fix: expose project index payload

Sync GitHub commit 2192785; ProjectIndex retains the validated payload for incremental dashboard refresh reuse.

hackathon_advisor/data.py

@@ -355,6 +355,7 @@ class ProjectIndex:
         self.index_generated_at = str(index_payload["generated_at"])
         self.index_algorithm = str(index_payload["algorithm"])
         self.snapshot_digest = str(index_payload["snapshot_digest"])
+        self.index_payload = index_payload
         self.embedding_metadata = dict(index_payload["embedding"])
         self.embedding_dimensions = int(self.embedding_metadata["dimensions"])
         self._query_embedder = query_embedder

tests/test_data.py

@@ -121,3 +121,11 @@ def test_project_index_rejects_mismatched_snapshot(tmp_path: Path) -> None:
         assert "different snapshot timestamp" in str(error)
     else:
         raise AssertionError("mismatched index should be rejected")
+
+
+def test_project_index_retains_validated_payload() -> None:
+    payload = json.loads(Path("data/project_index.json").read_text(encoding="utf-8"))
+    index = ProjectIndex.from_files(Path("data/projects.json"), Path("data/project_index.json"))
+
+    assert index.index_payload["snapshot_digest"] == payload["snapshot_digest"]
+    assert len(index.index_payload["documents"]) == len(index.projects)