@@ -20,11 +20,14 @@ enum HealthKitTypeMappings {
         let isPlausible: (Double) -> Bool
     }
 
-    /// Ported from PR #16. Stress / fatigue / blood-pressure / blood-sugar map to `nil`:
-    /// - stress & fatigue have no native HealthKit equivalent.
-    /// - blood pressure needs `HKCorrelation` pairing (an unpaired systolic/diastolic sample never
-    ///   surfaces as a reading in Health) plus new share-authorization types — a documented follow-up.
-    /// - blood sugar likewise needs its own share type. Follow-up.
+    /// Ported from PR #16. Two kinds still map to `nil`, for two different reasons:
+    ///
+    /// - **Stress and fatigue have no HealthKit type at all.** Not a follow-up — there is nothing to
+    ///   map them onto. `HKStateOfMind` (iOS 17) is a self-reported mood log, not a device-derived
+    ///   score, and writing a ring's 0–100 wellness number into it would misrepresent both.
+    /// - **Blood pressure is a correlation, not a quantity.** An unpaired systolic or diastolic
+    ///   sample never surfaces as a reading in Health, so it needs `HKCorrelation` pairing and gets
+    ///   its own export pass in `HealthSyncService` rather than a `QuantityMapping`.
     static func quantityMapping(for kind: MeasurementKind) -> QuantityMapping? {
         switch kind {
         case .heartRate:
@@ -45,17 +48,43 @@ enum HealthKitTypeMappings {
             guard let type = HKQuantityType.quantityType(forIdentifier: .bodyTemperature) else { return nil }
             return QuantityMapping(type: type, unit: .degreeCelsius(),
                                    convert: { $0 }, isPlausible: { $0 > 25 && $0 < 45 })
+        case .respiratoryRate:
+            guard let type = HKQuantityType.quantityType(forIdentifier: .respiratoryRate) else { return nil }
+            return QuantityMapping(type: type, unit: HKUnit.count().unitDivided(by: .minute()),
+                                   convert: { $0 }, isPlausible: { $0 >= 4 && $0 <= 60 })
+        case .vo2max:
+            guard let type = HKQuantityType.quantityType(forIdentifier: .vo2Max) else { return nil }
+            // mL/(kg·min) — HealthKit spells the same unit as a compound.
+            let unit = HKUnit.literUnit(with: .milli)
+                .unitDivided(by: HKUnit.gramUnit(with: .kilo).unitMultiplied(by: .minute()))
+            return QuantityMapping(type: type, unit: unit,
+                                   convert: { $0 }, isPlausible: { $0 >= 10 && $0 <= 90 })
+        case .bloodSugar:
+            guard let type = HKQuantityType.quantityType(forIdentifier: .bloodGlucose) else { return nil }
+            // Stored canonically in mg/dL; HealthKit's mass/volume unit spells that as mg/dL too.
+            let unit = HKUnit.gramUnit(with: .milli).unitDivided(by: .literUnit(with: .deci))
+            return QuantityMapping(type: type, unit: unit,
+                                   convert: { $0 }, isPlausible: { $0 >= 40 && $0 <= 600 })
         case .stress, .fatigue:
-            return nil   // No native HealthKit equivalent.
-        case .bloodPressureSystolic, .bloodPressureDiastolic, .bloodSugar:
-            return nil   // BP needs HKCorrelation pairing + new share types; blood sugar needs its own. Follow-up.
-        case .respiratoryRate, .vo2max:
-            // HealthKit has both (`respiratoryRate`, `vo2Max`), but exporting them needs new share
-            // types plus their own per-type toggles to keep the sync opt-in per metric. Follow-up.
-            return nil
+            return nil   // No HealthKit type exists for either — see the note above.
+        case .bloodPressureSystolic, .bloodPressureDiastolic:
+            return nil   // Exported as an HKCorrelation instead; see `bloodPressureSyncID`.
         }
     }
 
+    /// A paired blood-pressure reading, keyed by the instant both halves share so a re-export
+    /// upserts rather than duplicating.
+    static func bloodPressureSyncID(timestamp: Date) -> String {
+        "pl-bp-\(Int(timestamp.timeIntervalSince1970 * 1000))"
+    }
+
+    /// Plausibility guards for the two halves of a blood-pressure reading, mirroring
+    /// `RingEventBridge`'s persistence gates so a value that reached the store can still be rejected
+    /// here if it is nonsense as a *pair* (systolic at or below diastolic).
+    static func isPlausibleBloodPressure(systolic: Double, diastolic: Double) -> Bool {
+        (60...250).contains(systolic) && (30...160).contains(diastolic) && systolic > diastolic
+    }
+
     // MARK: - Workouts
 
     /// Maps a PulseLoop activity type onto the closest `HKWorkoutActivityType`.
 
@@ -60,7 +60,12 @@ final class HealthSyncService {
     private var quantityWriteTypes: [HKQuantityType] {
         var identifiers: [HKQuantityTypeIdentifier] = [
             .heartRate, .oxygenSaturation, .heartRateVariabilitySDNN, .bodyTemperature,
-            .stepCount, .activeEnergyBurned, .distanceWalkingRunning, .distanceCycling
+            .stepCount, .activeEnergyBurned, .distanceWalkingRunning, .distanceCycling,
+            // Ring-dependent: only some families produce these, but the share set is fixed at
+            // authorization time and can't be re-prompted per device, so all four are requested up
+            // front. A ring that never reports one simply never writes it.
+            .respiratoryRate, .vo2Max, .bloodGlucose,
+            .bloodPressureSystolic, .bloodPressureDiastolic
         ]
         // Dietary types join the share set only once the nutrition feature is enabled, so users
         // who never opted in never see dietary rows on the Health authorization sheet. Enabling
@@ -116,6 +121,8 @@ final class HealthSyncService {
 
         do { try await exportVitals(context: context, state: &state, counts: &counts, now: now, device: device) }
         catch { log.error("Vitals export failed: \(error.localizedDescription)") }
+        do { try await exportBloodPressure(context: context, state: &state, counts: &counts, now: now, device: device) }
+        catch { log.error("Blood-pressure export failed: \(error.localizedDescription)") }
         do { try await exportActivity(context: context, state: &state, counts: &counts, now: now, device: device) }
         catch { log.error("Activity export failed: \(error.localizedDescription)") }
         do { try await exportSleep(context: context, state: &state, counts: &counts, now: now, device: device) }
@@ -172,6 +179,10 @@ final class HealthSyncService {
         if prefs.syncSpO2 { kinds.append(.spo2) }
         if prefs.syncHRV { kinds.append(.hrv) }
         if prefs.syncTemperature { kinds.append(.temperature) }
+        if prefs.syncRespiratoryRate { kinds.append(.respiratoryRate) }
+        if prefs.syncVO2Max { kinds.append(.vo2max) }
+        if prefs.syncBloodSugar { kinds.append(.bloodSugar) }
+        // Blood pressure is deliberately absent: it exports as a correlation, not a quantity.
         return kinds
     }
 
@@ -235,6 +246,87 @@ final class HealthSyncService {
         )
     }
 
+    // MARK: - Blood-pressure pass
+
+    /// Blood pressure is the one vital that can't ride the quantity path: Health only recognises a
+    /// reading when systolic and diastolic are saved together inside an `HKCorrelation`. Saved
+    /// separately they are stored but never surface in the Health app, which looks exactly like a
+    /// silent failure.
+    ///
+    /// Rows for the two halves are written from one packet at one instant (`bloodPressureEvents`), so
+    /// the shared timestamp is the pairing key. A half without its partner is skipped rather than
+    /// guessed at.
+    ///
+    /// The watermark reuses the `bloodPressureSystolic` slot in `measurementWatermarks`: that kind is
+    /// never exported as a quantity, so the slot is free, and it inherits the reset/backfill handling
+    /// `resetWatermarks` already applies to every `MeasurementKind`.
+    private func exportBloodPressure(context: ModelContext, state: inout AppleHealthSyncState,
+                                     counts: inout SyncCounts, now: Date, device: HKDevice?) async throws {
+        guard prefsStore.prefs.syncBloodPressure,
+              let systolicType = HKQuantityType.quantityType(forIdentifier: .bloodPressureSystolic),
+              let diastolicType = HKQuantityType.quantityType(forIdentifier: .bloodPressureDiastolic),
+              let correlationType = HKCorrelationType.correlationType(forIdentifier: .bloodPressure),
+              canShare(systolicType), canShare(diastolicType) else { return }
+
+        let watermarkKey = MeasurementKind.bloodPressureSystolic.rawValue
+        let systolicRaw = MeasurementKind.bloodPressureSystolic.rawValue
+        let diastolicRaw = MeasurementKind.bloodPressureDiastolic.rawValue
+        let mockRaw = MeasurementSource.mock.rawValue
+        let watermark = state.measurementWatermarks[watermarkKey] ?? .distantPast
+
+        let systolicDescriptor = FetchDescriptor<Measurement>(
+            predicate: #Predicate { $0.kindRaw == systolicRaw && $0.sourceRaw != mockRaw && $0.createdAt > watermark },
+            sortBy: [SortDescriptor(\.createdAt, order: .forward)]
+        )
+        let systolicRows = (try? context.fetch(systolicDescriptor)) ?? []
+        guard !systolicRows.isEmpty else { return }
+
+        // Index the diastolic halves across the same instant span. Bounded by the batch's own range
+        // rather than the watermark, so a partner row that was persisted in a different pass — and
+        // therefore carries a different `createdAt` — is still found.
+        guard let spanStart = systolicRows.map(\.timestamp).min(),
+              let spanEnd = systolicRows.map(\.timestamp).max() else { return }
+        let diastolicDescriptor = FetchDescriptor<Measurement>(
+            predicate: #Predicate {
+                $0.kindRaw == diastolicRaw && $0.sourceRaw != mockRaw
+                    && $0.timestamp >= spanStart && $0.timestamp <= spanEnd
+            }
+        )
+        let diastolicByInstant = Dictionary(
+            ((try? context.fetch(diastolicDescriptor)) ?? []).map { ($0.timestamp, $0.value) },
+            uniquingKeysWith: { first, _ in first }
+        )
+
+        for chunk in systolicRows.chunked(into: 1000) {
+            let correlations: [HKCorrelation] = chunk.compactMap { row in
+                guard row.timestamp <= now, let diastolic = diastolicByInstant[row.timestamp],
+                      HealthKitTypeMappings.isPlausibleBloodPressure(systolic: row.value, diastolic: diastolic)
+                else { return nil }
+
+                let unit = HKUnit.millimeterOfMercury()
+                let metadata = HealthKitTypeMappings.metadata(
+                    syncID: HealthKitTypeMappings.bloodPressureSyncID(timestamp: row.timestamp), version: 1
+                )
+                let objects: Set<HKSample> = [
+                    HKQuantitySample(type: systolicType, quantity: HKQuantity(unit: unit, doubleValue: row.value),
+                                     start: row.timestamp, end: row.timestamp, device: device, metadata: nil),
+                    HKQuantitySample(type: diastolicType, quantity: HKQuantity(unit: unit, doubleValue: diastolic),
+                                     start: row.timestamp, end: row.timestamp, device: device, metadata: nil),
+                ]
+                return HKCorrelation(type: correlationType, start: row.timestamp, end: row.timestamp,
+                                     objects: objects, device: device, metadata: metadata)
+            }
+            if !correlations.isEmpty {
+                try await save(correlations)
+                counts.bloodPressure += correlations.count
+            }
+            if let maxCreated = chunk.map(\.createdAt).max() {
+                state.measurementWatermarks[watermarkKey] = maxCreated
+                prefsStore.syncState = state
+            }
+        }
+    }
+
     // MARK: - Daily activity pass
 
     private func exportActivity(context: ModelContext, state: inout AppleHealthSyncState,
@@ -497,6 +589,7 @@ final class HealthSyncService {
 
     struct SyncCounts {
         var vitals = 0
+        var bloodPressure = 0
         var sleepSegments = 0
         var dailyTotals = 0
         var workouts = 0
@@ -505,6 +598,7 @@ final class HealthSyncService {
         var summary: String {
             var parts: [String] = []
             if vitals > 0 { parts.append("\(vitals) vitals") }
+            if bloodPressure > 0 { parts.append("\(bloodPressure) BP reading\(bloodPressure == 1 ? "" : "s")") }
             if sleepSegments > 0 { parts.append("\(sleepSegments) sleep segment\(sleepSegments == 1 ? "" : "s")") }
             if dailyTotals > 0 { parts.append("\(dailyTotals) daily total\(dailyTotals == 1 ? "" : "s")") }
             if workouts > 0 { parts.append("\(workouts) workout\(workouts == 1 ? "" : "s")") }
 
@@ -104,6 +104,16 @@ enum MetricsRepository {
         return (try? context.fetch(descriptor)) ?? []
     }
 
+    /// Whether the store holds any reading of a kind. `fetchLimit: 1` — an existence check, not a
+    /// count, so it stays cheap enough to call from a settings `body`.
+    @MainActor
+    static func hasAnyMeasurement(kind: MeasurementKind, context: ModelContext) -> Bool {
+        let raw = kind.rawValue
+        var descriptor = FetchDescriptor<Measurement>(predicate: #Predicate { $0.kindRaw == raw })
+        descriptor.fetchLimit = 1
+        return ((try? context.fetch(descriptor)) ?? []).isEmpty == false
+    }
+
     /// Oldest measurement timestamp across all kinds (for the calibration "Day X of N" counter).
     /// `fetchLimit: 1` ascending — one row, not the whole table.
     @MainActor
 
@@ -28,6 +28,14 @@ struct AppleHealthPrefs: Codable, Equatable {
     var syncTemperature = true
     var syncSleep = true
     var syncActivity = true
+    /// The four ring metrics that reach Health but only exist on some hardware. Default **on** like
+    /// the rest — the settings screen hides the row entirely on a ring that can't produce the metric,
+    /// so an enabled-but-unreachable toggle never writes anything.
+    var syncRespiratoryRate = true
+    var syncVO2Max = true
+    var syncBloodSugar = true
+    /// Exported as an `HKCorrelation` pairing systolic + diastolic, not as two loose quantities.
+    var syncBloodPressure = true
     /// Whether finished workout sessions export as `HKWorkout`s (calories, distance, HR stats, GPS route).
     var exportWorkouts = true
     /// Whether logged meals export as dietary samples (energy + macros). Only effective when the
@@ -52,6 +60,10 @@ struct AppleHealthPrefs: Codable, Equatable {
         syncTemperature = try c.decodeIfPresent(Bool.self, forKey: .syncTemperature) ?? d.syncTemperature
         syncSleep = try c.decodeIfPresent(Bool.self, forKey: .syncSleep) ?? d.syncSleep
         syncActivity = try c.decodeIfPresent(Bool.self, forKey: .syncActivity) ?? d.syncActivity
+        syncRespiratoryRate = try c.decodeIfPresent(Bool.self, forKey: .syncRespiratoryRate) ?? d.syncRespiratoryRate
+        syncVO2Max = try c.decodeIfPresent(Bool.self, forKey: .syncVO2Max) ?? d.syncVO2Max
+        syncBloodSugar = try c.decodeIfPresent(Bool.self, forKey: .syncBloodSugar) ?? d.syncBloodSugar
+        syncBloodPressure = try c.decodeIfPresent(Bool.self, forKey: .syncBloodPressure) ?? d.syncBloodPressure
         exportWorkouts = try c.decodeIfPresent(Bool.self, forKey: .exportWorkouts) ?? d.exportWorkouts
         syncNutrition = try c.decodeIfPresent(Bool.self, forKey: .syncNutrition) ?? d.syncNutrition
         backfillChoice = try c.decodeIfPresent(HealthBackfillChoice.self, forKey: .backfillChoice) ?? d.backfillChoice
 
@@ -10,6 +10,7 @@ import UIKit
 /// can clean up after turning sync off).
 struct AppleHealthSettingsView: View {
     @Environment(\.modelContext) private var modelContext
+    @Environment(RingBLEClient.self) private var ble
     @State private var service = HealthSyncService.shared
     @State private var store = AppleHealthPrefsStore.shared
     /// First-enable backfill choice ("all history" vs "new only" vs cancel).
@@ -21,6 +22,12 @@ struct AppleHealthSettingsView: View {
 
     private var masterOn: Bool { store.prefs.masterEnabled }
 
+    /// What the connected ring can actually produce. Rows for metrics it can't are hidden outright
+    /// rather than shown-and-inert: a VO₂max toggle on a jring is a promise the hardware can't keep.
+    private var capabilities: Set<WearableCapability> {
+        MetricsService.activeCapabilities(context: modelContext, ble: ble)
+    }
+
     var body: some View {
         ScrollView {
             VStack(alignment: .leading, spacing: 22) {
@@ -96,17 +103,41 @@ struct AppleHealthSettingsView: View {
     @ViewBuilder private var dataTypesGroup: some View {
         SettingsGroup(
             header: "Data types",
-            footer: "Stress, fatigue, and blood pressure don't have an Apple Health equivalent yet, so they aren't synced."
+            footer: "Stress and fatigue have no Apple Health equivalent — Health has no type for a device "
+                + "wellness score — so they can't be synced. Rows appear only for metrics your ring can produce."
         ) {
             FormToggleRow(title: "Heart rate", isOn: prefBinding(\.syncHeartRate))
             FormToggleRow(title: "Blood oxygen", isOn: prefBinding(\.syncSpO2))
             FormToggleRow(title: "Heart rate variability", isOn: prefBinding(\.syncHRV))
             FormToggleRow(title: "Temperature", isOn: prefBinding(\.syncTemperature))
+            if shows(.respiratoryRate) {
+                FormToggleRow(title: "Respiratory rate", isOn: prefBinding(\.syncRespiratoryRate))
+            }
+            if shows(.vo2max) {
+                FormToggleRow(title: "Cardio fitness (VO₂max)", isOn: prefBinding(\.syncVO2Max))
+            }
+            if shows(.bloodSugar, capability: .bloodSugar) {
+                FormToggleRow(title: "Blood glucose", isOn: prefBinding(\.syncBloodSugar))
+            }
+            if shows(.bloodPressureSystolic, capability: .bloodPressure) {
+                FormToggleRow(title: "Blood pressure", isOn: prefBinding(\.syncBloodPressure))
+            }
             FormToggleRow(title: "Sleep", isOn: prefBinding(\.syncSleep))
             FormToggleRow(title: "Steps & activity", isOn: prefBinding(\.syncActivity))
         }
     }
 
+    /// Whether to offer a toggle for a ring-dependent metric.
+    ///
+    /// Shown when the connected ring declares the capability **or** the store already holds a reading
+    /// of that kind. The second arm matters for two cases the capability alone misses: respiratory
+    /// rate and VO₂max have no `WearableCapability` of their own (they ride the YCBT history records),
+    /// and history from a previously-paired ring should stay exportable after switching hardware.
+    private func shows(_ kind: MeasurementKind, capability: WearableCapability? = nil) -> Bool {
+        if let capability, capabilities.contains(capability) { return true }
+        return MetricsRepository.hasAnyMeasurement(kind: kind, context: modelContext)
+    }
+
     @ViewBuilder private var workoutsGroup: some View {
         SettingsGroup(
             header: "Workouts",