diff --git a/modules/modes/HeightTransferMode.js b/modules/modes/HeightTransferMode.js
index e2b8cfaf1..15e3a4cca 100644
--- a/modules/modes/HeightTransferMode.js
+++ b/modules/modes/HeightTransferMode.js
@@ -197,13 +197,24 @@ export class HeightTransferMode extends AbstractSystem {
     // plateauID once committed) and calling `_recompute()` -- which re-runs `findCandidates()`
     // (already excludes this candidate, since `findCandidates` filters against `transferredIDs`)
     // and emits 'change'. That means there's no need for a second manual emit here.
+    // The changeset `source` is assembled from the `dataUsed` on each edit's
+    // annotation (see `EditSystem#_gatherSources`). Without it the transfer
+    // records no provenance at all -- no `MLIT_PLATEAU`, no `RapiD_Plateau_JP`,
+    // no `source_ref` -- while accepting a building records all three.
+    // Same lookup the accept path uses in `UiRapidInspector`.
+    const rapid = this.context.systems.rapid;
+    const datasetID = (candidate.plateauFeature.__datasetid__ ?? 'plateauJapan')
+      .replace('-conflated', '');
+    const dataset = rapid?.datasets?.get(datasetID);
+
     const action = actionTransferPlateauTags(candidate.osmFeature.id, tagsToAdd);
     editor.perform(action);
     editor.commit({
       annotation: {
         type: action.actionName,
         plateauID: candidate.plateauFeature.id,
-        entityID: candidate.osmFeature.id
+        entityID: candidate.osmFeature.id,
+        dataUsed: dataset?.dataUsed || [datasetID]
       },
       selectedIDs: [ candidate.osmFeature.id ]
     });
diff --git a/test/browser/modes/HeightTransferMode.test.js b/test/browser/modes/HeightTransferMode.test.js
index c95b7ef2a..8b3c6d368 100644
--- a/test/browser/modes/HeightTransferMode.test.js
+++ b/test/browser/modes/HeightTransferMode.test.js
@@ -326,6 +326,40 @@ describe('HeightTransferMode', () => {
   });
 
 
+  it('apply() records the dataset on the annotation so the changeset gets a source', () => {
+    // Rapid#45: 建物を追加する経路は annotation に dataUsed を付けるが、タグ転記の
+    // 経路は付けていなかった。変更セットの source は EditSystem がこの値から
+    // 組み立てるので、無いと MLIT_PLATEAU も RapiD_Plateau_JP も source_ref も付かない。
+    const context = makeContext();
+    context.systems.rapid.datasets = new Map([
+      ['plateauJapan', { id: 'plateauJapan', dataUsed: ['osmf.jp', 'Plateau Buildings'] }]
+    ]);
+    const mode = new Rapid.HeightTransferMode(context);
+    mode.activate();
+
+    mode.apply(makeCandidate({
+      plateauFeature: { id: 'p1', tags: { height: '12' }, __datasetid__: 'plateauJapan' }
+    }));
+
+    const annotation = context.systems.editor.commitCalls[0].annotation;
+    expect(annotation.dataUsed).to.eql(['osmf.jp', 'Plateau Buildings']);
+  });
+
+
+  it('apply() falls back to the dataset id when the catalog has no entry', () => {
+    const context = makeContext();
+    const mode = new Rapid.HeightTransferMode(context);
+    mode.activate();
+
+    mode.apply(makeCandidate({
+      plateauFeature: { id: 'p1', tags: { height: '12' }, __datasetid__: 'plateauJapan' }
+    }));
+
+    const annotation = context.systems.editor.commitCalls[0].annotation;
+    expect(annotation.dataUsed).to.eql(['plateauJapan']);
+  });
+
+
   it('apply() fires change exactly once per call', () => {
     const context = makeContext();
     const mode = new Rapid.HeightTransferMode(context);