Smart contracts are designed to execute financial and business logic automatically, but the same immutability that makes blockchain powerful also makes security mistakes extremely expensive. A vulnerability that reaches production can potentially lead to irreversible loss of assets.

I wanted to explore whether Generative AI could make smart contract security analysis more intelligent, explainable, and actionable.

That led me to build SmartContractGuardian (VLD) — an AI-powered Solidity security platform that combines static analysis, Retrieval-Augmented Generation (RAG), local Large Language Models (LLMs), multi-agent reasoning, exploit validation, and secure smart-contract generation.

The project is available on GitHub:

SmartContractGuardian: https://github.com/sayeedur007-design/SmartContractGuardian

The Problem

Smart contract security is not a problem that can be solved reliably by simply asking an LLM:

"Find vulnerabilities in this Solidity contract."

A smart contract can contain subtle vulnerabilities involving:

• Access control
• Reentrancy
• Unsafe external calls
• State manipulation
• Arithmetic and accounting logic
• Randomness
• Business-logic flaws
• Incorrect assumptions about contract interactions

Traditional static-analysis tools are extremely useful because they provide deterministic evidence, but their output can sometimes be difficult for developers to interpret or connect to the broader context of a contract.

On the other hand, LLMs are good at understanding source code and explaining complex logic, but they can hallucinate vulnerabilities or miss important security details.

I wanted to combine the strengths of both approaches.

The Idea Behind SmartContractGuardian

The core idea is to create a pipeline where different techniques perform different jobs instead of expecting one AI model to do everything.

The system follows a workflow similar to:

Solidity Contract → Static Analysis → RAG Retrieval → Local AI Analysis → Independent Verification → Optional Exploit Validation → Secure Contract Generation → Final Validation

This separation is important.

Static analysis provides deterministic evidence.

RAG provides security-related context.

The LLM provides source-level reasoning and explanations.

A second agent challenges the initial findings.

Foundry can test whether generated exploit code actually executes.

Finally, the secure-contract generator produces a revised contract that must pass compilation and another security-analysis stage.

Why Local AI?

One of the design decisions I made was to keep the core AI workflow local.

Smart contracts can contain sensitive business logic, proprietary protocols, or unreleased code. Sending source code to an external AI service is not always desirable.

SmartContractGuardian therefore uses Ollama to run local models.

The current implementation uses:

• Qwen2.5-Coder 7B for the local coding/security agents
• nomic-embed-text for local embeddings
• ChromaDB for the vector database

This means the main AI analysis pipeline can operate without sending the analyzed Solidity source to a cloud LLM.

The repository currently uses the local model for several roles, including the Analyzer, Skeptic, Exploiter, Generator, Runner repair, and project-context workflows.

Adding RAG to Smart Contract Security

A major part of the project is Retrieval-Augmented Generation.

Instead of giving the LLM only the uploaded Solidity contract, SmartContractGuardian maintains a knowledge base containing known vulnerable Solidity examples and security information.

The system:

1. Processes known vulnerable contracts.
2. Splits relevant source into retrievable chunks.
3. Stores metadata such as vulnerability category and source information.
4. Generates embeddings locally using nomic-embed-text.
5. Stores the vectors in ChromaDB.
6. Builds retrieval queries from the uploaded contract and its security signals.
7. Retrieves relevant examples.
8. Adds the retrieved context to the Analyzer's reasoning process.

The important distinction is that retrieved contracts are treated as security context, not automatically as evidence that the uploaded contract contains the same vulnerability.

This reduces one of the common problems with naive RAG systems: assuming that similarity automatically means correctness.

Multi-Agent Reasoning

Another important part of SmartContractGuardian is the use of multiple specialized AI roles.

Instead of relying on a single LLM response, the system separates responsibilities.

Analyzer Agent

The Analyzer examines:

• Solidity source code
• Function information
• Static-analysis results
• Vulnerability categories
• Retrieved RAG context

It produces structured vulnerability findings.

Skeptic Agent

The Skeptic acts as an independent reviewer.

Its job is not simply to agree with the Analyzer.

It goes back to the original source and asks whether the proposed vulnerability is actually supported by the available evidence.

This creates a useful pattern:

Agent A proposes → Agent B challenges → System recalibrates confidence

That is much closer to a security-review workflow than simply generating an answer from one prompt.

Exploiter Agent

For eligible findings, the Exploiter can produce structured exploit plans.

However, the system deliberately separates an exploit hypothesis from a validated exploit.

A generated exploit plan is not treated as successful merely because an LLM produced it.

From AI Prediction to Actual Validation

This was one of the areas where I wanted to avoid overclaiming what an LLM can do.

SmartContractGuardian can integrate with Foundry to compile and execute generated Proof-of-Concept exploits.

The workflow can:

1. Generate a PoC.
2. Compile it.
3. Execute it inside an isolated temporary Foundry workspace.
4. Capture compiler and execution diagnostics.
5. Record execution results.
6. Classify the result as PASSED, FAILED, TIMEOUT, or ERROR.

This distinction matters.

A language model saying:

"This vulnerability can be exploited"

is not the same as an exploit actually executing successfully.

SmartContractGuardian therefore keeps generated plans, generated code, and validated execution results as separate pieces of evidence.

Secure Smart Contract Generation

The project does not stop after detecting vulnerabilities.

I also wanted to explore the opposite direction:

Can the system generate a safer version of the contract?

The Secure Contract Generator receives the original Solidity source together with validated vulnerability findings.

It then generates a revised contract.

But the generated code is not immediately presented as "secure."

Instead, it goes through additional validation:

Original Contract → Security Analysis → Vulnerability Verification → Secure Generation → Deterministic Checks → Compilation → Final Slither Analysis

If the generated contract fails certain checks, the system can perform a targeted repair-generation pass and validate the result again.

The final downloadable contract is exposed only after compilation and final static validation pass.

This creates an important principle for AI-generated security code:

Generation should be followed by verification.

Building with Google Antigravity

Google's developer tooling played an important role in building SmartContractGuardian.

I used Google Antigravity IDE as an agentic development environment while working across the frontend, backend, AI workflows, debugging, and project architecture.

What made it particularly useful for this project was that the development workflow was not limited to simple code completion.

Antigravity's agents can work across the editor, terminal, and browser, which is particularly useful for a project containing many interconnected components.

SmartContractGuardian contains multiple layers:

• React frontend
• Flask backend
• Socket.IO communication
• Solidity analysis
• Static-analysis tooling
• Local LLM agents
• RAG pipeline
• Vector database
• Foundry integration
• Contract generation
• Validation pipelines

Working on these components requires repeatedly moving between code, terminal output, generated files, tests, and the running application.

Antigravity helped me iterate across these surfaces instead of treating each coding task as an isolated file-editing problem.

Using the Antigravity SDK

I also explored the Google Antigravity SDK as part of the project development process.

The Antigravity SDK provides programmatic access to the Antigravity agent runtime, making it possible to build custom agentic workflows rather than interacting with an AI coding agent only through an IDE interface. Google describes the SDK as a Python library for prototyping and building applications on top of the Antigravity Agent Runtime.

This was particularly relevant to my project because SmartContractGuardian itself is fundamentally an agentic system.

The project contains specialized roles such as:

Analyzer → Skeptic → Exploiter → Generator → Runner

Exploring an agent-oriented development environment alongside an agent-oriented application gave me a better understanding of how AI agents can be used not only as chatbots, but as components of larger software workflows.

Where Google's Generative AI Ecosystem Fits

Although the current SmartContractGuardian security-analysis pipeline is intentionally local, Google's broader AI ecosystem provides interesting possibilities for future versions.

For example, the Google GenAI SDK provides official libraries for integrating Gemini models into applications using Python, JavaScript/TypeScript, Go, and Java.

A future version of SmartContractGuardian could optionally use Gemini for tasks such as:

• Natural-language explanations of vulnerabilities
• Interactive security-report generation
• Developer Q&A over analysis results
• Summarization of complex contract architectures
• Multimodal explanations of security workflows
• Cloud-based comparison against the local analysis

This would be an optional extension, rather than replacing the local-security architecture.

That distinction is important because privacy and local execution are core design goals of the current project.

Architecture

At a high level, the architecture looks like this:

                    Solidity Contract
                           │
                           ▼
                 ┌───────────────────┐
                 │  Static Analysis  │
                 │      Slither      │
                 └─────────┬─────────┘
                           │
                           ▼
                 ┌───────────────────┐
                 │ Contract Context  │
                 │ Functions / Calls │
                 │ Security Signals  │
                 └─────────┬─────────┘
                           │
                           ▼
                 ┌───────────────────┐
                 │   RAG Retrieval   │
                 │ ChromaDB + Local  │
                 │    Embeddings     │
                 └─────────┬─────────┘
                           │
                           ▼
                 ┌───────────────────┐
                 │   Local Analyzer  │
                 │  Qwen2.5-Coder    │
                 └─────────┬─────────┘
                           │
                           ▼
                 ┌───────────────────┐
                 │  Skeptic Agent    │
                 │ Independent Check │
                 └─────────┬─────────┘
                           │
                 ┌─────────┴─────────┐
                 ▼                   ▼
        Exploit Analysis       Secure Generation
                 │                   │
                 ▼                   ▼
             Foundry          Compile + Validation
                 │                   │
                 └─────────┬─────────┘
                           ▼
                    Final Results

What I Learned

Building SmartContractGuardian taught me that integrating Generative AI into a security application is not simply a matter of connecting an LLM to a prompt.

The difficult part is designing the surrounding system.

I learned several important lessons.

1. LLM output should not be treated as ground truth

An LLM can generate convincing explanations while still being wrong.

Security systems need independent evidence and validation.

2. RAG quality depends on retrieval quality

Adding a vector database does not automatically make an AI system reliable.

The retrieved context has to be relevant, correctly chunked, and properly interpreted.

3. Specialized agents can be more useful than one giant prompt

Separating analysis, skepticism, exploitation, generation, and validation makes the workflow easier to reason about and debug.

4. AI-generated code needs deterministic validation

Compilation, static analysis, and execution provide evidence that a language model cannot provide by itself.

5. Agentic development changes how software can be built

Using an agentic IDE such as Google Antigravity changed my development workflow from simply writing individual functions to delegating larger engineering tasks, reviewing generated changes, testing them, and iterating.

Challenges

The project was far from straightforward.

Some of the biggest challenges included:

• Getting Solidity compiler versions to work correctly with static analysis
• Handling malformed or incomplete LLM responses
• Preventing false positives from AI-generated vulnerability findings
• Designing useful RAG retrieval
• Coordinating multiple local AI agents
• Validating generated exploit code
• Handling failed compilation and repair attempts
• Making secure-contract generation deterministic enough to be useful
• Connecting long-running backend AI workflows to the frontend
• Debugging the interaction between static analysis, LLM reasoning, and generated code

These challenges reinforced an important idea:

The engineering around an AI model is often as important as the model itself.

Current Limitations

SmartContractGuardian is a research and development project, not a replacement for a professional smart-contract security audit.

Passing static analysis or an AI review does not prove that a contract is completely secure.

There can always be vulnerabilities that the current rules, datasets, models, or validation procedures fail to detect.

Similarly, a successful generated PoC demonstrates a particular exploit path but does not represent every possible attack.

The goal of the project is therefore not to claim:

"AI can guarantee secure smart contracts."

The goal is:

Use AI, retrieval, static analysis, and execution-based validation together to make smart-contract security analysis more powerful and actionable.

Future Direction

There are several directions I want to explore next.

Hybrid Local + Cloud AI

Keep sensitive contract analysis local while optionally using Gemini for higher-level explanations or interactive assistance.

Improved Security Benchmarks

Expand the vulnerability dataset and evaluate detection performance systematically across different vulnerability categories.

Better Agent Evaluation

Measure how often the Skeptic agent correctly rejects false positives and how much multi-agent verification improves precision.

Automated Regression Testing

Every improvement to the Analyzer or Generator should be evaluated against a fixed vulnerability benchmark to detect regressions.

More Secure Generation

The generator could move toward an iterative:

Generate → Analyze → Repair → Compile → Analyze Again

loop until the generated contract satisfies a defined validation policy.

Developer-Focused Security Reports

Future versions could transform raw findings into clearer remediation reports explaining:

• What went wrong
• Why it matters
• Where it occurs
• How it can be exploited
• How to fix it
• Whether the fix passed validation

Conclusion

SmartContractGuardian started with a simple question:

Can Generative AI help developers find and fix smart-contract vulnerabilities?

The project evolved into something broader.

It combines:

Static Analysis + RAG + Local LLMs + Multi-Agent Reasoning + Exploit Validation + Secure Code Generation

The biggest lesson from building it is that reliable AI applications need more than a powerful model.

They need evidence.

They need retrieval.

They need validation.

And they need carefully designed workflows around the model.

Using Google Antigravity and its agentic development capabilities also gave me an opportunity to experience how AI can participate directly in the software-engineering process, from implementation and debugging to iteration and verification.

SmartContractGuardian is my attempt to apply these ideas to one of the areas where reliability matters most: blockchain security.

Project

GitHub:
https://github.com/sayeedur007-design/SmartContractGuardian

Project: SmartContractGuardian (VLD)

Focus: AI-powered Solidity vulnerability detection, validation, and secure-contract generation

Core technologies: Solidity, Python, Flask, React, Slither, Ollama, Qwen2.5-Coder, ChromaDB, RAG, LangChain, Foundry, Socket.IO, Google Antigravity IDE, and Antigravity SDK.

Google Technologies

• Google Antigravity IDE — agentic software development
• Google Antigravity SDK — programmatic agent development
• Google GenAI SDK — potential future Gemini integration
• Gemini API — potential future cloud-AI extension

The project intentionally keeps its core security-analysis LLM workflow local while leaving room for optional integration with Google's generative AI ecosystem.