txir

A Conway-era Cardano transaction IR shaped as a dependency graph, with JSON serde round-tripping and validation.

txir models a transaction as a typed tree where each node carries exactly the data needed to construct it. A key InputNode depends only on a UTxO reference; a Plutus spend additionally carries the script source, datum source, redeemer, and execution units — all as typed fields, with no out-of-band registries mapping redeemers to inputs by index.

The whole tree is Serialize + Deserialize, so the IR doubles as a stable interchange format between builders, validators, snapshot tests, and non-Rust tooling.

Example

use txir::prelude::*;
use pallas_addresses::{Address, Network, ShelleyAddress, ShelleyDelegationPart, ShelleyPaymentPart};

let key_hash = PubKeyHash::new([0x11u8; 28]);
let addr = Address::Shelley(ShelleyAddress::new(
    Network::Testnet,
    ShelleyPaymentPart::key_hash(key_hash),
    ShelleyDelegationPart::Null,
));

let tx = TxIR {
    inputs: vec![InputNode {
        utxo: OutputRef { transaction_id: TxHash::new([0xabu8; 32]), index: 0 },
        resolved: None,
        witness: InputWitness::Key,
    }],
    outputs: vec![
        OutputNode { address: addr.clone(), value: build::value::lovelace(40_000_000), datum: None, reference_script: None },
        OutputNode { address: addr, value: build::value::lovelace(9_500_000), datum: None, reference_script: None },
    ],
    ..TxIR::new()
};

let json = serde_json::to_string_pretty(&tx).unwrap();
validate(&tx).expect("valid tx");

The deferred-resolution model

Several fields use Option or Auto variants to represent values that a downstream builder may fill in later:

Field	Deferred form	Meaning
InputNode.resolved	None	Builder resolves from chain
ScriptSource::Reference.body	None	Builder fetches for fee-calc
Redeemer.ex_units	None	Builder evaluates via Plutus VM
FeeNode	Auto	Builder computes from size + ex-units
CollateralPlan.total	None	Builder computes from collateral inputs

The dependency-tree principle

Each node holds the data it depends on directly. There are no side tables associating redeemers with inputs by ordinal, no implicit script lookups, no "you must also remember to add X to the witness set." If a Plutus action needs a redeemer, it's a field on that action.

Cross-references are explicit: ScriptSource::Reference names the OutputRef it depends on. validate() checks that every such reference resolves to an entry in tx.reference_inputs.

validate()

validate(tx: &TxIR) -> Result<(), Vec<ValidationError>> walks every node and reports every detectable invariant violation. No short-circuit — all checks run.

Checks include: duplicate inputs, dangling references, reference-script body integrity, mint-policy mismatches, empty mint assets, collateral rules, validity interval ordering, network consistency, datum presence, witness-kind/body agreement, and credential-witness matching.

Feature flags

Feature	Default	Description
json	yes	serde::Serialize/Deserialize on all public types
validate	yes	validate() function and ValidationError types
pallas-tx-convert	no	to_cbor() — CBOR encoding for simple payments only (inputs, outputs, fee, ttl); any other field returns ConvertError::Unsupported. See module docs.

Relationship to pallas and plutus-parser

• pallas-primitives — provides atomic Cardano types (TransactionInput, Value, NativeScript, etc.) and CBOR codec.
• pallas-addresses — address encoding/decoding.
• pallas-crypto — Blake2b hashing for script hash and datum hash computation.
• pallas-codec — CBOR serialization framework (minicbor).
• plutus-parser — PlutusData type and #[derive(AsPlutus)] derive macro.

txir does not build or submit transactions. It is an intermediate representation.

Conway era only

This crate covers Conway-era transactions only. Older eras are explicitly out of scope.

Examples

cargo run --example simple_payment
cargo run --example plutus_spend
cargo run --example mint_and_send
cargo run --example governance_vote

Pre-release

This crate is pre-release. APIs may change. Semantic versioning will begin at 0.2.0.