fix(llm): surface structured provider refusals

[bearsyankees]

Summary

• detect structured ResponseOutputRefusal items after a streamed run completes
• route provider refusals through the existing agent failure path so the TUI displays them in red
• preserve the provider's refusal text as the agent error

Why

Some providers return policy refusals as successful response output rather than raising an API exception. Strix previously treated those turns as normal final output and parked the interactive agent in waiting, hiding the actual failure.

Testing

• poetry run pytest tests/test_execution.py tests/test_execution_transient_retry.py tests/test_e2e_budget_lifecycle.py -q (44 passed)
• poetry run ruff check strix/core/execution.py tests/test_execution.py
• poetry run mypy strix/core/execution.py
• live OpenRouter/Anthropic structured refusal: agent rendered red as failed with the full provider message

[greptile-apps]

Greptile Summary

The PR now handles structured model-provider refusals through the normal agent failure lifecycle.

• Detects refusal output after streamed execution completes.
• Preserves the provider’s refusal text as the agent error.
• Marks interactive and non-interactive agents as failed and notifies child agents’ parents.
• Adds coverage for root-agent and child-agent refusal handling.

Confidence Score: 5/5

The PR appears safe to merge.

The previously reported non-interactive refusal issue is fixed: the refusal handler now records a failed terminal status and notifies the parent before returning, so the generic non-interactive re-raise is no longer reached.

Important Files Changed

Filename	Overview
strix/core/execution.py	Detects structured refusal items and routes them through terminal failure handling, including non-interactive child status updates and parent notification.
tests/test_execution.py	Adds focused tests confirming refusal text preservation, failed status transitions, and parent notification for non-interactive children.

_{Reviews (2): Last reviewed commit: "fix(llm): settle refused autonomous agen..." | Re-trigger Greptile}

[bearsyankees]

@greptileai