_continue_task 226->168 via _validate_continue_options;
_task_wait 158->139 via _validate_wait_params;
_task_thread_read 187->152 via _summarize_trace_entries;
_metrics 123->104 via _summarize_metrics_tasks.
No behaviour, message, status or route change; error strings verbatim.
New tests: test_longfunc_extra (9). Cloud full suite: 1439 OK, skipped=4.
Follows #229 pattern; must merge after #229 and be rebased/checked then.
