Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>
String=[Char] via pure-SX views, show, error, numeric tower, Data.Map, Data.Set, records, IORef, exceptions. Briefing updated to point at new plan; old phases 1-6 plan untouched. Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>