Specification: Explain the completed-task subset

Branch: t3/board-done-subset | Created: 2026-10-08 Input: Continue UI/UX quality with 2–3 further PRs, all brought to merge.

User story 1 (P1)

A user reads Done · 25 but sees only 20 cards. Explain that these are the latest 20 of the total without implying deletion or completeness. Acceptance: 25 finished tasks show total 25, exactly the newest 20 cards and “Showing latest 20 of 25”. At 20 or fewer no redundant subset notice appears. Empty board feedback remains unchanged.

Requirements

Keep existing task derivation, order, cap and activation. Notice is native text, wraps at narrow sizes, remains readable in light/dark and enlarged text. No new IPC, storage, dependency or motion.

Success criteria

A native production-board red regression proves missing subset feedback; after fix it checks total, visible count/order, notice absence for untruncated history and native render bounds. Full verification and independent review pass before merge.

Clarifications

This is presentation of existing data, not a pagination feature. Earlier board attention/refresh issues are separate PRs. No unresolved requirements or constitution deviations.