feat(twenty-front): relation traversal in filter dropdown (stacked) (#20533)

**Stacked on #20527** 




https://github.com/user-attachments/assets/48995655-401a-4c35-8094-e88da8408bdd





## Summary

Surfaces the one-hop relation traversal added in #20527 through the
existing **composite sub-field dropdown pattern**. Clicking a
MANY_TO_ONE relation field in the "+ Filter" picker now opens the same
second-level dropdown that composite fields (FULL_NAME, ADDRESS,
CURRENCY, etc.) already use — populated with the target object's
filterable fields. Picking one (e.g. `Company → Name`) builds a filter
that serializes to the nested GraphQL filter the backend now accepts: `{
company: { name: { ilike: "%X%" } } }`.

No new components. The whole feature reuses
`AdvancedFilterSubFieldSelectMenu` + the existing
`subFieldNameUsedInDropdownComponentState` + the existing `MenuItem
hasSubMenu` indicator. Only the conditions that gate the sub-menu (and
the sub-menu's content for relations) were broadened.

## What landed

| File | Change |
|---|---|
| `ObjectFilterDropdownFilterSelectMenuItem` | Sub-menu chevron now
shows on MANY_TO_ONE relations (`isManyToOneRelationField` util). |
| `AdvancedFilterFieldSelectMenu` | Relation clicks open the sub-menu
alongside composite clicks. |
| `AdvancedFilterSubFieldSelectMenu` | New branch: when the sub-menu
type is `'RELATION'`, render the target object's filterable fields via
`useFilterableFieldMetadataItems(targetObjectMetadataId)`. Composite
logic untouched. |
| `objectFilterDropdownSubMenuFieldType` state | Widened to accept a
`'RELATION'` sentinel. Role-permissions sub-field menu narrows it back
out (it doesn't traverse relations). |
| `useSelectFieldUsedInAdvancedFilterDropdown` | New optional
`targetFieldMetadataItem` arg. When present, the stored RecordFilter's
`type` is the target field's type so the operand picker and value input
render the target's operands (`'TEXT'` operators when filtering
`company.name`, etc.). |
| `turnRecordFilterIntoGqlOperationFilter` (shared) | When the filter
targets a `RELATION` field with a `subFieldName`, synthesize a
field-metadata for the target, recurse to build the inner filter, then
wrap it under the relation field's name → `{ relationName: {
targetFieldName: { ...operator } } }`. |

`RecordFilter.subFieldName` stays narrowly typed as
`CompositeFieldSubFieldName` so the wide downstream consumers
(`shouldShowFilterTextInput`, composite handlers in the serializer,
etc.) don't change. The relation target field's name is stored through a
narrowly-scoped cast at the dropdown's storage point — the serializer
checks `filter.type === 'RELATION'` before interpreting it as a target
field name, so the cast can't be mis-read by composite-only code paths.

## Test plan

- [ ] Open a table view on People, click "+ Filter", click "Company" →
sub-menu opens with Company's filterable fields
- [ ] Pick "Name" → operand picker shows TEXT operators (Contains,
Equals, …)
- [ ] Type "Airbnb" → filter applies, table shows people whose company
name contains "Airbnb"
- [ ] Verify network tab: the GraphQL filter variable is `{ company: {
name: { ilike: "%Airbnb%" } } }`
- [ ] Same flow with a composite target field (e.g. `Company →
annualRecurringRevenue → amountMicros`) — should work end-to-end
(backend supports composite-within-relation; #20527 has an integration
test covering this)
- [ ] Composite fields (FULL_NAME, ADDRESS) still open their normal
sub-menu and filter correctly — no regression
- [ ] Role-permissions field-select sub-field menu is unaffected (it
bails out early on the RELATION sentinel)

## Out of scope

- ONE_TO_MANY traversal (no backend support yet)
- Aggregates (`people.count > 5`)
- Persisting relation-traversal filters into a saved view (ViewFilter
has no `relationPath` column yet; that's a separate slice)
- REST API DSL changes
- AI Tools

🤖 Generated with [Claude Code](https://claude.com/claude-code)

---------

Co-authored-by: Claude Opus 4.7 <noreply@anthropic.com>

packages/twenty-server/src/engine/api/common/common-query-runners/common-group-by-query-runner.service.ts

@@ -231,6 +231,8 @@ export class CommonGroupByQueryRunnerService extends CommonBaseQueryRunnerServic
         recordFilterGroupId: viewFilter.viewFilterGroupId,
         positionInRecordFilterGroup: viewFilter.positionInViewFilterGroup,
         subFieldName: viewFilter.subFieldName as CompositeFieldSubFieldName,
+        relationTargetFieldMetadataId:
+          viewFilter.relationTargetFieldMetadataId ?? null,
       };
     });
 
@@ -254,6 +256,33 @@ export class CommonGroupByQueryRunnerService extends CommonBaseQueryRunnerServic
       options: field.options as PartialFieldMetadataItemOption[],
     }));
 
+    // Relation-traversal filters reference target fields on related objects
+    // that aren't in the source object's field list above. Resolve and add
+    // them so the shared dispatcher can look them up by id.
+    const relationTargetFieldsFromFilters = recordFilters
+      .map((filter) => filter.relationTargetFieldMetadataId)
+      .filter(isDefined)
+      .filter((id) => !fields.some((field) => field.id === id))
+      .map((id) => {
+        const field = findFlatEntityByIdInFlatEntityMaps({
+          flatEntityId: id,
+          flatEntityMaps: flatFieldMetadataMaps,
+        });
+
+        if (!field) return null;
+
+        return {
+          id: field.id,
+          name: field.name,
+          type: field.type,
+          label: field.label,
+          options: field.options as PartialFieldMetadataItemOption[],
+        };
+      })
+      .filter(isDefined);
+
+    fields.push(...relationTargetFieldsFromFilters);
+
     const filtersFromView = computeRecordGqlOperationFilter({
       recordFilters,
       recordFilterGroups: recordFilterGroups,