# chain_client_sdk (Dart)

gRPC client SDK for the Ch∆In hub. Used by F∆I Studio
(Tier-2 generic GUI) and any Tier-3 Dart/Flutter domain app
that wants to talk to a running `fai serve`.

One of the three SDK families documented in
`fai/platform/docs/architecture/sdks.md`:

  * `fai-module-sdk` (Rust) — flow modules
  * `fai-plugin-sdk` (Rust) — Studio plugins
  * `chain_client_sdk`  (Dart) — clients ← this package

Dir / repo carries the `_dart` / `-dart` language suffix
(`chain_client_sdk_dart` / `client-sdk-dart`); the Dart package
name itself does not (Dart-land doesn't need the suffix).

> **Status (2026-05-05):** scaffold. Public surface (`HubClient`,
> `HubEndpoint`) is committed; generated proto bindings land in
> a follow-up commit once the codegen step is wired in. Until
> then, downstream apps can compile against the stub and Studio
> uses mock data.

## Why a separate SDK package

The platform hub speaks gRPC. Each Dart consumer (Studio plus
each Tier-3 domain app) would otherwise re-generate proto
bindings independently and write near-identical client
boilerplate. This package centralises that work:

- One source of generated proto bindings.
- One typed `HubClient` wrapper with helpers.
- One place to bump when the wire protocol evolves.

## Layout

```
chain_client_sdk_dart/
├── lib/
│   ├── chain_client_sdk.dart        # Public API
│   └── src/
│       ├── hub_client.dart        # Typed client wrapper
│       ├── channel_factory_io.dart   # Native ClientChannel (HTTP/2)
│       ├── channel_factory_web.dart  # GrpcWebClientChannel.xhr (HTTP/1.1)
│       └── generated/             # protoc output (committed; pinned to platform tag)
├── tools/
│   └── generate.sh                # Wraps `protoc --dart_out=...` against ../fai_platform/proto
├── example/
└── pubspec.yaml
```

## Repo placement

Published as `fai/client-sdk-dart` on Forgejo
(`git.flemming.ai`).

## Versioning

Tracks the platform's wire-protocol version, not the platform
binary version. As long as `fai:platform@1.x` is current, this
SDK stays at `0.x` (will move to `1.0` once API stabilises);
when `fai:platform@2.0` lands, a `2.x` SDK ships in parallel
during the transition.