[Feature]: Add Opstack superchain registry support for genesis files

crates/optimism/op-chain-registry/Cargo.toml

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+[package]
+name = "op-chain-registry"
+version.workspace = true
+edition.workspace = true
+rust-version.workspace = true
+license.workspace = true
+homepage.workspace = true
+repository.workspace = true
+exclude.workspace = true
+
+[dependencies]
+reqwest = { version = "0.12.12", features = ["stream"] }
+tokio = { version = "1.0", features = ["full"] }
+serde_json = "1.0"
+zstd = "0.12"
+anyhow = "1.0"
+
+[lints]
+workspace = true

crates/optimism/op-chain-registry/src/chain_registry.rs

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+use reqwest;
+use serde_json::Value;
+use zstd::stream::read::Decoder;
+use zstd::dict::DecoderDictionary;
+use anyhow::{Result, Context};
+
+async fn download_file(url: &str) -> Result<Vec<u8>> {
+    println!("Downloading from URL: {}", url);
+    let response = reqwest::get(url)
+        .await
+        .context("Failed to download file")?;
+
+    if !response.status().is_success() {
+        anyhow::bail!("Failed to download: Status {}", response.status());
+    }
+
+    Ok(response.bytes().await?.to_vec())
+}
+
+async fn download_and_parse_zst(url: &str, dict_url: &str) -> Result<Value> {
+    // Download the dictionary
+    let dict_bytes = download_file(dict_url).await?;
+    println!("Downloaded dictionary: {} bytes", dict_bytes.len());
+
+    let dictionary = DecoderDictionary::copy(&dict_bytes);
+
+    // Download the main file
+    let compressed_bytes = download_file(url).await?;
+    println!("Downloaded compressed file: {} bytes", compressed_bytes.len());
+
+    // Create decoder with dictionary
+    let decoder = Decoder::with_prepared_dictionary(&compressed_bytes[..], &dictionary)
+        .context("Failed to create decoder with dictionary")?;
+
+    // Parse JSON
+    println!("Parsing JSON...");
+    let json: Value = serde_json::from_reader(decoder)
+        .context("Failed to parse JSON")?;
+
+    Ok(json)
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use anyhow::Result;
+
+    #[tokio::test]
+    async fn test_download_and_parse_genesis() -> Result<()> {
+        let file_url = "https://raw.githubusercontent.com/ethereum-optimism/superchain-registry/main/superchain/extra/genesis/mainnet/arena-z.json.zst";
+        let dict_url = "https://raw.githubusercontent.com/ethereum-optimism/superchain-registry/main/superchain/extra/dictionary";
+
+        let json_data = download_and_parse_zst(file_url, dict_url).await?;
+
+        assert!(json_data.is_object(), "Parsed JSON should be an object");
+
+        Ok(())
+    }
+}

crates/optimism/op-chain-registry/src/lib.rs

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+mod chain_registry;