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feat: add mints_strict field to payment requests #2007

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f2418cc
feat: add mints_strict field to payment requests
d4rp4t May 26, 2026
4490e3c
feat: add mints_strict field to payment requests
d4rp4t Jun 13, 2026
da6ce50
feat: add fee_reserve and supported_methods to payment requests
d4rp4t Jun 14, 2026
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21 changes: 21 additions & 0 deletions crates/cashu/examples/payment_request_encoding_benchmark.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -94,6 +94,9 @@ fn minimal_comparison() -> Result<(), Box<dyn std::error::Error>> {
unit: None,
single_use: None,
mints: vec![MintUrl::from_str("https://mint.example.com")?],
mints_strict: None,
fee_reserve: None,
supported_methods: vec![],
description: None,
transports: vec![],
nut10: None,
Expand All @@ -110,6 +113,9 @@ fn amount_unit_comparison() -> Result<(), Box<dyn std::error::Error>> {
unit: Some(CurrencyUnit::Sat),
single_use: None,
mints: vec![MintUrl::from_str("https://mint.example.com")?],
mints_strict: None,
fee_reserve: None,
supported_methods: vec![],
description: None,
transports: vec![],
nut10: None,
Expand All @@ -131,6 +137,9 @@ fn multiple_mints_comparison() -> Result<(), Box<dyn std::error::Error>> {
MintUrl::from_str("https://mint3.example.com")?,
MintUrl::from_str("https://backup-mint.cashu.space")?,
],
mints_strict: None,
fee_reserve: None,
supported_methods: vec![],
description: Some("Payment with multiple mint options".to_string()),
transports: vec![],
nut10: None,
Expand All @@ -156,6 +165,9 @@ fn transport_comparison() -> Result<(), Box<dyn std::error::Error>> {
unit: Some(CurrencyUnit::Sat),
single_use: Some(true),
mints: vec![MintUrl::from_str("https://mint.example.com")?],
mints_strict: None,
fee_reserve: None,
supported_methods: vec![],
description: Some("Payment with callback transport".to_string()),
transports: vec![transport],
nut10: None,
Expand Down Expand Up @@ -193,6 +205,9 @@ fn complete_with_nut10_comparison() -> Result<(), Box<dyn std::error::Error>> {
MintUrl::from_str("https://mint1.example.com")?,
MintUrl::from_str("https://mint2.example.com")?,
],
mints_strict: None,
fee_reserve: None,
supported_methods: vec![],
description: Some("Complete payment with P2PK locking and refund key".to_string()),
transports: vec![transport],
nut10: Some(nut10),
Expand Down Expand Up @@ -245,6 +260,9 @@ fn very_complex_comparison() -> Result<(), Box<dyn std::error::Error>> {
MintUrl::from_str("https://backup-mint-2.example.net")?,
MintUrl::from_str("https://emergency-mint.example.io")?,
],
mints_strict: None,
fee_reserve: None,
supported_methods: vec![],
description: Some("Complex payment with multiple mints and transports".to_string()),
transports: vec![transport1, transport2],
nut10: Some(nut10),
Expand Down Expand Up @@ -503,6 +521,9 @@ mod tests {
unit: Some(CurrencyUnit::Sat),
single_use: None,
mints: vec![MintUrl::from_str("https://mint.example.com").unwrap()],
mints_strict: None,
fee_reserve: None,
supported_methods: vec![],
description: Some("Test".to_string()),
transports: vec![],
nut10: None,
Expand Down
45 changes: 45 additions & 0 deletions crates/cashu/src/nuts/nut18/payment_request.rs
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Original file line number Diff line number Diff line change
Expand Up @@ -36,6 +36,18 @@ pub struct PaymentRequest {
#[serde(rename = "m")]
#[serde(skip_serializing_if = "Vec::is_empty", default)]
pub mints: Vec<MintUrl>,
/// Mints strict flag
#[serde(rename = "ms")]
#[serde(skip_serializing_if = "Option::is_none")]
pub mints_strict: Option<bool>,

@chatgpt-codex-connector chatgpt-codex-connector Bot Jun 17, 2026

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P1 Badge Honor non-strict mint lists when selecting a mint

When ms is Some(false), the mint list is only a suggestion, but WalletRepository::pay_request still rejects a specified mint and skips auto-selected wallets whenever payment_request.mints is non-empty. A payer with funds only at another mint will fail a non-strict request instead of using that mint, so the selection filters should be gated on mints_strict.unwrap_or(true).

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/// Additional fee reserve for payments from non-preferred mints
#[serde(rename = "fr")]
#[serde(skip_serializing_if = "Option::is_none")]
pub fee_reserve: Option<Amount>,
Comment on lines +43 to +46

@chatgpt-codex-connector chatgpt-codex-connector Bot Jun 17, 2026

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P2 Badge Remove the unassigned fee reserve request field

The referenced NUT-18/NUT-26 change only adds ms/tag 0x09; fr is not defined for payment requests. Because this field and its builder method are serialized into CBOR and NUT-26 tag 0x0a when set, callers can emit non-standard requests that may collide with future tag assignments, so this should be removed until the NUT assigns it.

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/// Supported payment methods the mint must support
#[serde(rename = "sm")]
#[serde(skip_serializing_if = "Vec::is_empty", default)]
pub supported_methods: Vec<String>,
Comment on lines +47 to +50

@chatgpt-codex-connector chatgpt-codex-connector Bot Jun 17, 2026

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P2 Badge Remove the unassigned supported methods field

The preferred-mints spec change does not define an sm payment-request field or NUT-26 tag 0x0b. If a caller sets supported_methods, this implementation serializes a non-standard field in both encodings, which other implementations may ignore and which can conflict with a future NUT assignment.

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/// Description
#[serde(rename = "d")]
pub description: Option<String>,
Expand Down Expand Up @@ -102,6 +114,9 @@ pub struct PaymentRequestBuilder {
unit: Option<CurrencyUnit>,
single_use: Option<bool>,
mints: Vec<MintUrl>,
mints_strict: Option<bool>,
fee_reserve: Option<Amount>,
supported_methods: Vec<String>,
description: Option<String>,
transports: Vec<Transport>,
nut10: Option<Nut10SecretRequest>,
Expand Down Expand Up @@ -150,6 +165,27 @@ impl PaymentRequestBuilder {
self
}

/// Set mints strict flag
pub fn mints_strict(mut self, mints_strict: bool) -> Self {
self.mints_strict = Some(mints_strict);
self
}

/// Set fee reserve for payments from non-preferred mints
pub fn fee_reserve<A>(mut self, fee_reserve: A) -> Self
where
A: Into<Amount>,
{
self.fee_reserve = Some(fee_reserve.into());
self
}

/// Set supported payment methods
pub fn supported_methods(mut self, methods: Vec<String>) -> Self {
self.supported_methods = methods;
self
}

/// Set description
pub fn description<S: Into<String>>(mut self, description: S) -> Self {
self.description = Some(description.into());
Expand Down Expand Up @@ -182,6 +218,9 @@ impl PaymentRequestBuilder {
unit: self.unit,
single_use: self.single_use,
mints: self.mints,
mints_strict: self.mints_strict,
fee_reserve: self.fee_reserve,
supported_methods: self.supported_methods,
description: self.description,
transports: self.transports,
nut10: self.nut10,
Expand Down Expand Up @@ -249,6 +288,9 @@ mod tests {
mints: vec!["https://nofees.testnut.cashu.space"
.parse()
.expect("valid mint url")],
mints_strict: None,
fee_reserve: None,
supported_methods: vec![],
description: None,
transports: vec![transport.clone()],
nut10: None,
Expand Down Expand Up @@ -693,6 +735,9 @@ mod tests {
unit: Some(CurrencyUnit::Sat),
single_use: None,
mints: vec![MintUrl::from_str("https://mint.example.com").unwrap()],
mints_strict: None,
fee_reserve: None,
supported_methods: vec![],
description: Some("Test both formats".to_string()),
transports: vec![],
nut10: None,
Expand Down
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