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name: weasel-gas description: Gas optimization analysis and implementation for Solidity contracts. Triggers on weasel gas, weasel optimize, or weasel efficiency.

Weasel Gas Optimizer

Expert in identifying and implementing gas optimizations for Solidity smart contracts.

When to Activate

• User wants to optimize gas usage
• User asks about efficiency
• User mentions gas costs

Workflow

1. Detect Chain - CRITICAL: Identify target chain BEFORE analysis
2. Scan - Run weasel_analyze with severity: "Gas"
3. Filter - Remove findings irrelevant to target chain
4. Summarize - Quick count by impact level (chain-adjusted)
5. Ask - "Fix high impact? Medium? All? Pick specific?"
6. Fix - Implement directly in code
7. Verify - Run tests

Step 1: Chain Detection (CRITICAL - DO NOT SKIP)

Before any gas analysis, determine the target chain.

Detection Methods

1. Config files (most reliable):

   Copyhardhat.config.js/ts → networks: { mainnet, arbitrum, optimism, polygon, bsc }
   foundry.toml → [rpc_endpoints] or comments
   truffle-config.js → networks section
   

2. README.md - Look for deployment targets, chain mentions

3. Dependencies/Files:

   • foundry.toml, hardhat.config.*, truffle-config.js → EVM (Supported)
   • @arbitrum/* → Arbitrum L2
   • @eth-optimism/* → Optimism L2
   • Anchor.toml, *.rs → Solana (NOT SUPPORTED)
   • Move.toml, *.move → Move (NOT SUPPORTED)
   • tronbox, tronweb → Tron (NOT SUPPORTED)
   • No .sol files → NOT SUPPORTED

4. Ask user if unclear: "Which EVM chain is this for? (Ethereum/Arbitrum/Optimism/Polygon/BSC/Other)"

   • If user says non-EVM (Tron, Solana, etc.) → Not supported, stop.

Chain Categories

Weasel supports Solidity on EVM chains only.

Chain-Specific Rules

EVM L1 (Ethereum Mainnet)

All standard gas optimizations apply:

• Storage caching (SLOAD = 2100 gas) ✓
• Struct packing ✓
• Unchecked math ✓
• Calldata vs memory ✓

EVM L2 (Arbitrum, Optimism, Base, zkSync)

Execution is cheap. Calldata dominates costs.

EVM L1 Cheap (Polygon, BSC, Avalanche)

Gas is cheap - micro-optimizations often pointless.

Rule: Only report if saves >1000 gas or is on hot path.

Non-EVM Chains (NOT SUPPORTED)

Weasel analyzes Solidity on EVM only. Non-EVM chains are not supported.

If detected (Tron, Solana, Move, CosmWasm, TON, etc.):

Copy❌ Cannot run gas analysis.

This project targets a non-EVM chain.
Weasel supports Solidity on EVM chains only.

Gas optimization skill does not apply.

Multi-chain / Unknown

If deploying to multiple EVM chains or unclear:

1. Ask: "Which EVM chain should I optimize for?"
2. If multi-chain, optimize for the most expensive (usually Ethereum mainnet)
3. Note that L2-specific optimizations may differ from L1

Impact Ranking (Chain-Adjusted)

Ethereum Mainnet

High Impact - Fix first:

• Storage caching (repeated SLOAD) - saves 2100+ gas
• Struct packing - saves 20000+ gas on writes
• Unchecked math in loops - saves ~60 gas per iteration
• Calldata vs memory for read-only

Medium Impact:

• Array length caching
• Short-circuit reordering

Low Impact - Usually skip:

• Prefix increment (saves 5 gas)
• Minor syntax tweaks

L2s (Arbitrum, Optimism, Base)

High Impact:

• Calldata size reduction (bytes32 vs string, packed structs in calldata)
• Event data minimization
• Batch operations

Low Impact (often skip):

• Storage caching - execution is cheap
• Unchecked math - negligible savings
• Most "save 100 gas" tweaks

Cheap L1s (Polygon, BSC)

Only report if:

• Saves >1000 gas
• Hot path (called frequently)
• Otherwise, skip - not worth readability trade-off

Output

Always include chain context:

CopyGas analysis for: Arbitrum (L2)

Raw findings: 12
After chain filter: 4 relevant

High (2):   calldata size (2)
Medium (2): event optimization (2)
Filtered out (8): storage caching, unchecked math - low impact on L2

Fix high impact issues? [yes/specific/skip]

For non-EVM chains:

Copy❌ Cannot run gas analysis.

Detected: Non-EVM project
Weasel supports Solidity on EVM chains only.

Gas optimization skill does not apply.

Fixing

When user confirms:

1. Fix one file at a time
2. Run tests after each fix
3. If tests fail, revert and explain why

Caveats

Mention when relevant:

• Readability trade-offs for marginal gains
• Some "optimizations" hurt readability for <100 gas
• Always test after changes
• Chain matters - L2 != L1 != non-EVM

Rationalizations to Reject

When NOT to Use

• Non-EVM projects (Solana, Tron, Move, CosmWasm, TON, etc.) - Not supported. Stop and inform user.
• No .sol files - Nothing to analyze
• L2-only projects - Filter heavily, focus on calldata
• Multi-chain - Ask which EVM chain to optimize for