HealthKit and WorkoutKit

You MUST use this skill for ANY HealthKit or WorkoutKit development including authorization, data queries, background delivery, workout sessions, planned workouts, wellbeing APIs (State of Mind), Medications, and Health Records.

Quick Reference

Symptom / Task	Reference
HealthKit framework model, HKHealthStore, data types, sample vs characteristic data	See skills/fundamentals.md
Capability setup, requestAuthorization, purpose strings, read-asymmetry, privacy	See skills/authorization-and-privacy.md
HKSampleQuery, Swift Concurrency query APIs, HKStatisticsCollectionQuery, sample writes	See skills/queries.md
Anchored queries, observer queries, HKDeletedObject, background-delivery entitlement	See skills/sync-and-background.md
HKWorkoutSession, HKLiveWorkoutBuilder, recovery, multi-device, iOS/iPadOS/watchOS workout tracking	See skills/workouts.md
WorkoutKit custom/planned workouts, scheduling, swimming workouts, previewing	See skills/workoutkit.md
State of Mind, Medications API, symptom logging, wellbeing APIs	See skills/wellbeing-and-medications.md
Health Records (FHIR), Mobility Health App, motion-based health	See skills/clinical-and-mobility.md

Cross-Suite Routes

These topics overlap with HealthKit/WorkoutKit but live in separate suites:

watchOS presentation

• Watch-specific workout presentation (Always On, Smart Stack), complication surfaces → See axiom-watchos
• Workout app structure on Apple Watch → See axiom-watchos (skills/platform-basics.md)

Concurrency

• Swift 6 concurrency, actors, Sendable → See axiom-concurrency
• HealthKit queries bridging to Swift Concurrency → skills/queries.md is the canonical example

SwiftUI

• Charts rendering for health data → See axiom-swiftui
• @Observable view models for health data → See axiom-swiftui

Data and sync

• General cross-platform sync patterns (CloudKit, GRDB) → See axiom-data
• HealthKit anchored/observer queries as a generalizable sync mechanism → skills/sync-and-background.md

Security and privacy

• Keychain storage, encryption, data-protection entitlements → See axiom-security

Conflict Resolution

axiom-health vs axiom-watchos: For workout apps on Apple Watch:

1. Use axiom-health for HKWorkoutSession lifecycle, HKLiveWorkoutBuilder, recovery APIs, multi-device mirroring — these are HealthKit concepts, not watch concepts
2. Use axiom-watchos for watch-specific presentation: Always On display, Smart Stack placement, watchOS background mode coordination
3. Both apply for a watch-native workout app — start with axiom-health for session lifecycle, then axiom-watchos for presentation

axiom-health vs axiom-concurrency: For HealthKit query patterns:

1. Use axiom-health for which query type to choose and HealthKit-specific gotchas
2. Use axiom-concurrency for general Swift 6 actor isolation rules that apply to query callbacks

axiom-health vs axiom-data: For change-tracked data synchronization:

1. Use axiom-health for HKAnchoredObjectQuery, HKObserverQuery, HKDeletedObject
2. Use axiom-data for application-level data sync across devices (CloudKit, GRDB, SwiftData)

Decision Tree

digraph health {
    start [label="HealthKit / workout task" shape=ellipse];
    what [label="What area?" shape=diamond];

    start -> what;
    what -> "skills/fundamentals.md" [label="framework basics, data types"];
    what -> "skills/authorization-and-privacy.md" [label="permissions, purpose strings, privacy"];
    what -> "skills/queries.md" [label="reading data, rollups, writes"];
    what -> "skills/sync-and-background.md" [label="change tracking, background delivery"];
    what -> "skills/workouts.md" [label="HKWorkoutSession, live workouts"];
    what -> "skills/workoutkit.md" [label="planned/custom workouts"];
    what -> "skills/wellbeing-and-medications.md" [label="State of Mind, Medications"];
    what -> "skills/clinical-and-mobility.md" [label="Health Records, Mobility"];
    what -> "axiom-watchos" [label="watch-specific presentation"];
    what -> "axiom-concurrency" [label="general actor isolation rules"];
    what -> "axiom-swiftui" [label="Charts, data visualization"];
}

Resources

WWDC: 2019-218, 2020-10182, 2020-10184, 2020-10664, 2021-10009, 2021-10287, 2022-10005, 2023-10016, 2023-10023, 2024-10084, 2024-10109, 2025-321, 2025-322

Docs: /healthkit, /healthkit/about-the-healthkit-framework, /healthkit/authorizing-access-to-health-data, /healthkit/protecting-user-privacy, /healthkit/reading-data-from-healthkit, /healthkit/running-queries-with-swift-concurrency, /healthkit/executing-anchored-object-queries, /healthkit/executing-observer-queries, /healthkit/hkworkoutsession, /healthkit/hklivewobuilder, /workoutkit, /healthkit/accessing-health-records

Skills: axiom-watchos, axiom-concurrency, axiom-swiftui, axiom-data, axiom-security