Add incremental adapter compiler boundary

src/docforge/changesets.py

@@ -158,6 +158,33 @@ class ChangesetStore:
             },
         )
 
+    def propose_relationship_update(
+        self,
+        *,
+        changeset_id: str,
+        expected_changeset_hash: str,
+        node_id: str,
+        expected_content_hash: str,
+        relationship_changes: list[dict[str, Any]],
+        rationale: str,
+    ) -> dict[str, object]:
+        """Queue relationship-only changes against one exact existing node."""
+
+        if not relationship_changes:
+            raise DocForgeError(
+                "invalid_operation", "Relationship-only updates require at least one change"
+            )
+        return self.propose_update(
+            changeset_id=changeset_id,
+            expected_changeset_hash=expected_changeset_hash,
+            node_id=node_id,
+            expected_content_hash=expected_content_hash,
+            metadata=None,
+            content=None,
+            relationship_changes=relationship_changes,
+            rationale=rationale,
+        )
+
     def propose_delete(
         self,
         *,