registry: describe an Alexa interface as data

src/registry/ holds what the library knows about an interface: namespace, version, the page it was read from,
properties with their value schemas and directives with their payload schemas. Five interfaces are described
(Alexa, PowerController, BrightnessController, TemperatureSensor, EndpointHealth); the other 65 names of
AlexaInterfaceType are stubs with the version and property names of 1.5.2. schema.ts is the run-time check behind
it (241 lines, no new dependency), catalog.ts the vocabularies of the pages: 103 assets (23 units), 6 actions,
9 states, 56 display categories, 22 reserved words, 73 error types under 11 namespaces.

AlexaInterface.getVersion() and getProps() read the registry; the two switch statements are gone (-167 lines).
On the wire: Alexa.EndpointHealth is announced at 3.1 (was 3.3; the page is titled 3.1 and no page mentions 3.3),
and TimeHoldController and Camera.LiveViewController at 3 and 1.7 (1.5.2 sent the string "UNKNOWN").
DisplayCategory gains VACUUM. New exports: registry, DeclarationError, SchemaError, Assets, Units, Actions,
States, DisplayCategories and the descriptor types.

Tests: 20 JSON examples of the five pages under test/fixtures/alexa-docs; every directive payload and property
value in them parses with its descriptor. npm test: 57 pass (was 30) in 10.8 s, also on Node 18.20.8 and 20.20.2.

Co-Authored-By: Claude Fable 5.1 <noreply@anthropic.com>

test/fixtures/types.ts

@@ -1,8 +1,14 @@
 // Compiled, never run (test/typings.test.js, npm run check): a CommonJS TypeScript consumer of the declarations in
 // dist/types, resolved through the package's "exports". A "@ts-expect-error" line fails the compile when the
 // declaration stops rejecting what follows it.
-import { ActionMapping, AlexaActions, AlexaInterfaceType, DisplayCategory, EndpointHealth, PowerController } from "alex2node";
-import type { Alex2MQTT, Alex2MQTTOptions, AlexaInterface, AlexaStatusMessage, ChangeCause, Device, SupportedMode } from "alex2node";
+import {
+  ActionMapping, AlexaActions, AlexaInterfaceType, Assets, DeclarationError, DisplayCategory, EndpointHealth, PowerController,
+  registry,
+} from "alex2node";
+import type {
+  Alex2MQTT, Alex2MQTTOptions, AlexaInterface, AlexaStatusMessage, AssetId, ChangeCause, Device, DisplayCategoryName, Infer,
+  InterfaceDescriptor, Schema, SupportedMode, Temperature, UnitOfMeasure,
+} from "alex2node";
 
 declare const bridge: Alex2MQTT;
 declare const message: AlexaStatusMessage;
@@ -33,4 +39,24 @@ const sent: Promise<string> = device.getChangeReport(cause).addPowerControllerPr
 // @ts-expect-error not a cause Alexa knows
 device.getChangeReport("BUTTON");
 
-export { options, added, chained, sent };
+// The registry: a descriptor by its namespace or by the 1.x enum member
+const described: InterfaceDescriptor = registry.get("Alexa.PowerController");
+const version: string = registry.get(AlexaInterfaceType.ENDPOINT_HEALTH).version;
+const refused: Error = new DeclarationError({ endpointId: "lamp-1", namespace: described.namespace }, "declared twice");
+
+// The vocabularies are unions of what the pages list
+const opening: AssetId = Assets[0];
+const percent: UnitOfMeasure = "Alexa.Unit.Percent";
+const vacuum: DisplayCategoryName = "VACUUM";
+// @ts-expect-error not in the global Alexa catalog
+const misspelt: AssetId = "Alexa.Setting.Openning";
+// @ts-expect-error an asset, but not a unit of measure
+const notAUnit: UnitOfMeasure = "Alexa.Setting.Opening";
+
+// A schema types what it parses
+declare const temperature: Schema<Temperature>;
+const measured: Infer<typeof temperature> = { value: 20, scale: "CELSIUS" };
+// @ts-expect-error not a temperature scale
+const rankine: Infer<typeof temperature> = { value: 20, scale: "RANKINE" };
+
+export { options, added, chained, sent, version, refused, opening, percent, vacuum, misspelt, notAUnit, measured, rankine };