Retirement issues are checked against main before they are handed out: one whose class or rule is already gone is closed with the commit that removed it #5983

#4691 and #4616 were each handed to builders twice after their work had already landed (66d71d7c, f8970686). Each run closed its pull with nothing to change. That is spend with no benefit.

Done when:

• [ ] Before the picker hands out an issue whose title says a class or rule "leaves the stylesheet" or "leaves §5d", it greps main for the names in its done list. If none is found, it writes the existing Done on main already note (src/core/done_on_main.ts), naming the commit that last touched them (git log -S), and does not hand the issue out.
• [ ] Names are taken only from backticked .class tokens in the title and body. An issue without them is handed out as today.
• [ ] Tests: an issue whose classes are gone gets the note and is skipped, one whose classes remain is handed out, and one with no names is handed out. Do not touch src/http/mcp.ts, src/contract/openapi.ts or docs/DESIGN.md.