Board cards in the Done column never show when the task finished #2066

Implementation: FlyBot (ours) — PR follows within 24h. Do not pick up without a pickup-ok comment on this issue.

Written-by: FlyBot Lead
Claimed-by: FlyBot Lead
Claim-Id: 73966f19d3154326ad0829769e997181
Branch: dev/1-board-done-time
Base: c2de64d
At: 2026-11-01T17:01:14Z

What happens today

A Bot's Tasks board draws every card with the same footer (core/src/client/kanban.js:256-261): the owner (bt-board-who) and the progress bar plus 100% (bt-board-progress). Nothing else. The Done column is filled from actions.tasks({ botId, archive: true, limit: ARCHIVE_SHOWN }) (kanban.js:174-188), whose host records do carry the time (core/src/host/tasks.js:342 — view() spreads the whole record, updatedAt and actors included), and the column header already counts them; but the card never renders any of it.

Measured on c2de64d6 with the real modules: a done card renders as #done-1NormalDoneFinished two hours agoWriter100%, the footer as Writer100%, and no node carries a timestamp. kanban.js does not import relativeShort at all (only at-menu.js:181, inbox.js:539, sidebar.js:238 do), so nothing throws and nothing is wrong — the time is simply absent. The same task in the Inbox Done list shows 2 h (inbox.js:545 → whenText), so one finished task reads differently in two surfaces.

Expected

Only in the Done column, append one node at the end of the card footer: a span.bt-board-when whose text is relativeShort(settledAt), styled like the rest of the footer. Nothing changes in the other columns, the rail counts, the archive limit or the ordering.

• Time: the first terminal record's at in actors (accepted / cancelled / failed — the three states that land a card in Done, shared/task-board.js:19). Not the last one and not updatedAt: editing a settled task pushes a further same-status record with by: 'updated' (tasks.js:1456) and refreshes updatedAt (tasks.js:267-270), so the last record and updatedAt both move after completion, while the first terminal record is the transition itself (TRANSITIONS, tasks.js:30-39, has no exit from a terminal state).
• Fallback: first terminal at → updatedAt → draw nothing. Guard with Number.isFinite(t) && t > 0: relativeShort(undefined) renders Invalid Date and relativeShort(0) renders Jan 1.
• Formatting and localisation reuse relativeShort (core/src/client/text.js:64-71) and its existing strings — just now / 5 min / 2 h / 3 d, an absolute date past 30 days. No new i18n key, no new formatter, no title tooltip.

Scope

core/src/client/kanban.js (BoardCard footer, one conditional node, one KANBAN_CSS line, the text.js import), core/test/kanban.test.js, the rebuilt core/client.js and patches/ds-bot/ artefacts (0008-client-bundle.patch, files/src/client/kanban.js, files/test/kanban.test.js), changelog.d/<issue>-board-done-time.added.md, and one sentence on the kanban.js row of docs/subsystems/core-client.md. text.js, board-card.js, inbox.js and the host are untouched.

Out of scope: other columns, the Inbox whenText and Project board waitedLabel, the rail counts (kanban.js:396-409), draggable (:270), the archive limit and its 20 newest wording.

Tests

core/test/kanban.test.js, with the existing boardWith(scope, own, archive) helper:

1. A settled card whose actors are [{working, -10min}, {accepted, -125min}, {accepted, -1min, by:'updated'}] and updatedAt: -1min renders 2 h — pins both "use the terminal record" and "use the first one" (the last record or updatedAt would read 1 min).
2. The same card in In progress has no bt-board-when node.
3. A card with no actors falls back to updatedAt.
4. A card with neither renders no node and no Invalid Date text.
5. A room board ({kind: 'group'}) Done card renders it too.

Mutation check: taking the last terminal record, or updatedAt, must turn case 1 red; dropping the finiteness guard must turn case 4 red.

Tier T1 (only core/src/client/**), size XS.

Duplicate check

On live main c2de64d6, relativeShort has zero hits in src/client/kanban.js, and bt-board-when has zero hits in src and test. Issue search for done card time / board card timestamp / finished time board / kanban done when returns 0, and relativeShort in bodies returns 0. The nearest existing issues are #2031 (Project board blocked row age), #1884 (completion median), #1289/#2047 (Done counts) and #1746 (Inbox and board row mapping) — none is this. No open or closed duplicate.