add cl_factor UI and state to iOS cue

cue-ios/CueIOS/AppState.swift

@@ -93,6 +93,8 @@ final class AppState {
     var calTempC: String = "40"
     var calCellConstant: Double? = nil
     var calRs: Double? = nil
+    var clFactor: Double? = nil
+    var clCalKnownPpm: String = "5"
 
     // Clean
     var cleanV: String = "1200"
@@ -251,6 +253,10 @@ final class AppState {
         case .cellK(let k):
             calCellConstant = Double(k)
             status = String(format: "Device cell constant: %.4f cm\u{207B}\u{00B9}", k)
+
+        case .clFactor(let f):
+            clFactor = Double(f)
+            status = String(format: "Device Cl factor: %.6f", f)
         }
     }
 

cue-ios/CueIOS/Transport/UDPManager.swift

@@ -95,6 +95,7 @@ final class UDPManager: @unchecked Sendable {
             send(buildSysexGetTemp())
             send(buildSysexGetConfig())
             send(buildSysexGetCellK())
+            send(buildSysexGetClFactor())
             startTimers()
             receiveLoop()
 

cue-ios/CueIOS/Views/CalibrateView.swift

@@ -14,6 +14,7 @@ struct CalibrateView: View {
             inputSection
             resultsSection
             cellConstantSection
+            chlorineCalSection
         }
         .navigationTitle("Calibrate")
     }
@@ -115,6 +116,48 @@ struct CalibrateView: View {
         }
     }
 
+    // MARK: - Chlorine calibration
+
+    private var chlorineCalSection: some View {
+        Section("Chlorine Calibration") {
+            if let f = state.clFactor {
+                Text(String(format: "Cl factor: %.6f ppm/\u{00B5}A", f))
+            }
+            if let r = state.clResult {
+                Text(String(format: "Last free Cl peak: %.3f \u{00B5}A", r.iFreeUa))
+            }
+
+            HStack {
+                Text("Known Cl ppm")
+                Spacer()
+                TextField("ppm", text: $state.clCalKnownPpm)
+                    .multilineTextAlignment(.trailing)
+                    .frame(width: 80)
+                    #if os(iOS)
+                    .keyboardType(.decimalPad)
+                    #endif
+            }
+
+            Button("Set Cl Factor") {
+                guard let r = state.clResult else {
+                    state.status = "No chlorine measurement"
+                    return
+                }
+                let knownPpm = Double(state.clCalKnownPpm) ?? 0
+                let peak = abs(Double(r.iFreeUa))
+                guard peak > 0 else {
+                    state.status = "Peak current is zero"
+                    return
+                }
+                let factor = knownPpm / peak
+                state.clFactor = factor
+                state.send(buildSysexSetClFactor(Float(factor)))
+                state.status = String(format: "Cl factor: %.6f ppm/\u{00B5}A", factor)
+            }
+            .disabled(state.clResult == nil)
+        }
+    }
+
     // MARK: - Calculations
 
     private func saltGrams(volumeGal: Double, ppm: Double) -> Double {

cue-ios/CueIOS/Views/ChlorineView.swift

@@ -68,6 +68,12 @@ struct ChlorineView: View {
                 Text(String(format: "Combined: %.3f uA", r.iTotalUa - r.iFreeUa))
                     .foregroundStyle(.secondary)
 
+                if let f = state.clFactor {
+                    let ppm = f * Double(abs(r.iFreeUa))
+                    Text(String(format: "Free Cl: %.2f ppm", ppm))
+                        .foregroundStyle(.cyan)
+                }
+
                 if let (_, refR) = state.clRef {
                     Divider().frame(height: 16)
                     Text(String(format: "vs Ref: dFree=%.3f dTotal=%.3f",