v0.13.0

The release that gave arkhe a client.

Everything the API can do is now reachable from Python without anyone writing their own
requests — and, more to the point, without anyone writing their own idea of which calls
are safe to retry. A ledger whose identifiers cannot be reissued cannot afford that
decision to be made once per caller.

Added

• A Python client (clients/python, arkhe-client). It covers every endpoint of
  the minter and the resolver, and it makes the three decisions the API document cannot
  express:

  Minting carries an idempotency key. Every mint() sends a request_id, generated
  when the caller does not supply one, and a retry sends the same one, so a lost answer
  cannot leave a number spent with nobody holding it. Ark.resent says which happened.
  mint_many() keys every row, which is what makes an interrupted batch safe to send
  again. Only calls that can be sent twice without acting twice are retried; anything
  else raises TransportError and leaves the decision to the caller.

  The 307 to another minter is not followed. Following it would send one
  organisation's credential to another organisation's endpoint, and an ARK minted over
  there is one this ledger knows nothing about. It is raised as Delegated, carrying
  .minter and .about.

  Refusals carry their ARKHE-xxxx code, as typed exceptions under ArkheError.
  Refusals that carry no code — the {field: what is wrong} shape the domain raises and
  the screens show beside the field — keep what they said rather than becoming a bare
  400.

  It is hand-written rather than generated, because what a generator adds is coverage and
  coverage is the part that can be checked: clients/python/tests/test_contract.py
  compares the client with the published OpenAPI documents in both directions, so an
  endpoint added to the server fails the build until someone decides whether the client
  should carry it. 39 checks run against a stub and 14 against the real stack.

• The end-to-end suite seeds a namespace whose minting is delegated (99999/d9), so
  that the 307 can be checked from outside rather than only in a unit test.

Changed

• pytest also collects clients/python/tests, and the English-only check now
  covers clients/. The client is checked in the same net as the server it speaks to.

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Changelog in Japanese
· Full Changelog: v0.12.1...v0.13.0