feat: add actions to FeedSource interface

Add listActions() and executeAction() to FeedSource for write
operations back to external services. Actions use arktype schemas
for input validation via StandardSchemaV1.

- ActionDefinition type with optional input schema
- FeedEngine routes actions with existence and ID validation
- Source IDs use reverse-domain format (aris.location, aris.tfl)
- LocationSource: update-location action with schema validation
- TflSource: set-lines-of-interest action with lineId validation
- No-op implementations for sources without actions

Co-authored-by: Ona <no-reply@ona.com>

packages/aris-source-location/package.json

@@ -8,6 +8,7 @@
 		"test": "bun test src/"
 	},
 	"dependencies": {
-		"@aris/core": "workspace:*"
+		"@aris/core": "workspace:*",
+		"arktype": "^2.1.0"
 	}
 }

packages/aris-source-location/src/index.ts

@@ -1,6 +1,2 @@
-export {
-	LocationSource,
-	LocationKey,
-	type Location,
-	type LocationSourceOptions,
-} from "./location-source.ts"
+export { LocationSource, LocationKey } from "./location-source.ts"
+export { Location, type LocationSourceOptions } from "./types.ts"

packages/aris-source-location/src/location-source.test.ts

@@ -16,7 +16,7 @@ describe("LocationSource", () => {
 	describe("FeedSource interface", () => {
 		test("has correct id", () => {
 			const source = new LocationSource()
-			expect(source.id).toBe("location")
+			expect(source.id).toBe("aris.location")
 		})
 
 		test("fetchItems always returns empty array", async () => {
@@ -147,4 +147,40 @@ describe("LocationSource", () => {
 			expect(listener2).toHaveBeenCalledTimes(1)
 		})
 	})
+
+	describe("actions", () => {
+		test("listActions returns update-location action", async () => {
+			const source = new LocationSource()
+			const actions = await source.listActions()
+
+			expect(actions["update-location"]).toBeDefined()
+			expect(actions["update-location"]!.id).toBe("update-location")
+			expect(actions["update-location"]!.input).toBeDefined()
+		})
+
+		test("executeAction update-location pushes location", async () => {
+			const source = new LocationSource()
+
+			expect(source.lastLocation).toBeNull()
+
+			const location = createLocation({ lat: 40.7128, lng: -74.006 })
+			await source.executeAction("update-location", location)
+
+			expect(source.lastLocation).toEqual(location)
+		})
+
+		test("executeAction throws on invalid input", async () => {
+			const source = new LocationSource()
+
+			await expect(
+				source.executeAction("update-location", { lat: "not a number" }),
+			).rejects.toThrow()
+		})
+
+		test("executeAction throws for unknown action", async () => {
+			const source = new LocationSource()
+
+			await expect(source.executeAction("nonexistent", {})).rejects.toThrow("Unknown action")
+		})
+	})
 })

packages/aris-source-location/src/location-source.ts

@@ -1,22 +1,9 @@
-import type { Context, FeedSource } from "@aris/core"
+import type { ActionDefinition, Context, FeedSource } from "@aris/core"
 
-import { contextKey, type ContextKey } from "@aris/core"
+import { UnknownActionError, contextKey, type ContextKey } from "@aris/core"
+import { type } from "arktype"
 
-/**
- * Geographic coordinates with accuracy and timestamp.
- */
-export interface Location {
-	lat: number
-	lng: number
-	/** Accuracy in meters */
-	accuracy: number
-	timestamp: Date
-}
-
-export interface LocationSourceOptions {
-	/** Number of locations to retain in history. Defaults to 1. */
-	historySize?: number
-}
+import { Location, type LocationSourceOptions } from "./types.ts"
 
 export const LocationKey: ContextKey<Location> = contextKey("location")
 
@@ -29,7 +16,7 @@ export const LocationKey: ContextKey<Location> = contextKey("location")
  * Does not produce feed items - always returns empty array from `fetchItems`.
  */
 export class LocationSource implements FeedSource {
-	readonly id = "location"
+	readonly id = "aris.location"
 
 	private readonly historySize: number
 	private locations: Location[] = []
@@ -39,6 +26,31 @@ export class LocationSource implements FeedSource {
 		this.historySize = options.historySize ?? 1
 	}
 
+	async listActions(): Promise<Record<string, ActionDefinition>> {
+		return {
+			"update-location": {
+				id: "update-location",
+				description: "Push a new location update",
+				input: Location,
+			},
+		}
+	}
+
+	async executeAction(actionId: string, params: unknown): Promise<void> {
+		switch (actionId) {
+			case "update-location": {
+				const result = Location(params)
+				if (result instanceof type.errors) {
+					throw new Error(result.summary)
+				}
+				this.pushLocation(result)
+				return
+			}
+			default:
+				throw new UnknownActionError(actionId)
+		}
+	}
+
 	/**
 	 * Push a new location update. Notifies all context listeners.
 	 */

packages/aris-source-location/src/types.ts

@@ -0,0 +1,17 @@
+import { type } from "arktype"
+
+/** Geographic coordinates with accuracy and timestamp. */
+export const Location = type({
+	lat: "number",
+	lng: "number",
+	/** Accuracy in meters */
+	accuracy: "number",
+	timestamp: "Date",
+})
+
+export type Location = typeof Location.infer
+
+export interface LocationSourceOptions {
+	/** Number of locations to retain in history. Defaults to 1. */
+	historySize?: number
+}