# .NET Client Projects

The .NET client workspace contains the MXAccess Gateway client library, test
CLI, and unit tests.

## Projects

| Project | Purpose |
|---------|---------|
| `MxGateway.Client` | .NET 10 library entry point, raw gRPC calls, and session helpers. |
| `MxGateway.Client.Cli` | Test CLI for smoke and diagnostic commands. |
| `MxGateway.Client.Tests` | Unit tests for client options, generated contract wiring, auth metadata, session helpers, cancellation, and event streaming. |

The projects reference `src/MxGateway.Contracts/MxGateway.Contracts.csproj` so
the client compiles against the same generated protobuf and gRPC types as the
gateway. `clients/dotnet/generated` remains reserved for generator output if a
future client build switches to client-local `Grpc.Tools` generation.

## Build And Test

```powershell
dotnet build clients/dotnet/MxGateway.Client.sln
dotnet test clients/dotnet/MxGateway.Client.sln --no-build
```

## Client Usage

`MxGatewayClient` opens a gRPC channel to the gateway and attaches the API key
to every unary and streaming call as `authorization: Bearer <api-key>`.
Cancellation tokens passed to the public methods flow to the generated gRPC
call. Client-side cancellation stops waiting for the gateway response; it does
not abort an MXAccess COM call that is already executing inside a worker.

```csharp
await using MxGatewayClient client = MxGatewayClient.Create(
    new MxGatewayClientOptions
    {
        Endpoint = new Uri("http://localhost:5000"),
        ApiKey = apiKey,
    });

MxGatewaySession session = await client.OpenSessionAsync();
try
{
    int serverHandle = await session.RegisterAsync("sample-client");
    int itemHandle = await session.AddItemAsync(
        serverHandle,
        "Area001.Pump001.Speed");

    await session.AdviseAsync(serverHandle, itemHandle);
}
finally
{
    await session.CloseAsync();
}
```

Use `OpenSessionRawAsync`, `CloseSessionRawAsync`, `InvokeAsync`, and
`StreamEventsAsync` when tests or parity tools need direct generated protobuf
messages. `MxGatewaySession.OpenSessionReply` keeps the raw session-open reply
available, and command helpers have `*RawAsync` variants when callers need the
complete `MxCommandReply`.

`MxGatewaySession.CloseAsync` is explicit and idempotent. Repeated calls return
the first `CloseSessionReply` instead of sending another close request.

## Values, Status, And Errors

The client provides extension helpers for generated protobuf values. Use
`ToMxValue()` on .NET scalar values and typed arrays to create `MxValue`
instances for `Write` and `Write2`. Use `ToClrValue()` and
`GetProjectionKind()` when test or diagnostic code needs to inspect generated
`MxValue` replies while preserving `rawDiagnostic`, raw data type fields, and
raw byte payloads.

`MxStatusProxy.IsSuccess()` and `ToDiagnosticSummary()` expose MXAccess status
arrays without collapsing them into a single gateway success flag. Command
reply helpers follow the same split:

```csharp
reply.EnsureProtocolSuccess();
reply.EnsureMxAccessSuccess();
```

`EnsureProtocolSuccess()` raises gateway, session, worker, or command
exceptions for gateway-level failures. It leaves
`PROTOCOL_STATUS_CODE_MXACCESS_FAILURE` to `EnsureMxAccessSuccess()` so callers
can keep the full `MxCommandReply`, HRESULT, and status array when MXAccess
itself rejects a command. `MxAccessException.Reply` contains the raw generated
reply.

## CLI Usage

The test CLI supports deterministic JSON output for automation:

```powershell
dotnet run --project clients/dotnet/MxGateway.Client.Cli -- version --json
dotnet run --project clients/dotnet/MxGateway.Client.Cli -- open-session --endpoint http://localhost:5000 --api-key-env MXGATEWAY_API_KEY --json
dotnet run --project clients/dotnet/MxGateway.Client.Cli -- register --session-id <id> --client-name mxgw-dotnet-cli --json
dotnet run --project clients/dotnet/MxGateway.Client.Cli -- add-item --session-id <id> --server-handle 1 --item Area001.Pump001.Speed --json
dotnet run --project clients/dotnet/MxGateway.Client.Cli -- advise --session-id <id> --server-handle 1 --item-handle 1 --json
dotnet run --project clients/dotnet/MxGateway.Client.Cli -- write --session-id <id> --server-handle 1 --item-handle 1 --type int32 --value 123 --json
dotnet run --project clients/dotnet/MxGateway.Client.Cli -- write2 --session-id <id> --server-handle 1 --item-handle 1 --type int32 --value 123 --timestamp 2026-01-01T00:00:00Z --json
dotnet run --project clients/dotnet/MxGateway.Client.Cli -- stream-events --session-id <id> --max-events 1 --json
dotnet run --project clients/dotnet/MxGateway.Client.Cli -- smoke --endpoint http://localhost:5000 --api-key-env MXGATEWAY_API_KEY --item Area001.Pump001.Speed --json
```

`smoke` opens a session, registers a client, adds one item, advises it,
optionally writes a value when `--type` and `--value` are supplied, reads a
bounded event stream, and closes the session in a `finally` block. CLI error
output redacts API keys supplied through `--api-key`.