fix(blocks): render the option label in a select trigger - #8

What does this PR do?

A Block Kit select rendered the raw option value in its closed trigger instead of the option's label, and rendered completely empty when the value was "", null or absent.

Root cause, in two halves:

• packages/blocks/src/elements/select.tsx passed the options only as Select.Option children — no items, placeholder or renderValue. Kumo 2.6 wraps Base UI 1.5 (not Radix), and Base UI's Select.Value only resolves a label when the root has items: without it, resolveSelectedLabel(value, undefined, undefined) falls through to serializeValue(value), i.e. the value itself.
• Base UI's store counts "" as "no value" (hasSelectedValue runs the value through serializeValue and compares to ""), so a select whose value was an empty string rendered a blank trigger. With no placeholder either, an unset value was blank too.

The fix:

• Pass the options as items as well. That is Base UI's documented mechanism — "When specified, <Select.Value> renders the label of the selected item instead of the raw value" — and it is what the admin's own DynamicSelect already does. items only feeds label resolution in the store; it does not touch selection semantics. The children still render the popup, so option order, keys and DOM are unchanged.
• Add an optional placeholder to SelectElement, mirroring Kumo's Select prop and the existing combobox / text_input / date_input fields (type, validation.ts, elements.select() builder, docs).
• Default that placeholder to the label of an option whose value is "", and otherwise to Select.... Because Base UI treats "" and "unset" as the same display state, they must share one string; the common { value: "", label: "All statuses" } filter entry is the author's own empty-state label, so it wins over an invented default. An explicit placeholder always wins over both.

Backward compatibility: display-only. Submitted values are untouched — including an empty-string option value, which is still selectable and still submits "" (verified by test and in the browser). A select that previously showed a blank trigger now shows a label or placeholder; nothing about the payload changes.

Scoped out, after checking: combobox already passes items and uses the option object as its value, so Base UI resolves value.label — verified rendering "Published" for value: "pub_1". radio has no selected-value display surface at all (every Radio.Item carries its own label), so the root cause cannot reach it. Neither needed a change.

Closes #

Type of change

• Bug fix
• Feature (requires maintainer-approved Discussion)
• Refactor (no behavior change)
• Translation
• Documentation
• Performance improvement
• Tests
• Chore (dependencies, CI, tooling)

Checklist

• I have read CONTRIBUTING.md
• pnpm typecheck passes
• pnpm lint passes (pnpm lint:json → 0 diagnostics)
• pnpm test passes (all packages; @emdash-cms/blocks 106 tests, @emdash-cms/admin 1249 tests)
• pnpm format has been run (oxfmt --check clean)
• I have added/updated tests for my changes (if applicable)
• User-visible strings in the admin UI are wrapped for translation — n/a: packages/blocks has no Lingui setup; the new default follows the neighbouring combobox's literal "Search...". Localising Block Kit element strings is a separate, package-wide change.
• I have added a changeset (if this PR changes a published package)
• New features link to an approved Discussion — n/a, bug fix. The added placeholder field is the additive minimum needed to fix the empty trigger.

AI-generated code disclosure

• This PR includes AI-generated code — model/tool: Claude Opus 5 (Claude Code)

Screenshots / test output

New suite packages/blocks/tests/select-element.test.tsx renders the real Kumo Select (no mock — a mocked Select cannot exhibit the bug). Against main 6 of its 9 tests fail; the 3 value-submission tests pass both before and after, which is the backward-compatibility check:

× renders the label of the selected option, not its value   → expected 'pub_1' to contain 'Published'
× renders the label of the option picked by the user        → expected 'dft_2' to contain 'Draft'
× renders a placeholder when nothing is selected            → expected '' to contain 'Any status'
× renders a default placeholder when the element has none   → expected '' to contain 'Select...'
× renders the label of an empty-value option ...            → expected '' to contain 'All statuses'
× prefers an explicit placeholder over an empty-value ...   → expected '' to contain 'Filter by status'
✓ submits the option value unchanged
✓ submits an empty-string option value unchanged
✓ reports the value through onAction when no onChange is given

After the fix, all 9 pass (pnpm --filter @emdash-cms/blocks test: 4 files, 106 tests).

Also exercised in a real browser (Chromium, blocks playground). Trigger text vs. the value in the hidden form input:

The existing SEO template's select in the playground shows None (extractive) where it previously showed none.