Productizes the event-driven cascade on a real component (not the explicit
`<Cascade>` orchestrator). When a DropdownMenu opens, its items fade in
staggered by structural order — the appearance flows from the `open` (emerge)
event, nothing in the app wires it.
Architecture: a +1 GENERIC selector branch in the motion generator, NOT a
per-item `data-state`. A `menuitem` isn't open/closed — the menu is — and eidos
writing a state attr is a smell. The new container-driven form
`[data-stagger][data-state='open'] > [data-animation-style='X']` fires each
child's ENTER off the container's `data-state` (which soma already writes via
the morfo `commits`); items carry only `data-animation-style`. ENTER only: the
coordinated EXIT cascade (retain the container until children finish) is the
deferred soma PresenceGroup work, so a closing container can't drive a child
exit that would be cut off on unmount.
- render-css.ts: `renderCssPresetRules` adds the container-driven enter branch
(same declarations, shared comma selector) — reuses the existing presets +
the foundation `:nth-child` stagger index; zero new system.
- DropdownMenu: Content marks itself `[data-stagger]` +
`--motion-stagger-each: var(--motion-stagger)` (20ms, themeable, no magic
number); item/checkbox-item/radio-item carry `data-animation-style="fade"`
(overridable). `fade` so item opacity doesn't fight the panel's own scale.
- regen generated/base.css (8 css presets gain the container-driven enter).
Verified in browser (frozen frame): index from `:nth-child`, `delay = idx ×
each`, opacity gradient in flight (Ruler 0.98 → Grid 0.89 → Guides 0.69, Log
out 0.00). Honest limit (documented): only DIRECT-child items cascade — items in
a <Group>/<RadioGroup> DOM wrapper aren't `:nth-child` of the panel, so they
appear instantly (the "transparent intermediate").
Docs: dropdown README §Motion, cascade README §2 (concrete consumer), RFC §D.11.4.
Co-Authored-By: Claude Opus 4.8 (1M context) <noreply@anthropic.com>
Soma's MenuCheckboxItem / MenuRadioItem default `closeOnSelect=true`
(matches Radix Primitives), but for toggle-state items that's the
wrong UX default — the user wants to flip multiple checkboxes or
switch a radio choice without re-opening the menu each time.
Override the default in the eidos wrappers for both DropdownMenu and
ContextMenu (4 components total: CheckboxItem + RadioItem in each).
Activating Item (plain command) still closes by default; only the
state-toggle parts stay open.
Consumers who genuinely want close-on-toggle can pass
`closeOnSelect={true}` explicitly.
Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>
dev