Record the service of each operation

[VegetarianOrc]

Summary

• Add Operation.service. @nexusrpc.service and @service_handler set this value to the service definition of the decorated class. Thus, a caller can find the service from an operation or from a handler method alone.
• Each decorated class now has its own operations. A service definition copies each inherited operation. A service handler wraps each inherited operation method. Thus, an operation reports the service of the class that holds it, not the service of the parent class.
• Handler method operations now get their name and types from the service definition. Before this change, when a service definition renamed an operation, the handler method reported the method name and not the operation name.
• service is not part of Operation equality or repr.

Why

This was added to provide some convenience to targeting operations with Nexus Handler Callbacks in the Temporal Python SDK.

@nexusrpc.handler.service_handler(name="callback.test.NotificationService")
class ExampleHandler:
    @nexusrpc.handler.sync_operation
    async def on_complete(
        self,
        _ctx: nexusrpc.handler.StartOperationContext,
        input: notifications.OnCompleteRequest[EchoOutput, CallbackContext],
    ) -> notifications.OnCompleteResponse:
        ...


# Referencing the operation by reference previously only gave access to the operation definition.
# After this change, this reference is enough to resolve both the Nexus service as well as the operation
# name.
operation = ExampleHandler.on_complete


# The change allows users to provide a reference without needing to provide both the service and the
# operation. It helps provide more ergonomic APIs like:

nexus.create_completion_callback(
    # service and operation read from this one reference
    operation=ExampleHandler.on_complete,
    task_queue=completion_task_queue,
    source_context=CallbackContext(label="success"),
)

Test plan

• uv run poe lint (basedpyright, pyright, mypy, ruff)
• uv run pytest (112 passed)
• New tests in tests/test_operation_service.py cover definitions, handlers, inheritance, renamed operations, sync and async methods, and @operation_handler factories.

🤖 Generated with Claude Code

[bergundy]

Can you add a "why" section to the PR description?

[bergundy]

And do you see us adding this to all of the Nexus SDKs?

[VegetarianOrc]

And do you see us adding this to all of the Nexus SDKs?

Spoke offline about this, but at this time I don't think it's necessary for other SDKs as they already have avenues for idiomatic/ergonomic operation targeting.