Screen Time API Engineer

Use this skill to implement and harden Screen Time API apps with a docs-first evidence model.

Rules

• Use this evidence order for decisions:
  1. Canonical Apple docs and WWDC
  2. Local SDK interfaces/headers
  3. Project-observed implementations (Project Alpha/Project Beta)
  4. Field notes (forums/medium)
• If sources conflict, prefer canonical + SDK behavior.
• Mark uncertain conclusions as inference and include a caveat.

SDK Baseline

• Evidence re-verified against the iOS 27.0 SDK (Xcode 27.0, build 27A266a) on 2026-10-21.
• iOS 26.2 to 26.5 added Screen Time APIs: picker title, data access (EU only), shield submenus, token refresh, store lifecycle. iOS 27.0 added none.
• Gate any API newer than the app's deployment target with #available and state the iOS version it needs.

Quick Start Workflow

1. Identify user goal category.
2. Open matching references from references/guides.
3. Cross-check critical API claims in references/evidence.
4. If implementation quality or regressions matter, use references/rundowns.
5. Produce output with explicit source/confidence labeling.

Goal to Reference Map

• Entitlements, signing, distribution approval:
  • references/guides/02-authorization-setup.md
  • references/guides/19-release-and-app-review-checklist.md
• Family activity picker and token handling:
  • references/guides/03-familycontrols-selection-and-token-model.md
  • references/guides/04-displaying-activity-labels-and-real-app-icons.md
• Shield policy and store behavior:
  • references/guides/05-managedsettings-enforcement-patterns.md
  • references/guides/06-web-blocking-and-webdomain-policy.md
• Custom shield UI/action:
  • references/guides/07-managedsettingsui-custom-shield-systems.md
  • references/guides/08-shield-actions-and-response-strategies.md
• Scheduling and monitor callbacks:
  • references/guides/09-deviceactivity-scheduling-thresholds-and-errors.md
  • references/guides/10-deviceactivity-monitor-extension-playbook.md
• Usage analytics reporting:
  • references/guides/11-deviceactivity-report-analytics-architecture.md
• Reading usage data in the host app (iOS 26.4+, EU only):
  • references/guides/02-authorization-setup.md
  • references/guides/11-deviceactivity-report-analytics-architecture.md
• Web usage control/reporting via ScreenTime framework:
  • references/guides/12-screentime-framework-web-usage-reporting.md
• Onboarding and permission UX:
  • references/guides/13-onboarding-and-permission-ui-blueprints.md
• End-to-end implementation reference:
  • references/guides/14-app-and-website-blocking-reference-implementation.md
• Project deep dives and comparative hardening:
  • references/guides/15-project-alpha-implementation-analysis.md
  • references/guides/16-project-beta-implementation-analysis.md
  • references/rundowns/12-cross-project-rundown.md
• Bug prevention, testing, and preflight:
  • references/guides/17-hardening-checklist-bug-prevention.md
  • references/guides/18-testing-matrix-device-only-edge-cases.md
  • references/guides/21-preflight-rundown.md

Evidence Files (Use When Verifying API Contracts)

• references/evidence/01-familycontrols-sdk-signatures.md
• references/evidence/02-managedsettings-sdk-signatures.md
• references/evidence/03-managedsettingsui-sdk-signatures.md
• references/evidence/04-deviceactivity-sdk-signatures.md
• references/evidence/05-deviceactivity-report-sdk-signatures.md
• references/evidence/06-screentime-framework-headers.md
• references/evidence/07-claim-reconciliation.md
• references/evidence/00-source-url-inventory.md

Output Contract

When using this skill for implementation guidance, include:

1. Chosen API path and why.
2. Risks/failure modes.
3. Validation checklist.
4. Source citations with confidence labels.

Boundaries

• Do not infer private APIs or unsupported token conversion techniques. The iOS 26.4 data-access APIs are the only documented way for the host app to read the bundle IDs or domains behind a person's apps and sites.
• Do not claim behavior beyond canonical/SDK support without explicit caveats.
• Do not skip extension-signing parity checks when discussing release readiness.