diff --git a/.changeset/master-detail-field-tombstone-4811.md b/.changeset/master-detail-field-tombstone-4811.md
new file mode 100644
index 000000000..853c188dc
--- /dev/null
+++ b/.changeset/master-detail-field-tombstone-4811.md
@@ -0,0 +1,9 @@
+---
+---
+
+Comment-only: `MasterDetailField` (`packages/fields/src/widgets/MasterDetailField.tsx`)
+gains a header tombstone recording that it is absent from `fieldWidgetMap`, unreachable
+from any form path (`master_detail` deliberately resolves to `LookupField`), and that its
+only in-repo consumer is its own test — so future `widgets/**` audits (the #3291 / #3318 /
+#4788 class) skip this file instead of re-discovering and re-investigating it each time
+(objectui#4811). No behaviour, export, or public API changes.
diff --git a/packages/fields/src/widgets/MasterDetailField.tsx b/packages/fields/src/widgets/MasterDetailField.tsx
index 16175a6f9..73258aee0 100644
--- a/packages/fields/src/widgets/MasterDetailField.tsx
+++ b/packages/fields/src/widgets/MasterDetailField.tsx
@@ -3,6 +3,21 @@ import { Button, Badge, cn } from '@object-ui/components';
 import { Plus, X, ExternalLink } from 'lucide-react';
 import { FieldWidgetComponentProps } from './types';
 
+// TOMBSTONE (objectui#4811): this widget is NOT in `fieldWidgetMap`
+// (packages/fields/src/index.tsx) and is unreachable from any form path —
+// `registerField`/`registerAllFields` only walk `fieldWidgetMap`'s keys, and
+// the `master_detail` key there deliberately resolves to `LookupField`, not
+// this component (see the comment above that map entry: the child-side FK
+// must render as a single-value lookup picker, not the one-to-many list this
+// widget models). Its only in-repo consumer is its own test
+// (complex-widgets.test.tsx), which renders it directly and proves nothing
+// about form reachability. It remains solely because its named export
+// (`export * from './widgets/MasterDetailField'` in index.tsx) is a public
+// API surface, and removing it is a breaking change left to the maintainer
+// (see #4811). Auditors of `widgets/**` (the #3291 / #3318 / #4788 class of
+// sweep): skip this file — it is a known, deliberate orphan, not a gap in
+// your coverage.
+
 /**
  * Master-Detail relationship data structure
  */