# "Proximity" — A Near-Field Social Connection App
## Product Proposal & iOS Technical Design Specification

---

## 1. Executive Summary

**Proximity** is an iOS application that reimagines social networking around *physical presence* rather than *online profiles*. The core premise: technology has made us hyper-visible to institutions (AirTags, Flock cameras, location tracking) while simultaneously making us invisible to each other. Proximity inverts this — it uses the same proximity-sensing hardware to let strangers in the real world acknowledge each other as human beings.

The defining constraint, and the product's soul: **you cannot connect with someone unless you are physically near them.** There is no global search, no "add by username," no online-only discovery. The network graph grows only through real-world encounters.

---

## 2. Problem Statement

| The Problem | The Evidence |
|---|---|
| Urban isolation | People pass thousands of strangers daily without interaction |
| Asymmetric surveillance | We're tracked by cameras and tags, but never "seen" by each other |
| Parasocial networking | Online platforms connect us to people we never meet, while eroding local community |
| Attention economy | Apps optimize for time-on-screen, not real-world connection |

**The insight:** The *same* hardware stack used to surveil us (UWB, BLE beacons, geolocation) can be repurposed for *mutual, consented, human connection*.

---

## 3. Product Vision

> *"A social network you can only enter by being physically present. Every connection is a real-world encounter. The map is your neighborhood, not the internet."*

**Core loop:**
1. **Opt in** — You signal "I'm open to connection" (a digital handshake-ready state).
2. **Encounter** — You pass someone nearby who has also opted in.
3. **Handshake** — Devices exchange anonymous tokens via proximity hardware.
4. **Grow the network** — The encounter becomes a "possible connection" in your graph.
5. **Optional reveal** — Either party can choose to reveal identity and start a conversation.

---

## 4. How It Works (Product Behavior)

### 4.1 Distance Tiers
Proximity operates across a spectrum of physical range, each using different technology:

| Tier | Range | Technology | Use Case |
|---|---|---|---|
| **Tier 1 — "Right here"** | 0–9 m | UWB (Nearby Interaction) | Precise, directional handshake — "this exact person" |
| **Tier 2 — "Nearby"** | 10–100 m | BLE / iBeacon | Room, cafe, street-corner presence |
| **Tier 3 — "In the area"** | 100 m–50 mi | Server + opt-in location | Regional community graph, events, neighborhoods |

### 4.2 The Encounter Flow
1. Both users have **"Open to Connect"** toggled on.
2. As they approach, devices exchange **ephemeral anonymous tokens** (no names, no photos, no personal data).
3. A subtle, non-intrusive notification: *"You passed 3 people who are open to connection."*
4. The encounter is stored as a **"Possible Connection"** — a silhouette, not a profile.
5. If both parties **mutually** choose to "wave," identities are revealed and a chat opens.

### 4.3 Anti-Harassment & Consent
- **Mutual opt-in required** for any reveal. No unilateral contact.
- **Silhouette-only** until mutual consent.
- **Block/ignore** removes you from the graph permanently.
- **Incognito mode** — be present but invisible.

---

## 5. Technical Architecture

### 5.1 The Honest Constraint (Important)
iOS imposes hard limits on background proximity sensing. A naive "always-on background scanner" is **not possible** on iOS. The design must work *with* the platform:

| Framework | Foreground | Background | Notes |
|---|---|---|---|
| **Core NFC** | ✅ Read/write NDEF tags | ❌ No background reading; no card emulation | Requires user-initiated tap; short range (~4 cm) |
| **Nearby Interaction (UWB)** | ✅ Precise ranging (~9 m) | ❌ Not available in background | Requires U1/U2 chip (iPhone 11+) |
| **Core Bluetooth** | ✅ Advertise + scan | ⚠️ Severely restricted; ~1 advertisement | Background scanning unreliable |
| **Core Location (iBeacon)** | ✅ | ✅ Region monitoring works in background | The *only* reliable background mechanism |

**Architectural conclusion:** Use a **hybrid, foreground-first** model where the phone is the active "handshake device," supplemented by **iBeacon region monitoring** for background wake-ups and **push notifications** to prompt re-engagement.

### 5.2 System Diagram

```
┌─────────────────────────────────────────────────────────┐
│                     iOS Client (Swift)                  │
│                                                         │
│  ┌──────────────┐  ┌──────────────┐  ┌───────────────┐  │
│  │ NearbyInter. │  │ CoreBluetooth│  │  CoreLocation │  │
│  │   (UWB)      │  │   (BLE)      │  │  (iBeacon)    │  │
│  └──────┬───────┘  └──────┬───────┘  └───────┬───────┘  │
│         │                 │                  │          │
│         └────────┬────────┘                  │          │
│                  ▼                           ▼          │
│         ┌────────────────┐        ┌──────────────────┐  │
│         │  Encounter     │        │  Region Monitor  │  │
│         │  Engine        │        │  (background)    │  │
│         └───────┬────────┘        └────────┬─────────┘  │
│                 ▼                          ▼           │
│         ┌──────────────────────────────────────────┐    │
│         │         Local Graph Store (SQLite)       │    │
│         └───────────────────┬──────────────────────┘    │
└─────────────────────────────┼───────────────────────────┘
                              │ HTTPS (TLS 1.3) / WebSocket
                              ▼
                    ┌─────────────────────┐
                    │   Backend (Server)  │
                    │  - Token relay      │
                    │  - Graph database   │
                    │  - Push (APNs)      │
                    │  - Consent ledger   │
                    └─────────────────────┘
```

---

## 6. iOS Technical Design (Swift)

### 6.1 Target & Minimums
- **Minimum iOS:** 15.0 (UWB/NI requires 14+; 15 for broader BLE reliability)
- **Recommended:** iOS 17+ for modern concurrency and background improvements
- **Hardware:** iPhone 11 or newer (U1/U2 chip for UWB); BLE fallback for older devices
- **Language:** Swift 5.9+ with Swift Concurrency (async/await)

### 6.2 Framework Usage

**Nearby Interaction (UWB)** — Tier 1 handshake
```swift
import NearbyInteraction

final class UWBHandshake: NSObject, NISessionDelegate {
    private var session = NISession()
    private var peerToken: NIDiscoveryToken?

    func beginHandshake(peerToken: NIDiscoveryToken) {
        session.delegate = self
        session.delegateQueue = .main
        let config = NINearbyPeerConfiguration(peerToken: peerToken)
        session.run(config)
    }

    func session(_ session: NISession,
                 didUpdate nearbyObjects: [NINearbyObject]) {
        guard let object = nearbyObjects.first else { return }
        // object.distance (meters), object.direction (vector)
        if let distance = object.distance, distance < 2.0 {
            triggerEncounter()   // within ~2m → mutual handshake
        }
    }
}
```

**Core Bluetooth (BLE)** — Tier 2 presence
```swift
import CoreBluetooth

// Advertise an ephemeral, rotating service UUID (privacy)
let serviceUUID = CBUUID(string: "A1B2...")   // rotates per session
peripheralManager.startAdvertising([
    CBAdvertisementDataServiceUUIDsKey: [serviceUUID],
    CBAdvertisementDataLocalNameKey: ""        // empty = anonymous
])
```

**Core Location (iBeacon)** — Tier 2 background wake-up
```swift
let region = CLBeaconRegion(
    uuid: UUID(uuidString: "...")!,
    identifier: "proximity.region"
)
locationManager.startMonitoring(for: region)   // works in background
```

**Core NFC** — Tier 1b, physical tap (optional "meet at the door" mode)
```swift
import CoreNFC
// NFCNDEFReaderSession — foreground, user-initiated tap
// Used for "tap phones to connect" at events/doors
```

### 6.3 Data Model (Local SQLite via SwiftData/Core Data)

```
User (local identity)
 ├── PublicKey (for E2E handshake)
 ├── Preferences (open-to-connect, radius, incognito)
 └──
Encounter
 ├── EncounterID (UUID)
 ├── AnonToken (ephemeral, rotating)
 ├── Timestamp
 ├── GeoHash (coarse, optional)
 ├── DistanceTier (1/2/3)
 └── Status (.silhouette, .mutual, .blocked)

Connection
 ├── UserA, UserB
 ├── MutualConsent (bool)
 ├── RevealedAt
 └── ChatThreadID
```

### 6.4 Privacy & Security Architecture
- **Ephemeral rotating tokens** — no persistent identifiers broadcast.
- **End-to-end encryption** for revealed conversations (Signal-style, via libsodium or CryptoKit).
- **Zero-knowledge graph** — server sees tokens, not identities.
- **On-device consent ledger** — the user controls all data.
- **Right to be forgotten** — delete account purges graph + tokens.
- **No location history stored server-side** by default.

---

## 7. MVP Scope (v1.0)

| Feature | Priority | Framework |
|---|---|---|
| Opt-in "Open to Connect" toggle | P0 | — |
| Foreground UWB handshake (Tier 1) | P0 | NearbyInteraction |
| Silhouette encounter list | P0 | SwiftData |
| Mutual "wave" → reveal + chat | P0 | WebSocket + CryptoKit |
| BLE presence (Tier 2) | P1 | CoreBluetooth |
| iBeacon background wake-up | P1 | CoreLocation |
| Regional graph (Tier 3, 50 mi) | P2 | Backend |
| NFC tap-to-connect | P2 | CoreNFC |
| Block/incognito/privacy controls | P0 | — |

---

## 8. Key Risks & Mitigations

| Risk | Mitigation |
|---|---|
| iOS background sensing limits | Foreground-first UX; iBeacon + push for background; set expectations |
| Battery drain (UWB/BLE) | Duty-cycling, session timeouts, user-controlled scanning windows |
| Harassment / stalking | Mutual consent, silhouettes, blocking, no persistent IDs |
| Cold start (network effect) | Event mode, "meet at the door" NFC, regional Tier 3 seeding |
| App Store privacy review | Transparent privacy nutrition labels; clear consent flows |

---

## 9. Roadmap

- **Phase 0 (4–6 wks):** Tech spike — UWB handshake + BLE presence proof-of-concept.
- **Phase 1 (8–12 wks):** MVP — Tier 1 handshake, silhouettes, mutual reveal, chat.
- **Phase 2:** Tier 2/3, background monitoring, regional graph.
- **Phase 3:** Android interoperability (via BLE + server relay), events, communities.

---

## 10. Summary

**Proximity** is a deliberate counterpoint to both the surveillance state *and* the attention economy. It uses the same proximity hardware that tracks us — UWB, BLE, geolocation — to restore what that tracking erases: **mutual, consensual, real-world human connection.** The technical design is feasible on iOS today using a hybrid of Nearby Interaction, Core Bluetooth, Core Location, and Core NFC, with a privacy-first architecture where the network graph grows only through physical presence.