## Why
In the side panel and on mobile, a tab holding a single widget renders
with no gutter at all: the field list sits flush against the panel
border. Regression from #23109.
`getWidgetCardVariant` checked the derived presentation before the
surface:
```ts
if (presentation === 'solo') return 'solo';
const isSideColumnContext = isInPinnedTab || isMobile || isInSidePanel;
```
So a single-widget tab resolved to `'solo'` even in the side panel or on
mobile, and `'solo'` has no branch in `WidgetCard`'s padding switch, so
it falls through to `0`. The same widget used to match `variant ===
'side-column' && !isEditable` and get `spacing[3]` (12px).
The pinned left panel escaped this only because `PageLayoutLeftPanel`
hardcodes `presentation: 'stack'` — the rule was already there ("the
pinned left panel is always a column, a surface rule not a widget
rule"), just applied at one call site instead of being the rule.
## Why only the Home tab looks broken
Every widget that used to live on a `CANVAS` tab carries its own gutter,
so losing the card padding costs them nothing:
| Widget | Own horizontal padding |
|---|---|
| Timeline | `spacing[6]` |
| Notes | `spacing[6]` |
| Files | `spacing[6]` |
| Tasks | `spacing[6]` |
| **Fields** | **none** |
`Fields` was the only widget on a `VERTICAL_LIST` tab, so it was the
only one relying on the card for its gutter, and the only one that ends
up flush.
## What
Resolve the surface first: a column surface (pinned panel, side panel,
mobile) is always a column of cards, whatever the tab presentation is.
Solo stays a main-tab-area concept.
Header visibility is untouched: `showHeader` keys off `presentation`,
not the variant, so a solo tab still shows no bare title row. The
`Fields` widget does not regain the header it lost in #23109.
## Measured
Side panel, custom object whose Home tab holds a single Fields widget
(1600x1000, panel at x=1200):
| | Card padding | First label x |
|---|---|---|
| main | `0px` | 1221 |
| this PR | `12px` | 1233 |
12px restored, matching what the pinned left panel gives the same
widget.
## Trade-off worth a second opinion
In the side panel and on mobile, the activity widgets now resolve to
`'side-column'` instead of `'solo'`, so they pick up the card's 12px on
top of their own 24px, i.e. 36px instead of 24px. Nothing overlaps or
clips, but it is a visible change on those tabs. If you would rather
keep them at 24px, the follow-up is to drop the intrinsic `spacing[6]`
from the activity cards and let the surface own the gutter everywhere.
## Test plan
- `getWidgetCardVariant` tests extended: `'side-column'` now wins over
`'solo'` for each of `isInPinnedTab` / `isMobile` / `isInSidePanel`. 13
tests pass.
- 88 suites / 620 tests across `page-layout/widgets` pass.
- `lint:diff-with-main twenty-front` clean.
- Verified against a local stack: side panel on a single-widget Home
tab, before and after.
Félix Malfait
3f0236b590