What should and should not be recorded on-chain?

A public ledger is a poor place for anything sensitive. It is permanent, replicated and readable, which makes it unsuitable for prompts, model inputs and outputs, personal data, site addresses or commercially confidential metrics.

It can be a reasonable place for a small set of coordination facts: a node identity anchor, a signed attestation that a defined unit of work completed, and a settlement reference where machine-to-machine payment is used.

Even then, prefer commitments over content: publish a hash and keep the underlying record in your own systems, disclosed only to parties who need it.

Solana is described here strictly as an optional coordination layer for future node identity, verifiable service receipts and USDC machine-to-machine settlement. It is not a requirement to operate a Sol Node, and nothing here concerns tokens, trading or financial products.