[PratikDhanave (PratikDhanave)]

Motivation & Context

InProcRunnerContext.send_request_info_response validates the response against the request's response_type and, on mismatch, raises TypeError with a message built from event.response_type.__name__.

response_type is not restricted to plain classes — is_instance_of(data, target_type: type | UnionType | Any) explicitly accepts unions, and callers pass them (e.g. response_type=int | str). types.UnionType has no __name__ on Python 3.10/3.11 (it was only added in 3.12, gh-105499). Since the package declares requires-python = ">=3.10", on those interpreters the error path itself raises AttributeError — masking the intended TypeError with a confusing, unrelated exception. On 3.12+ it doesn't crash but yields the unhelpful "expected Union".

Description & Review Guide

Compute the display name defensively: use __name__ for real classes, and str(...) for anything else (unions, generics):

expected = (
    event.response_type.__name__
    if isinstance(event.response_type, type)
    else str(event.response_type)
)

• Impact: mismatch errors now name the actual expected type on every supported Python — int | str, list[int], as well as plain int. No API/signature change.
• Tests: added a regression test with response_type=int | str and a mismatched (float) response, asserting the message reads expected int | str, got float. On 3.10/3.11 the old code raised AttributeError (no TypeError at all); on 3.12+ it produced expected Union. Fails before, passes after. Full test_request_info_event_rehydrate.py suite green (11 passed).

Related Issue

N/A - trivial change: a localized hardening of one error-message expression, covered by a new unit test.

AI Assistance

• No material AI assistance was used.
• This is an AI-assisted contribution. I reviewed, understood, and verified all submitted content and accept responsibility for it.

AI assistance details: This change was developed with Claude Code (an AI agent) — it located the bug, wrote the fix and the regression test, and ran verification (pytest). PratikDhanave (@PratikDhanave) to review and tick the AI-assisted attestation above before merge.

Contribution Checklist

• The code builds clean without any errors or warnings
• All unit tests pass, and I have added new tests where possible

[Copilot]

🟡 Changes recommended

The new union argument conflicts with the typed request-info API and will fail test type-checking.

1 open finding

• Widen request_info response_type annotations for UnionType support · New

What changed in this PR

Improves workflow response mismatch errors for union and generic response types.

Changes:

• Adds defensive expected-type formatting.
• Adds a union mismatch regression test.

File	Description
_runner_context.py	Formats non-class response types readably.
test_request_info_event_rehydrate.py	Tests union mismatch errors.

🧠 Review effort: Balanced

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