How is the share price calculated, and what's with the decimals?

Share price = the vault's total assets ÷ total shares. Total assets = the USDC the vault holds on HyperEVM plus the capital it has working on Hyperliquid Core (read on-chain via precompiles) — so your share value reflects the whole position, not just idle cash.

Decimals: USDC has 6 decimals; the vault share has 12. The extra 6 (a "decimals offset") is anti-inflation-attack hardening — it makes the classic first-depositor attack economically infeasible. You never deal with raw units: the app shows everything in USD.