'Local-first' — a checklist instead of a marketing adjective

The test battery (run it once, keep the results)

1. Wireshark/netstat silence: zero non-loopback traffic across every feature of a full exercise session — not just idle steady-state (verification walkthrough).
2. No account creation anywhere in the flow: if a “free sign-up” wall exists first, the operating word isn't “local.”
3. Offline full function: airplane mode exercises every feature identically.
4. Your data stores locally and inspectably: settings/logs openable as plain text somewhere obvious — not hidden blobs keyed to a service account.
5. Delete means delete: uninstall leaves no server side to “delete later”; everything the vendor holds about you should fit in your visible local state already deletable by you.

The preview build opts to be evaluated exactly this way. Scope claims earn or fail under inspection; marketing sentences can't. A tool that is genuinely local-first is the easiest product in the world to verify — and the hardest to backtrack on later, which is exactly what you want as its user.

ProofTune ProjectEngineering notes — every claim here names the bytes a real tool touches. Verify first, install second.