feat: persist participant-scoped proposal recovery

server/api/store_adapters_test.go

@@ -15,3 +15,13 @@ func TestAssignmentProviderFromStorePreservesPlayerScopedRecoveryBoundary(t *tes
 		t.Fatal("nil store was treated as an available assignment source")
 	}
 }
+
+func TestProposalProviderFromStoreFailsClosedWithoutDatabase(t *testing.T) {
+	provider := ProposalProviderFromStore(nil)
+	if provider == nil {
+		t.Fatal("proposal store provider was not created")
+	}
+	if _, err := provider.Get(context.Background(), "player-1", "proposal-1", time.Unix(1000, 0)); err == nil {
+		t.Fatal("nil store was treated as an available proposal source")
+	}
+}