The per-file 100% coverage gate flagged surface.ts line 46 — the
branch where a surface-eligible event type carries no surfaceOp marker
(isSurfaceEvent returns false). Exercise both guards directly: the
type-only eligibility check, the positive narrowing path, a
non-eligible type, and the markerless-but-eligible branch.
Reconcile the session-surface feature with master's package reorg and
simplifications:
- Adopt master's folded usage (assistant/message.usage; standalone `usage`
event dropped) and re-attach surface metadata (surfaceOp/sourceEventSeqs).
- Add surface opts to master's new max-tokens assistant/message append.
- Port surface columns onto the coordinator-refactored SQLite backend at its
new path; drop the dead v1->v2 migration (bump-and-reject, no migration per
pre-release policy).
- Move the session-surface RFC into implemented/architecture/ and refresh its
stale body (no migration, SESSION_FORMAT_VERSION=0, renamed package paths).
- Update the core-data-structures catalog SessionEvent blocks for the two new
surface fields; regenerate the cordis catalog.
- Re-harvest ACP snapshot fixtures (keyless replay) to carry surface metadata.
