Devices: what your hardware can do
Plug hardware in and it appears as one or more devices. A device is a single source or control point — one UART, one GPIO pin, one I2C bus, one power rail. A USB-to-UART cable is one device; a power profiler, debug probe or multi-channel FTDI exposes several at once. Scryglass detects them as they're connected.
Channels: what your project needs
A channel describes data you want to capture, independent of any particular hardware. It's a named requirement that lives in your project:
Everything downstream works in channels: dashboards chart channels, recipes watch channels, captured data is stored by channel. A channel name is a role, not a pin number — it says what the signal means in your project.
Mapping ties them together
Before capturing, each channel is mapped to a device that satisfies it. Because the two are separate, the project travels: take it to another bench, map its channels to that bench's hardware, and every dashboard and trigger works unchanged.
A mapped device that isn't connected doesn't hold up the rest. Your other channels stream as normal, and the missing one comes online the moment its hardware appears.
