bug(plugin-kanban): swimlanes below the fold are UNREACHABLE — the swimlane region is overflow-hidden and the document does not scroll

[os-justin]

Filed by the domain:ui PM seat (session_01YBWFb5YgMU5dw8p2VKj16S) on behalf of the objectui#7303 dev, who measured it in a real browser while landing PR #8430 and could not file it (search_issues rate-limited). ⛔ Not claimed.

Measured (Chromium 1194, 1600×1000, three swimlanes)

swimlane region   scrollHeight 2104   clientHeight 1000   overflow: hidden
document.documentElement                                   not scrollable

⇒ lanes 2 and 3 cannot be reached at all. Not "awkward to reach" — there is no scroll affordance on either the region or the document, so the content below the fold is simply inaccessible.

This is a different defect class from objectui#7303 (a collapsed header row) and from objectui#8448 (two horizontal axes out of sync): those are about labels, this is about content the user cannot get to.

Why it is a ruling, not a mechanical fix

Choosing where a swimlane board scrolls vertically is a layout decision with more than one defensible answer, and it interacts with the board's h-full height-bounding:

• A — the swimlane region scrolls. overflow-y: auto on the region. Keeps the board inside its allotted height; the column-header row then needs a decision of its own (does it stick?), which is where this meets objectui#8448.
• B — the board grows and the page scrolls. Drop the height bound. Simplest for the user; changes the board from a self-contained pane into something that stretches its container, which other surfaces embedding it may not expect.
• C — lanes collapse by default beyond the first N. Sidesteps the scroll question; adds an interaction that did not exist.

⚠️ A interacts with PR #8430's fix. That fix works because the header row is a scroll container whose automatic minimum size is zeroed and it was the only shrinkable flex item; adding another scrollable region to the same column changes the shrink arithmetic. PR #8430's pin asserts the invariant (the row must not be both a scroll container and shrinkable), so a careless A will redden it — which is the intended behaviour, not an obstacle.

Reachability

Whoever takes it should establish how many lanes a real board has in practice before grading urgency: at 1600×1000 the measurement used three lanes and lost two. A board grouped by a low-cardinality field is fine; one grouped by owner or account is not.

Related

objectui#7303 / PR #8430 (the browser measurement this came from) · objectui#8448 (the horizontal half of the same layout)

Dedup

⚠️ Not run, declared rather than hidden. The reporting dev was rate-limited and this seat has not run a targeted search. No dedup claim is made. Suggested query for a triager: kanban swimlane vertical scroll overflow hidden lanes unreachable.