feat(spec): page form filter-mode widget + ADR-0047 §3.4a (omit-is-none)

docs/adr/0047-object-ui-run-modes.md

@@ -153,6 +153,44 @@ have; we do not rely on lint to forbid what the type can simply not express.
 | User-created views | Allowed, governed by permissions + view `sharing` | Never |
 | Filter state | Session-scoped (URL-param sync is a later, orthogonal step) | Session-scoped |
 
+### 3.4a "No filter bar" is omission, not a literal `element: 'none'`
+
+Airtable's User-filters control is a single tri-state selector
+(**None / Tabs / Dropdown**). We deliberately do **not** mirror "none" as a
+literal enum value: **"none" is the ABSENCE of `userFilters`**.
+
+Rationale (declarative-metadata hygiene):
+
+- **Consistency.** Every optional capability in the protocol is "off = key
+  absent" (`kanban`, `grouping`, …). A literal `element: 'none'` would be the
+  one special case authors and tooling must learn.
+- **No dead config.** `element: 'none'` would leave an object whose `fields` /
+  `tabs` are orphaned — undefined semantics for validation, overlay merge, and
+  AI generation. Omission has one unambiguous meaning.
+- **Cleaner diffs / overlays.** Disabling the bar is a key deletion (ADR-0005
+  overlay semantics), not a value mutation dragging stale sub-config along.
+- **Orthogonal axes.** "Is there a filter bar?" (presence) and "what style?"
+  (`element`) are independent; one enum would couple them.
+
+**`toggle` is deprecated; authoring offers Airtable's three.** The `element`
+enum keeps `dropdown | tabs | toggle` for back-compat (existing configs keep
+rendering), but `toggle` is **not** an authoring choice: it overlaps `tabs`
+(presets) and `dropdown` (per-field values) without adding expressive power,
+needs per-field `defaultValues` to be useful at all, and was the least-
+exercised path. A homogeneous "everything is a toggle" bar only fits all-boolean
+field sets — a narrow case better served by letting field *type* drive the
+control inside `dropdown`. If stackable one-click quick-filters become a
+validated need, design them explicitly (à la Linear filter chips), not via the
+half-spec'd `toggle`.
+
+**Storage and authoring UI are separate layers.** The Studio editor exposes a
+first-class **None / Tabs / Dropdown** segmented selector (the `filter-mode`
+widget) — selecting *None* writes `onChange(undefined)`, removing the key.
+Authors get Airtable's explicit affordance; the protocol stays clean.
+
+If a "disable but remember the configured fields/tabs" need ever arises, the
+right shape is a separate `enabled: false` flag — never `element: 'none'`.
+
 ### 3.5 AI authoring rules (inherits ADR-0033's draft gate)
 
 1. **Default output**: objects + list views + navigation → objects. *No pages.*

packages/spec/src/ui/page.form.ts

@@ -50,7 +50,29 @@ export const pageForm = defineForm({
           field: 'interfaceConfig',
           type: 'composite',
           helpText:
-            'source/sourceView bind the object view (columns, base filter and sort are inherited — the iron rule); userFilters picks the element style (dropdown / tabs / toggle) and exposed fields; appearance.allowedVisualizations whitelists renderers (one entry = locked); userActions toggles the toolbar.',
+            'source/sourceView bind the object view (columns, base filter and sort are inherited — the iron rule); appearance.allowedVisualizations whitelists renderers (one entry = locked); userActions toggles the toolbar.',
+          // Explicit sub-fields so `userFilters` can use the dedicated
+          // filter-mode selector (None / Tabs / Dropdown, ADR-0047 §3.4a).
+          // None maps to ABSENCE of userFilters — the protocol stores
+          // "no filter bar" as omission, not a literal element: 'none'.
+          // (`element: 'toggle'` stays valid but deprecated — not offered.)
+          // Keep this list in sync with InterfacePageConfigSchema.
+          fields: [
+            { field: 'source' },
+            { field: 'sourceView' },
+            { field: 'levels' },
+            { field: 'filterBy', type: 'repeater' },
+            { field: 'appearance', type: 'composite' },
+            {
+              field: 'userFilters',
+              widget: 'filter-mode',
+              helpText: 'End-user filter bar: None (no bar) / Tabs (named presets) / Dropdown (per-field). None removes the config.',
+            },
+            { field: 'userActions', type: 'composite' },
+            { field: 'addRecord', type: 'composite' },
+            { field: 'showRecordCount' },
+            { field: 'allowPrinting' },
+          ],
         },
       ],
     },

packages/spec/src/ui/view.zod.ts

@@ -309,8 +309,13 @@ export const UserFilterFieldSchema = lazySchema(() => z.object({
  * @see Airtable Interface → "User filters" panel (Elements: tabs / dropdowns)
  */
 export const UserFiltersSchema = lazySchema(() => z.object({
+  // `toggle` is DEPRECATED (ADR-0047 §3.4a): it overlaps `tabs` (presets) and
+  // `dropdown` (per-field values) without adding expressive power, needs
+  // per-field defaultValues to be useful, and authoring tooling no longer
+  // offers it (None / Tabs / Dropdown only). Kept in the enum so existing
+  // configs keep rendering; do not author new `toggle` filters.
   element: z.enum(['dropdown', 'tabs', 'toggle']).default('dropdown')
-    .describe('Filter control style: dropdown selectors per field, tab presets, or on/off toggles'),
+    .describe('Filter control style: "dropdown" (per-field value selectors) or "tabs" (named presets). "toggle" is deprecated.'),
   fields: z.array(UserFilterFieldSchema).optional()
     .describe('Fields exposed as quick filters (dropdown/toggle elements)'),
   tabs: z.array(ViewTabSchema).optional()