🔌 Modular Plugin System using Delegatecall

This project demonstrates a modular and upgradeable smart contract architecture using the delegatecall pattern. The Core contract dynamically delegates logic execution to external plugin contracts that share a standard interface.

📆 Tech Stack

• Solidity 0.8.28
• Foundry
• OpenZeppelin Contracts

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🧱 Architecture Overview

• Core.sol – Central contract that manages plugins and delegates calls

• Plugins (e.g., VaultPlugin.sol) – Independent logic units using deterministic storage slots

• IPlugin.sol – Common interface for all plugins

📁 Project Structure

├── out/                      # Compiled contract ABIs and bytecode
├── broadcast/                # Deployment logs and transactions
│
script/
├── DeployCore.sol            # Deployment script for Core
├── DeployPlugins.sol         # Deployment script for Plugins
│
src/
├── core/
│   └── Core.sol              # The main contract with plugin registry
├── interface/
│   └── IPlugin.sol           # Plugin interface
├── plugins/
│   └── ExamplePlugin.sol     # Plugin to demonstrate dynamic dispatch
│   └── VaultPlugin.sol       # Plugin to manage vaults
│
test/
├── unit/                     # Unit Tests
│   └── VaultPlugin.t.sol     # Foundry tests for VaultPlugin
│
├── foundry.toml
├── remappings.txt
└── README.md

Note: The out/ folder contains compiled contract ABIs and bytecode. The broadcast/ folder contains details of recently deployed contracts including calldata and receipts. It’s automatically generated during deployment

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🛠 Setup Instructions

📦 Prerequisites

• Foundry (install via Foundryup)

forge --version

1. 📅 Install Foundry

If you haven’t already:

curl -L https://foundry.paradigm.xyz | bash
foundryup

2. 🔧 Install Dependencies (Using soldeer for Dependency management)

forge soldeer install

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⚙️ Foundry Configuration (Replace your files with these)

🔧 foundry.toml

[profile.default]
src = "src"
out = "out"
libs = ["lib", "dependencies"]

[rpc_endpoints]
sepolia = "${SEPOLIA_RPC_URL}"

[etherscan]
sepolia = { key = "${ETHERSCAN_API_KEY}" }

[dependencies]
forge-std = "1.9.6"
"@openzeppelin-contracts" = "5.3.0"

🔗 remappings.txt

@openzeppelin-contracts/=dependencies/@openzeppelin-contracts-5.3.0/
forge-std/=dependencies/forge-std-1.9.6/src/

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⚙️ Compilation

forge build

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🚀 Deployment

🛰 Deploy in Testnet (Sepolia)

Set environment variables:

export SEPOLIA_RPC_URL=https://...
export PRIVATE_KEY=your_private_key
export ETHERSCAN_API_KEY=your_key (optional)

IMPORTANT: Run source .env to load these variables into console.

Deploy with:

forge script script/Deploy.s.sol:Deploy --rpc-url $SEPOLIA_RPC_URL --private-key $PRIVATE_KEY --broadcast --verify

Note: If you don't want to verify the contracts on Etherscan, remove --verify from the command.

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🧪 Running Tests

forge test

Verbose output (If you want the logs to displayed):

forge test -vv

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📘 Usage Guide

🔹 Register Plugin

Call registerPlugin(pluginAddress) in Core to register a plugin.

🔹 Perform Action

The Core contract delegates to a plugin using:

core.performPluginAction(pluginId, abi.encode(input));

This performs a delegatecall into the plugin's performAction method.

🧼 Cleanup

To clean build artifacts:

forge clean

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👨‍💼 Author

Anurag Munda

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