Ultimate Web3 (Architecture & Strategy)

Architect-level skill for cross-chain, cross-discipline Web3 design decisions. The body is intentionally thin; depth lives in reference/. Open only the files you actually need.

Companion skills (route to these first)

This skill is the architecture layer. Defer to companion skills for their domains:

If the question is about how to build something at the implementation layer, route to the specialist skill above. Use this skill for what to build, on which platform, with which architecture, and how to operate it.

Token economy rules for the agent

1. Do not paste back code the user already shared.
2. Read at most 2 reference files per turn. Choose by the routing table below.
3. Never inline content from a companion skill (frontend code, test code, vulnerability classes); link to the companion skill instead.
4. Prefer tables, decision trees, and matrices over prose.
5. Use WebSearch for L2 rankings, TVL, bridge security incidents, and active EIPs. Do not memorize dynamic facts.
6. When the user asks "which chain / which rollup / which bridge / which oracle", read reference/chain-selection.md first; do not improvise a recommendation.

Routing table

Golden rules (non-negotiable)

1. Custody is design, not configuration. Decide hot/warm/cold separation, multisig/MPC, deploy-key isolation, and rotation policy before writing the first line of contract code. See reference/custody-and-keys.md.
2. Choose the rollup stack before the chain. OP Stack vs Arbitrum Orbit vs ZK stacks affects bridges, gas economics, blob inclusion, and decentralization roadmap more than the brand name. See reference/l2-and-rollups.md.
3. Bridges are your weakest link. Cross-chain messaging has caused most of the largest exploits in Web3 history. If you can avoid bridging, do. If you must bridge, prefer canonical bridges or intent-based systems with explicit settlement guarantees. See reference/bridges-and-interop.md.
4. Oracles are part of your trust model. Push vs pull, single oracle vs aggregate, manipulation cost, staleness checks, and TWAP windows are protocol-level decisions, not integration details. See reference/oracles-indexers.md.
5. Upgradeability is a liability. Proxies are not free: storage layout, initializer races, admin compromise, and selector clashes are all real. Pin a clear upgrade strategy (none / UUPS / diamond / migrate-by-deploy) and document it. See reference/solidity-architecture.md.
6. Deployment is a protocol moment, not a sysadmin task. Multi-chain CREATE2, deterministic addresses, verification across explorers, post-deploy monitoring, and pause/freeze paths must exist on day one. See reference/deployment-ops.md.
7. Verify before recommending. Use WebSearch for current L2 stage classifications, TVL, bridge incidents, EntryPoint version, and active EIPs. Ecosystem facts change month-to-month.

Default stack matrix

Defaults to use unless the user has different constraints. Document any deviation.

Chain decision shortcut

If you only have time to read one tree, read this. For depth, see reference/chain-selection.md.

Constraint -> Default chain
|
|-- "EVM compatibility required"
|   |-- "Coinbase / consumer distribution"     -> Base
|   |-- "DeFi composability, deepest TVL"      -> Arbitrum One
|   |-- "ZK finality required"                 -> zkSync Era / Linea / Scroll / StarkNet
|   |-- "Need own chain, EVM"                  -> OP Stack rollup or Arbitrum Orbit
|   `-- "L1 only, conservative"                -> Ethereum mainnet
|
|-- "Highest throughput, lowest cost"
|   |-- "Rust team"                            -> Solana (Anchor)
|   `-- "Move team"                            -> Aptos or Sui (verify ecosystem fit first)
|
|-- "Sovereign chain, IBC interop"             -> Cosmos SDK + CosmWasm
|-- "Telegram-native distribution"             -> TON (Tact)
`-- "Privacy-first, novel L1"                  -> Custom design (read privacy-l1.md)

When NOT to apply this skill

• Frontend implementation: web3-frontend (wagmi, viem, RainbowKit, SIWE, transaction UX).
• Test writing: web3-testing (Foundry, Hardhat, fuzz, invariants, fork).
• Solidity vulnerability prevention at the function level: solidity-security.
• Repository vulnerability audit or findings report: security-audit.
• Whitepaper structure and citations: whitepapers.
• Public-facing token / governance copy review: legalizer.
• Pure cryptography research (new ZK schemes, novel signature constructions): out of scope.

If the question fits one of the above, route there and stop reading this skill.