Wayfinder reversal

This builds on a wayfinder map. If there is no map yet, tell the user to run /wayfinder to chart one.

Use when a grilling answer contradicts a closed ticket, when the owner rejects a resolution after close, or when the map's last driveable ticket closes and /to-spec is next. Tracker conventions live in docs/agents/issue-tracker.md. The map is one issue ($MAP below, often #1) with Notes, Decisions so far, Not yet specified, and Out of scope sections.

Reversal inside a ticket (owner rejects a closed resolution)

1. gh issue reopen <n> --comment "Reopened: <what changed>. Re-grilling the delta."
2. Call the Skill tool with "grilling" and grill only the delta. List what survives from the first resolution up front.
3. Post a new comment headed ## Resolution (second, supersedes the one above). Leave the old one unedited.
4. Rewrite the ticket's line in the map body in place, rather than appending a second one.
5. Update glossary terms in place (call the Skill tool with "domain-modeling" for the GLOSSARY.md format), then commit and push GLOSSARY.md.

Reversal across tickets (new ticket contradicts old ones)