feat: add Base blockchain optional skill

* add base support

* fix: correct skill author attribution to youssefea

---------

Co-authored-by: youssefea <youcefea99@gmail.com>

optional-skills/blockchain/base/SKILL.md

@@ -0,0 +1,231 @@
+---
+name: base
+description: Query Base (Ethereum L2) blockchain data with USD pricing — wallet balances, token info, transaction details, gas analysis, contract inspection, whale detection, and live network stats. Uses Base RPC + CoinGecko. No API key required.
+version: 0.1.0
+author: youssefea
+license: MIT
+metadata:
+  hermes:
+    tags: [Base, Blockchain, Crypto, Web3, RPC, DeFi, EVM, L2, Ethereum]
+    related_skills: []
+---
+
+# Base Blockchain Skill
+
+Query Base (Ethereum L2) on-chain data enriched with USD pricing via CoinGecko.
+8 commands: wallet portfolio, token info, transactions, gas analysis,
+contract inspection, whale detection, network stats, and price lookup.
+
+No API key needed. Uses only Python standard library (urllib, json, argparse).
+
+---
+
+## When to Use
+
+- User asks for a Base wallet balance, token holdings, or portfolio value
+- User wants to inspect a specific transaction by hash
+- User wants ERC-20 token metadata, price, supply, or market cap
+- User wants to understand Base gas costs and L1 data fees
+- User wants to inspect a contract (ERC type detection, proxy resolution)
+- User wants to find large ETH transfers (whale detection)
+- User wants Base network health, gas price, or ETH price
+- User asks "what's the price of USDC/AERO/DEGEN/ETH?"
+
+---
+
+## Prerequisites
+
+The helper script uses only Python standard library (urllib, json, argparse).
+No external packages required.
+
+Pricing data comes from CoinGecko's free API (no key needed, rate-limited
+to ~10-30 requests/minute). For faster lookups, use `--no-prices` flag.
+
+---
+
+## Quick Reference
+
+RPC endpoint (default): https://mainnet.base.org
+Override: export BASE_RPC_URL=https://your-private-rpc.com
+
+Helper script path: ~/.hermes/skills/blockchain/base/scripts/base_client.py
+
+```
+python3 base_client.py wallet   <address> [--limit N] [--all] [--no-prices]
+python3 base_client.py tx       <hash>
+python3 base_client.py token    <contract_address>
+python3 base_client.py gas
+python3 base_client.py contract <address>
+python3 base_client.py whales   [--min-eth N]
+python3 base_client.py stats
+python3 base_client.py price    <contract_address_or_symbol>
+```
+
+---
+
+## Procedure
+
+### 0. Setup Check
+
+```bash
+python3 --version
+
+# Optional: set a private RPC for better rate limits
+export BASE_RPC_URL="https://mainnet.base.org"
+
+# Confirm connectivity
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py stats
+```
+
+### 1. Wallet Portfolio
+
+Get ETH balance and ERC-20 token holdings with USD values.
+Checks ~15 well-known Base tokens (USDC, WETH, AERO, DEGEN, etc.)
+via on-chain `balanceOf` calls. Tokens sorted by value, dust filtered.
+
+```bash
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py \
+  wallet 0xd8dA6BF26964aF9D7eEd9e03E53415D37aA96045
+```
+
+Flags:
+- `--limit N` — show top N tokens (default: 20)
+- `--all` — show all tokens, no dust filter, no limit
+- `--no-prices` — skip CoinGecko price lookups (faster, RPC-only)
+
+Output includes: ETH balance + USD value, token list with prices sorted
+by value, dust count, total portfolio value in USD.
+
+Note: Only checks known tokens. Unknown ERC-20s are not discovered.
+Use the `token` command with a specific contract address for any token.
+
+### 2. Transaction Details
+
+Inspect a full transaction by its hash. Shows ETH value transferred,
+gas used, fee in ETH/USD, status, and decoded ERC-20/ERC-721 transfers.
+
+```bash
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py \
+  tx 0xabc123...your_tx_hash_here
+```
+
+Output: hash, block, from, to, value (ETH + USD), gas price, gas used,
+fee, status, contract creation address (if any), token transfers.
+
+### 3. Token Info
+
+Get ERC-20 token metadata: name, symbol, decimals, total supply, price,
+market cap, and contract code size.
+
+```bash
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py \
+  token 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
+```
+
+Output: name, symbol, decimals, total supply, price, market cap.
+Reads name/symbol/decimals directly from the contract via eth_call.
+
+### 4. Gas Analysis
+
+Detailed gas analysis with cost estimates for common operations.
+Shows current gas price, base fee trends over 10 blocks, block
+utilization, and estimated costs for ETH transfers, ERC-20 transfers,
+and swaps.
+
+```bash
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py gas
+```
+
+Output: current gas price, base fee, block utilization, 10-block trend,
+cost estimates in ETH and USD.
+
+Note: Base is an L2 — actual transaction costs include an L1 data
+posting fee that depends on calldata size and L1 gas prices. The
+estimates shown are for L2 execution only.
+
+### 5. Contract Inspection
+
+Inspect an address: determine if it's an EOA or contract, detect
+ERC-20/ERC-721/ERC-1155 interfaces, resolve EIP-1967 proxy
+implementation addresses.
+
+```bash
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py \
+  contract 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
+```
+
+Output: is_contract, code size, ETH balance, detected interfaces
+(ERC-20, ERC-721, ERC-1155), ERC-20 metadata, proxy implementation
+address.
+
+### 6. Whale Detector
+
+Scan the most recent block for large ETH transfers with USD values.
+
+```bash
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py \
+  whales --min-eth 1.0
+```
+
+Note: scans the latest block only — point-in-time snapshot, not historical.
+Default threshold is 1.0 ETH (lower than Solana's default since ETH
+values are higher).
+
+### 7. Network Stats
+
+Live Base network health: latest block, chain ID, gas price, base fee,
+block utilization, transaction count, and ETH price.
+
+```bash
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py stats
+```
+
+### 8. Price Lookup
+
+Quick price check for any token by contract address or known symbol.
+
+```bash
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py price ETH
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py price USDC
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py price AERO
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py price DEGEN
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py price 0x833589fCD6eDb6E08f4c7C32D4f71b54bdA02913
+```
+
+Known symbols: ETH, WETH, USDC, cbETH, AERO, DEGEN, TOSHI, BRETT,
+WELL, wstETH, rETH, cbBTC.
+
+---
+
+## Pitfalls
+
+- **CoinGecko rate-limits** — free tier allows ~10-30 requests/minute.
+  Price lookups use 1 request per token. Use `--no-prices` for speed.
+- **Public RPC rate-limits** — Base's public RPC limits requests.
+  For production use, set BASE_RPC_URL to a private endpoint
+  (Alchemy, QuickNode, Infura).
+- **Wallet shows known tokens only** — unlike Solana, EVM chains have no
+  built-in "get all tokens" RPC. The wallet command checks ~15 popular
+  Base tokens via `balanceOf`. Unknown ERC-20s won't appear. Use the
+  `token` command for any specific contract.
+- **Token names read from contract** — if a contract doesn't implement
+  `name()` or `symbol()`, these fields may be empty. Known tokens have
+  hardcoded labels as fallback.
+- **Gas estimates are L2 only** — Base transaction costs include an L1
+  data posting fee (depends on calldata size and L1 gas prices). The gas
+  command estimates L2 execution cost only.
+- **Whale detector scans latest block only** — not historical. Results
+  vary by the moment you query. Default threshold is 1.0 ETH.
+- **Proxy detection** — only EIP-1967 proxies are detected. Other proxy
+  patterns (EIP-1167 minimal proxy, custom storage slots) are not checked.
+- **Retry on 429** — both RPC and CoinGecko calls retry up to 2 times
+  with exponential backoff on rate-limit errors.
+
+---
+
+## Verification
+
+```bash
+# Should print Base chain ID (8453), latest block, gas price, and ETH price
+python3 ~/.hermes/skills/blockchain/base/scripts/base_client.py stats
+```