric, this is the effective limit.                                                                      
                                                                                                                                                                                                                       
  Blinded route size: There's no hard protocol max, but practically:                                                                                                                                                     
  - A standard invoice: ~300-400 chars                                                                                                                                                                                   
  - With 1 blinded path (2-3 hops): ~600-800 chars                                                                                                                                                                       
  - With 3 blinded paths (3-5 hops each): ~1,200-2,000 chars                                                                                                                                                           
  - Extreme cases: could exceed 3,000+ chars         

  So even large blinded invoices should fit within the QR limit. No need to disable --qr for blinded paths.

ziggie1984 · 2026-03-15T18:00:22Z

docs/release-notes/release-notes-0.21.0.md

  inputs for fee estimation.

+* The `addinvoice` command now supports a `--qr` flag that renders the payment
+  request as a QR code directly in the terminal, making it easy to scan from a


This entry belongs under ## lncli Updates, not ## lncli Additions. Additions is for new commands; this is a new flag on an existing command. For reference, the --include_log flag added to getdebuginfo in the same file follows this convention correctly.

Thanks, fixed!

ziggie1984 · 2026-03-15T18:00:22Z

docs/release-notes/release-notes-0.21.0.md

  inputs for fee estimation.

+* The `addinvoice` command now supports a `--qr` flag that renders the payment
+  request as a QR code directly in the terminal, making it easy to scan from a


This entry is missing a PR hyperlink. All other entries in the surrounding sections link to their PR, e.g. [description](https://github.com/lightningnetwork/lnd/pull/XXXXX). Please update once the PR number is known.

Fixed as well.

ziggie1984

LGTM, expect for the below nits

regarding the new dependency I think it is ok to pull it in pretty small footprint

Dependency Evaluation: qrterminal/v3 v3.2.1 + rsc.io/qr v0.2.0

  Licenses: MIT + BSD-3-Clause. Both permissive, compatible with lnd.

  Footprint: Two new packages. golang.org/x/term (also pulled in) is already in lnd's tree.

  What the code does: Pure data transformation — string → Unicode characters written to an io.Writer. No network I/O, no file I/O, no goroutines, no syscalls.

  Known defect: qr.Encode errors are silently discarded; a nil return would panic on dereference. Not reachable in practice: lnd's MaxPaymentRequestSize (4096 bytes) fits within a Level-L
   Version-40 QR code's capacity (4296 alphanumeric chars).

  Provenance: qrterminal/v3 is the standard Go terminal QR library. rsc.io/qr is by Russ Cox (Go core team), stable since 2022.

  Blast radius: Import exists in one file (cmd/commands/cmd_invoice.go), compiled into one binary (lncli). Unreachable from the lnd daemon — no server, RPC, channel, or payment logic is
  affected. Worst-case failure is a garbled terminal.

ziggie1984 · 2026-03-16T16:33:55Z

@Roasbeef are you also ok with pulling this new dependency?

saubyk · 2026-03-16T16:34:49Z

cmd/commands/cmd_invoice.go

 	"strings"

 	"github.com/lightningnetwork/lnd/lnrpc"
+	qrterminal "github.com/mdp/qrterminal/v3"


what's our policy on adding new libraries?

Add a `--qr` flag to the `addinvoice` CLI command that renders the payment request as a QR code directly in the terminal using the qrterminal library. This makes it convenient to scan invoices from a mobile wallet without needing to copy-paste the payment request string.

lightninglabs-deploy · 2026-03-30T17:37:39Z

@hieblmi, remember to re-request review from reviewers when ready

gemini-code-assist bot reviewed Mar 9, 2026

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cmd/commands/cmd_invoice.go Show resolved Hide resolved

hieblmi marked this pull request as draft March 9, 2026 13:07

hieblmi changed the title ~~Invoice qr~~ cmd: addinvoice --qr to print invoice QR Mar 9, 2026

hieblmi force-pushed the invoice-qr branch from f36c579 to 82b785b Compare March 9, 2026 13:24

hieblmi self-assigned this Mar 9, 2026

hieblmi added the lncli label Mar 9, 2026

hieblmi requested a review from ziggie1984 March 9, 2026 13:51

hieblmi marked this pull request as ready for review March 9, 2026 14:21

ziggie1984 reviewed Mar 9, 2026

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hieblmi force-pushed the invoice-qr branch from 82b785b to bd2ef24 Compare March 10, 2026 08:54

hieblmi requested a review from ziggie1984 March 10, 2026 08:54

ziggie1984 reviewed Mar 15, 2026

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ziggie1984 approved these changes Mar 15, 2026

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hieblmi force-pushed the invoice-qr branch from bd2ef24 to 37efa77 Compare March 15, 2026 19:40

saubyk reviewed Mar 16, 2026

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hieblmi added 2 commits March 19, 2026 09:02

docs: add release notes for addinvoice --qr flag

e45800f

hieblmi force-pushed the invoice-qr branch from 37efa77 to e45800f Compare March 19, 2026 08:02

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hieblmi commented Mar 9, 2026 •

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