Nutshell 0.21.0

Nutshell 0.21.0 brings security hardening, Lightning backend improvements, wallet fixes, and the retirement of deprecated integrations and APIs.

Compatibility Notes

• Removed Lightning backends: BlinkWallet, LNbitsWallet, and the deprecated CoreLightningRestWallet. Operators using these must switch to a supported backend before upgrading. Core Lightning users should use CLNRestWallet with xpay available.
• Removed legacy API support: deprecated mint endpoints and wallet compatibility fallbacks for older mint responses have been retired. Integrations should use the current /v1 API.

Notable Changes

Mint

• LND self-payments: optional support through MINT_LND_ALLOW_SELF_PAYMENT, disabled by default, for both REST and gRPC backends.
• LND invoice compatibility: fixes for millisatoshi invoice creation and sub-satoshi rounding, plus clearer errors for unsupported partial self-payments.
• Core Lightning: CLNRestWallet now uses xpay for outgoing payments.
• NUT-06 request limits: /v1/info now advertises max_array_length, allowing wallets to size requests before submitting them.
• Standardized error codes: aligned with the Cashu specifications, including error 12002 for inactive output keysets.
• Spark: updated the Breez SDK dependency.

Wallet

• Named wallets: receiving tokens and listing wallets now consistently use the correct wallet name and database.
• CLI invoice handling: unpaid invoices are no longer reported as paid, and waiting for WebSocket payment notifications is bounded.
• Lightning change: blank change outputs now use amount 0 for NUT-08 compatibility.
• npub.cash: correctly recognizes already-issued quotes using the updated mint error code.

Other

• Added scheduled mutation testing and expanded Lightning, Spark, mint, wallet, and authentication integration tests.
• Removed obsolete regtest tooling and standardized LF line endings.

New Contributors

• @orangeshyguy21
• @SatsAndSports
• @Hardeezah

Full Changelog: 0.20.3...0.21.0

What's Changed

• chore: remove dead regtest tooling by @orangeshyguy21 in #1098
• feat: update nut29 test vector with uuidv7 by @KvngMikey in #1099
• add SECURITY.md by @callebtc in #1102
• fix(wallet): pass wallet name when constructing mint_wallet on receive paths by @KvngMikey in #1089
• Refactor: use central constants for method and subscription kind strings by @KvngMikey in #1101
• fix(mint): validate blinded output points by @a1denvalu3 in #1106
• fix a variety of issues with SIG_ALL and its interaction with P2PK and HTLC by @SatsAndSports in #1008
• Align route and payment state handling by @a1denvalu3 in #1108
• feat(lightning): add setting to allow LND self-payments Closes #1092 by @Hardeezah in #1107
• Chore/retire deprecated code by @callebtc in #1086
• fix(wallet): handle unpaid invoices in the CLI invoice command by @edgarmuyomba in #1022
• fix(lightning): improve error message for unsupported LND partial self-payments by @Hardeezah in #1113
• test: melt with real routing fees on regtest by @orangeshyguy21 in #1103
• fix(wallet): send blank change outputs with amount 0 by @robwoodgate in #1118
• chore(lightning): remove Blink and LNbits backends by @callebtc in #1110
• feat: add scheduled mutation testing by @a1denvalu3 in #1094
• fix(mint): return error 12002 for inactive output keysets by @callebtc in #1120
• fix(mint): enable balance watchdog with SIGTERM process shutdown by @Hardeezah in #1117
• use cln xpay by @callebtc in #1127
• fix(ci): restore mutation testing reports by @a1denvalu3 in #1136
• feat(mint): advertise the maximum request array length by @robwoodgate in #1115
• Fix: Standardize error codes by @KvngMikey in #1129
• fix(deps): bump breez-sdk-spark to ^0.17.0… by @KvngMikey in #1144
• chore: enforce LF line endings by @a1denvalu3 in #1141
• fix(wallet): dispatch NPC already-issued check on 20002 not 11000 by @KvngMikey in #1142
• ci: pin regtest setup and update fee-rounding test by @a1denvalu3 in #1148
• fix(mint): unblock mutation tests with RPC state cleanup by @a1denvalu3 in #1149
• fix(auth): align auth promises schema with the mint CRUD by @KvngMikey in #1145
• fix(ci): run Keycloak auth integration tests by @a1denvalu3 in #1150
• fix: use wallet name in wallets command by @orangeshyguy21 in #1155
• fix: LND msat invoice creation by @callebtc in #1156
• refactor(mint): align ledger execution and Lightning backend contracts by @callebtc in #1157
• fix(lightning): don't treat sub-satoshi rounding as a partial payment by @gorrdy in #1153
• chore(release): bump version to 0.21.0 by @callebtc in #1158
• test(spark): run shared mint and wallet regtests by @a1denvalu3 in #1147

New Contributors

• @orangeshyguy21 made their first contribution in #1098
• @SatsAndSports made their first contribution in #1008
• @Hardeezah made their first contribution in #1107

Full Changelog: 0.20.3...0.21.0