feat(base): enforce unique property names per base

apps/client/src/features/base/components/formula/formula-editor.tsx

@@ -25,6 +25,7 @@ type Props = {
   editingPropertyId: string | null;
   initialSource?: string;
   name?: string;
+  disabled?: boolean;
   onSave: (
     source: string,
     ast: unknown,
@@ -39,6 +40,7 @@ export function FormulaEditor({
   editingPropertyId,
   initialSource = "",
   name,
+  disabled = false,
   onSave,
   onCancel,
 }: Props) {
@@ -49,7 +51,7 @@ export function FormulaEditor({
     editingPropertyId,
     registry,
   );
-  const canSave = parseState.state === "ok";
+  const canSave = parseState.state === "ok" && !disabled;
   const insertAtEnd = (snippet: string) =>
     setSource((s) => `${s}${s ? " " : ""}${snippet}`);
 

apps/client/src/features/base/components/property/create-property-popover.tsx

@@ -66,6 +66,14 @@ export function CreatePropertyPopover({ baseId, properties, onPropertyCreated }:
     return name.trim().length > 0 || Object.keys(typeOptions).length > 0;
   }, [name, typeOptions]);
 
+  const nameTaken = useMemo(() => {
+    const trimmed = name.trim().toLowerCase();
+    if (!trimmed) return false;
+    return (properties ?? []).some(
+      (p) => p.name.trim().toLowerCase() === trimmed,
+    );
+  }, [name, properties]);
+
   const resetState = useCallback(() => {
     setPanel("typePicker");
     setSelectedType(null);
@@ -112,7 +120,7 @@ export function CreatePropertyPopover({ baseId, properties, onPropertyCreated }:
   }, [panel]);
 
   const handleCreate = useCallback(() => {
-    if (!selectedType) return;
+    if (!selectedType || nameTaken) return;
     const finalName = name.trim() || selectedTypeLabel;
     createPropertyMutation.mutate(
       {
@@ -130,7 +138,7 @@ export function CreatePropertyPopover({ baseId, properties, onPropertyCreated }:
       },
     );
     handleClose();
-  }, [selectedType, name, selectedTypeLabel, typeOptions, baseId, createPropertyMutation, handleClose, onPropertyCreated]);
+  }, [selectedType, nameTaken, name, selectedTypeLabel, typeOptions, baseId, createPropertyMutation, handleClose, onPropertyCreated]);
 
   const handleBackToTypePicker = useCallback(() => {
     setPanel("typePicker");
@@ -242,13 +250,16 @@ export function CreatePropertyPopover({ baseId, properties, onPropertyCreated }:
                 placeholder={selectedTypeLabel}
                 value={name}
                 onChange={(e) => setName(e.currentTarget.value)}
+                error={nameTaken ? t("A property with this name already exists") : undefined}
               />
               <FormulaEditor
                 properties={properties ?? []}
                 editingPropertyId={null}
                 name={name.trim() || undefined}
                 onCancel={handleBackToTypePicker}
+                disabled={nameTaken}
                 onSave={(source, ast, resultType, dependencies) => {
+                  if (nameTaken) return;
                   createPropertyMutation.mutate(
                     {
                       baseId,
@@ -279,6 +290,7 @@ export function CreatePropertyPopover({ baseId, properties, onPropertyCreated }:
                 value={name}
                 onChange={(e) => setName(e.currentTarget.value)}
                 onKeyDown={handleNameKeyDown}
+                error={nameTaken ? t("A property with this name already exists") : undefined}
                 mb="xs"
               />
               <UnstyledButton
@@ -316,7 +328,7 @@ export function CreatePropertyPopover({ baseId, properties, onPropertyCreated }:
                 <Button variant="default" size="xs" onClick={attemptClose}>
                   {t("Cancel")}
                 </Button>
-                <Button size="xs" onClick={handleCreate}>
+                <Button size="xs" onClick={handleCreate} disabled={nameTaken}>
                   {t("Create field")}
                 </Button>
               </Group>

apps/server/src/core/base/services/base-property.service.ts

@@ -88,6 +88,8 @@ export class BasePropertyService {
   async create(workspaceId: string, dto: CreatePropertyDto, actorId?: string) {
     const type = dto.type as BasePropertyTypeValue;
 
+    await this.ensureNameUnique(dto.baseId, dto.name);
+
     let validatedTypeOptions: unknown;
     if (type === 'formula') {
       const sourceCandidate = (dto.typeOptions as any)?.source;
@@ -192,6 +194,10 @@ export class BasePropertyService {
       throw new BadRequestException('Property does not belong to this base');
     }
 
+    if (dto.name !== undefined) {
+      await this.ensureNameUnique(dto.baseId, dto.name, dto.propertyId);
+    }
+
     // Block concurrent type changes — the worker still owns the previous
     // conversion, and letting a second one through would race on `type`.
     if (property.pendingType) {
@@ -418,6 +424,27 @@ export class BasePropertyService {
    * has to happen after the outer transaction commits so socket consumers
    * never race ahead of visibility.
    */
+  private async ensureNameUnique(
+    baseId: string,
+    candidate: string,
+    excludePropertyId?: string,
+  ): Promise<void> {
+    const trimmed = candidate.trim();
+    if (!trimmed) return;
+    const existing = await this.basePropertyRepo.findByBaseId(baseId);
+    const lower = trimmed.toLowerCase();
+    const clash = existing.find(
+      (p) =>
+        p.id !== excludePropertyId &&
+        p.name.trim().toLowerCase() === lower,
+    );
+    if (clash) {
+      throw new BadRequestException(
+        `A property named "${trimmed}" already exists in this base`,
+      );
+    }
+  }
+
   private async loadAndEmit(
     dto: UpdatePropertyDto,
     workspaceId: string,

apps/server/src/database/migrations/20260424T120000-base-properties-name-unique.ts

@@ -0,0 +1,20 @@
+import { type Kysely, sql } from "kysely";
+
+/*
+ * Enforce one property name per base (case-insensitive, excluding soft-deleted).
+ * Formulas reference properties by name via `prop("Name")`, and the resolver
+ * builds a `Map<name, id>` — duplicates would silently clobber and make
+ * references non-deterministic. Belt-and-suspenders against races that slip
+ * past service-layer validation.
+ */
+export async function up(db: Kysely<any>): Promise<void> {
+  await sql`
+    CREATE UNIQUE INDEX base_properties_name_unique
+    ON base_properties (base_id, lower(name))
+    WHERE deleted_at IS NULL
+  `.execute(db);
+}
+
+export async function down(db: Kysely<any>): Promise<void> {
+  await sql`DROP INDEX IF EXISTS base_properties_name_unique`.execute(db);
+}