The all-sessions coverage GET dies: the per-session block is the coverage surface

Extraction-UX close-out interlude (master dispatch 2026-09-24, off UI's
ff1ec7a confirmation): nothing client-side consumes GET /api/graph/coverage
— the sidebar block and the chat-bar ring both read GET /api/chats/[id]'s
coverage block. The dead route (app/api/graph/coverage/route.ts) is
deleted; the manual-extract front door (POST /api/graph/coverage/extract)
stays by design.

No server helper was orphaned — the route was composition-only over
shared seams (chatStore, extractionStatuses, stores, coverageOf). The
sessionCoverage doc + the chats/[id] route comment now point at the
per-session block as THE coverage surface.

Pin (tests/coverage.test.ts): the route file's absence (prompt-overrides'
structural-pin precedent) + the Extract POST's survival — a merge cannot
resurrect the dead surface silently.

src/server/chats.ts

@@ -114,10 +114,11 @@ export async function deleteChatSession(chatId: string, mode: ChatDeleteMode): P
 }
 
 /** One session's coverage read (extraction-UX redesign, owner dispatch
- *  2026-09-24): the chat view's ring meter + popover data — the same
- *  derivation the all-sessions list serves (/api/graph/coverage), scoped
- *  to one chat. "Uncovered" stays DERIVED per request (fingerprint the
- *  transcript, diff the coverage ledger — never dual-tracked).
+ *  2026-09-24): the chat view's ring meter + popover data, scoped to one
+ *  chat (the all-sessions GET died with this redesign — nothing consumed
+ *  it once the sidebar and ring read here; the Extract POST stays).
+ *  Uncovered stays DERIVED per request (fingerprint the transcript,
+ *  diff the coverage ledger — never dual-tracked).
  *
  *  lastFoldedAt: the newest coverage row's fold timestamp — a cheap single
  *  pass over the chat's ledger rows (the ring popover's "last extraction"