Foundation for surfacing per-driver runtime state from the Server process to
the Admin UI. #152 shipped GetAutoProhibitedRanges() as an in-process
accessor; #154 makes it reachable across processes.
Server side (HealthEndpointsHost):
- New URL family: /diagnostics/drivers/{driverInstanceId}/{driverType}/{topic}
- First wired topic: /diagnostics/drivers/{id}/modbus/auto-prohibited
- Driver-agnostic at the URL level — future driver types add their own
segments[3] cases (e.g. /diagnostics/drivers/{id}/s7/dropped-pdus).
- 404 when the driver instance doesn't exist; 400 when the driver exists
but isn't a Modbus driver (the per-type endpoint is wrong for this row).
- Response shape is flat JSON (unitId / region / startAddress / endAddress /
lastProbedUtc / bisectionPending) so consumers don't have to reference the
Driver.Modbus assembly's ModbusAutoProhibition record.
- Re-uses the existing HttpListener bound to localhost:4841 — same auth /
reachability story as /healthz and /readyz.
Admin side:
- DriverDiagnosticsClient (Services/) — HttpClient wrapper that fetches the
per-driver Modbus prohibition list. Returns null on 404/400 (driver
missing or wrong type); throws on transport failures.
- ModbusAutoProhibitionsResponse + ModbusAutoProhibitionRow flat DTOs —
client doesn't take a dep on Driver.Modbus.
- ModbusDiagnostics.razor at /modbus/diagnostics/{driverInstanceId} —
table view with BISECTING (warning yellow) / ISOLATED (danger red)
badges, relative timestamps (e.g. "5m ago"), Refresh button. Errors
surface inline rather than swallowing.
- HttpClient registration in Program.cs reads
DriverDiagnostics:ServerBaseUrl from appsettings.json (default
http://localhost:4841/ for same-host deployments).
Tests (3 new in HealthEndpointsHostTests):
- Diagnostics_ReturnsModbusAutoProhibitions_ForLiveDriver — registers a
Modbus driver with a programmable transport that protects register 102,
records the prohibition via a coalesced ReadAsync, hits the endpoint,
asserts the returned JSON matches (unitId / region / start / end / pending).
- Diagnostics_404_When_Driver_Not_Found
- Diagnostics_400_When_Driver_Is_Wrong_Type
Architecture note: the Admin-side bUnit-style component test isn't included
because Admin.Tests doesn't have bUnit set up. The DriverDiagnosticsClient
is unit-testable on its own with a mock HandlerStub if needed — left as a
follow-up alongside the broader bUnit setup task.
The diagnostic page is now reachable at /modbus/diagnostics/{driverId} from
any Admin instance pointing at a Server endpoint URL. Future driver types
(S7, AbCip) plug into the same channel by adding their own URL segments
in HealthEndpointsHost.WriteDriverDiagnosticsAsync.
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