[solo applicant] keep workspace state consistent when a view switch and a drag-completion race

Walk the cross-cutting story scenarios that span pipeline + collaboration: three actors converging after an extract, adding a column mid-score, switching the view group mid-drag, friend-edits during a tailor, the agent-tailors-while-user-offline path, mid-tailor section adds, and the no-workspace-delete safety. These specs catch races that single-actor suites cannot see.

Story-focused browser specs tied to the behaviour catalog. This gate keeps the story-to-test translation honest while staying runner-only.

Proof set for User changes active view while friend is dragging a job — friend's drag completes; group ID resolves under both views correctly