[moetemp]

What changed?

This PR lets a resource declare its type parameters, in Python, TypeScript and .NET.

A resource names each type parameter alias that it uses with @nexus.type-parameter "<alias>", in order. The alias can come from another interface through use. The resource class is then generic, and it keeps a runtime type for each parameter.

• An operation that returns the resource takes one runtime type for each parameter, since its request can't give one. The create of the stream sample is create_stream(Turn, stream_id=...) in Python, and it returns a Stream[Turn].
• An operation that a method binds takes a runtime type for each parameter that only its output uses. The read takes one, and the append takes none, since its request carries the values.
• The data converter decodes the generic values of a response with the runtime types. Python passes ReadRecordsResponse[body_type] as the output type. TypeScript converts the response with the model's create<Model>TransferTypeConverter factory and the handle's TypeInfo. .NET calls the generic operation with the class's TBody.
• Go and Java refuse a generic resource.

nexgen also refuses a resource that uses a parameter that it doesn't declare (also through a proto-backed record), a declared parameter that the resource doesn't use, and a parameter of a bound operation that the resource doesn't declare. A generic resource can't be the result of an operation with no @nexus.proto message, or a field of a record, since neither carries the type arguments.

The stream samples take the parameter body-t on the bodies of append-record and stream-data, and the Stream and the writer declare it. Brook's WIT takes the same directives later.

The TypeScript resource methods now branch on a string parameter only when the parameter is a function reference. Before, a bound operation with a generic request made every optional string parameter branch.

It is for review here before it goes upstream. It sits on the upstream stack temporalio#308, temporalio#310, temporalio#311, temporalio#297, temporalio#296, temporalio#303, temporalio#304, temporalio#309, temporalio#318, temporalio#319, temporalio#320, temporalio#321, temporalio#322, temporalio#323, temporalio#324, temporalio#325, whose head is review/p3-base.

Why?

The Stream API of the proposal is generic in its value type, as in Stream[Turn]. The generated Stream class is that API, so the body of a read must decode as the handle's type, not as a raw payload. A resource couldn't use a type parameter at all before this PR.

How did you test it?

Python tests decode a read through the System Nexus converter with the handle's body type, and check Stream[Turn] and ReadRecordsResponse[Turn] with assert_type under basedpyright. A TypeScript test checks that the started read decodes a body with the handle's TypeInfo, and it checks the types with expectTypeOf. A .NET test round trips a data item as ReadRecordsResponse<Turn>, and a compile check reads a Stream<Turn>. Unit tests cover the runtime types of each stream operation, and a writer parameter that use brings in. Rejection fixtures cover each refusal.
cargo validate passes.

[moetemp]

Duplicate of #78, which has the same commit.