feat: implement Solana chain module (#22)

Cargo.toml

@@ -21,6 +21,14 @@ hex = "0.4"
 rand = "0.8"
 async-trait = "0.1"
 url = "2"
+bs58 = { version = "0.5", optional = true }
+solana-sdk = { version = "2", optional = true }
+solana-client = { version = "2", optional = true }
+spl-token = { version = "7", optional = true }
+
+[features]
+default = []
+solana = ["bs58", "solana-sdk", "solana-client", "spl-token"]
 
 [dev-dependencies]
 tokio-test = "0.4"

README.md

@@ -65,7 +65,7 @@ async fn main() -> Result<()> {
 
 ## Features
 
-- **Multi-chain** — EVM (Ethereum, Arbitrum, Optimism, Base, Avalanche, Tempo) from one agent. Solana and Cosmos planned.
+- **Multi-chain** — EVM (Ethereum, Arbitrum, Optimism, Base, Avalanche, Tempo) and Solana from one agent. Cosmos planned.
 - **Wallet management** — Generate, import, derive. Sign transactions. Manage multiple wallets.
 - **DEX interaction** — Swap, add/remove liquidity, read pool state. Uniswap V3, Aerodrome, Trader Joe.
 - **MPP payments** — Native support for Machine Payments Protocol. Agent pays for APIs, services, compute.
@@ -84,7 +84,7 @@ async fn main() -> Result<()> {
 | `arka::dex` | 🚧 WIP | DEX swap execution, routing |
 | `arka::mpp` | 🚧 WIP | Machine Payments Protocol client |
 | `arka::oracle` | 🚧 WIP | Price feeds, TWAP |
-| `arka::solana` | 📋 Planned | Solana chain connector |
+| `arka::solana` | ✅ MVP | Solana chain connector, balance, transfer |
 | `arka::cosmos` | 📋 Planned | Cosmos chain connector |
 
 ## Quick Start

examples/multi_chain.rs

@@ -1,4 +1,8 @@
-//! Multi-chain example — same wallet across Base, Arbitrum, and Optimism.
+//! Multi-chain example — same wallet across EVM chains + Solana.
+//!
+//! Run with:
+//!   cargo run --example multi_chain
+//!   cargo run --example multi_chain --features solana
 
 use arka::prelude::*;
 
@@ -7,11 +11,11 @@ async fn main() -> Result<()> {
     tracing_subscriber::fmt::init();
 
     let wallet = Wallet::generate()?;
-    println!("Wallet: {:?}\n", wallet.address());
+    println!("EVM Wallet: {:?}\n", wallet.address());
 
-    let chains = [Chain::Base, Chain::Arbitrum, Chain::Optimism, Chain::Tempo];
+    let evm_chains = [Chain::Base, Chain::Arbitrum, Chain::Optimism, Chain::Tempo];
 
-    for chain in chains {
+    for chain in evm_chains {
         let agent = Agent::builder()
             .chain(chain)
             .wallet(wallet.clone())
@@ -34,5 +38,22 @@ async fn main() -> Result<()> {
         );
     }
 
+    #[cfg(feature = "solana")]
+    {
+        use arka::chains::solana::{SolanaConnector, SolanaWallet};
+        println!("\n--- Solana ---");
+        let sol_wallet = SolanaWallet::generate();
+        println!("Solana Wallet: {}", sol_wallet.address());
+
+        let connector = SolanaConnector::new("https://api.devnet.solana.com")
+            .expect("Solana connector");
+        let block = connector.block_height().unwrap_or(0);
+        println!(
+            "{:12} | block: {:>10} | balance: N/A (RPC required) | gas: native",
+            Chain::SolanaDevnet,
+            block,
+        );
+    }
+
     Ok(())
 }

src/chain/mod.rs

@@ -18,10 +18,16 @@ pub enum Chain {
     Bsc,
     Tempo,
     TempoTestnet,
+    /// Solana mainnet — uses ed25519 keypairs and a very different tx model.
+    /// Supported behind the ``solana`` feature flag.
+    Solana,
+    /// Solana devnet.
+    SolanaDevnet,
 }
 
 impl Chain {
-    /// Chain ID for EVM networks.
+    /// Chain ID. For EVM chains this is the EIP-155 chain ID; for non-EVM chains
+    /// (e.g. Solana) this returns 0 and is semantically meaningless.
     pub fn chain_id(&self) -> u64 {
         match self {
             Chain::Ethereum => 1,
@@ -33,6 +39,7 @@ impl Chain {
             Chain::Bsc => 56,
             Chain::Tempo => 4217,
             Chain::TempoTestnet => 42429,
+            Chain::Solana | Chain::SolanaDevnet => 0,
         }
     }
 
@@ -48,6 +55,8 @@ impl Chain {
             Chain::Bsc => "https://bsc-dataseed.binance.org",
             Chain::Tempo => "https://rpc.tempo.xyz",
             Chain::TempoTestnet => "https://rpc.testnet.tempo.xyz",
+            Chain::Solana => "https://api.mainnet-beta.solana.com",
+            Chain::SolanaDevnet => "https://api.devnet.solana.com",
         }
     }
 
@@ -58,7 +67,8 @@ impl Chain {
             Chain::Avalanche => "AVAX",
             Chain::Polygon => "MATIC",
             Chain::Bsc => "BNB",
-            Chain::Tempo | Chain::TempoTestnet => "USDC", // Tempo has no native gas token
+            Chain::Tempo | Chain::TempoTestnet => "USDC",
+            Chain::Solana | Chain::SolanaDevnet => "SOL",
         }
     }
 
@@ -67,6 +77,11 @@ impl Chain {
         matches!(self, Chain::Tempo | Chain::TempoTestnet)
     }
 
+    /// Whether this chain is Solana-based (non-EVM).
+    pub fn is_solana(&self) -> bool {
+        matches!(self, Chain::Solana | Chain::SolanaDevnet)
+    }
+
     /// Block explorer base URL.
     pub fn explorer(&self) -> &'static str {
         match self {
@@ -79,6 +94,8 @@ impl Chain {
             Chain::Bsc => "https://bscscan.com",
             Chain::Tempo => "https://explorer.tempo.xyz",
             Chain::TempoTestnet => "https://explorer.testnet.tempo.xyz",
+            Chain::Solana => "https://solscan.io",
+            Chain::SolanaDevnet => "https://solscan.io/?cluster=devnet",
         }
     }
 }

src/chains/mod.rs

@@ -7,3 +7,6 @@
 //! deployments arka is designed to support.
 
 pub mod arbitrum;
+
+#[cfg(feature = "solana")]
+pub mod solana;