diff --git a/src/lib/measurements/__tests__/apple-health-mapping.test.ts b/src/lib/measurements/__tests__/apple-health-mapping.test.ts
index 00f8dd029..ac8475f94 100644
--- a/src/lib/measurements/__tests__/apple-health-mapping.test.ts
+++ b/src/lib/measurements/__tests__/apple-health-mapping.test.ts
@@ -119,6 +119,69 @@ describe("HK_QUANTITY_TYPE_DEFERRED", () => {
     }
   });
 
+  // v1.4.25 W16a — explicit coverage gate for the iOS-17 + iOS-18
+  // long-tail. The brief flagged these as "the iOS app may emit them
+  // when the user has the relevant HealthKit category enabled"; the
+  // deferred set means the batch endpoint treats them as
+  // skipped-but-known rather than unknown-and-dropped.
+  it("covers the iOS-17 + iOS-18 long-tail identifiers", () => {
+    const expectedLongTail = [
+      // Cardiovascular / clinical
+      "HKQuantityTypeIdentifierAtrialFibrillationBurden",
+      "HKQuantityTypeIdentifierPeripheralPerfusionIndex",
+      // Mobility
+      "HKQuantityTypeIdentifierAppleWalkingSteadiness",
+      "HKQuantityTypeIdentifierNumberOfTimesFallen",
+      "HKCategoryTypeIdentifierAppleWalkingSteadinessEvent",
+      // Respiratory / pulmonary
+      "HKQuantityTypeIdentifierForcedExpiratoryVolume1",
+      "HKQuantityTypeIdentifierForcedVitalCapacity",
+      "HKQuantityTypeIdentifierPeakExpiratoryFlowRate",
+      "HKQuantityTypeIdentifierInhalerUsage",
+      // Other quantity identifiers
+      "HKQuantityTypeIdentifierInsulinDelivery",
+      "HKQuantityTypeIdentifierUVExposure",
+      "HKQuantityTypeIdentifierElectrodermalActivity",
+      "HKQuantityTypeIdentifierBloodAlcoholContent",
+      "HKQuantityTypeIdentifierNikeFuel",
+      // Heart-rhythm event flags
+      "HKCategoryTypeIdentifierLowHeartRateEvent",
+      "HKCategoryTypeIdentifierHighHeartRateEvent",
+      "HKCategoryTypeIdentifierIrregularHeartRhythmEvent",
+      "HKCategoryTypeIdentifierLowCardioFitnessEvent",
+      // Audio-exposure events
+      "HKCategoryTypeIdentifierEnvironmentalAudioExposureEvent",
+      "HKCategoryTypeIdentifierHeadphoneAudioExposureEvent",
+      "HKCategoryTypeIdentifierEnvironmentalSoundReduction",
+      // Behavioural / habit
+      "HKCategoryTypeIdentifierHandwashingEvent",
+      "HKCategoryTypeIdentifierToothbrushingEvent",
+      // Reproductive / fertility / pregnancy
+      "HKCategoryTypeIdentifierContraceptive",
+      "HKCategoryTypeIdentifierLactation",
+      "HKCategoryTypeIdentifierPregnancy",
+      "HKCategoryTypeIdentifierPregnancyTestResult",
+      "HKCategoryTypeIdentifierProgesteroneTestResult",
+      "HKCategoryTypeIdentifierSexualActivity",
+      "HKCategoryTypeIdentifierSleepChanges",
+      "HKCategoryTypeIdentifierPersistentIntermenstrualBleeding",
+      "HKCategoryTypeIdentifierProlongedMenstrualPeriods",
+      "HKCategoryTypeIdentifierIrregularMenstrualCycles",
+      "HKCategoryTypeIdentifierInfrequentMenstrualCycles",
+    ];
+    for (const id of expectedLongTail) {
+      expect(
+        HK_QUANTITY_TYPE_DEFERRED.has(id),
+        `${id} should be in the deferred set`,
+      ).toBe(true);
+    }
+  });
+
+  it("does not duplicate any deferred identifier", () => {
+    const ids = Array.from(HK_QUANTITY_TYPE_DEFERRED);
+    expect(new Set(ids).size).toBe(ids.length);
+  });
+
   it("converts oxygen saturation from 0..1 fraction to 0..100 percent", () => {
     const mapping =
       APPLE_HEALTH_TYPE_MAP.HKQuantityTypeIdentifierOxygenSaturation;
diff --git a/src/lib/measurements/apple-health-mapping.ts b/src/lib/measurements/apple-health-mapping.ts
index f642e94d2..a780a447b 100644
--- a/src/lib/measurements/apple-health-mapping.ts
+++ b/src/lib/measurements/apple-health-mapping.ts
@@ -382,6 +382,59 @@ export const HK_QUANTITY_TYPE_DEFERRED = new Set<string>([
   // Scored assessments (iOS 18) — v1.5 (PHQ-9 / GAD-7 mapping TBD)
   "HKScoredAssessmentTypeIdentifierGAD7",
   "HKScoredAssessmentTypeIdentifierPHQ9",
+  // ── v1.4.25 W16a — iOS-17 + iOS-18 long-tail closure ──
+  // Cardiovascular / clinical (iOS 16+) — no HealthLog counterpart yet;
+  // clinical decision-support territory, defer behind a stricter user
+  // opt-in than the existing Health-share prompt.
+  "HKQuantityTypeIdentifierAtrialFibrillationBurden",
+  "HKQuantityTypeIdentifierPeripheralPerfusionIndex",
+  // Mobility (iOS 15+) — surface as a wellness signal in v1.5 once the
+  // Insights cardio sub-page has room for a steadiness gauge.
+  "HKQuantityTypeIdentifierAppleWalkingSteadiness",
+  "HKQuantityTypeIdentifierNumberOfTimesFallen",
+  "HKCategoryTypeIdentifierAppleWalkingSteadinessEvent",
+  // Respiratory / pulmonary clinical (iOS 17) — pair with FHIR clinical
+  // bucket; no Measurement enum mapping today.
+  "HKQuantityTypeIdentifierForcedExpiratoryVolume1",
+  "HKQuantityTypeIdentifierForcedVitalCapacity",
+  "HKQuantityTypeIdentifierPeakExpiratoryFlowRate",
+  "HKQuantityTypeIdentifierInhalerUsage",
+  // Other quantity identifiers — explicit hold (privacy / not in scope).
+  "HKQuantityTypeIdentifierInsulinDelivery",
+  "HKQuantityTypeIdentifierUVExposure",
+  "HKQuantityTypeIdentifierElectrodermalActivity",
+  "HKQuantityTypeIdentifierBloodAlcoholContent",
+  "HKQuantityTypeIdentifierNikeFuel", // legacy Nike+iPod fitness points
+  // Heart-rhythm event flags (iOS 9+ but watch-detected; iOS 18
+  // refreshed surfaces) — would land as Measurement annotations rather
+  // than rows; defer until the annotation column lands.
+  "HKCategoryTypeIdentifierLowHeartRateEvent",
+  "HKCategoryTypeIdentifierHighHeartRateEvent",
+  "HKCategoryTypeIdentifierIrregularHeartRhythmEvent",
+  "HKCategoryTypeIdentifierLowCardioFitnessEvent",
+  // Audio-exposure events (iOS 13+) — the continuous AUDIO_EXPOSURE_*
+  // quantity identifiers ARE mapped above; these are the
+  // "loud-event-fired" flags that pair with them. Defer until we
+  // surface event chips in the Insights audio sub-page.
+  "HKCategoryTypeIdentifierEnvironmentalAudioExposureEvent",
+  "HKCategoryTypeIdentifierHeadphoneAudioExposureEvent",
+  "HKCategoryTypeIdentifierEnvironmentalSoundReduction",
+  // Behavioural / habit category-types — not in HealthLog scope yet.
+  "HKCategoryTypeIdentifierHandwashingEvent",
+  "HKCategoryTypeIdentifierToothbrushingEvent",
+  // Reproductive / fertility / pregnancy — explicit privacy hold
+  // (matches the menstrual-flow stance already encoded above).
+  "HKCategoryTypeIdentifierContraceptive",
+  "HKCategoryTypeIdentifierLactation",
+  "HKCategoryTypeIdentifierPregnancy",
+  "HKCategoryTypeIdentifierPregnancyTestResult",
+  "HKCategoryTypeIdentifierProgesteroneTestResult",
+  "HKCategoryTypeIdentifierSexualActivity",
+  "HKCategoryTypeIdentifierSleepChanges",
+  "HKCategoryTypeIdentifierPersistentIntermenstrualBleeding",
+  "HKCategoryTypeIdentifierProlongedMenstrualPeriods",
+  "HKCategoryTypeIdentifierIrregularMenstrualCycles",
+  "HKCategoryTypeIdentifierInfrequentMenstrualCycles",
 ] as const);
 
 /** Input to `mapAppleHealthEntry()`. */