Validate reference_targets hrefs; append to issues on invalid. Call from parsing process after fill_names (pass list so task-output anchors can be validated).
| allow_http_refs |
true for task list (creation/iteration), false for refinement output. If true, http(s) URLs accepted; if false rejected (use tool calls in ## Tool Calls instead). Task output refs use task URI only. Future: taskname plus tool id plus .md when TaskResult map exists. |