feat(solana): implement SolanaIFTSendCallConstructor

[mariuszzak]

Description

• Adds SolanaIFTSendCallConstructor, a Solidity contract that builds the complete ABI-encoded GmpSolanaPayload
  (accounts + instruction data) on-chain at send time, eliminating the relayer-controlled hint account
• Adds eth-to-solana and solana-to-eth relayer modules for bidirectional Ethereum-Solana relay
• Replaces manual ABI parsing in ics27-gmp with alloy-sol-types sol! macro
• Adds E2E tests covering single-token and two-token IFT transfers between Ethereum and Solana

How it works

The constructor stores 6 Solana PDAs as immutables at deploy time. When a user sends tokens, constructMintCall packs these PDAs together with the dynamic receiver (wallet + ATA) into the GmpSolanaPayload format that Solana's GMP program expects. The entire execution payload is committed in the IBC packet on Ethereum — the relayer just reads it and forwards it.

Why the receiver encodes both wallet and ATA

On Solana, wallets don't hold SPL tokens directly. Each token balance lives in a dedicated Associated Token Account (ATA) — a PDA derived from the wallet address, the token program and the mint (the on-chain account that defines the token type, analogous to an ERC-20 contract address on Ethereum). The receiver field must include both the wallet and its ATA because the IFT mint instruction uses init_if_needed to create the ATA if it doesn't exist yet.

Creating or validating an ATA requires the wallet as the authority seed — the ATA address alone is not enough.

// programs/solana/programs/ift/src/instructions/ift_mint.rs
#[account(
    init_if_needed,
    payer = payer,
    associated_token::mint = mint,
    associated_token::authority = receiver_owner, // wallet needed as seed
    associated_token::token_program = token_program,
)]
pub receiver_token_account: InterfaceAccount<'info, TokenAccount>,

Flow Diagram

graph TB
    subgraph Deployment["Deployment Phase"]
        direction LR
        D1[Derive 6 PDAs off-chain] --> D2[Deploy Constructor]
        D2 --> D3["Store as immutables:<br/>APP_STATE, APP_MINT_STATE,<br/>IFT_BRIDGE, MINT,<br/>MINT_AUTHORITY,
GMP_ACCOUNT"]
    end

    U[User]

    subgraph Ethereum["Ethereum"]
        direction LR
        IFT[IFT Contract] -->|"2. constructMintCall(receiver, amount)"| CST[SolanaIFTSendCallConstructor]
        CST -->|"3. Pack 11 accounts<br/>(6 PDAs + wallet + ATA + 3 programs)"| PAYLOAD["4.
abi.encode(packedAccounts,<br/>instructionData, payerPosition)"]
        PAYLOAD -->|return| IFT
        IFT -->|"5. sendPacket"| IBC[IBC Router]
    end

    subgraph Relayer["Relayer"]
        direction LR
        R1{"encoding?"} -->|"ABI<br/>(Ethereum)"| ABI["abi_decode →<br/>parse 34-byte<br/>packed accounts"]
        R1 -->|"Protobuf<br/>(Cosmos)"| PB["protobuf decode →<br/>native account structs"]
        ABI --> TX["Build recv_packet tx:<br/>14 ICS26 accounts +<br/>[gmp_pda,
target_program,<br/>...execution_accounts]"]
        PB --> TX
    end

    subgraph Solana["Solana"]
        direction LR
        ROUTER["ICS26 Router"] -->|"CPI: on_recv_packet<br/>(dest_port = gmpport)"| GMP["ICS27 GMP Program"]
        GMP -->|"Decode payload,<br/>inject payer at payerPosition,<br/>CPI to target program"| IFTS[IFT Program]
        IFTS -->|Mint tokens| ATA[Receiver ATA]
    end

    Deployment -.-> Ethereum
    U -->|"1. iftTransfer(clientId, receiver, amount)"| IFT
    IBC --> Relayer
    TX -->|"recv_packet"| ROUTER

    style Deployment fill:#e8daef,stroke:#8e44ad,stroke-width:2px
    style Ethereum fill:#d4efdf,stroke:#27ae60,stroke-width:2px
    style Relayer fill:#fdebd0,stroke:#e67e22,stroke-width:2px
    style Solana fill:#d6eaf8,stroke:#2980b9,stroke-width:2px

    style U fill:#f9e79f,stroke:#f39c12,stroke-width:2px
    style IFT fill:#a9dfbf,stroke:#1e8449
    style CST fill:#a9dfbf,stroke:#1e8449
    style PAYLOAD fill:#a9dfbf,stroke:#1e8449
    style IBC fill:#a9dfbf,stroke:#1e8449
    style R1 fill:#fad7a0,stroke:#ca6f1e
    style ABI fill:#fad7a0,stroke:#ca6f1e
    style PB fill:#fad7a0,stroke:#ca6f1e
    style TX fill:#fad7a0,stroke:#ca6f1e
    style ROUTER fill:#aed6f1,stroke:#2471a3
    style GMP fill:#aed6f1,stroke:#2471a3
    style IFTS fill:#aed6f1,stroke:#2471a3
    style ATA fill:#aed6f1,stroke:#2471a3
    style D1 fill:#d2b4de,stroke:#7d3c98
    style D2 fill:#d2b4de,stroke:#7d3c98
    style D3 fill:#d2b4de,stroke:#7d3c98

Loading

Key changes

• contracts/utils/SolanaIFTSendCallConstructor.sol — constructor contract with 6 immutable PDAs, builds packed
  accounts and Borsh-encoded instruction data using inline assembly
• packages/relayer/modules/eth-to-solana/ — new relayer module for Ethereum to Solana packet relay, including
  ABI payload decoding and Solana transaction building
• packages/relayer/modules/solana-to-eth/ — new relayer module for Solana to Ethereum relay
• programs/solana/programs/ics27-gmp/src/abi.rs — replaced ~400 lines of manual ABI parsing with
  alloy-sol-types sol! macro types
• e2e/interchaintestv8/ethereum_solana_ift_test.go — E2E tests for single and two-token transfers
• scripts/DeploySolanaIFTConstructor.s.sol — forge deploy script that reads PDAs from env vars

---

This PR is based on #928 - proposes an alternative solution.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.91%. Comparing base (06999ca) to head (e60c5e6).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #959   +/-   ##
=======================================
  Coverage   99.91%   99.91%           
=======================================
  Files          27       28    +1     
  Lines        1123     1191   +68     
=======================================
+ Hits         1122     1190   +68     
  Misses          1        1           

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.