Feat(sncast): Add utility for calculating a contract's class hash (#3651)

<!-- Reference any GitHub issues resolved by this PR -->

Closes #3584

## Introduced changes

<!-- A brief description of the changes -->


## Checklist

<!-- Make sure all of these are complete -->

- [x] Linked relevant issue
- [x] Updated relevant documentation
- [x] Added relevant tests
- [x] Performed self-review of the code
- [x] Added changes to `CHANGELOG.md`

---------

Co-authored-by: Nnamdi Aninye <[email protected]>
Co-authored-by: ddoktorski <[email protected]>
Co-authored-by: Maksymilian Kowalski <[email protected]>

Author: 4 people

CHANGELOG.md

@@ -35,6 +35,12 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - A bug that caused `#[fuzzer]` attribute to fail when used with generic structs
 
+### Cast
+
+#### Added
+
+- `utils class-hash` command to calculate the class hash for a contract
+
 ## [0.48.0] - 2025-08-05
 
 ### Forge

crates/sncast/src/main.rs

@@ -420,7 +420,16 @@ async fn run_async_command(cli: Cli, config: CastConfig, ui: &UI) -> Result<()>
             Ok(())
         }
 
-        Commands::Utils(utils) => utils::utils(utils, config, ui).await,
+        Commands::Utils(utils) => {
+            utils::utils(
+                utils,
+                config,
+                ui,
+                cli.json,
+                cli.profile.clone().unwrap_or("release".to_string()),
+            )
+            .await
+        }
 
         Commands::Multicall(multicall) => {
             multicall::multicall(multicall, config, ui, wait_config).await

crates/sncast/src/response/class_hash.rs

@@ -0,0 +1,35 @@
+use conversions::padded_felt::PaddedFelt;
+use conversions::{serde::serialize::CairoSerialize, string::IntoPaddedHexStr};
+use foundry_ui::{Message, styling};
+use serde::{Deserialize, Serialize};
+use serde_json::json;
+
+use crate::response::{cast_message::SncastMessage, command::CommandResponse};
+
+#[derive(Clone, Serialize, Deserialize, CairoSerialize, Debug, PartialEq)]
+pub struct ClassHashResponse {
+    pub class_hash: PaddedFelt,
+}
+
+impl CommandResponse for ClassHashResponse {}
+
+impl Message for SncastMessage<ClassHashResponse> {
+    fn text(&self) -> String {
+        styling::OutputBuilder::new()
+            .field(
+                "Class Hash",
+                &self.command_response.class_hash.into_padded_hex_str(),
+            )
+            .build()
+    }
+
+    fn json(&self) -> serde_json::Value {
+        serde_json::to_value(&self.command_response).unwrap_or_else(|err| {
+            json!({
+                "error": "Failed to serialize response",
+                "command": self.command,
+                "details": err.to_string()
+            })
+        })
+    }
+}

crates/sncast/src/response/mod.rs

@@ -1,6 +1,7 @@
 pub mod account;
 pub mod call;
 pub mod cast_message;
+pub mod class_hash;
 pub mod command;
 pub mod declare;
 pub mod deploy;

crates/sncast/src/starknet_commands/utils/class_hash.rs

@@ -0,0 +1,45 @@
+use anyhow::Context;
+use clap::Args;
+use conversions::{IntoConv, byte_array::ByteArray};
+use scarb_api::StarknetContractArtifacts;
+use sncast::{
+    ErrorData,
+    response::{class_hash::ClassHashResponse, errors::StarknetCommandError},
+};
+use starknet::core::types::contract::SierraClass;
+use std::collections::HashMap;
+
+#[derive(Args, Debug)]
+#[command(about = "Generate the class hash of a contract", long_about = None)]
+pub struct ClassHash {
+    /// Contract name
+    #[arg(short = 'c', long = "contract-name")]
+    pub contract: String,
+
+    /// Specifies scarb package to be used
+    #[arg(long)]
+    pub package: Option<String>,
+}
+
+#[allow(clippy::result_large_err)]
+pub fn get_class_hash(
+    class_hash: &ClassHash,
+    artifacts: &HashMap<String, StarknetContractArtifacts>,
+) -> Result<ClassHashResponse, StarknetCommandError> {
+    let contract_artifacts = artifacts.get(&class_hash.contract).ok_or(
+        StarknetCommandError::ContractArtifactsNotFound(ErrorData {
+            data: ByteArray::from(class_hash.contract.as_str()),
+        }),
+    )?;
+
+    let contract_definition: SierraClass = serde_json::from_str(&contract_artifacts.sierra)
+        .context("Failed to parse sierra artifact")?;
+
+    let class_hash = contract_definition
+        .class_hash()
+        .map_err(anyhow::Error::from)?;
+
+    Ok(ClassHashResponse {
+        class_hash: class_hash.into_(),
+    })
+}

crates/sncast/src/starknet_commands/utils/mod.rs

@@ -1,12 +1,25 @@
 use clap::{Args, Subcommand};
 use foundry_ui::UI;
-use sncast::{helpers::configuration::CastConfig, response::errors::handle_starknet_command_error};
+use sncast::{
+    helpers::{
+        configuration::CastConfig,
+        scarb_utils::{
+            BuildConfig, assert_manifest_path_exists, build_and_load_artifacts,
+            get_package_metadata,
+        },
+    },
+    response::errors::handle_starknet_command_error,
+};
 
 use crate::{
     process_command_result,
-    starknet_commands::{self, utils::serialize::Serialize},
+    starknet_commands::{
+        self,
+        utils::{class_hash::ClassHash, serialize::Serialize},
+    },
 };
 
+pub mod class_hash;
 pub mod serialize;
 
 #[derive(Args)]
@@ -19,9 +32,18 @@ pub struct Utils {
 #[derive(Debug, Subcommand)]
 pub enum Commands {
     Serialize(Serialize),
+
+    /// Get contract class hash
+    ClassHash(ClassHash),
 }
 
-pub async fn utils(utils: Utils, config: CastConfig, ui: &UI) -> anyhow::Result<()> {
+pub async fn utils(
+    utils: Utils,
+    config: CastConfig,
+    ui: &UI,
+    json: bool,
+    profile: String,
+) -> anyhow::Result<()> {
     match utils.command {
         Commands::Serialize(serialize) => {
             let result = starknet_commands::utils::serialize::serialize(serialize, config, ui)
@@ -30,6 +52,28 @@ pub async fn utils(utils: Utils, config: CastConfig, ui: &UI) -> anyhow::Result<
 
             process_command_result("serialize", Ok(result), ui, None);
         }
+
+        Commands::ClassHash(class_hash) => {
+            let manifest_path = assert_manifest_path_exists()?;
+            let package_metadata = get_package_metadata(&manifest_path, &class_hash.package)?;
+
+            let artifacts = build_and_load_artifacts(
+                &package_metadata,
+                &BuildConfig {
+                    scarb_toml_path: manifest_path,
+                    json,
+                    profile,
+                },
+                false,
+                ui,
+            )
+            .expect("Failed to build contract");
+
+            let result = class_hash::get_class_hash(&class_hash, &artifacts)
+                .map_err(handle_starknet_command_error)?;
+
+            process_command_result("class-hash", Ok(result), ui, None);
+        }
     }
 
     Ok(())

crates/sncast/tests/e2e/class_hash.rs

@@ -0,0 +1,22 @@
+use crate::helpers::{
+    constants::CONTRACTS_DIR, fixtures::duplicate_contract_directory_with_salt, runner::runner,
+};
+use indoc::indoc;
+use shared::test_utils::output_assert::assert_stdout_contains;
+
+#[test]
+fn test_happy_case_get_class_hash() {
+    let contract_path = duplicate_contract_directory_with_salt(
+        CONTRACTS_DIR.to_string() + "/map",
+        "put",
+        "human_readable",
+    );
+
+    let args = vec!["utils", "class-hash", "--contract-name", "Map"];
+
+    let snapbox = runner(&args).current_dir(contract_path.path());
+
+    let output = snapbox.assert().success();
+
+    assert_stdout_contains(output, indoc! {r"Class Hash: 0x0[..]"});
+}

crates/sncast/tests/e2e/mod.rs

@@ -1,5 +1,6 @@
 mod account;
 mod call;
+mod class_hash;
 mod completions;
 mod declare;
 mod deploy;

docs/src/SUMMARY.md

@@ -150,6 +150,7 @@
     * [completions](appendix/sncast/completions.md)
     * [utils](appendix/sncast/utils/utils.md)
         * [serialize](appendix/sncast/utils/serialize.md)
+        * [class-hash](appendix/sncast/utils/class_hash.md)
 * [`sncast` Library Reference](appendix/sncast-library.md)
     * [declare](appendix/sncast-library/declare.md)
     * [deploy](appendix/sncast-library/deploy.md)

docs/src/appendix/sncast/utils/class_hash.md

@@ -0,0 +1,23 @@
+# Calculate contract class hash
+
+## Overview
+Use the `sncast utils class-hash` command to calculate the class hash of a contract.
+
+## Examples
+
+### General Example
+
+```shell
+$ sncast utils \
+  class-hash \
+  --contract-name HelloSncast
+```
+
+<details>
+<summary>Output:</summary>
+
+```shell
+Class Hash: 0x0[..]
+```
+</details>
+<br>