Why: make material, background work, confirmations and files accessible to nontechnical users across desktop and mobile.
Evidence: Dev SELF receipts for Frontend tsc, 190 tests, knip baseline, build, nine fixture browser cases and two real HTTP/browser smoke cases using MockRunner.
Impact: existing API and permissions remain authoritative; stale events/queries and duplicate effects are guarded, while one file preview and reading state are preserved.
Refs: work-companion-ui design r0.2 and plan r1 U2-U5; UI01-UI13.
