Diagnostic transport events

The EventBus can also report transport and controller diagnostics. These records are distinct from semantic frontend-operation events, but they inherit enclosing operation context when available.

Component	Events	Fields
io.Serial, io.USB, io.FTDI	io.read, io.write	transport payload details
Hamilton USB driver	firmware.command.started, .completed, .failed	issuing module, command, response or error details
Brooks PreciseFlex	precise_flex.firmware_command.started, .completed, .failed	controller device, command, response or error details

Use diagnostic records when controller-level or transport-level detail is needed. Semantic events remain the authoritative description of a public PLR operation.