fix(openapi): honor query parameter style and explode

[1aifanatic]

Link to Issue or Description of Change

1. Link to an existing issue (if applicable):

• Closes: RestApiTool ignores query parameter style/explode: object query params are sent as a Python dict repr #7204

Problem:

RestApiTool passed query values to httpx as the model produced them, and ApiParameter did not record the spec's style/explode. httpx repeats the key for a list, which only matches the default for arrays, and sends a dict as its Python repr. So every object-typed query parameter went out as filter={'status': 'open'}, and non-exploded or delimited arrays were exploded.

Solution:

• ApiParameter gets optional style and explode fields (default None, so serialized ParsedOperations still load), and OperationParser copies them from the spec's Parameter.
• A small _serialize_query_param() applies them to query values, following OpenAPI 3:
  • objects are spread (form, exploded, the default), bracketed (deepObject), or k,v,... (form, not exploded);
  • non-exploded arrays are joined with , (form), (spaceDelimited), or | (pipeDelimited);
  • scalars and default arrays are passed through unchanged, so existing behavior for them doesn't change.

Testing Plan

Unit Tests:

• I have added or updated unit tests for my change.

• All unit tests pass locally.

• test_rest_api_tool.py::TestRestApiTool::test_prepare_request_params_query_style_and_explode, parametrized over the style/explode/type combinations above. The 6 serialization cases fail on main; the default-array and scalar cases are controls and pass on both.

• test_operation_parser.py::test_process_operation_parameters_keeps_style_and_explode fails on main.

$ pytest tests/unittests/tools/openapi_tool
350 passed

$ pytest tests/unittests -n 8   # Python 3.12, Windows 11
44 failed, 15152 passed, 102 skipped, 27 xfailed, 2 xpassed

Every failure outside the new tests also fails on an unmodified origin/main (3f4bb8f) on the same machine, where the same run gives 47 failed. Most are deterministic Windows-specific tests (cli/ deploy, conformance, scripts/check_new_py_files, path normalization, the unsafe local code executor, the import allowlist, yaml). The remainder differ between runs: telemetry functional/node-functional schema cases, and streaming/test_streaming_tool_events.py::test_delivered_event_carries_the_message_and_nothing_else, which failed 1/10 in isolation on clean main versus 2/10 on this branch. I ran on Python 3.12 only, not the full tox matrix.

Manual End-to-End (E2E) Tests:

A real Runner + LlmAgent + OpenAPIToolset whose spec has a default-style object param, a deepObject param, and a form/explode: false array, with a mocked model and an httpx.MockTransport backend. The script is in #7204.

Before (main @ 3f4bb8f):

query sent: match={'status':+'open',+'priority':+'P1'}&filter={'assignee':+'me'}&fields=id&fields=title

After:

query sent: status=open&priority=P1&filter[assignee]=me&fields=id,title

Checklist

• I have read the CONTRIBUTING.md document.
• I have performed a self-review of my own code.
• I have commented my code, particularly in hard-to-understand areas.
• I have added tests that prove my fix is effective or that my feature works.
• New and existing unit tests pass locally with my changes.
• I have manually tested my changes end-to-end.
• Any dependent changes have been merged and published in downstream modules.

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https://claude.ai/code/session_013vXxD1ga1hnCq2uFRwNks7