Push subscription setup ran synchronously inside the root widget build,
so an invalid subscription could replace the entire app with Flutter's
error surface. Push initialization and the cold-start native
notification read could also prevent the app from rendering.
Keep push work independent of the app subtree, observe asynchronous
persistence failures, and retain the original errors and stack traces.
Setup retries use bounded backoff; Settings shows a failure and offers
manual retry without resetting navigation. Retry preserves a healthy
revocation worker, and community-removal callbacks follow a recovered
worker so lease cleanup continues after setup recovery.
Related: [#8608](https://github.com/block/buzz/pull/8608) fixes the
specific unrelated-mute input that exposed this startup coupling.
### Validation
Added Flutter journeys cover invalid subscriptions, asynchronous storage
failure, dependency initialization failure, retry exhaustion and manual
recovery, navigation preservation, accessible retry actions, and
pending/failed native startup reads with notification-target recovery.
Both original rendering regressions failed before the fix.
Community-removal coverage also verifies cleanup after a worker
initialization failure and after retrying healthy setup; that regression
failed before the worker fix.
The full mobile suite passed (3,782 tests; 19 existing skips), as did
the four unconfigured-build tests and static analysis. The corrected
head also passed the full pre-push mobile checks and tests, plus 42
focused push and community tests. Rendered widget evidence uses mocked
native platform channels; no device APNs delivery test was performed.
Rendered Flutter widget evidence with synthetic data and mocked native
platform views.
### Setup failure
The app remains usable and Settings offers a retry after push
initialization fails.
### Recovery
Retry clears the error without replacing the navigator or leaving
Settings.
<!-- buzz-review-completed -->
---------
Signed-off-by: Tom Brow <tomb@block.xyz>
This PR implements MVP, iOS-only,
[NIP-PL](8d2d0ff5ad/docs/nips/NIP-PL.md)-compliant
push notifications.
A relay with `BUZZ_PUSH_ENABLED` will send a push notification for any
message that appears in the in-app Notifications tab.
## Enrollment flow
The first time the client first connects to a relay with
`BUZZ_PUSH_ENABLED`:
```mermaid
sequenceDiagram
autonumber
participant App as Buzz iOS app
participant iOS
participant Relay as Buzz relay
participant Attest as Apple App Attest
participant Gateway as Push gateway
App->>Relay: Fetch NIP-11 push capability
Relay-->>App: Push profile, current relay public key, and limits
par
App->>iOS: Request notification permission
iOS-->>App: Permission result
and
App->>iOS: Register for remote notifications
iOS-->>App: Device token
end
App->>Gateway: Request installation challenge
Gateway-->>App: Single-use challenge
App->>Attest: Attest installation transcript
Attest-->>App: Attestation proof
App->>Gateway: Enroll device token and proof
Gateway-->>App: Installation handle
App->>Gateway: Request delegation challenge
Gateway-->>App: Single-use challenge
App->>Attest: Assert relay-key delegation
Attest-->>App: Assertion
App->>Gateway: Create delegation
Gateway-->>App: Opaque endpoint grant
App->>Relay: Publish encrypted push lease and filters
Relay-->>App: Lease acknowledged
```
## Push-time flow
When a notification-eligible event is received by the relay:
```mermaid
%%{init: {
"sequence": {
"actorMargin": 20,
"width": 110,
"messageMargin": 18,
"diagramMarginX": 8,
"wrap": true
}
}}%%
sequenceDiagram
autonumber
participant Relay as Buzz relay
participant Gateway as Push gateway
participant APNs as Apple Push<br/>Notification service
participant iOS
participant NSE as Notification service<br/>extension
Relay->>Gateway: POST /v1/deliveries/apns<br/>opaque endpoint grant, request ID, expiry, NIP-98 authorization
Gateway->>APNs: POST /3/device/{device-token}<br/>topic, request ID, expiry, constant mutable-content payload
APNs-->>Gateway: 200 OK: request accepted
Gateway-->>Relay: 200 OK: accepted status
APNs-->>iOS: Notification: constant reconnect alert<br/>mutable-content = 1
iOS->>NSE: Invoke extension<br/>original notification content
NSE->>Relay: POST /query: subscription filters, limit 10<br/>NIP-98 authorization
Relay-->>NSE: 200 OK: signed Nostr events<br/>kinds 9, 40002, 45001, or 45003
NSE->>iOS: Complete notification: title, body, subtitle<br/>thread ID, exact-message target
```
relay → push gateway → APNs -> NSE -> Notification Center
## Known limitations
The APNs wake payload is intentionally constant and opaque: it contains
no originating community or message identifier, in keeping with the
implemented NIP-PL privacy design.
The Notification Service Extension must therefore reconnect to the relay
and resolve eligible messages after each wake. Around overlapping wakes,
timing boundaries, or resolution windows, notification presentation may
occasionally omit an expected message or display a message more than
once.
This best-effort behavior is deliberately accepted for the current
implementation and will be measured during the internal rollout to
determine whether the user experience is acceptable before any broader
deployment; the implementation does not claim exactly-once presentation.
## Validation
Live end-to-end hardware validation used an internal remotely hosted
development relay and push gateway, the APNs sandbox, and a physical
iPhone 12 mini:
- A second real Buzz client published a uniquely marked message through
the hosted relay.
- The relay matched the message and sent the constant opaque wake
through the hosted gateway. The gateway made an actual APNs request; no
`simctl push` or simulated notification was used.
- The iPhone received the notification on its lock screen. The
Notification Service Extension reconnected to the relay, fetched the
event, verified its ID and signature, and replaced the placeholder
content with the real notification title and body.
- After the app populated its shared presentation cache, a final marked
notification visibly showed the sender display name, sender avatar, and
hashtag-prefixed channel name.
- Tapping a lock-screen notification opened Buzz and exercised the
notification-response path and navigated to the corresponding message.
Final validation with a dogfood-signed artifact and production App
Attest/APNs configuration remains a release step.
## Independent pre-reviews
- **First pass:**
[Carl](buzz://message?channel=18882f4c-289f-41db-942f-81f6f8066da1&id=74ab9a93bb227f3e762568f1cf9fee66d7495b0edc3918735ff787238b9cc585)
found missing transient retries, executor-key rotation suppression,
duplicate installation renewal, and an unauthenticated challenge write
amplifier. These were resolved by [retry-safe
bootstrap](https://github.com/block/buzz/pull/6269/changes/12c66ea62)
and [authenticated renewal plus a cross-replica
quota](https://github.com/block/buzz/pull/6269/changes/8e5ece0bd).
[sol-max](buzz://message?channel=ad83385f-8e9e-4461-9a35-c1bf2e208532&id=d26d53daa4684669e2ed354638241f13f36c3a97027fe8b4dd738aff09038962)
found delegation generation burning and an edited applied migration,
resolved by [exact-generation
revocation](https://github.com/block/buzz/pull/6269/changes/c26d2159d)
and a [forward-only
migration](https://github.com/block/buzz/pull/6269/changes/956c1d099).
[k3-max](buzz://message?channel=5e46055d-a766-4065-ae25-05d1e4aaa6b2&id=d43139138a0b15f806cbdbeeedd8f69d992cadf2e805876db6fdde6a34c7eda1)
found no blockers.
- **Exact-head re-review:**
[Carl](buzz://message?channel=18882f4c-289f-41db-942f-81f6f8066da1&id=a897721673459301b0cf26e8b85a1478d7ebbb56a4621f93d774c98d395b8f68),
[sol-max](buzz://message?channel=ad83385f-8e9e-4461-9a35-c1bf2e208532&id=fb2159f709ec68f74f7b21459acd76da0e8a7c5c0f3d469f99826b0cc2380849),
and
[k3-max](buzz://message?channel=5e46055d-a766-4065-ae25-05d1e4aaa6b2&id=2ce2842910435f562e9d9cc718595848f281b122c94605e523a4b964254b8bfb)
independently returned **NO BLOCKERS** at `7eb3a650b`; k3-max also
revalidated every remediation and the endpoint-specific App Attest
enrollment bound.
---------
Signed-off-by: Tom Brow <tomb@squareup.com>
Signed-off-by: Tom Brow <tomb@block.xyz>
Co-authored-by: Tom Brow <tomb@squareup.com>
Co-authored-by: Codex <noreply@openai.com>
Co-authored-by: Jordan Mecom <jm@squareup.com>
Tom Brow
