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Python: [Bug]: Functional workflow accepts HITL responses that violate response_type #8308
Description
Summary
Functional workflows accept a response whose runtime type does not match the response_type declared in RunContext.request_info() during response-only HITL resume.
Reproduction
from agent_framework import RunContext, workflow
@workflow
async def typed_review(data: str, ctx: RunContext) -> str:
answer = await ctx.request_info("number", response_type=int, request_id="typed")
return f"{answer}:{type(answer).__name__}"
caller = typed_review.build()
await caller.run("input")
resumed = await caller.run(responses={"typed": "not-an-int"})
print(resumed.get_outputs())On current main, the response is accepted and the output is:
['not-an-int:str']
Expected behavior
A response that violates the declared response_type should be validated consistently with the graph workflow runtime: valid values may be coerced according to the existing workflow typing rules, while incompatible values should raise a clear type-mismatch error before the workflow produces output.
Impact
A malformed or incorrectly deserialized HITL response can silently enter a functional workflow as the wrong Python type. This makes the declared response_type ineffective and can produce incorrect downstream decisions, formatting, or persistence without an error at the response boundary.
Related context
The review discussion on the original functional workflow implementation in #4238 identified that response-only resumes accept responses without the type/request validation enforced by the existing workflow runtime. This issue tracks that unresolved follow-up. It is separate from #8299, which concerns user state being lost during the same response-only resume path, and from #8292, which concerns concurrent cached-step result ordering.
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CoralGarden52 commentedon Sep 11, 2026
Clarification: existing functional workflow behavior and regression tests intentionally allow a
Noneresponse (with a warning), even whenresponse_typeis non-optional. The proposed validation will preserve that compatibility behavior and reject only non-Nonevalues that cannot be coerced to the declared response type.github-actions commentedon Sep 11, 2026
🤖 Automated triage reproduction notes (agent-authored — trust but verify)
Agent analysis
Repro:
python/packages/core/agent_framework/_workflows/_functional.py::RunContext.request_infoat lines 244-247 returns the raw value populated by_set_responseswithout checking the declared response type. It triggers afterrequest_info(..., response_type=int, request_id="typed")pauses a functional workflow andrun(responses={"typed": "not-an-int"})resumes it; the minimal test expectsValueErrorbut observes['not-an-int:str'].python/packages/core/tests/workflow/test_functional_workflow.py1.18.0