# Backend Handoff Checklist: Member App Channel

This checklist defines backend requirements for app-native member communication.

## Required Endpoints

1. `POST /member/channel/device/register`
2. `POST /member/channel/device/unregister`
3. `GET /member/channel/events`
4. `POST /member/channel/events/{event_id}/ack`

## Contract Source

1. `docs/api/member-channel.openapi.yaml`
2. `docs/api/examples/member-channel.examples.md`

## Deterministic Rules

1. Wallet session is mandatory for all channel calls.
2. Membership status must be active for event delivery.
3. Event ids and dedupe keys are immutable once emitted.
4. Event ordering is monotonic by server sequence.
5. `ack` is idempotent per `event_id` + `device_id`.

## Data Requirements

Persist at minimum:

1. Device channel binding (`wallet`, `device_id`, `platform`, `push_provider`, `push_token`)
2. Membership status snapshot at event emission time
3. Event envelope (`event_id`, class, title/body, payload, policy_hash, dedupe_key)
4. Delivery and ack timestamps

## Security Requirements

1. Rate limit register/events/ack paths.
2. Validate wallet in request matches authenticated session wallet.
3. Reject event polling for suspended/revoked memberships.
4. Protect against cursor tampering and replay.

## Observability Requirements

1. Counter metrics per event class emitted.
2. Counter metrics for successful/failed ack calls.
3. Channel registration churn metrics by platform.
4. Correlation id in all responses and logs.

## Done Criteria

1. App can register channel and poll events deterministically.
2. Push loss does not lose events because inbox polling is canonical.
3. Membership status changes immediately gate event visibility.
4. API behavior matches OpenAPI contract and examples.