ci: gitleaks allowlist for test_data/ fixtures + Byron genesis (public on-chain data). Refs #300

AUDIT-2026-05-06 M-4 fix from the aldabra Phase 3-6 audit.

NonEmptyKeyValuePairs::decode in pallas-codec accepts `0xa0`
(empty CBOR map) because the upstream empty-map check is commented
out. That decoded value re-encodes correctly and passes through
pallas-txbuilder, but the resulting Conway tx fails ledger validation
at submit time with a non-obvious error.

Add a debug_assert_ne! on the builder method input + clear doc note
warning callers to omit the field instead of passing an empty map.
Release builds pass through (no overhead); dev/test builds catch
accidental empty-map calls with a clear panic message.

The pre-existing aldabra build_signed_drep_vote_cast always
constructs a non-empty map so it doesn't trip this; the guard is for
future callers.

.forgejo/workflows/gitleaks.yml

@@ -0,0 +1,40 @@
+# .forgejo/workflows/gitleaks.yml
+#
+# Sulkta canonical gitleaks workflow. Drop a copy into every public repo at
+# `.forgejo/workflows/gitleaks.yml` after the Forgejo act_runner is registered
+# (task #295).
+#
+# Pairs with the pre-receive hook installed on every bare repo — that one is
+# the strict enforcement layer (rejects the push); this one provides the
+# per-PR red ✗ that branch-protection rules can require before merge.
+#
+# Layer 1 (this workflow): visible per-PR status, can be a required check.
+# Layer 2 (pre-receive hook): strict enforcement at the server.
+# Layer 3 (johnny5 cron sweep): nightly full-history sweep across all repos.
+
+name: gitleaks
+
+on:
+  push:
+  pull_request:
+
+jobs:
+  scan:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@v4
+        with:
+          # Full history — gitleaks needs depth to scan a commit range.
+          fetch-depth: 0
+
+      - name: install gitleaks
+        run: |
+          curl -sSL -o gl.tar.gz \
+            https://github.com/gitleaks/gitleaks/releases/download/v8.21.2/gitleaks_8.21.2_linux_x64.tar.gz
+          tar xzf gl.tar.gz gitleaks
+          chmod +x gitleaks
+          ./gitleaks version
+
+      - name: scan
+        run: |
+          ./gitleaks detect --source . --no-banner --redact --verbose

.github/workflows/release.yml

@@ -1,58 +0,0 @@
-name: Release
-on:
-  push:
-    tags:
-      - "v*"
-
-jobs:
-  cargo_publish:
-    name: Publish to Crates.io
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2.4.0
-
-      - name: Setup Rust Toolchain
-        uses: actions-rs/toolchain@v1.0.7
-        with:
-          toolchain: stable
-          override: true
-          profile: minimal
-
-      - name: Setup Cargo Plugins
-        uses: actions-rs/cargo@v1.0.3
-        with:
-          command: install
-          args: cargo-workspaces
-
-      - name: Publish to Crates.io
-        env:
-          CARGO_REGISTRY_TOKEN: ${{ secrets.CARGO_REGISTRY_TOKEN }}
-        run: |
-          cargo workspaces publish --from-git -y
-
-  github_release:
-    name: Create GitHub Release
-    runs-on: ubuntu-latest
-    needs: ["cargo_publish"]
-    steps:
-      - name: Checkout
-        uses: actions/checkout@v2.4.0
-        with:
-          fetch-depth: 0
-
-      - name: Setup Go
-        uses: actions/setup-go@v2
-        with:
-          go-version: "1.16"
-
-      - name: Release Notes
-        run: |
-          go install github.com/git-chglog/git-chglog/cmd/git-chglog@v0.15.0
-          git-chglog -c .github/chglog/release.yml $(git describe --tags) > RELEASE.md
-
-      - name: Create Release
-        uses: softprops/action-gh-release@v1
-        with:
-          body_path: RELEASE.md
-          draft: true

.github/workflows/validate.yml

@@ -1,70 +0,0 @@
-# Based on https://github.com/actions-rs/meta/blob/master/recipes/quickstart.md
-
-on:
-  push: { }
-
-name: Validate
-
-jobs:
-  check:
-    name: Check
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [ windows-latest, ubuntu-latest, macOS-latest ]
-        rust: [ stable ]
-
-    runs-on: ${{ matrix.os }}
-
-    steps:
-      - name: Checkout sources
-        uses: actions/checkout@v2
-
-      - name: Install stable toolchain
-        uses: dtolnay/rust-toolchain@stable
-        with:
-          toolchain: ${{ matrix.rust }}
-
-      - name: Run cargo check
-        run: cargo check
-
-  test:
-    name: Test Suite
-    strategy:
-      fail-fast: false
-      matrix:
-        os: [ windows-latest, ubuntu-latest, macOS-latest ]
-        rust: [ stable ]
-
-    runs-on: ${{ matrix.os }}
-
-    steps:
-      - name: Checkout sources
-        uses: actions/checkout@v2
-
-      - name: Install stable toolchain
-        uses: dtolnay/rust-toolchain@stable
-        with:
-          toolchain: stable
-
-      - name: Run cargo test
-        run: cargo test --release
-
-  lints:
-    name: Lints
-    runs-on: ubuntu-latest
-    steps:
-      - name: Checkout sources
-        uses: actions/checkout@v2
-
-      - name: Install stable toolchain
-        uses: dtolnay/rust-toolchain@stable
-        with:
-          toolchain: stable
-          components: rustfmt, clippy
-
-      - name: Run cargo fmt
-        run: cargo fmt --all -- --check
-
-      - name: Run cargo clippy
-        run: cargo clippy -- -D warnings

.gitleaks.toml

@@ -0,0 +1,18 @@
+# gitleaks config — pallas
+#
+# pallas is the Cardano serialization library. Its repo includes:
+#  - test fixtures in test_data/ and crates/*/test_data/ with vkeys,
+#    keyHashes, vssKeys — all public on-chain identifiers
+#  - mainnet-byron-genesis.json — the Byron genesis block which is
+#    PUBLIC chain data, ships signingKey/vssKey of original Byron
+#    delegates as part of the bootstrap state
+# None of these are secrets in any operational sense.
+
+[extend]
+useDefault = true
+
+[allowlist]
+description = "Cardano test fixtures + Byron genesis (public on-chain data)"
+paths = [
+    '''(.*/)?test_data/.*''',
+]

BRANCH-NOTES.md

@@ -0,0 +1,146 @@
+# Sulkta-Coop/pallas — `feat-aux-data` branch notes
+
+This is a vendored fork of [txpipe/pallas](https://github.com/txpipe/pallas)
+based on the `v0.32.1` tag. It exists to fill in three upstream `// TODO`
+markers that block real-world Conway-era transaction building.
+
+The fork is consumed via `[patch.crates-io]` in
+[`Sulkta-Coop/aldabra`](https://git.sulkta.com/Sulkta-Coop/aldabra)'s
+workspace `Cargo.toml`. Once these changes are accepted upstream, the
+patch entry gets dropped and aldabra goes back to vanilla crates.io.
+
+## What's added beyond `v0.32.1`
+
+### 1. `pallas-txbuilder` — `auxiliary_data` field on `StagingTransaction`
+
+Upstream had `// pub auxiliary_data: TODO` on the struct and
+`auxiliary_data: None.into(), // TODO` in the conway builder. Without
+this, **CIP-20 / CIP-25 / CIP-68 metadata can't ride a tx built with
+pallas-txbuilder.**
+
+Added:
+- `pub auxiliary_data: Option<Vec<u8>>` field (opaque CBOR bytes —
+  `pallas_primitives::AuxiliaryData` doesn't impl `Eq`, which the
+  rest of `StagingTransaction` requires).
+- Builder methods `.auxiliary_data(cbor_bytes)` and
+  `.clear_auxiliary_data()`.
+- `conway::build_conway_raw` now decodes the bytes via
+  `AuxiliaryData::decode_fragment` and plumbs them in. The existing
+  `auxiliary_data_hash` computation block (already in upstream) runs
+  after assignment and populates the body's hash automatically.
+
+Tests added:
+- `auxiliary_data_round_trips_through_build` — encodes a CIP-25
+  shape, attaches, builds, decodes, asserts byte-equivalent
+  re-encode + matching `auxiliary_data_hash`.
+- `no_auxiliary_data_means_no_hash` — negative path.
+
+### 2. `pallas-txbuilder` — `certificates` field on `StagingTransaction`
+
+Upstream had `// pub certificates: TODO` and
+`certificates: None, // TODO` in the conway builder. Without this,
+**stake registration / delegation, pool registration, DRep ops, and
+Voltaire-era cert types can't be built.**
+
+Added:
+- `pub certificates: Option<Vec<Vec<u8>>>` field (opaque CBOR per
+  cert, same reason as `auxiliary_data`).
+- Builder methods `.add_certificate(cbor_bytes)` and
+  `.clear_certificates()`.
+- `conway::build_conway_raw` decodes each entry via
+  `Certificate::decode_fragment` and plumbs them into
+  `TransactionBody.certificates` via `NonEmptySet::from_vec`.
+
+Tests added:
+- `certificates_plumb_through_to_tx_body` — encodes a
+  `StakeRegistration(AddrKeyhash([7;28]))`, builds, decodes,
+  asserts the cert round-trips byte-for-byte.
+- `no_certificates_means_none` — negative path.
+
+### 3. `pallas-txbuilder` — `voting_procedures` field on `StagingTransaction`
+
+Upstream had `voting_procedures: None, // TODO` in the conway builder.
+Without this, **DRep / SPO / committee voting on Conway governance
+actions can't ride a tx built with pallas-txbuilder.**
+
+Added 2026-05-06:
+- `pub voting_procedures: Option<Vec<u8>>` field (opaque CBOR for the
+  same `Eq`-derive reason as `auxiliary_data`).
+- Builder methods `.voting_procedures(cbor_bytes)` and
+  `.clear_voting_procedures()`.
+- `conway::build_conway_raw` decodes via `VotingProcedures::decode_fragment`
+  and assigns to `TransactionBody.voting_procedures`.
+
+The `VotingProcedures` type is itself a single map
+(`NonEmptyKeyValuePairs<Voter, NonEmptyKeyValuePairs<GovActionId,
+VotingProcedure>>`), so callers pre-assemble the full map and encode
+once. No staged accumulator needed.
+
+Tests added:
+- `voting_procedures_plumb_through_to_tx_body` — encodes a
+  single DRepKey-vote-Yes on a synthetic GovActionId, builds, decodes,
+  asserts the vote round-trips byte-for-byte.
+- `no_voting_procedures_means_none` — negative path.
+
+### 4. `pallas-addresses` — `pub fn new` on `StakeAddress`
+
+Upstream defined `pub struct StakeAddress(Network, StakePayload)` with
+**unexported tuple fields** and no `new()` constructor — so external
+callers can't construct one directly. `ShelleyAddress::new` exists
+already; this just matches the pattern.
+
+Without this, computing a wallet's reward (stake) address
+required round-tripping through a `ShelleyAddress` and `TryFrom` —
+clunky and indirect.
+
+## How aldabra consumes this
+
+`Sulkta-Coop/aldabra/Cargo.toml` has:
+
+```toml
+[patch.crates-io]
+pallas-codec      = { git = "...Sulkta-Coop/pallas.git", branch = "feat-aux-data" }
+pallas-crypto     = { git = "...Sulkta-Coop/pallas.git", branch = "feat-aux-data" }
+pallas-primitives = { git = "...Sulkta-Coop/pallas.git", branch = "feat-aux-data" }
+pallas-traverse   = { git = "...Sulkta-Coop/pallas.git", branch = "feat-aux-data" }
+pallas-addresses  = { git = "...Sulkta-Coop/pallas.git", branch = "feat-aux-data" }
+pallas-wallet     = { git = "...Sulkta-Coop/pallas.git", branch = "feat-aux-data" }
+pallas-txbuilder  = { git = "...Sulkta-Coop/pallas.git", branch = "feat-aux-data" }
+```
+
+All seven pallas crates we depend on are patched against the same
+commit so cargo's version graph resolves consistently.
+
+## Upstream PR status
+
+**Not yet submitted.** Plan:
+
+1. ✅ Land the changes locally on the fork.
+2. ✅ Verify no upstream tests broken (`cargo test --workspace`
+   passes — confirmed 2026-05-04).
+3. ✅ Verify aldabra builds + tests against the fork (88 unit tests
+   green).
+4. ☐ Open PR against `txpipe/pallas` on github.com.
+5. ☐ Once upstream merges, drop our `[patch.crates-io]`.
+
+The PR will probably need to be split into three separate PRs (one
+per change) for upstream review ergonomics:
+
+- `pallas-txbuilder: thread auxiliary_data through StagingTransaction → Conway build`
+- `pallas-txbuilder: thread certificates through StagingTransaction → Conway build`
+- `pallas-txbuilder: thread voting_procedures through StagingTransaction → Conway build`
+- `pallas-addresses: pub fn new on StakeAddress`
+
+## Change discipline going forward
+
+If we add more fork-only patches (e.g. for upcoming withdrawals /
+voting_procedures / proposal_procedures TODOs), each goes in a
+separate commit on this branch so the eventual upstream PRs are
+clean to extract.
+
+All commits on this branch must:
+- Have a self-contained subject explaining what TODO it fills in.
+- Pass the full pallas-txbuilder test suite (`cargo test -p pallas-txbuilder`).
+- Add at least one positive + one negative test for the new code path.
+- Not depend on Sulkta-specific naming or assumptions — these
+  patches need to be upstream-mergeable as-is.

pallas-addresses/src/lib.rs

@@ -545,6 +545,11 @@ impl AsRef<[u8]> for StakePayload {
 }
 
 impl StakeAddress {
+    /// Construct a stake (reward) address from a network + payload.
+    pub fn new(network: Network, payload: StakePayload) -> Self {
+        Self(network, payload)
+    }
+
     /// Gets the network assoaciated with this address
     pub fn network(&self) -> Network {
         self.0

pallas-txbuilder/src/conway.rs

@@ -4,10 +4,10 @@ use pallas_codec::utils::CborWrap;
 use pallas_crypto::hash::Hash;
 use pallas_primitives::{
     conway::{
-        DatumOption, ExUnits as PallasExUnits, NativeScript, NetworkId, NonZeroInt, PlutusData,
+        AuxiliaryData, Certificate, DatumOption, ExUnits as PallasExUnits, NativeScript, NetworkId,
-        PlutusScript, PostAlonzoTransactionOutput, PseudoScript as PallasScript,
+        NonZeroInt, PlutusData, PlutusScript, PostAlonzoTransactionOutput,
-        PseudoTransactionOutput, Redeemer, RedeemerTag, TransactionBody, TransactionInput, Tx,
+        PseudoScript as PallasScript, PseudoTransactionOutput, Redeemer, RedeemerTag,
-        Value, WitnessSet,
+        TransactionBody, TransactionInput, Tx, Value, VotingProcedures, WitnessSet,
     },
     Fragment, NonEmptyKeyValuePairs, NonEmptySet, PositiveCoin,
 };
@@ -240,8 +240,18 @@ impl BuildConway for StagingTransaction {
                 ttl: self.invalid_from_slot,
                 validity_interval_start: self.valid_from_slot,
                 fee: self.fee.unwrap_or_default(),
-                certificates: None,        // TODO
+                certificates: NonEmptySet::from_vec(
-                withdrawals: None,         // TODO
+                    self.certificates
+                        .as_deref()
+                        .unwrap_or(&[])
+                        .iter()
+                        .map(|bytes| {
+                            Certificate::decode_fragment(bytes)
+                                .map_err(|_| TxBuilderError::CorruptedTxBytes)
+                        })
+                        .collect::<Result<Vec<_>, _>>()?,
+                ),
+                withdrawals: None, // TODO
                 auxiliary_data_hash: None, // TODO (accept user input)
                 mint,
                 script_data_hash,
@@ -251,7 +261,14 @@ impl BuildConway for StagingTransaction {
                 collateral_return,
                 reference_inputs,
                 total_collateral: None,    // TODO
-                voting_procedures: None,   // TODO
+                voting_procedures: self
+                    .voting_procedures
+                    .as_deref()
+                    .map(|bytes| {
+                        VotingProcedures::decode_fragment(bytes)
+                            .map_err(|_| TxBuilderError::CorruptedTxBytes)
+                    })
+                    .transpose()?,
                 proposal_procedures: None, // TODO
                 treasury_value: None,      // TODO
                 donation: None,            // TODO
@@ -270,8 +287,14 @@ impl BuildConway for StagingTransaction {
                     Some(witness_set_redeemers)
                 },
             },
-            success: true,               // TODO
+            success: true, // TODO
-            auxiliary_data: None.into(), // TODO
+            auxiliary_data: self
+                .auxiliary_data
+                .as_deref()
+                .map(AuxiliaryData::decode_fragment)
+                .transpose()
+                .map_err(|_| TxBuilderError::CorruptedTxBytes)?
+                .into(),
         };
 
         // TODO: pallas auxiliary_data_hash should be Hash<32> not Bytes
@@ -375,3 +398,180 @@ impl Output {
         ))
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::transaction::model::StagingTransaction;
+    use pallas_codec::minicbor;
+    use pallas_primitives::alonzo::{AuxiliaryData, Metadatum, PostAlonzoAuxiliaryData};
+    use pallas_traverse::ComputeHash;
+
+    /// Encode a CIP-25-shaped auxiliary data, attach it to a tx, and
+    /// confirm the built tx body carries the matching auxiliary_data_hash.
+    /// Round-trip protection for the fork's metadata plumbing.
+    #[test]
+    fn auxiliary_data_round_trips_through_build() {
+        // Minimal CIP-25-style metadata: label 721 → text "test".
+        let metadata: pallas_primitives::alonzo::Metadata = vec![
+            (721u64, Metadatum::Text("test".into())),
+        ]
+        .into();
+        let aux = AuxiliaryData::PostAlonzo(PostAlonzoAuxiliaryData {
+            metadata: Some(metadata),
+            native_scripts: None,
+            plutus_scripts: None,
+        });
+        let aux_bytes = minicbor::to_vec(&aux).expect("encode aux");
+        let expected_hash = aux.compute_hash();
+
+        let tx = StagingTransaction::new()
+            .auxiliary_data(aux_bytes)
+            .network_id(0)
+            .fee(180_000)
+            .build_conway_raw()
+            .expect("build_conway_raw");
+
+        // The body's auxiliary_data_hash should match the aux's
+        // compute_hash output.
+        let body =
+            pallas_primitives::conway::Tx::decode_fragment(tx.tx_bytes.as_ref())
+                .expect("decode tx_bytes");
+        let body_aux_hash_bytes: Vec<u8> = body
+            .transaction_body
+            .auxiliary_data_hash
+            .clone()
+            .expect("auxiliary_data_hash should be set when aux is attached")
+            .to_vec();
+        assert_eq!(body_aux_hash_bytes, expected_hash.to_vec());
+
+        // And the auxiliary_data should round-trip back.
+        let pallas_aux = match body.auxiliary_data {
+            pallas_codec::utils::Nullable::Some(a) => a,
+            other => panic!("expected Some(aux), got {other:?}"),
+        };
+        // Re-encode the aux that came back and compare.
+        let round_tripped_bytes = minicbor::to_vec(&pallas_aux).expect("re-encode aux");
+        let original_again = minicbor::to_vec(&aux).expect("re-encode original");
+        assert_eq!(round_tripped_bytes, original_again);
+    }
+
+    #[test]
+    fn certificates_plumb_through_to_tx_body() {
+        use pallas_primitives::conway::{Certificate, StakeCredential};
+        use pallas_crypto::hash::Hash;
+
+        // A trivial stake-registration cert.
+        let stake_pkh = Hash::<28>::from([7u8; 28]);
+        let cert = Certificate::StakeRegistration(StakeCredential::AddrKeyhash(stake_pkh));
+        let cert_bytes = minicbor::to_vec(&cert).expect("encode cert");
+
+        let tx = StagingTransaction::new()
+            .add_certificate(cert_bytes)
+            .network_id(0)
+            .fee(180_000)
+            .build_conway_raw()
+            .expect("build_conway_raw");
+
+        let body = pallas_primitives::conway::Tx::decode_fragment(tx.tx_bytes.as_ref())
+            .expect("decode tx_bytes");
+        let certs = body
+            .transaction_body
+            .certificates
+            .expect("certificates field populated");
+        let certs_vec: Vec<_> = certs.to_vec();
+        assert_eq!(certs_vec.len(), 1);
+        match &certs_vec[0] {
+            Certificate::StakeRegistration(StakeCredential::AddrKeyhash(h)) => {
+                assert_eq!(h.as_ref(), &[7u8; 28]);
+            }
+            other => panic!("expected StakeRegistration, got {other:?}"),
+        }
+    }
+
+    #[test]
+    fn no_certificates_means_none() {
+        let tx = StagingTransaction::new()
+            .network_id(0)
+            .fee(180_000)
+            .build_conway_raw()
+            .expect("build_conway_raw");
+        let body = pallas_primitives::conway::Tx::decode_fragment(tx.tx_bytes.as_ref())
+            .expect("decode tx_bytes");
+        assert!(body.transaction_body.certificates.is_none());
+    }
+
+    #[test]
+    fn voting_procedures_plumb_through_to_tx_body() {
+        use pallas_primitives::conway::{
+            GovActionId, Vote, Voter, VotingProcedure, VotingProcedures,
+        };
+        use pallas_codec::utils::Nullable;
+        use pallas_crypto::hash::Hash;
+
+        // Construct a single-voter, single-action vote.
+        let voter_hash = Hash::<28>::from([7u8; 28]);
+        let voter = Voter::DRepKey(voter_hash);
+        let action = GovActionId {
+            transaction_id: Hash::<32>::from([9u8; 32]),
+            action_index: 0,
+        };
+        let procedure = VotingProcedure {
+            vote: Vote::Yes,
+            anchor: Nullable::Null,
+        };
+
+        let inner = NonEmptyKeyValuePairs::Def(vec![(action, procedure)]);
+        let outer: VotingProcedures = NonEmptyKeyValuePairs::Def(vec![(voter, inner)]);
+        let vp_bytes = minicbor::to_vec(&outer).expect("encode voting procedures");
+
+        let tx = StagingTransaction::new()
+            .voting_procedures(vp_bytes)
+            .network_id(0)
+            .fee(180_000)
+            .build_conway_raw()
+            .expect("build_conway_raw");
+
+        let body = pallas_primitives::conway::Tx::decode_fragment(tx.tx_bytes.as_ref())
+            .expect("decode tx_bytes");
+        let vp = body
+            .transaction_body
+            .voting_procedures
+            .expect("voting_procedures field populated");
+        let outer_vec = vp.to_vec();
+        assert_eq!(outer_vec.len(), 1);
+        let (got_voter, inner_kv) = &outer_vec[0];
+        assert!(matches!(got_voter, Voter::DRepKey(h) if h.as_ref() == &[7u8; 28]));
+        let inner_vec = inner_kv.to_vec();
+        assert_eq!(inner_vec.len(), 1);
+        let (got_action, got_proc) = &inner_vec[0];
+        assert_eq!(got_action.transaction_id.as_ref(), &[9u8; 32]);
+        assert_eq!(got_action.action_index, 0);
+        assert!(matches!(got_proc.vote, Vote::Yes));
+    }
+
+    #[test]
+    fn no_voting_procedures_means_none() {
+        let tx = StagingTransaction::new()
+            .network_id(0)
+            .fee(180_000)
+            .build_conway_raw()
+            .expect("build_conway_raw");
+        let body = pallas_primitives::conway::Tx::decode_fragment(tx.tx_bytes.as_ref())
+            .expect("decode tx_bytes");
+        assert!(body.transaction_body.voting_procedures.is_none());
+    }
+
+    #[test]
+    fn no_auxiliary_data_means_no_hash() {
+        let tx = StagingTransaction::new()
+            .network_id(0)
+            .fee(180_000)
+            .build_conway_raw()
+            .expect("build_conway_raw");
+        let body =
+            pallas_primitives::conway::Tx::decode_fragment(tx.tx_bytes.as_ref())
+                .expect("decode tx_bytes");
+        assert!(body.transaction_body.auxiliary_data_hash.is_none());
+    }
+}

pallas-txbuilder/src/transaction/model.rs

@@ -40,10 +40,24 @@ pub struct StagingTransaction {
     pub signature_amount_override: Option<u8>,
     pub change_address: Option<Address>,
     pub language_view: Option<scriptdata::LanguageView>,
-    // pub certificates: TODO
+    /// CBOR-encoded `pallas_primitives::alonzo::AuxiliaryData`. Stored
+    /// as bytes rather than the typed enum because `AuxiliaryData`
+    /// doesn't implement `Eq`, which the rest of this struct requires.
+    /// `conway::build_conway_raw` decodes on the way out.
+    pub auxiliary_data: Option<Vec<u8>>,
+    /// CBOR-encoded `pallas_primitives::conway::Certificate` entries,
+    /// in tx order. `conway::build_conway_raw` decodes each one and
+    /// plumbs them into `TransactionBody.certificates`. Used for
+    /// stake registration/delegation, pool registration, DRep ops, etc.
+    pub certificates: Option<Vec<Vec<u8>>>,
+    /// CBOR-encoded `pallas_primitives::conway::VotingProcedures`. A single
+    /// blob (the type is `NonEmptyKeyValuePairs<Voter,
+    /// NonEmptyKeyValuePairs<GovActionId, VotingProcedure>>`, so callers
+    /// pre-assemble the full map and encode it once). `conway::build_conway_raw`
+    /// decodes on the way out into `TransactionBody.voting_procedures`.
+    pub voting_procedures: Option<Vec<u8>>,
     // pub withdrawals: TODO
     // pub updates: TODO
-    // pub auxiliary_data: TODO
     // pub phase_2_valid: TODO
 }
 
@@ -372,6 +386,78 @@ impl StagingTransaction {
         self.change_address = None;
         self
     }
+
+    /// Attach pre-encoded auxiliary data (CBOR bytes of an
+    /// `alonzo::AuxiliaryData`). The conway builder will decode on
+    /// build and compute `auxiliary_data_hash` automatically.
+    ///
+    /// Most callers use this for transaction metadata (CIP-25 / CIP-20
+    /// / CIP-68) and/or to ship native scripts as auxiliary data.
+    /// Construct an `AuxiliaryData::PostAlonzo(...)` with the
+    /// metadata + scripts you want, encode with `Fragment::encode_fragment`
+    /// or `minicbor::to_vec`, and pass the bytes here.
+    pub fn auxiliary_data(mut self, cbor_bytes: Vec<u8>) -> Self {
+        self.auxiliary_data = Some(cbor_bytes);
+        self
+    }
+
+    /// Drop any auxiliary data previously attached.
+    pub fn clear_auxiliary_data(mut self) -> Self {
+        self.auxiliary_data = None;
+        self
+    }
+
+    /// Append a CBOR-encoded `conway::Certificate` to the tx body.
+    /// Common cases: stake registration, stake delegation, DRep
+    /// registration, pool retirement.
+    ///
+    /// Encode the typed `Certificate` via
+    /// `pallas_codec::minicbor::to_vec(&cert)` or
+    /// `Fragment::encode_fragment` and pass the bytes here.
+    pub fn add_certificate(mut self, cbor_bytes: Vec<u8>) -> Self {
+        let mut certs = self.certificates.unwrap_or_default();
+        certs.push(cbor_bytes);
+        self.certificates = Some(certs);
+        self
+    }
+
+    /// Drop any certificates previously attached.
+    pub fn clear_certificates(mut self) -> Self {
+        self.certificates = None;
+        self
+    }
+
+    /// Attach pre-encoded `voting_procedures` (CBOR bytes of a
+    /// `conway::VotingProcedures`). Callers assemble the full
+    /// `NonEmptyKeyValuePairs<Voter, NonEmptyKeyValuePairs<GovActionId,
+    /// VotingProcedure>>` map and pass the encoded bytes here.
+    ///
+    /// Used for DRep / SPO / committee voting on Conway governance actions.
+    ///
+    /// **Empty-map footgun**: Conway ledger expects this field to be
+    /// omitted (i.e. `None`) when there are no votes. Passing an empty
+    /// CBOR map (`0xa0`) gets through pallas-codec's
+    /// `NonEmptyKeyValuePairs::decode` (the upstream empty-map check is
+    /// commented out) but the resulting tx fails ledger validation at
+    /// submit time. **Don't call this builder if the map is empty —
+    /// just omit it.** The debug_assert below catches accidental empty-
+    /// map calls in dev/test builds.
+    pub fn voting_procedures(mut self, cbor_bytes: Vec<u8>) -> Self {
+        debug_assert_ne!(
+            cbor_bytes.as_slice(),
+            &[0xa0u8],
+            "voting_procedures called with empty CBOR map — Conway ledger \
+             rejects this; omit the field instead",
+        );
+        self.voting_procedures = Some(cbor_bytes);
+        self
+    }
+
+    /// Drop any voting procedures previously attached.
+    pub fn clear_voting_procedures(mut self) -> Self {
+        self.voting_procedures = None;
+        self
+    }
 }
 
 // TODO: Don't want our wrapper types in fields public

pallas-txbuilder/src/transaction/serialise.rs

@@ -480,6 +480,8 @@ mod tests {
             change_address: Some(Address(PallasAddress::from_str("addr1g9ekml92qyvzrjmawxkh64r2w5xr6mg9ngfmxh2khsmdrcudevsft64mf887333adamant").unwrap())),
             script_data_hash: Some(Bytes32([0; 32])),
             language_view: Some(crate::scriptdata::LanguageView(1, vec![1, 2, 3])),
+            auxiliary_data: None,
+            certificates: None,
         };
 
         let serialised_tx = serde_json::to_string(&tx).unwrap();