diff --git a/.changeset/tombstone-citation-unwritten-decision.md b/.changeset/tombstone-citation-unwritten-decision.md
new file mode 100644
index 0000000000..3315d59611
--- /dev/null
+++ b/.changeset/tombstone-citation-unwritten-decision.md
@@ -0,0 +1,5 @@
+---
+'@objectstack/spec': patch
+---
+
+The `namespace` tombstone's rejection message no longer cites "ADR-0006 D4" — a decision letter no version of ADR-0006 declares. The retirement itself is unchanged and still enforced; the message keeps the fix (`name: "sys_user"`) and the #4001 parse-path history. The letter citation comes back when the retirement decision is actually written into an ADR.
diff --git a/packages/spec/src/data/object.zod.ts b/packages/spec/src/data/object.zod.ts
index 29ff73b851..b0531e63e1 100644
--- a/packages/spec/src/data/object.zod.ts
+++ b/packages/spec/src/data/object.zod.ts
@@ -1464,7 +1464,7 @@ const UNKNOWN_KEY_GUIDANCE: Record<string, string> = {
   // Tombstones age out too: drop an entry ~two majors after the removal
   // (by then it's archaeology, not an upgrade; see CHANGELOG.md for history).
   namespace:
-    '`namespace` was retired in ADR-0006 D4 — the object `name` IS the canonical id ' +
+    '`namespace` was retired — the object `name` IS the canonical id ' +
     'everywhere (API, ObjectQL, REST, SDK, DB table), so there is no separate namespace ' +
     'to declare. Embed the module prefix in the name instead: `namespace: "sys", ' +
     'name: "user"` becomes `name: "sys_user"`. Until #4001 closed this shape on the ' +