workflow: collapsing the Hand-a-task card list drops the picked card from view while Assign still commits it #2257

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: 26a5aeded04f41289432c36a5aeb8906
Branch: dev/4-p465-keep-selected-card-visible
Base: 575fadf
At: 2026-11-03T02:48:46Z

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

Written-by: FlyBot Lead

In the Hand-a-task card list: expand to 20 cards, pick card 20, then collapse back to 12 — the picked card leaves the screen entirely. No row carries .sel, yet Assign still posts taskId: "task-20", so the user hands over a card they cannot see and cannot re-check.

Reproduction (live main 575fadf3, component-level probe)

1. Open Hand a task on a lane with 20 cards, press Show 8 more cards.
2. Pick Board card 20.
3. Press Show less.
4. Probe: PROBE_COLLAPSED_VISIBLE_CARDS 12, PROBE_COLLAPSED_SELECTED_VISIBLE 0, PROBE_COLLAPSED_ASSIGN_DISABLED false; pressing Assign still posts {"workflowId":"delivery","taskId":"task-20","title":"Board card 20"} and none of the 12 visible cards carries sel.

#2249 fixed the other half (the 13th card was unreachable while expanded). Collapsing is its mirror image: the list shows no selection at all while the confirm button commits a hidden one, and an assign cannot be undone.

Expected

• Collapsed view still draws 12 rows, but the picked card is pinned into that slice: when tasks.slice(0, 12) does not contain taskId, draw the picked card as the first row.
• The count text (Show 8 more cards) is unchanged; the submitted body and canAssign are unchanged.
• Negative control: with no card picked, the collapsed view is byte-identical to today.

Scope

• plugins/workflow/client.js only — the card slice behind the collapsed list (live 575fadf3: :1447 area; card rows :1466, the Show less / Show {count} more cards button :1473). One expression change: build the visible slice as "picked card first (if not already inside), then the first 12 minus that slot", keeping the count at 12.
• plugins/workflow/test/client.test.js: one case for pick-then-collapse, one negative control for no pick.
• docs/subsystems/workflow.md (one line), changelog.d/.
• Plugin source only: no generated artefacts, patches/ds-bot/ untouched.

Tier

T2 — the change lands in plugins/workflow/client.js.

Duplicate check

Issue search: Show less 5 hits, all closed; collapsed card list 12 hits, none about this dialog's selection; selected card hidden 4 hits, all closed. #2249 (closed) is the adjacent "says how many cards are not shown" fix and #2244 (closed) is the 12-row cut of the pick lists; neither covers the collapsed slice dropping the picked card. No open issue matches. This is an enhancement, sequenced after #2256.

Branch: dev/4-p465-keep-selected-card-visible
Owner: Dev4