Staging branch bea89ce4 introduced duplicate dead code after a `return`
in the delegate_task error-handling block — the first occurrence was the
correct fix (adding isinstance(err, str)), but the second occurrence (now
unreachable) made the block fragile. Main already has the correct code;
this branch adds an explanatory comment and regression tests.
The non-tool delegate_task() in a2a_tools.py uses httpx.AsyncClient
directly (not send_a2a_message) and must handle three A2A proxy error
shapes:
{"error": "plain string"} ← the bug fix: isinstance(err, str)
{"error": {"message": "...", ...}} ← pre-existing path
{"error": {"nested": "object"}} ← falls through to str(err)
Adds TestDelegateTaskDirect:
test_string_form_error_returns_error_message — regression for AttributeError
test_dict_form_error_returns_error_message — pre-existing path still works
test_success_returns_result_text — happy path still works
Co-Authored-By: Claude Opus 4.7 <noreply@anthropic.com>
