Ghost Note – Ephemeral Location-Based Messaging

Ghost Note is a mobile app that lets users drop anonymous text notes at any GPS coordinate. Anyone within 50 meters can see and reply to notes left in that spot. Each note has a 24-hour lifespan; after that, it self-destructs. Think of it as a temporary, location-based anonymous forum. The vision is to create spontaneous, hyper-local conversations that don't clutter the internet forever. The app would be built entirely over a single weekend, using Firebase for backend (real-time database, authentication, cloud functions), React Native for a cross-platform mobile app, and Mapbox for map rendering. The core feature is simple: open map, tap to place a pin, type a message, submit. Nearby users see pins within their radius. Tap a pin to view and reply. All notes auto-delete after 24 hours. Moderation is minimal due to ephemerality, but users can report abusive notes which get removed immediately. The entire codebase would be under 2000 lines of code, emphasizing simplicity and speed.

Public spaces are increasingly silent. People pass each other without connection. Online conversations are permanent and detached from place. Ghost Note scratches the itch of leaving a temporary digital trace in a physical location, like a digital version of 'I was here' or a secret note under a rock. It also serves as a tool for activists, artists, or just curious souls to create fleeting pop-up conversations.

• Enable anonymous note dropping at any location.
• Notes last exactly 24 hours, then auto-delete.
• Real-time push notifications for replies.
• Simple, intuitive map interface.
• Moderation via reporting.
• Build everything in one weekend (Saturday 8am to Sunday 11pm).

• No user profiles or persistent identity.
• No photo or video uploads (text only).
• No public feed or friend system.
• No saving or archiving notes.
• No web or desktop client.
• No complex spam filtering beyond reports.
• No offline mode.

React Native (Expo) for mobile app, Firebase Firestore for real-time database, Firebase Cloud Functions for scheduled note deletion (cron), Firebase Anonymous Auth, Mapbox GL JS via @mapbox/react-native-mapbox-gl, and Expo Location. All deployed via Expo EAS.

Client app shows a map centered on user location. On tap, a modal opens to write a note (max 500 chars) and submit. Note document stored in Firestore with fields: location (geopoint), text, timestamp, reportCount. Cloud function runs every hour querying notes older than 23h and deletes them. Client uses GeoQueries to fetch notes within 50m radius. Replies are stored as subcollections under each note. Real-time listeners update pins on map. Anonymous auth via Firebase Anonymous sign-in generates a temporary unique ID for reply attribution (not persistent). No profile sync.

• Abuse: anonymous nature could lead to harassment. Mitigated by reporting and auto-deletion.
• Data privacy: location data stored even if note is deleted? Cloud function ensures entire document deletion.
• Performance: GeoQueries might be slow with many notes. Firestore's geohash indexing helps.
• Weekend timeline: might be too ambitious for two days. Prioritize core feature; leave advanced moderation and push notifications for later.

• Should we allow image attachments via a text-to-image link? (Decision: No, text only for simplicity.)
• How to handle overlapping high-density areas (concerts, protests)? Notes could pile up. Limit one note per user per location? Or just let them accumulate.
• Should we implement a 'note radius' slider? (No, fixed 50m.)
• How to handle spam without user accounts? (Rate limiting per device ID from Expo's Constants.)

The plan was solid, but after sketching the architecture, I realized the weekend would be too tight even for a prototype. Life got busy, and the idea simmered. Later, similar apps like 'Jodel' (though not ephemeral) showed up, and the motivation faded. It remains a neat 'what if' – a tiny, respectful ghost of a project.

This project was intentionally designed for a single weekend build, imposing constraints that forced ruthless prioritization. The diversity angle of 'built in a weekend' was embedded from the start – the entire plan is structured around that driving constraint.