feat: sync read/unread state to backend with persistent device ID

- APIClient: generate and persist a stable device UUID (jarvis.device.id
  in UserDefaults); attach as X-Jarvis-Device-Id header on every request
- Add markStoryRead / markStoryUnread — POST/DELETE /stories/:id/read with
  device_id, read_at, and source fields
- Wire both calls into all three read-toggle sites: SignalFeedView,
  ArticleReaderView, StoryDetailView
- Add postVoid helper for fire-and-forget POST calls (no response body needed)
- Pass include_read param on stories fetch for future server-side filtering
- CacheMaintenance: recentHours 84→72 (mirrors backend 72h story window);
  markerHours 96→192 so read suppression survives a full weekly news cycle

Co-Authored-By: Claude Sonnet 4.6 <noreply@anthropic.com>

Jarvis/Networking/APIClient.swift

@@ -33,23 +33,37 @@ private struct APIErrorResponse: Decodable {
     let error: Inner
 }
 
+private struct EmptyResponse: Decodable {}
+
 actor APIClient {
     static let shared = APIClient()
 
     private var baseURL: URL?
     private let session: URLSession
     private let decoder: JSONDecoder
+    private let deviceId: String
 
     private init() {
         let config = URLSessionConfiguration.default
         config.timeoutIntervalForRequest = 10
         self.session = URLSession(configuration: config)
+        self.deviceId = APIClient.loadDeviceId()
 
         self.decoder = JSONDecoder()
         self.decoder.dateDecodingStrategy = .iso8601
         self.decoder.keyDecodingStrategy = .convertFromSnakeCase
     }
 
+    private static func loadDeviceId() -> String {
+        let key = "jarvis.device.id"
+        if let existing = UserDefaults.standard.string(forKey: key), !existing.isEmpty {
+            return existing
+        }
+        let value = UUID().uuidString.lowercased()
+        UserDefaults.standard.set(value, forKey: key)
+        return value
+    }
+
     func configure(host: String) throws {
         guard let url = URL(string: "http://\(host)/api/v1") else {
             throw APIError.invalidURL
@@ -70,9 +84,10 @@ actor APIClient {
         topic: String? = nil,
         tags: Set<String> = [],
         minSignal: Int? = nil,
-        limit: Int = 20
+        limit: Int = 20,
+        includeRead: Bool = false
     ) async throws -> PaginatedStories {
-        var params: [String: String] = ["limit": "\(limit)"]
+        var params: [String: String] = ["limit": "\(limit)", "include_read": includeRead ? "true" : "false"]
         if let cursor   { params["after"] = cursor }
         if let topic    { params["topic"] = topic }
         if !tags.isEmpty { params["tags"] = tags.sorted().joined(separator: ",") }
@@ -84,6 +99,18 @@ actor APIClient {
         try await get("/stories/\(id)")
     }
 
+    func markStoryRead(id: String) async throws {
+        try await postVoid("/stories/\(id)/read", body: [
+            "device_id": deviceId,
+            "read_at": ISO8601DateFormatter().string(from: Date()),
+            "source": "ios",
+        ])
+    }
+
+    func markStoryUnread(id: String) async throws {
+        try await delete("/stories/\(id)/read")
+    }
+
     // MARK: - Articles
 
     func fetchArticle(id: String) async throws -> Article {
@@ -118,6 +145,7 @@ actor APIClient {
         guard let url = components.url else { throw APIError.invalidURL }
         var request = URLRequest(url: url)
         request.httpMethod = "GET"
+        request.setValue(deviceId, forHTTPHeaderField: "X-Jarvis-Device-Id")
         return try await execute(request)
     }
 
@@ -126,16 +154,32 @@ actor APIClient {
         let url = base.appendingPathComponent(path)
         var request = URLRequest(url: url)
         request.httpMethod = "POST"
+        request.setValue(deviceId, forHTTPHeaderField: "X-Jarvis-Device-Id")
         request.setValue("application/json", forHTTPHeaderField: "Content-Type")
         request.httpBody = try JSONSerialization.data(withJSONObject: body)
         return try await execute(request)
     }
 
+    private func postVoid(_ path: String, body: [String: Any]) async throws {
+        guard let base = baseURL else { throw APIError.notConnected }
+        let url = base.appendingPathComponent(path)
+        var request = URLRequest(url: url)
+        request.httpMethod = "POST"
+        request.setValue(deviceId, forHTTPHeaderField: "X-Jarvis-Device-Id")
+        request.setValue("application/json", forHTTPHeaderField: "Content-Type")
+        request.httpBody = try JSONSerialization.data(withJSONObject: body)
+        let (_, response) = try await session.data(for: request)
+        guard let http = response as? HTTPURLResponse, (200...299).contains(http.statusCode) else {
+            throw APIError.serverError(code: "post_failed", message: "Post failed", status: 500)
+        }
+    }
+
     private func delete(_ path: String) async throws {
         guard let base = baseURL else { throw APIError.notConnected }
         let url = base.appendingPathComponent(path)
         var request = URLRequest(url: url)
         request.httpMethod = "DELETE"
+        request.setValue(deviceId, forHTTPHeaderField: "X-Jarvis-Device-Id")
         let (_, response) = try await session.data(for: request)
         guard let http = response as? HTTPURLResponse, http.statusCode == 204 else {
             throw APIError.serverError(code: "delete_failed", message: "Delete failed", status: 500)

Jarvis/Store/CacheMaintenance.swift

@@ -10,8 +10,8 @@ enum CacheMaintenance {
     private static let hour: TimeInterval = 3_600
     private static let day: TimeInterval = 86_400
 
-    private static let recentHours = 84.0    // 3.5 days: survives weekends
+    private static let recentHours = 72.0    // 3 days: mirrors backend active story window
-    private static let markerHours = 96.0   // 4 days: active window + buffer
+    private static let markerHours = 192.0  // 8 days: read suppression survives weekly repeats
     private static let articleDays = 14.0    // cached article bodies (backend article retention)
 
     /// Age-based eviction. Run on launch. Cheap; protects saved stories.

Jarvis/Views/Home/SignalFeedView.swift

@@ -114,6 +114,7 @@ struct SignalFeedView: View {
             FetchDescriptor<ReadStory>(predicate: #Predicate { $0.id == id })))?.first {
             modelContext.delete(row)
             try? modelContext.save()
+            Task { try? await APIClient.shared.markStoryUnread(id: id) }
         }
     }
 
@@ -632,6 +633,7 @@ struct SignalFeedView: View {
         if existing?.first == nil {
             modelContext.insert(ReadStory(id: id))
             try? modelContext.save()
+            Task { try? await APIClient.shared.markStoryRead(id: id) }
             withAnimation(.snappy) { showRead = true }
         }
     }

Jarvis/Views/Reader/ArticleReaderView.swift

@@ -431,8 +431,10 @@ struct ArticleReaderView: View {
         if let row = (try? modelContext.fetch(
             FetchDescriptor<ReadStory>(predicate: #Predicate { $0.id == id })))?.first {
             modelContext.delete(row)
+            Task { try? await APIClient.shared.markStoryUnread(id: id) }
         } else {
             modelContext.insert(ReadStory(id: id))
+            Task { try? await APIClient.shared.markStoryRead(id: id) }
         }
         try? modelContext.save()
     }

Jarvis/Views/Story/StoryDetailView.swift

@@ -142,6 +142,7 @@ struct StoryDetailView: View {
         else { return }
         modelContext.insert(ReadStory(id: id))
         try? modelContext.save()
+        Task { try? await APIClient.shared.markStoryRead(id: id) }
     }
 
     private func toggleRead() {
@@ -149,8 +150,10 @@ struct StoryDetailView: View {
         if let row = (try? modelContext.fetch(
                 FetchDescriptor<ReadStory>(predicate: #Predicate { $0.id == id })))?.first {
             modelContext.delete(row)
+            Task { try? await APIClient.shared.markStoryUnread(id: id) }
         } else {
             modelContext.insert(ReadStory(id: id))
+            Task { try? await APIClient.shared.markStoryRead(id: id) }
         }
         try? modelContext.save()
     }