VeChain Core Skill

CRITICAL RULES

Read reference files FIRST. When the user's request involves any topic in the reference table below, read those files before doing anything else — before writing code, before making decisions. Briefly mention which files you are reading so the user can confirm the skill is active (e.g., "Reading fee delegation reference...").
Information priority for VeChain topics: (a) Reference files in this skill — always the primary source. (b) VeChain MCP tools — use @vechain/mcp-server for on-chain data, transaction building, and live network queries; use Kapa AI MCP for VeChain documentation lookups. (c) Web search — only as a last resort, and only for topics NOT covered in the reference files.
Prefer working directly in the main conversation for VeChain tasks. Plan mode and subagents do not inherit skill context and may fall back to web search instead of using reference files.
After compaction or context loss, re-read this SKILL.md to restore awareness of the reference table and operating procedure before continuing work.

Scope

Use this Skill for general VeChain development:

SDK usage (@vechain/sdk-core, @vechain/sdk-network, ethers adapter)
Fee delegation (VIP-191) — gasless transactions, backend sponsorship, vechain.energy
Multi-clause transactions — atomic batching of multiple operations
Dual-token model (VET for value, VTHO for gas)
Legacy migration from Connex/thor-devkit to VeChain SDK
General VeChainThor development patterns and reference links

For specialized topics, see the companion skills:

frontend — Generic frontend patterns: React Query, Turborepo, state management, Chakra UI, i18n, transaction UX
vechain-kit — VeChain Kit and dapp-kit packages: hooks, components, wallet connection, social login
smart-contract-development — Solidity, Hardhat, testing, security, gas optimization
vebetterdao — X2Earn apps, B3TR/VOT3, governance, VeVote
stargate — NFT staking, validators, delegation, VTHO rewards

Default stack

Layer	Default	Alternative
SDK	`@vechain/sdk-core` + `@vechain/sdk-network`	`@vechain/sdk-ethers-adapter`
Node	Node 20 LTS (managed via `nvm`)	--

Operating procedure

1. Check Node version

Before installing dependencies or running any command:

Check if .nvmrc exists in the project root. If yes, run nvm use to switch to the required version.
If .nvmrc does not exist, create one with 20 (Node 20 LTS) and run nvm use.

2. Detect project structure

turbo.json present → follow Turborepo conventions (apps/, packages/*)

3. Clarify before implementing

When the user's request is ambiguous or could be solved multiple ways, ask before building. Do not silently research alternatives and pick one. Separate research from implementation:

If the scope is unclear, ask the user to narrow it
If multiple architectures are viable, present trade-offs and let the user choose
Only proceed to implementation once the approach is agreed upon

4. Implement with VeChain-specific correctness

Network: always explicit (mainnet/testnet/solo)
Gas: estimate first, use fee delegation where appropriate
Transactions: use multi-clause when batching benefits atomicity or UX
Tokens: VET for value, VTHO for gas (dual-token model)

5. Verify and deliver

A task is not complete until all applicable gates pass:

Code compiles — no build errors
Tests pass — existing tests still pass; new logic has test coverage
Risk notes documented — any signing, fee, or token-transfer implications are called out

Then provide:

Files changed + diffs
Install/build/test commands
Risk notes for signing, fees, token transfers

Reference files

Read the matching files BEFORE doing anything else. See Critical Rules above.

Topic	File	Read when user mentions...
Fee delegation	references/fee-delegation.md	gasless, sponsored, VIP-191, delegator, vechain.energy
Multi-clause	references/multi-clause-transactions.md	batch, multi-clause, atomic, multiple operations
Legacy migration	references/sdk-migration.md	Connex, thor-devkit, migration, deprecated
Reference links	references/resources.md	docs URL, npm link, GitHub repo

vechain-core