Win back dormant app users with tailored push notifications

Every Monday at 10am, run a win-back campaign that wakes up my dormant app users without spamming them, using Firebase and Slack Bot. Use a cron trigger for this rather than a poll trigger: I am targeting an existing cohort of people who already went quiet, not reacting to new records as they arrive.

Start with the Firebase "Run Firestore Query" operation against my users collection to pull the dormant cohort. I want users whose last activity timestamp is fourteen or more days old, who still have push enabled, and who have a stored FCM device token. Firestore structured queries handle "this field is missing or older than X" conditions badly, so pull the dormant and opted-in set in the query itself, then filter out anyone contacted in the last thirty days after fetching, treating a missing last-contacted field as eligible.

Field names like lastActiveAt, fcmToken, notificationsEnabled and lastReengagedAt are illustrative. Call out clearly in the workflow where I need to map them to whatever my own schema actually calls these fields, so nobody assumes these names are magic.

Sort the returned users into a small number of behavioural segments based on what they last did in the app. Sensible starting segments are: signed up but never finished setup, was active for a while then went quiet, and left items in a cart without checking out. Include a fallback segment for anyone who does not fit cleanly. For each segment, write short tailored push copy that speaks to that specific behaviour instead of sending one generic blast to the whole cohort. Segmented, behaviour based notifications such as abandoned cart reminders and personalised offers consistently outperform generic sends, so this segmentation step is the core of the workflow and not a nice to have.

Send each message with the Firebase "Send Push Notification (FCM)" operation, addressed to that user's stored device token, carrying the copy written for their segment. Keep the title short and the body to roughly two lines so it reads well on a lock screen.

Handle token failures explicitly. FCM drops messages to devices it considers inactive, and on Android a registration that has been inactive for 270 days is expired and garbage collected, after which sends to it are rejected. When a send is rejected, do not fail the whole run: record the user and the failure reason, carry on with the rest of the cohort, and surface those stale registrations in the summary so they can be cleaned up. Reference: https://firebase.google.com/docs/cloud-messaging/manage-tokens

After each successful send, use the Firebase "Update Firestore Document" operation to patch that user's document with lastReengagedAt set to the current time and the segment they were placed in. Patch only those fields, do not overwrite the rest of the document. This stamp is the thing that stops anyone being pinged twice inside a month, so only write it for users who actually received a message, never for ones whose send failed.

Apply a sensible volume cap per run, defaulting to around 500 users, so a large dormant cohort does not turn into a mass blast in a single Monday. If the cohort is bigger than the cap, prioritise the most recently active users first and note the leftover count in the summary. Also respect quiet hours: let me configure a send window so notifications land during reasonable daytime hours rather than the middle of the night.

Never message anyone who has not opted in. Push consent is a legal requirement in many markets, so the notifications-enabled flag is a hard filter, and the workflow must never fall back to messaging users whose consent state is unknown or missing.

Finish with the Slack Bot "Send a Message" operation to post a summary in my growth channel. Cover how many users were reached per segment, the exact copy that went out for each segment, and every token that failed along with its reason so we can clean up stale registrations. If a run reaches nobody, post that too, so I can tell the difference between a quiet week and a broken workflow.