Prove exact migration from tagged v1 state

tests/test_milestone5_migration.py

@@ -0,0 +1,31 @@
+from __future__ import annotations
+
+import unittest
+
+from tools.milestone5_migration import build_migration_evidence
+
+
+class Milestone5MigrationTests(unittest.TestCase):
+    def test_actual_v1_project_index_and_proposal_migrate_exactly(self) -> None:
+        evidence = build_migration_evidence()
+
+        self.assertEqual("v1.0.0", evidence["tag"])
+        self.assertEqual("1.4.0", evidence["current"]["version"])
+        self.assertEqual(1, evidence["current"]["index_schema_before"])
+        self.assertEqual(3, evidence["current"]["index_schema_after"])
+        self.assertEqual(
+            {
+                "canonical_bytes_preserved": True,
+                "graph_preserved": True,
+                "proposal_preserved": True,
+                "legacy_index_rebuilt": True,
+                "cli_superset": True,
+                "mcp_superset": True,
+                "v1_version_mismatch_recorded": True,
+            },
+            evidence["proofs"],
+        )
+
+
+if __name__ == "__main__":
+    unittest.main()