Make ChangeStrategy values usable outside of the context of zcash_client_backend

pczt/tests/end_to_end.rs

@@ -88,7 +88,7 @@ fn transparent_to_orchard() {
         },
     );
     builder
-        .add_transparent_input(transparent_pubkey, utxo, coin.clone())
+        .add_transparent_p2pkh_input(transparent_pubkey, utxo, coin.clone())
         .unwrap();
     builder
         .add_orchard_output::<zip317::FeeRule>(

zcash_client_backend/CHANGELOG.md

@@ -22,6 +22,7 @@ workspace.
   - `LightdInfo` has added fields `upgrade_name`, `upgrade_height`, and `lighwallet_protocol_version`
   - `GetMempoolTxRequest` (previously named `Exclude`) has added field `pool_types`
 - `impl From<zcash_client_backend::proposal::ProposalError> for zcash_client_backend::data_api::wallet::input_selection::InputSelectorError<...>`
+- `zcash_client_backend::fees::MetaSource`
 
 ### Changed
 - Migrated to `orchard 0.12`, `sapling-crypto 0.6`, `zip321 0.7`
@@ -51,6 +52,9 @@ workspace.
     IVK.
 - `zcash_client_backend::data_api::WalletRead` has added method `get_received_outputs`.
 - `zcash_client_backend::proposal::ProposalError` has added variant `PaymentAmountMissing`
+- The associated type `zcash_client_backend::fees::ChangeStrategy::MetaSource` is now
+  bounded on the newly added `MetaSource` type instead of
+  `zcash_client_backend::data_api::InputSource`.
 
 ## [0.21.0] - 2025-11-05
 

zcash_client_backend/src/data_api/wallet.rs

@@ -1299,7 +1299,7 @@ where
     #[cfg(feature = "transparent-inputs")]
     let utxos_spent = {
         let mut utxos_spent: Vec<OutPoint> = vec![];
-        let mut add_transparent_input =
+        let mut add_transparent_p2pkh_input =
             |builder: &mut Builder<_, _>,
              utxos_spent: &mut Vec<_>,
              recipient_address: &TransparentAddress,
@@ -1320,13 +1320,13 @@ where
                 };
 
                 utxos_spent.push(outpoint.clone());
-                builder.add_transparent_input(pubkey, outpoint, txout)?;
+                builder.add_transparent_p2pkh_input(pubkey, outpoint, txout)?;
 
                 Ok(())
             };
 
         for utxo in proposal_step.transparent_inputs() {
-            add_transparent_input(
+            add_transparent_p2pkh_input(
                 &mut builder,
                 &mut utxos_spent,
                 utxo.recipient_address(),
@@ -1349,7 +1349,7 @@ where
                 .ok_or(ProposalError::ReferenceError(*input_ref))?
                 .vout[outpoint.n() as usize];
 
-            add_transparent_input(
+            add_transparent_p2pkh_input(
                 &mut builder,
                 &mut utxos_spent,
                 &address,

zcash_client_backend/src/fees.rs

@@ -1,4 +1,5 @@
 use std::{
+    convert::Infallible,
     fmt::{self, Debug, Display},
     num::{NonZeroU64, NonZeroUsize},
 };
@@ -483,18 +484,41 @@ impl EphemeralBalance {
     }
 }
 
+/// A trait that defines a set of types used in wallet metadata retrieval. Ordinarily, this will
+/// correspond to a type that implements [`InputSource`], and a blanket implementation of this
+/// trait is provided for all types that implement [`InputSource`].
+///
+/// If more capabilities are required of the backend than are exposed in the [`InputSource`] trait,
+/// the implementer of this trait should define their own trait that descends from [`InputSource`]
+/// and adds the required capabilities there, and then implement that trait for their desired
+/// database backend.
+pub trait MetaSource {
+    type Error;
+    type AccountId;
+    type NoteRef;
+}
+
+impl MetaSource for Infallible {
+    type Error = Infallible;
+    type AccountId = Infallible;
+    type NoteRef = Infallible;
+}
+
+impl<I: InputSource> MetaSource for I {
+    type Error = I::Error;
+    type AccountId = I::AccountId;
+    type NoteRef = I::NoteRef;
+}
+
 /// A trait that represents the ability to compute the suggested change and fees that must be paid
 /// by a transaction having a specified set of inputs and outputs.
 pub trait ChangeStrategy {
     type FeeRule: FeeRule + Clone;
     type Error: From<<Self::FeeRule as FeeRule>::Error>;
 
     /// The type of metadata source that this change strategy requires in order to be able to
-    /// retrieve required wallet metadata. If more capabilities are required of the backend than
-    /// are exposed in the [`InputSource`] trait, the implementer of this trait should define their
-    /// own trait that descends from [`InputSource`] and adds the required capabilities there, and
-    /// then implement that trait for their desired database backend.
-    type MetaSource: InputSource;
+    /// retrieve required wallet metadata.
+    type MetaSource: MetaSource;
 
     /// Tye type of wallet metadata that this change strategy relies upon in order to compute
     /// change.
@@ -509,10 +533,10 @@ pub trait ChangeStrategy {
     fn fetch_wallet_meta(
         &self,
         meta_source: &Self::MetaSource,
-        account: <Self::MetaSource as InputSource>::AccountId,
+        account: <Self::MetaSource as MetaSource>::AccountId,
         target_height: TargetHeight,
-        exclude: &[<Self::MetaSource as InputSource>::NoteRef],
-    ) -> Result<Self::AccountMetaT, <Self::MetaSource as InputSource>::Error>;
+        exclude: &[<Self::MetaSource as MetaSource>::NoteRef],
+    ) -> Result<Self::AccountMetaT, <Self::MetaSource as MetaSource>::Error>;
 
     /// Computes the totals of inputs, suggested change amounts, and fees given the
     /// provided inputs and outputs being used to construct a transaction.

zcash_client_backend/src/fees/zip317.rs

@@ -19,7 +19,7 @@ use crate::{
 };
 
 use super::{
-    ChangeError, ChangeStrategy, DustOutputPolicy, EphemeralBalance, SplitPolicy,
+    ChangeError, ChangeStrategy, DustOutputPolicy, EphemeralBalance, MetaSource, SplitPolicy,
     TransactionBalance,
     common::{SinglePoolBalanceConfig, single_pool_output_balance},
     sapling as sapling_fees,
@@ -95,7 +95,7 @@ impl<R, I> SingleOutputChangeStrategy<R, I> {
 impl<R, I> ChangeStrategy for SingleOutputChangeStrategy<R, I>
 where
     R: Zip317FeeRule + Clone,
-    I: InputSource,
+    I: MetaSource,
     <R as FeeRule>::Error: From<BalanceError>,
 {
     type FeeRule = R;
@@ -110,10 +110,10 @@ where
     fn fetch_wallet_meta(
         &self,
         _meta_source: &Self::MetaSource,
-        _account: <Self::MetaSource as InputSource>::AccountId,
+        _account: <Self::MetaSource as MetaSource>::AccountId,
         _target_height: TargetHeight,
-        _exclude: &[<Self::MetaSource as InputSource>::NoteRef],
-    ) -> Result<Self::AccountMetaT, <Self::MetaSource as InputSource>::Error> {
+        _exclude: &[<Self::MetaSource as MetaSource>::NoteRef],
+    ) -> Result<Self::AccountMetaT, <Self::MetaSource as MetaSource>::Error> {
         Ok(())
     }
 

zcash_client_sqlite/src/wallet/init/migrations/receiving_key_scopes.rs

@@ -369,7 +369,7 @@ mod tests {
         );
         let mut transparent_signing_set = TransparentSigningSet::new();
         builder
-            .add_transparent_input(
+            .add_transparent_p2pkh_input(
                 transparent_signing_set.add_key(
                     usk0.transparent()
                         .derive_external_secret_key(NonHardenedChildIndex::ZERO)

zcash_primitives/CHANGELOG.md

@@ -13,6 +13,7 @@ workspace.
 ### Added
 - `zcash_primitives::transaction::builder`:
   - `impl<FE> From<coinbase::Error> for Error<FE>`
+  - `Builder::add_transparent_p2pkh_input`
 
 ### Changed
 - MSRV is now 1.85.1.
@@ -21,6 +22,9 @@ workspace.
   - `Error` has a new `Coinbase` variant.
   - `Builder::add_orchard_output`'s `value` parameter now has type `Zatoshis`
     instead of `u64`.
+  - `Builder::add_transparent_input` now takes a `zcash_transparent::builder::TransparentInputInfo`
+    instead of its constituent parts. Use `Builder::add_transparent_p2pkh_input` if you need the
+    previous API.
   - `BuildConfig`:
     -  The `Coinbase` variant now includes an `Option<zcash_script::opcode::PushValue>` payload.
     -  No longer implements `Copy`.

zcash_primitives/src/transaction/builder.rs

@@ -551,15 +551,21 @@ impl<P: consensus::Parameters, U> Builder<'_, P, U> {
             .map_err(Error::SaplingBuild)
     }
 
+    /// Adds a transparent coin to be spent in this transaction.
+    #[cfg(feature = "transparent-inputs")]
+    pub fn add_transparent_input(&mut self, input: TransparentInputInfo) {
+        self.transparent_builder.add_input(input)
+    }
+
     /// Adds a transparent P2PKH coin to be spent in this transaction.
     #[cfg(feature = "transparent-inputs")]
-    pub fn add_transparent_input(
+    pub fn add_transparent_p2pkh_input(
         &mut self,
         pubkey: secp256k1::PublicKey,
         utxo: transparent::bundle::OutPoint,
         coin: TxOut,
     ) -> Result<(), transparent::builder::Error> {
-        self.transparent_builder.add_input(pubkey, utxo, coin)
+        self.transparent_builder.add_p2pkh_input(pubkey, utxo, coin)
     }
 
     /// Adds a transparent P2SH coin to be spent in this transaction.
@@ -1383,7 +1389,7 @@ mod tests {
                 .into(),
         );
         builder
-            .add_transparent_input(pubkey, OutPoint::fake(), prev_coin)
+            .add_transparent_p2pkh_input(pubkey, OutPoint::fake(), prev_coin)
             .unwrap();
 
         // Create a tx with only t output. No binding_sig should be present

zcash_transparent/CHANGELOG.md

@@ -17,6 +17,9 @@ workspace.
 - `impl core::error::Error` for:
   -` zcash_transparent::builder::Error`
   - `zcash_transparent::coinbase::Error`
+- `zcash_transparent::builder::SpendInfo`
+- `zcash_transparent::builder::TransparentInputInfo::{from_parts, spend_info}`
+- `zcash_transparent::builder::Builder::add_p2pkh_input`
 
 ### Changed
 - MSRV is now 1.85.1.
@@ -25,6 +28,9 @@ workspace.
     - `InvalidExternalSignature`
     - `MissingPreimage`
     - `UnsupportedPubkey`
+- `zcash_transparent::builder::Builder::add_input` now takes a `TransparentInputInfo`
+  instead of its constituent parts. Use `Builder::add_p2pkh_input` if you need the
+  previous API.
 
 ## [0.6.3] - 2025-12-17