austintgriffith · awixor · Feb 23, 2026
diff --git a/l2s/SKILL.md b/l2s/SKILL.md
@@ -23,53 +23,54 @@ description: Ethereum Layer 2 landscape — Arbitrum, Optimism, Base, zkSync, Sc
 
 ## L2 Comparison Table (Feb 2026)
 
-| L2 | Type | TVL | Tx Cost | Block Time | Finality | Chain ID |
-|----|------|-----|---------|------------|----------|----------|
-| **Arbitrum** | Optimistic | $18B+ | $0.001-0.003 | 250ms | 7 days | 42161 |
-| **Base** | Optimistic (OP Stack) | $12B+ | $0.0008-0.002 | 2s | 7 days | 8453 |
-| **Optimism** | Optimistic (OP Stack) | $8B+ | $0.001-0.003 | 2s | 7 days | 10 |
-| **Unichain** | Optimistic (OP Stack) | Growing | $0.001-0.003 | 1s | 7 days | 130 |
-| **Celo** | Optimistic (OP Stack) | $200M+ | <$0.001 | 5s | 7 days | 42220 |
-| **Linea** | ZK | $900M+ | $0.003-0.006 | 2s | 30-60min | 59144 |
-| **zkSync Era** | ZK | $800M+ | $0.003-0.008 | 1s | 15-60min | 324 |
-| **Scroll** | ZK | $250M+ | $0.002-0.005 | 3s | 30-120min | 534352 |
-| ~~Polygon zkEVM~~ | ~~ZK~~ | — | — | — | — | ~~1101~~ |
+| L2                | Type                  | TVL     | Tx Cost       | Block Time | Finality  | Chain ID |
+| ----------------- | --------------------- | ------- | ------------- | ---------- | --------- | -------- |
+| **Arbitrum**      | Optimistic            | $18B+   | $0.001-0.003  | 250ms      | 7 days    | 42161    |
+| **Base**          | Optimistic (OP Stack) | $12B+   | $0.0008-0.002 | 2s         | 7 days    | 8453     |
+| **Optimism**      | Optimistic (OP Stack) | $8B+    | $0.001-0.003  | 2s         | 7 days    | 10       |
+| **Unichain**      | Optimistic (OP Stack) | Growing | $0.001-0.003  | 1s         | 7 days    | 130      |
+| **Celo**          | Optimistic (OP Stack) | $200M+  | <$0.001       | 5s         | 7 days    | 42220    |
+| **Linea**         | ZK                    | $900M+  | $0.003-0.006  | 2s         | 30-60min  | 59144    |
+| **zkSync Era**    | ZK                    | $800M+  | $0.003-0.008  | 1s         | 15-60min  | 324      |
+| **Scroll**        | ZK                    | $250M+  | $0.002-0.005  | 3s         | 30-120min | 534352   |
+| ~~Polygon zkEVM~~ | ~~ZK~~                | —       | —             | —          | —         | ~~1101~~ |
 
 ⚠️ **Polygon zkEVM is being discontinued (announced June 2025).** Do not start new projects there. Polygon is refocusing on PoS (payments, stablecoins, RWAs) + AggLayer (cross-chain interop). MATIC → POL token migration ~85% complete.
 
 **Mainnet for comparison:** $50B+ TVL, $0.002-0.01, 8s blocks, instant finality.
 
 ## Cost Comparison (Real Examples, Feb 2026)
 
-| Action | Mainnet | Arbitrum | Base | zkSync | Scroll |
-|--------|---------|----------|------|--------|--------|
-| ETH transfer | $0.002 | $0.0003 | $0.0003 | $0.0005 | $0.0004 |
-| Uniswap swap | $0.015 | $0.003 | $0.002 | $0.005 | $0.004 |
-| NFT mint | $0.015 | $0.002 | $0.002 | $0.004 | $0.003 |
-| ERC-20 deploy | $0.118 | $0.020 | $0.018 | $0.040 | $0.030 |
+| Action        | Mainnet | Arbitrum | Base    | zkSync  | Scroll  |
+| ------------- | ------- | -------- | ------- | ------- | ------- |
+| ETH transfer  | $0.002  | $0.0003  | $0.0003 | $0.0005 | $0.0004 |
+| Uniswap swap  | $0.015  | $0.003   | $0.002  | $0.005  | $0.004  |
+| NFT mint      | $0.015  | $0.002   | $0.002  | $0.004  | $0.003  |
+| ERC-20 deploy | $0.118  | $0.020   | $0.018  | $0.040  | $0.030  |
 
 ## L2 Selection Guide
 
-| Need | Choose | Why |
-|------|--------|-----|
-| Consumer / social apps | **Base** | Farcaster, Smart Wallet, Coinbase on-ramp, OnchainKit |
-| Deepest DeFi liquidity | **Arbitrum** | $18B TVL, GMX, Pendle, Camelot, most protocols |
-| Yield strategies | **Arbitrum** | Pendle (yield tokenization), GMX, Aave |
-| Cheapest gas | **Base** | ~50% cheaper than Arbitrum/Optimism |
-| Coinbase users | **Base** | Direct on-ramp, free Coinbase→Base transfers |
-| No 7-day withdrawal wait | **ZK rollup** (zkSync, Scroll, Linea) | 15-120 min finality |
-| AI agents | **Base** | ERC-8004, x402, consumer ecosystem, AgentKit |
-| Gasless UX (native AA) | **zkSync Era** | Native account abstraction, paymasters, no bundlers needed |
-| Multi-chain deployment | **Base or Optimism** | Superchain / OP Stack, shared infra |
-| Maximum EVM compatibility | **Scroll or Arbitrum** | Bytecode-identical |
-| Mobile / real-world payments | **Celo** | MiniPay, sub-cent fees, Africa/LatAm focus |
-| MEV protection | **Unichain** | TEE-based priority ordering, private mempool |
-| Rust smart contracts | **Arbitrum** | Stylus (WASM VM alongside EVM, 10-100x gas savings) |
-| Stablecoins / payments / RWA | **Polygon PoS** | $500M+ monthly payment volume, 410M+ wallets |
+| Need                         | Choose                                | Why                                                        |
+| ---------------------------- | ------------------------------------- | ---------------------------------------------------------- |
+| Consumer / social apps       | **Base**                              | Farcaster, Smart Wallet, Coinbase on-ramp, OnchainKit      |
+| Deepest DeFi liquidity       | **Arbitrum**                          | $18B TVL, GMX, Pendle, Camelot, most protocols             |
+| Yield strategies             | **Arbitrum**                          | Pendle (yield tokenization), GMX, Aave                     |
+| Cheapest gas                 | **Base**                              | ~50% cheaper than Arbitrum/Optimism                        |
+| Coinbase users               | **Base**                              | Direct on-ramp, free Coinbase→Base transfers               |
+| No 7-day withdrawal wait     | **ZK rollup** (zkSync, Scroll, Linea) | 15-120 min finality                                        |
+| AI agents                    | **Base**                              | ERC-8004, x402, consumer ecosystem, AgentKit               |
+| Gasless UX (native AA)       | **zkSync Era**                        | Native account abstraction, paymasters, no bundlers needed |
+| Multi-chain deployment       | **Base or Optimism**                  | Superchain / OP Stack, shared infra                        |
+| Maximum EVM compatibility    | **Scroll or Arbitrum**                | Bytecode-identical                                         |
+| Mobile / real-world payments | **Celo**                              | MiniPay, sub-cent fees, Africa/LatAm focus                 |
+| MEV protection               | **Unichain**                          | TEE-based priority ordering, private mempool               |
+| Rust smart contracts         | **Arbitrum**                          | Stylus (WASM VM alongside EVM, 10-100x gas savings)        |
+| Stablecoins / payments / RWA | **Polygon PoS**                       | $500M+ monthly payment volume, 410M+ wallets               |
 
 ## Key Chain Details (What LLMs Get Wrong)
 
 ### Unichain
+
 - **Launched:** February 10, 2025 (mainnet). Chain ID 130.
 - **Type:** OP Stack L2 (Superchain member, Stage 1)
 - **Key innovation: TEE-based block building** (built with Flashbots Rollup-Boost)
@@ -79,19 +80,21 @@ description: Ethereum Layer 2 landscape — Arbitrum, Optimism, Base, zkSync, Sc
 - **Flashblocks:** Currently 1s blocks, roadmap to 250ms sub-blocks
 
 ### Celo
+
 - **Was:** Independent L1 blockchain (2020-2025)
 - **Now:** OP Stack L2 on Ethereum — **migrated March 26, 2025** (block 31056500)
 - **Focus:** Mobile-first payments, emerging markets
 - **MiniPay:** Stablecoin wallet in Opera Mini + standalone app. Phone-to-phone transfers, sub-cent fees. Primary market: Africa (Kenya, Nigeria).
 - **Multi-currency stablecoins:** cUSD (`0x765de816845861e75a25fca122bb6898b8b1282a`), cEUR (`0xd8763cba276a3738e6de85b4b3bf5fded6d6ca73`), cREAL (`0xe8537a3d056DA446677B9E9d6c5dB704EaAb4787`)
 
 ### Dominant DEX Per Chain
-| Chain | Dominant DEX | Model | Why NOT Uniswap |
-|-------|-------------|-------|-----------------|
-| Base | **Aero** (was Aerodrome) | ve(3,3) — LPs earn emissions, voters earn fees | Deeper liquidity for most pairs |
-| Optimism | **Aero** (was Velodrome) | ve(3,3) — merged Nov 2025 under Dromos Labs | Same flywheel, unified brand |
-| Arbitrum | Camelot + GMX | Native DEX + perps | Camelot for spot, GMX for perps |
-| zkSync | SyncSwap | Classic AMM | Largest native DEX on zkSync |
+
+| Chain    | Dominant DEX             | Model                                          | Why NOT Uniswap                 |
+| -------- | ------------------------ | ---------------------------------------------- | ------------------------------- |
+| Base     | **Aero** (was Aerodrome) | ve(3,3) — LPs earn emissions, voters earn fees | Deeper liquidity for most pairs |
+| Optimism | **Aero** (was Velodrome) | ve(3,3) — merged Nov 2025 under Dromos Labs    | Same flywheel, unified brand    |
+| Arbitrum | Camelot + GMX            | Native DEX + perps                             | Camelot for spot, GMX for perps |
+| zkSync   | SyncSwap                 | Classic AMM                                    | Largest native DEX on zkSync    |
 
 See `addresses/SKILL.md` for verified contract addresses for all these protocols.
 
@@ -104,46 +107,83 @@ Members contribute **15% of sequencer revenue** to the Optimism Collective. Cros
 ## Deployment Differences (Gotchas)
 
 ### Optimistic Rollups (Arbitrum, Optimism, Base, Unichain, Celo)
+
 ✅ Deploy like mainnet — just change RPC URL and chain ID. No code changes.
 
 **Gotchas:**
+
 - Don't use `block.number` for time-based logic (increments at different rates). Use `block.timestamp`.
 - Arbitrum's `block.number` returns L1 block number, not L2.
 - **Unichain:** Transactions are priority-ordered by time, not gas. Don't waste gas on priority fees.
 
 ### ZK Rollups
+
 - **zkSync Era:** Must use `zksolc` compiler. No `EXTCODECOPY` (compile-time error). 65K instruction limit. Non-inlinable libraries must be pre-deployed. Native account abstraction (all accounts are smart contracts).
 - **Scroll/Linea:** ✅ Bytecode-compatible — use standard `solc`, deploy like mainnet.
 
 ### Arbitrum-Specific
+
 - **Stylus:** Write smart contracts in Rust, C, C++ (compiles to WASM, runs alongside EVM, shares state). Use for compute-heavy operations (10-100x gas savings). Contracts must be "activated" via `ARB_WASM_ADDRESS` (0x0000…0071).
 - **Orbit:** Framework for launching L3 chains on Arbitrum. 47 live on mainnet.
 
+## zkSync Developer Patterns
+
+### Native Account Abstraction
+
+- How zkSync AA differs from ERC-4337: no bundlers, no UserOperation mempool, no EntryPoint
+- Every account has smart contract code (EOAs use `DefaultAccount.sol`)
+- `IAccount` interface: `validateTransaction`, `executeTransaction`, `payForTransaction`, `prepareForPaymaster`
+- Account deployment: `createAccount` / `create2Account` (not regular `create`)
+- Must implement EIP-1271 for signature validation
+- Nonce management via `NonceHolder` system contract
+
+### Paymaster Implementation
+
+- `IPaymaster` interface with exact function signatures
+- Two flows: General (paymaster just pays) vs Approval-based (user sets token allowance)
+- Magic value: `PAYMASTER_VALIDATION_SUCCESS_MAGIC = IPaymaster.validateAndPayForPaymasterTransaction.selector`
+- Gas considerations (paymaster txs cost more: internal computation + fund transfer + allowance management)
+- Complete code example for a basic paymaster
+
+### zksolc Compiler Gotchas
+
+- No `EXTCODECOPY` — `address(..).code` is a compile-time error
+- Contract size limit: 2^16 (65,535) instructions max
+- Workarounds: `--zk-force-evmla=true`, `--zk-fallback-oz=true`, or split contracts
+- Non-inlinable libraries must be pre-deployed and linked at compile time
+- Compilation pipeline: Solidity → Yul → LLVM IR → zkEVM bytecode
+- Foundry-zksync: use `--zksync` flag
+
+### zkSync-Specific Protocols
+
+- SyncSwap (dominant native DEX)
+- Ecosystem TVL context (~$110M — much smaller than Base/Arbitrum)
+
 ## RPCs and Explorers
 
-| L2 | RPC | Explorer |
-|----|-----|----------|
-| Arbitrum | `https://arb1.arbitrum.io/rpc` | https://arbiscan.io |
-| Base | `https://mainnet.base.org` | https://basescan.org |
-| Optimism | `https://mainnet.optimism.io` | https://optimistic.etherscan.io |
-| Unichain | `https://mainnet.unichain.org` | https://uniscan.xyz |
-| Celo | `https://forno.celo.org` | https://celoscan.io |
-| zkSync | `https://mainnet.era.zksync.io` | https://explorer.zksync.io |
-| Scroll | `https://rpc.scroll.io` | https://scrollscan.com |
-| Linea | `https://rpc.linea.build` | https://lineascan.build |
+| L2       | RPC                             | Explorer                        |
+| -------- | ------------------------------- | ------------------------------- |
+| Arbitrum | `https://arb1.arbitrum.io/rpc`  | https://arbiscan.io             |
+| Base     | `https://mainnet.base.org`      | https://basescan.org            |
+| Optimism | `https://mainnet.optimism.io`   | https://optimistic.etherscan.io |
+| Unichain | `https://mainnet.unichain.org`  | https://uniscan.xyz             |
+| Celo     | `https://forno.celo.org`        | https://celoscan.io             |
+| zkSync   | `https://mainnet.era.zksync.io` | https://explorer.zksync.io      |
+| Scroll   | `https://rpc.scroll.io`         | https://scrollscan.com          |
+| Linea    | `https://rpc.linea.build`       | https://lineascan.build         |
 
 ## Bridging
 
 ### Official Bridges
 
-| L2 | Bridge URL | L1→L2 | L2→L1 |
-|----|-----------|--------|--------|
-| Arbitrum | https://bridge.arbitrum.io | ~10-15 min | ~7 days |
-| Base | https://bridge.base.org | ~10-15 min | ~7 days |
-| Optimism | https://app.optimism.io/bridge | ~10-15 min | ~7 days |
-| Unichain | https://app.uniswap.org/swap | ~10-15 min | ~7 days |
-| zkSync | https://bridge.zksync.io | ~15-30 min | ~15-60 min |
-| Scroll | https://scroll.io/bridge | ~15-30 min | ~30-120 min |
+| L2       | Bridge URL                     | L1→L2      | L2→L1       |
+| -------- | ------------------------------ | ---------- | ----------- |
+| Arbitrum | https://bridge.arbitrum.io     | ~10-15 min | ~7 days     |
+| Base     | https://bridge.base.org        | ~10-15 min | ~7 days     |
+| Optimism | https://app.optimism.io/bridge | ~10-15 min | ~7 days     |
+| Unichain | https://app.uniswap.org/swap   | ~10-15 min | ~7 days     |
+| zkSync   | https://bridge.zksync.io       | ~15-30 min | ~15-60 min  |
+| Scroll   | https://scroll.io/bridge       | ~15-30 min | ~30-120 min |
 
 ### Fast Bridges (Instant Withdrawals)
 
@@ -169,12 +209,12 @@ forge create src/MyContract.sol:MyContract \
 
 ## Testnets
 
-| L2 | Testnet | Chain ID | Faucet |
-|----|---------|----------|--------|
-| Arbitrum | Sepolia | 421614 | https://faucet.arbitrum.io |
-| Base | Sepolia | 84532 | https://faucet.quicknode.com/base/sepolia |
-| Optimism | Sepolia | 11155420 | https://faucet.optimism.io |
-| Unichain | Sepolia | 1301 | https://faucet.unichain.org |
+| L2       | Testnet | Chain ID | Faucet                                    |
+| -------- | ------- | -------- | ----------------------------------------- |
+| Arbitrum | Sepolia | 421614   | https://faucet.arbitrum.io                |
+| Base     | Sepolia | 84532    | https://faucet.quicknode.com/base/sepolia |
+| Optimism | Sepolia | 11155420 | https://faucet.optimism.io                |
+| Unichain | Sepolia | 1301     | https://faucet.unichain.org               |
 
 ## Further Reading