feat: add query downstream api

[leavesster]

oomol/oocana-rust#229 's python implementation

[Copilot]

Pull Request Overview

This PR introduces a new query_downstream API to the Python SDK, a corresponding example flow, and an end-to-end test to exercise the feature.

• Adds Context.query_downstream async method for retrieving downstream nodes.
• Provides a new example flow (query-downstream) with two Python scriptlets.
• Adds an integration test in TypeScript to run the new flow.

Reviewed Changes

Copilot reviewed 5 out of 5 changed files in this pull request and generated 4 comments.

Show a summary per file

File	Description
oocana/oocana/context.py	Added query_downstream method to Context with request/response handling.
flow-examples/test/flow.test.ts	Added a test case for running the query-downstream flow.
flow-examples/flows/query-downstream/scriptlets/+scriptlet#1.py	Scriptlet that calls context.query_downstream and prints results.
flow-examples/flows/query-downstream/scriptlets/+scriptlet#2.py	Scriptlet that returns a dummy output for the downstream node.
flow-examples/flows/query-downstream/flow.oo.yaml	Defined the new query-downstream flow with two Python nodes.

Comments suppressed due to low confidence (3)

oocana/oocana/context.py:589

• The docstring parameter name does not match the function signature (handles vs handle). Update the :param to handles to align with the parameter name.

        :param handle: the handle of the output, should be defined in the block schema output defs. If None means query all handles.

oocana/oocana/context.py:594

• [nitpick] The variable name f is ambiguous. Consider renaming it to future or result_future for better readability.

        f: asyncio.Future[Dict[str, Any]] = loop.create_future()

flow-examples/test/flow.test.ts:58

• [nitpick] The test only verifies the exit code; consider adding assertions to validate the output from query_downstream (e.g., checking logged results or returned events) to ensure the flow behaves as expected.

      expect(code).toBe(0);