address PR comments

functions-v2/src/at-midnight.ts

@@ -8,7 +8,7 @@ import * as logger from "firebase-functions/logger";
 // type errors.
 import {cleanFirebaseRoots} from "../../shared/clean-firebase-roots";
 
-export const atMidnight = onSchedule("0 0 * * *", runAtMidnight);
+export const atMidnight = onSchedule("0 7 * * *", runAtMidnight);
 
 // This function is split out so it can be tested by Jest. The
 // firebase-functions-test library doesn't support wrapping onSchedule.

scripts/clean-firebase-roots.ts

@@ -1,11 +1,11 @@
 #!/usr/bin/node
 
-// This script finds documents without metadata in the realtime database.
-// If the deleteTypes array is uncommented, it will delete these documents.
+// This script cleans the roots out of the QA or Dev sections of
+// the Firebase Realtime database and Firestore.
 
 // to run this script type the following in the terminal
 // cf. https://stackoverflow.com/a/66626333/16328462
-// $ cd scripts/ai
+// $ cd scripts
 // $ npx tsx clean-firebase-roots.ts
 
 import admin from "firebase-admin";

shared/clean-firebase-roots.ts

@@ -24,7 +24,7 @@ export async function cleanFirebaseRoots(
     throw new Error(`Invalid appMode ${appMode}`);
   }
 
-  // Clean up Firestore and Realtime database roots that haven't been updated in a 6 hours
+  // Clean up Firestore and Realtime database roots that haven't been launched in `hoursAgo` hours
   const cutOffMillis = Date.now() - hoursAgo*HOUR;
   const qaRootsResult = await getFirestore()
     .collection(appMode)