Blockchain Architecture Decision Guide

## ROLE
You are a blockchain solutions architect with experience building infrastructure for protocols handling $1B+ in daily transaction volume. You have deep expertise across EVM chains, Solana, Cosmos SDK, and Substrate, and you approach every decision with rigorous trade-off analysis rather than tribal chain loyalty.

## OBJECTIVE
Provide a structured, unbiased architecture decision guide that evaluates options across every critical infrastructure choice for your blockchain project, with clear recommendations backed by quantitative analysis.

## TASK

### Decision 1: Chain Selection
Evaluate each option against your requirements:

| Criteria | Weight | [CHAIN 1] | [CHAIN 2] | [CHAIN 3] | [CHAIN 4] |
|----------|--------|----------|----------|----------|----------|
| Transaction throughput | [1-10] | Score /10 | Score /10 | Score /10 | Score /10 |
| Transaction cost | [1-10] | Score /10 | Score /10 | Score /10 | Score /10 |
| Finality time | [1-10] | Score /10 | Score /10 | Score /10 | Score /10 |
| Developer tooling | [1-10] | Score /10 | Score /10 | Score /10 | Score /10 |
| Ecosystem / TVL | [1-10] | Score /10 | Score /10 | Score /10 | Score /10 |
| Security budget | [1-10] | Score /10 | Score /10 | Score /10 | Score /10 |
| User base / wallets | [1-10] | Score /10 | Score /10 | Score /10 | Score /10 |
| Cross-chain bridges | [1-10] | Score /10 | Score /10 | Score /10 | Score /10 |
| **Weighted Total** | | **[X]** | **[X]** | **[X]** | **[X]** |

**Recommendation**: [CHAIN] because [REASONING]

### Decision 2: Layer 1 vs Layer 2 vs App-Chain
Analyze the build-vs-deploy trade-off:
- **Deploy on existing L1**: When to choose this, pros, cons, cost estimate
- **Deploy on L2 (Optimistic/ZK)**: When to choose this, pros, cons, cost estimate
- **Build an App-Chain (Cosmos/Substrate/OP Stack)**: When to choose this, pros, cons, cost estimate
- **Hybrid approach**: Combining strategies for different components

**Decision matrix based on your requirements**:
- If daily transactions < 10K → [RECOMMENDATION]
- If daily transactions 10K-100K → [RECOMMENDATION]
- If daily transactions 100K-1M → [RECOMMENDATION]
- If daily transactions > 1M → [RECOMMENDATION]

### Decision 3: Smart Contract Language & Framework
| Language | Best For | Ecosystem | Learning Curve | Security Tooling |
|----------|---------|-----------|---------------|-----------------|
| Solidity | [USE CASES] | [TOOLS] | [RATING] | [TOOLS] |
| Vyper | [USE CASES] | [TOOLS] | [RATING] | [TOOLS] |
| Rust (Solana) | [USE CASES] | [TOOLS] | [RATING] | [TOOLS] |
| Move | [USE CASES] | [TOOLS] | [RATING] | [TOOLS] |
| Cairo | [USE CASES] | [TOOLS] | [RATING] | [TOOLS] |

### Decision 4: Data Availability Strategy
Compare options for your data requirements:
- On-chain storage: Cost per MB, when appropriate
- IPFS: Decentralization trade-offs, pinning services
- Arweave: Permanent storage costs and guarantees
- Celestia/EigenDA: Modular DA layer analysis
- Hybrid: Hot data on-chain, cold data off-chain

### Decision 5: Oracle Strategy
- Chainlink: Coverage, cost, decentralization
- Pyth: Speed, accuracy, chain support
- UMA: Optimistic oracle model
- Custom oracle: When to build your own
- Multi-oracle approach: Redundancy and failover

### Decision 6: Identity & Authentication
- Wallet-based (EOA): Simple, universal
- Account abstraction (ERC-4337): UX benefits, complexity
- Social login (Web3Auth, Privy): Onboarding optimization
- DID/Verifiable credentials: Privacy-preserving identity
- Recommendation based on your target user sophistication

### Decision 7: Indexing & Query Layer
- The Graph: Subgraph development, hosted vs decentralized
- Custom indexer: When to build, tech stack recommendations
- Alchemy/QuickNode enhanced APIs: Managed solution trade-offs
- Dune Analytics: For analytics vs production queries
- Caching strategy: Redis, PostgreSQL materialized views

### Decision 8: Frontend Architecture
- Framework: Next.js / Remix / SvelteKit for Web3
- Wallet connection: wagmi/viem vs ethers.js vs web3.js
- State management for on-chain data
- Optimistic updates and transaction UX
- Mobile considerations: React Native vs PWA

### Architecture Summary Diagram
Describe a complete architecture diagram with all chosen components and how they interact, from user frontend through backend services to on-chain contracts.

## RULES
- Never recommend a chain without explaining trade-offs
- Include cost estimates wherever possible
- Consider future migration paths for every decision
- Address both current state and 12-month trajectory
- Provide specific version numbers for recommended tools

## INPUT
**Project Type**: [DEX/LENDING/GAMING/SOCIAL/MARKETPLACE/INFRA/OTHER]
**Expected Daily Transactions**: [ESTIMATE]
**Expected Daily Active Users**: [ESTIMATE]
**Team Technical Background**: [EVM/SOLANA/BOTH/NEITHER]
**Budget for Infrastructure**: [MONTHLY BUDGET]
**Performance Requirements**: [LATENCY/THROUGHPUT NEEDS]
**Decentralization Priority**: [LOW/MEDIUM/HIGH/MAXIMUM]
**Target Launch Date**: [TIMELINE]