# Gateway Dashboard Detailed Design

## Purpose

The gateway should host a basic web dashboard for operators and developers. The
dashboard is diagnostic and operational visibility only for v1. It should show
gateway health, active MXAccess worker instances, session state, and basic
statistics in real time.

## Technology Choice

Decision: Blazor Server with Bootstrap CSS/JS.

Allowed UI stack:

- ASP.NET Core Blazor Server,
- Bootstrap CSS,
- Bootstrap JavaScript,
- small local CSS for layout and status styling,
- built-in Blazor components.

Not allowed for v1:

- MudBlazor,
- Radzen,
- Syncfusion,
- Telerik,
- other Blazor UI component libraries,
- client-side SPA framework replacement.

Rationale: Blazor Server keeps the dashboard in the gateway process, avoids a
separate frontend build, and gives real-time UI updates through the Blazor
SignalR circuit. Bootstrap is sufficient for a basic dashboard.

## Hosting Model

The dashboard is hosted by `MxGateway.Server` alongside the gRPC API. When
`MxGateway:Dashboard:Enabled` is `true`, `MapGatewayDashboard()` maps the
configured `Dashboard:PathBase` to the Blazor Server app and maps the login,
logout, and access-denied HTTP endpoints beside it. When dashboard hosting is
disabled, those routes are not mapped.

Endpoint layout:

```text
/dashboard
/dashboard/sessions
/dashboard/sessions/{sessionId}
/dashboard/workers
/dashboard/events
/dashboard/settings
/dashboard/_blazor
```

The app should redirect `/` to `/dashboard` only if the deployment wants the
dashboard as the default web page. Otherwise leave gRPC/API hosting unaffected.

## High-Level Components

```text
MxGateway.Server
  Dashboard/
    Components/
      App.razor
      Routes.razor
      DashboardPageBase.cs
      DashboardDisplay.cs
      Layout/
        DashboardLayout.razor
      Pages/
        DashboardHome.razor
        SessionsPage.razor
        SessionDetailsPage.razor
        WorkersPage.razor
        EventsPage.razor
        SettingsPage.razor
      Shared/
        MetricCard.razor
        StatusBadge.razor
        FaultList.razor
    DashboardSnapshotService.cs
    DashboardAuthorizationHandler.cs
    DashboardAuthenticator.cs
    DashboardSnapshot.cs
    DashboardSessionSummary.cs
    DashboardWorkerSummary.cs
    DashboardMetricSummary.cs
```

Blazor Server provides the SignalR circuit for UI updates. The implementation
does not add a separate public dashboard hub.

## Dashboard Data Source

The dashboard should consume read-only snapshots from gateway services:

- `SessionRegistry`,
- `SessionManager`,
- `WorkerClient`,
- `GatewayMetrics`,
- health checks,
- structured fault/event counters.

Do not let Razor components directly mutate gateway session or worker objects.
Create a small read-only dashboard service that projects gateway state into
plain DTOs.

`GatewayMetrics.GetSnapshot()` is the metrics input for the first dashboard
projection. It carries current session and worker gauges, command and event
counters, queue depth, and fault totals. The dashboard reads that snapshot
instead of reading raw `Meter` instruments because exporter configuration is an
operations concern, not a UI dependency.

Suggested service:

```csharp
public interface IDashboardSnapshotService
{
    DashboardSnapshot GetSnapshot();
    IAsyncEnumerable<DashboardSnapshot> WatchSnapshotsAsync(
        CancellationToken cancellationToken);
}
```

Snapshot updates can be driven by:

- periodic timer, default every 1 second,
- session lifecycle notifications,
- worker heartbeat updates,
- event counter updates,
- fault notifications.

Use immutable snapshot DTOs so Razor components can render without locking
gateway internals.

## Realtime Updates

Use Blazor Server component state updates for real-time dashboard refresh.

Implemented pattern:

1. Page/component subscribes to `WatchSnapshotsAsync`.
2. Snapshot service emits updates from a bounded channel or timer.
3. Component stores the latest snapshot.
4. Component calls `InvokeAsync(StateHasChanged)`.
5. Component cancels subscription on dispose.

Default update cadence:

- periodic metrics refresh every 1 second,
- event counters update on the next snapshot tick.

Avoid pushing every MXAccess data-change event to the dashboard. Aggregate event
counts and rates instead.

## Pages

### Dashboard Home

Show top-level status:

- gateway status,
- gateway version,
- uptime,
- open sessions,
- workers running,
- sessions faulted,
- command rate,
- command failure count,
- event rate,
- event queue depth,
- worker restart/kill count.

Use Bootstrap cards for individual metric summaries. Keep the layout compact
and operational.

### Sessions Page

Show active and recent sessions in a table:

- session id,
- client identity or API key display name,
- state,
- backend,
- worker process id,
- open time,
- last client activity,
- last worker heartbeat,
- active event subscribers,
- pending commands,
- event queue depth,
- last fault summary.

Rows should link to session details.

### Session Details Page

Show:

- session metadata,
- worker metadata,
- command counters by method,
- event counters by family,
- active server handles and item counts if gateway shadow state has them,
- latest faults,
- last heartbeat payload,
- close/kill controls only if admin actions are later enabled.

For v1, details should be read-only unless an explicit admin action design is
added.

### Workers Page

Show:

- worker process id,
- session id,
- executable path/version,
- state,
- startup duration,
- memory and CPU if available,
- last heartbeat,
- current command correlation id,
- pending command count,
- event queue depth,
- restart/kill reason if terminal.

### Events Page

Show aggregate event diagnostics:

- event rate by session,
- event rate by event family,
- total events since start,
- queue overflow count,
- stream disconnect count,
- recent terminal faults.

Do not display full tag values by default. If value display is later added, make
it opt-in and redacted.

### Settings Page

Show read-only effective configuration:

- worker executable path,
- configured timeouts,
- queue capacities,
- auth mode,
- SQLite auth database path with sensitive parts redacted if needed,
- dashboard enabled state,
- protocol version.

Do not show API key secrets or pepper values.

## Authentication And Authorization

Dashboard access uses the same API-key authentication model as gRPC where
practical.

Implemented v1 behavior:

- when enabled, require API key auth,
- require `admin` scope for dashboard access,
- accept API key through a secure cookie established by a simple login form,
- do not put API keys in query strings,
- validate anti-forgery tokens for login and logout posts.

The implementation path is:

1. Add `/dashboard/login`.
2. User submits API key over HTTPS.
3. Gateway validates key and `admin` scope.
4. Gateway issues an HTTP-only secure auth cookie for the dashboard.
5. Dashboard pages require that cookie.
6. Logout clears the cookie.

For local development, allow an explicit `Dashboard:AllowAnonymousLocalhost`
option. It must default to false.

`DashboardAuthenticator` keeps API-key validation outside UI components. It
formats the submitted key as a bearer authorization header for
`IApiKeyVerifier`, rejects non-admin keys when `Dashboard:RequireAdminScope` is
enabled, and creates the dashboard cookie principal without storing raw API key
material. `DashboardAuthorizationHandler` enforces the cookie, admin-scope, and
explicit loopback bypass decisions for all protected dashboard routes.

## Configuration

Suggested configuration:

```json
{
  "MxGateway": {
    "Dashboard": {
      "Enabled": true,
      "PathBase": "/dashboard",
      "RequireAdminScope": true,
      "AllowAnonymousLocalhost": false,
      "SnapshotIntervalMilliseconds": 1000,
      "RecentFaultLimit": 100,
      "RecentSessionLimit": 200,
      "ShowTagValues": false
    }
  }
}
```

## Security Rules

- Do not display API key secrets.
- Do not display credential-bearing MXAccess command values.
- Do not display full tag values by default.
- Do not expose worker pipe names with nonce or sensitive details.
- Protect dashboard auth cookies with `HttpOnly`, `Secure`, and `SameSite`.
- Require TLS for remote dashboard access.
- Use anti-forgery protection for login/logout and any future admin actions.

## Styling

The dashboard serves Bootstrap 5.3.3 assets from
`src/MxGateway.Server/wwwroot/lib/bootstrap/` and local layout/status styling
from `src/MxGateway.Server/wwwroot/css/dashboard.css`.

Recommended visual language:

- compact tables,
- status badges,
- metric cards,
- Bootstrap alerts for faults,
- restrained colors,
- no decorative hero sections,
- no charting dependency for v1.

If charts are added later, prefer simple server-generated data tables first. Do
not add a JavaScript charting dependency without a specific need.

## Testing

Dashboard unit/component tests should cover:

- snapshot projection,
- dashboard auth authorization decisions,
- login API-key validation behavior,
- pages render with empty state,
- pages render with active sessions,
- pages render with faulted sessions,
- realtime subscription disposal,
- redaction of API keys and credential values.

Use bUnit if component testing is added. Otherwise keep the first tests focused
on snapshot services and authorization logic.

Integration tests should verify:

- dashboard disabled returns not found or configured fallback,
- dashboard requires auth when enabled,
- admin-scoped key can access dashboard,
- non-admin key is denied,
- live snapshot updates when a fake session changes state.

## Initial Implementation Slice

The first dashboard slice implements:

1. Blazor Server hosting in `MxGateway.Server`.
2. local Bootstrap static assets.
3. dashboard configuration binding.
4. dashboard auth using API key login and HTTP-only cookie.
5. read-only `DashboardSnapshotService`.
6. home page with metric cards.
7. sessions page with active session table and session details.
8. workers page with worker table.
9. events page with aggregate counters.
10. settings page with redacted effective configuration.
11. periodic realtime refresh through Blazor Server.
12. route-mapping tests, disabled-dashboard tests, auth tests, and snapshot
    projection/redaction tests.