initial commit: Proximity iOS app proposal, full Swift code scaffold, reference backend, testing docs, generated Xcode project

Proximity/Models/Encounter.swift

@@ -0,0 +1,55 @@
+import Foundation
+
+/// A real-world encounter between two present users.
+///
+/// An encounter is deliberately **anonymous** until both parties mutually
+/// consent to reveal. Until then it is a "silhouette" — a proof that two
+/// humans were physically near each other, with no identity attached.
+struct Encounter: Identifiable, Codable, Hashable {
+    let id: UUID
+    let remoteAnonToken: String
+    let timestamp: Date
+    let tier: DistanceTier
+    let engine: ProximityEngine
+
+    /// Coarse geohash (optional). Never precise location.
+    var geohash: String?
+
+    /// The relationship state of this encounter.
+    var status: EncounterStatus
+
+    /// A human-readable hint, e.g. "Cafe on 5th Ave" if the user tagged it.
+    var placeHint: String?
+
+    init(
+        id: UUID = UUID(),
+        remoteAnonToken: String,
+        timestamp: Date = Date(),
+        tier: DistanceTier,
+        engine: ProximityEngine,
+        geohash: String? = nil,
+        status: EncounterStatus = .silhouette,
+        placeHint: String? = nil
+    ) {
+        self.id = id
+        self.remoteAnonToken = remoteAnonToken
+        self.timestamp = timestamp
+        self.tier = tier
+        self.engine = engine
+        self.geohash = geohash
+        self.status = status
+        self.placeHint = placeHint
+    }
+}
+
+/// Relationship lifecycle of an encounter.
+enum EncounterStatus: String, Codable, Hashable {
+    /// Seen but not yet acknowledged. A silhouette.
+    case silhouette
+    /// This user has sent a "wave" (interest) but the other hasn't replied.
+    case waved
+    /// Both parties waved — identities revealed, chat unlocked.
+    case mutual
+    /// One party declined or blocked. Permanently removed from the graph.
+    case declined
+}