# Solo desktop/mobile contract

The current Solo producer is **[block/buzz-app](https://github.com/block/buzz-app)**,
not the older `desktop/` client retained in this repository.

The captured producer revision is
[`64726576ed3b082daa5786e5e7ca6b5a018663a1`](https://github.com/block/buzz-app/commit/64726576ed3b082daa5786e5e7ca6b5a018663a1):

- [`SoloDraft.tsx`](https://github.com/block/buzz-app/blob/64726576ed3b082daa5786e5e7ca6b5a018663a1/src/features/solo/SoloDraft.tsx) calls `session.channelWrites.create`.
- [`channel-writes.ts`](https://github.com/block/buzz-app/blob/64726576ed3b082daa5786e5e7ca6b5a018663a1/src/features/relay/channel-writes.ts) emits kind 9007 with `channel_type=stream`, `visibility=private`, and `t=buzz.solo`. Its existing production-service test is “creates a Solo chat in its single durable outbox command” in `channel-writes.test.ts`.
- [`model.ts`](https://github.com/block/buzz-app/blob/64726576ed3b082daa5786e5e7ca6b5a018663a1/src/features/channel-templates/model.ts) retains project assignments but drops the legacy `groups.channels` discovery list.

The desktop does **not** author `P`. The relay derives the creator from the
signed creation event. In this repository, `channel_labels_from_tags` in
`crates/buzz-relay/src/handlers/side_effects.rs` parses creation labels;
`group_state_identity_tags` in `crates/buzz-core/src/channel.rs` emits the
leading type `t`, subsequent label `t` tags, and uppercase creator `P`.
`emit_group_discovery_events` uses that builder for relay metadata. Mobile reads those
facts through `ChannelData.fromEvent` and its channel providers.

## Reproducible contract coverage

`test-fixtures/solo-creation.json` contains an **actual captured production
create command**, plus expected relay identity tags using a synthetic creator.
To recapture it from a checkout of the pinned desktop revision:

```sh
node --experimental-transform-types scripts/contracts/capture-solo-creation.mjs /path/to/buzz-app > test-fixtures/solo-creation.json
```

The script invokes `createChannelWrites(...).create(...)` and captures its
outbox command without publishing anything. The core test
`desktop_solo_creation_preserves_mobile_identity_contract` feeds those command
labels through the production parser and relay identity builder. The mobile
regression “refresh replaces stale Solo details before opening and sending”
consumes the same identity tags through the real list/detail providers, primes
old details, refreshes, opens Solo, and sends through the personal sender with
an empty legacy chat list. Existing widget coverage checks project and unfiled
placement and shared-chat ordinary sending.

These are compositional contract tests, not a live desktop/relay/device E2E
run. Physical-device installation and launch alone do not prove that journey.