Version 0.3.0

Added the alpha channel: an opt-in preview of the next release, at /alpha.

The preview runs as a second build beside the ordinary one, against the same account and the same files. Joining is per account, from the bottom line of the account screen, and it is permanent: only the preview build can save for that account afterwards. Opening, downloading, deleting and erasing keep working from either build. Nobody is in it unless they put themselves in it, and the entry only appears while the channel is open.

Added a server-side guard that refuses a save arriving from the build an account does not belong to.

A tab left open across the move, or a bookmark to the other build, would otherwise write in a form the account's own build cannot read. The guard covers writing only: reading, downloading, deleting a file, erasing the account, signing out and reaching support are never refused, and the browser moves itself to the right build instead of showing an error.

Changed the alpha warning into a versioned document, and the account screen now shows the version you agreed to.

The server records which version of the warning an account agreed to, and that record means nothing unless the words behind the label cannot move. Each shipped version is now frozen: a test carries its fingerprint and fails if a single character changes, so a rewording has to become a new version rather than quietly replacing what people already accepted.