v0.9.1

A release that brings the documentation back level with the implementation. Three
findings from a mechanical sweep of the whole repository, all of them changes made
today that had not reached the prose.

The heaviest: the invariants page was two releases behind — the page that states what
this system promises was out of date about its central promise.

Twice today it turned out that putting something in the runbook was not enough, so the
version and the migration head named in STATUS.md are now checked by a test.

Fixed

• The invariants page was two releases behind. Its section "a published ARK is never
  deleted" knew about neither purge (0.3.0) nor withdrawing from publication
  (0.4.0) — meaning the page that states what this system promises was out of date
  about its central promise.

  It now says there are two ways out (withdrawing comes back; deleting and purging do
  not), that the ORM guard keys on whether the name was ever published rather than on
  whether it is published now, and that NR holds either way: a name that went out
  and was removed answers 404 forever and never comes to mean something else. The same
  wording survived in the Quickstart, the federation guide, the data model and the CLI
  reference, and was corrected there too.

• The versioning policy did not
  know what had happened to it. It listed "a published ARK becomes deletable" as an
  example of a major change — and 0.4.0 did exactly that. The line is redrawn: what
  counts as weakening is not removal itself but removal without a reason, without the
  ARK retyped, or from outside the caller's reach.

• STATUS.md named a migration head one behind. alembic check compares the schema
  with the models but never reads the documentation. A test now checks that the
  version and the head named there match reality — the second time today that putting
  something in the runbook turned out not to be enough.

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日本語の変更履歴
· Full Changelog: v0.9.0...v0.9.1