shareplay-developer

---
name: shareplay-developer
description: Build, integrate, and troubleshoot SharePlay GroupActivities features for visionOS 27, including GroupActivity definitions, activation flows, GroupSession lifecycle, messaging and journals, ShareLink and SharePlay UI surfaces, and spatial coordination.
---

# SharePlay Developer

## Quick Start

1. Decide whether this experience is launch-only co-location or shared state
   sync.
2. Add the Group Activities capability and required entitlement before
   building SharePlay UI.
3. Define one `GroupActivity` per experience and keep the payload minimal and
   `Codable`.
4. Load the right reference only after you know the workflow.
5. For spatial personas or immersive spaces, load
   [`spatial-coordination.md`](references/spatial-coordination.md) before
   joining.

## Load References When

| Reference | When to Use |
|-----------|-------------|
| [`activation-ui.md`](references/activation-ui.md) | When wiring the SharePlay entry point or start button flow. |
| [`activity-definition.md`](references/activity-definition.md) | When defining the `GroupActivity` payload, metadata, or transfer representation. |
| [`group-session-lifecycle.md`](references/group-session-lifecycle.md) | When joining, leaving, observing, or presenting a `GroupSession`. |
| [`messaging-journal.md`](references/messaging-journal.md) | When using `GroupSessionMessenger`, `GroupSessionJournal`, or late-joiner sync. |
| [`shareplay-spatial-api.md`](references/shareplay-spatial-api.md) | When checking the official GroupActivities APIs for activation, association, session ownership, and spatial coordination. |
| [`spatial-coordination.md`](references/spatial-coordination.md) | When configuring `SystemCoordinator`, spatial templates, or group immersive-space behavior. |
| [`visionos-immersive-space.md`](references/visionos-immersive-space.md) | When implementing launch-only SharePlay for a visionOS immersive space. |
| [`groupactivities-patterns.md`](references/groupactivities-patterns.md) | When you need broader GroupActivities patterns or sample-backed examples. |

## Workflow

1. Define the activity and choose the activation surface.
2. Observe and configure the session before joining.
3. Add messaging or journal synchronization only if shared state is required.
4. Configure spatial coordination when the experience shares an immersive
   space.
5. Summarize the session lifecycle, sync model, and launch surface clearly.

## When To Switch Skills

- Switch to `build-run-debug` when the blocker is app launch, simulator state,
  or runtime debugging rather than SharePlay behavior.
- Switch to `signing-entitlements` when the issue is capabilities,
  entitlements, or privacy gating.
- Switch to `telemetry` when proof of event ordering or session state changes
  matters more than API design.

## Guardrails

- Keep `GroupActivity` data small and `Codable`.
- Join only after the UI and local state are ready.

## Output Expectations

Provide:
- the activity type and activation surface
- the chosen session and sync model
- which references were used
- the coordination model if immersive space is involved
- the next skill to use if the blocker is execution, signing, or testing