A capability is a descriptor plus what the endpoint declares (device/Capability.ts), and its discovery object is
generated from the two. The new API is bridge.addDevice({ endpointId, name, categories, ... }) and
device.add(PowerController, options): both throw a DeclarationError that names the endpoint, the interface and
the instance (device/validate.ts), and leave the bridge and the device as they were. AlexaInterface is the same
Capability with the 1.x methods on it; it, ActionMapping and the enums moved to src/compat/, Device to src/device/.
What a 1.x caller can observe:
- every endpoint ends with { type: "AlexaInterface", interface: "Alexa", version: "3" } (alexa-interface.html);
new Alex2MQTT(..., { alexaInterface: false }) leaves it out
- the fields of a capability object come in the order of Amazon's examples; their content is unchanged
- addCapability() with a name that is not an interface throws (1.5.2 announced it with the version "UNKNOWN")
- ActionMapping takes the payload as an object; a JSON string is parsed (1.5.2 sent the string), any other throws
- what Alexa would reject in a 1.x declaration is not refused: device.check() lists it and the bridge logs each
line once, as "warning: ..." through the log hook, when it answers a discovery
- a device whose JSON cannot be built is left out of the answer and reported as an error event
- PowerController and EndpointHealth are the descriptors and keep ON/OFF and OK/UNREACHABLE; PowerState is new
Tests: six zoo devices declared the 1.x way give the JSON that Alexa accepted from 1.5.2 on 2026-09-28, plus the
Alexa capability. npm test: 85 pass (was 57) in 10-12 s, also on Node 18.20.8 and 20.20.2.
Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>
David
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