Make the 51Did client asynchronous with no synchronous form

[jwrosewell]

What changed

Every method on DidClient that reaches the cloud is now a coroutine, and the synchronous forms are removed outright. This is one of a set of changes making every 51Did client and every OWID port asynchronous where the network is involved, so the libraries behave the same way in every language.

Methods that never touch the network are unchanged, so endpoint, resource_key, has_licence_key, the parsing helpers and the key selection helpers all stay synchronous.

Removed

• def public_keys(self) -> List[PublicKeyEntry]
• def public_key_for(self, fod_id) -> Optional[PublicKeyEntry]
• def verify_signature(self, fod_id) -> bool
• def verify_signature_detailed(self, fod_id) -> SignatureCheck
• def verify(self, fod_id) -> bool
• def redeem(self, fod_id, result, ...) -> RedeemResult

New

The same six with the same names, arguments and return types, as async def. The transport type changes with them.

Transport = Callable[[urllib.request.Request], Awaitable[Tuple[int, bytes]]]

The default transport wraps the existing urllib call on a worker thread through asyncio.to_thread, so it is not fully non-blocking. The module documentation says so and points at aiohttp or httpx for a transport that is. No dependency was added and the supported Python version is unchanged.

Kept exactly

The two step verification, the licence key handling, the redeem outcome types, key selection by the latest start at or before the date, and the 401 handling, all as the tests pin them. The key cache now also holds the in-flight fetch, so concurrent callers waiting on one key list make a single request.

The example server and the package documentation were converted with the client, and there are no callers of the removed methods anywhere else in the repository.

Verification

pytest over the package with the owid submodule on the path: 150 passed, 2 skipped. New tests cover two concurrent key list requests making one HTTP call, and concurrent selections past the newest start sharing one fetch.

This client does not use the OWID library's fetch, only its cryptography, so it does not wait on the OWID asynchronous work in SWAN-community.

Notes

Written with AI assistance and reviewed before merging.