diff --git a/reme/steps/index/reindex.py b/reme/steps/index/reindex.py
index 6ba44655..acbc9d83 100644
--- a/reme/steps/index/reindex.py
+++ b/reme/steps/index/reindex.py
@@ -4,6 +4,24 @@ from ..base_step import BaseStep
 from ...components import R
 
 
+def _render_reindex(details: dict) -> str:
+    """Render the store's reindex report as one readable summary line.
+
+    ReMe Studio's settings panel shows ``response.answer`` when it is a string
+    and otherwise falls back to a generic "index rebuilt" message
+    (``reme_studio/app/settings-center.tsx``). Returning the report dict as the
+    answer left that branch unreachable, so the operator never learned what was
+    actually rebuilt. The report itself stays in ``metadata`` for programmatic
+    consumers.
+    """
+    scope = str(details.get("scope") or "all")
+    per_scope = {name: entry for name, entry in details.items() if isinstance(entry, dict)}
+    if per_scope:
+        counts = ", ".join(f"{name}={entry.get('indexed', 0)}" for name, entry in per_scope.items())
+        return f"Reindexed scope={scope}: {counts}"
+    return f"Reindexed scope={scope}: {details.get('indexed', 0)} indexed"
+
+
 @R.register("reindex_step")
 class ReindexStep(BaseStep):
     """Rebuild BM25, embeddings, and/or tags without scanning workspace files."""
@@ -13,7 +31,7 @@ class ReindexStep(BaseStep):
         scope = str(self.context.get("scope", "all"))
         details = await self.file_store.reindex(scope)
 
-        self.context.response.answer = details
+        self.context.response.answer = _render_reindex(details)
         self.context.response.metadata.update(details)
         self.context.response.metadata["scope"] = scope
         return self.context.response
diff --git a/tests/unit/test_reindex.py b/tests/unit/test_reindex.py
index 64bd1a43..b0a350ed 100644
--- a/tests/unit/test_reindex.py
+++ b/tests/unit/test_reindex.py
@@ -23,6 +23,7 @@ async def test_reindex_step_delegates_scope(scope):
     store.reindex.assert_awaited_once_with(scope)
     store.clear.assert_not_called()
     assert response.metadata == {"indexed": 3, "scope": scope}
+    assert response.answer == f"Reindexed scope={scope}: 3 indexed"
 
 
 @pytest.mark.asyncio
@@ -41,6 +42,33 @@ async def test_reindex_step_delegates_all_once():
 
     store.reindex.assert_awaited_once_with("all")
     assert response.metadata == details
+    assert response.answer == "Reindexed scope=all: bm25=3, embedding=3, tag=3"
+
+
+@pytest.mark.asyncio
+async def test_reindex_answer_is_a_readable_summary_of_the_report():
+    """The answer is a string, so Studio shows it instead of a generic message.
+
+    ReMe Studio only displays ``response.answer`` when it is a string
+    (``reme_studio/app/settings-center.tsx``); a dict answer silently fell back
+    to the generic "index rebuilt" text and the operator never saw the counts.
+    The full report stays in metadata either way.
+    """
+    store = LocalFileStore(name="test_reindex_answer", embedding_store="")
+    store.reindex = AsyncMock(
+        return_value={
+            "scope": "all",
+            "bm25": {"scope": "bm25", "indexed": 7},
+            "embedding": {"scope": "embedding", "indexed": 5},
+            "tag": {"scope": "tag", "indexed": 2},
+        },
+    )
+
+    response = await ReindexStep(file_store=store)(RuntimeContext(scope="all"))
+
+    assert isinstance(response.answer, str)
+    assert response.answer == "Reindexed scope=all: bm25=7, embedding=5, tag=2"
+    assert response.metadata["bm25"] == {"scope": "bm25", "indexed": 7}
 
 
 def test_reindex_job_schema_exposes_tag_scope():