test(core): remove legacy integration tests

Tests were for DataSource/ContextProvider/ContextBridge which are now
deprecated in favor of FeedSource.

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

.oxfmtrc.json

@@ -8,5 +8,5 @@
 		"ignoreCase": true,
 		"newlinesBetween": true
 	},
-	"ignorePatterns": []
+	"ignorePatterns": [".claude", "fixtures"]
 }

AGENTS.md

@@ -0,0 +1,42 @@
+# AGENTS.md
+
+## Project
+
+ARIS is an AI-powered personal assistant that aggregates data from various sources into a contextual feed. Monorepo with `packages/` (shared libraries) and `apps/` (applications).
+
+## Commands
+
+- Install: `bun install`
+- Test: `bun test` (run in the specific package directory)
+- Lint: `bun run lint`
+- Format: `bun run format`
+- Type check: `bun tsc --noEmit`
+
+Use Bun exclusively. Do not use npm or yarn.
+
+## Code Style
+
+- File names: kebab-case (`data-source.ts`)
+- Prefer function declarations over arrow functions
+- Never use `any` - use `unknown` and narrow types
+- Enums: use const objects with corresponding types:
+  ```typescript
+  const Priority = {
+  	Low: "Low",
+  	High: "High",
+  } as const
+  type Priority = (typeof Priority)[keyof typeof Priority]
+  ```
+- File organization: types first, then primary functions, then helpers
+
+## Before Committing
+
+1. Format: `bun run format`
+2. Test the modified package: `cd packages/<package> && bun test`
+3. Fix all type errors related to your changes
+
+## Git
+
+- Branch: `feat/<task>`, `fix/<task>`, `ci/<task>`, etc.
+- Commits: conventional commit format, title <= 50 chars
+- Signing: If `GPG_PRIVATE_KEY_PASSPHRASE` env var is available, use it to sign commits with `git commit -S`

README.md

@@ -6,10 +6,25 @@ To install dependencies:
 bun install
 ```
 
-To run:
+## Packages
+
+### @aris/data-source-tfl
+
+TfL (Transport for London) data source for tube, overground, and Elizabeth line alerts.
+
+#### Testing
 
 ```bash
-bun run index.ts
+cd packages/aris-data-source-tfl
+bun run test
 ```
 
-This project was created using `bun init` in bun v1.3.6. [Bun](https://bun.com) is a fast all-in-one JavaScript runtime.
+#### Fixtures
+
+Tests use fixture data from real TfL API responses stored in `fixtures/tfl-responses.json`.
+
+To refresh fixtures:
+
+```bash
+bun run fetch-fixtures
+```

bun.lock

@@ -17,10 +17,34 @@
       "name": "@aris/core",
       "version": "0.0.0",
     },
+    "packages/aris-data-source-tfl": {
+      "name": "@aris/data-source-tfl",
+      "version": "0.0.0",
+      "dependencies": {
+        "@aris/core": "workspace:*",
+        "arktype": "^2.1.0",
+      },
+    },
+    "packages/aris-data-source-weatherkit": {
+      "name": "@aris/data-source-weatherkit",
+      "version": "0.0.0",
+      "dependencies": {
+        "@aris/core": "workspace:*",
+        "arktype": "^2.1.0",
+      },
+    },
   },
   "packages": {
     "@aris/core": ["@aris/core@workspace:packages/aris-core"],
 
+    "@aris/data-source-tfl": ["@aris/data-source-tfl@workspace:packages/aris-data-source-tfl"],
+
+    "@aris/data-source-weatherkit": ["@aris/data-source-weatherkit@workspace:packages/aris-data-source-weatherkit"],
+
+    "@ark/schema": ["@ark/schema@0.56.0", "", { "dependencies": { "@ark/util": "0.56.0" } }, "sha512-ECg3hox/6Z/nLajxXqNhgPtNdHWC9zNsDyskwO28WinoFEnWow4IsERNz9AnXRhTZJnYIlAJ4uGn3nlLk65vZA=="],
+
+    "@ark/util": ["@ark/util@0.56.0", "", {}, "sha512-BghfRC8b9pNs3vBoDJhcta0/c1J1rsoS1+HgVUreMFPdhz/CRAKReAu57YEllNaSy98rWAdY1gE+gFup7OXpgA=="],
+
     "@oxfmt/darwin-arm64": ["@oxfmt/darwin-arm64@0.24.0", "", { "os": "darwin", "cpu": "arm64" }, "sha512-aYXuGf/yq8nsyEcHindGhiz9I+GEqLkVq8CfPbd+6VE259CpPEH+CaGHEO1j6vIOmNr8KHRq+IAjeRO2uJpb8A=="],
 
     "@oxfmt/darwin-x64": ["@oxfmt/darwin-x64@0.24.0", "", { "os": "darwin", "cpu": "x64" }, "sha512-vs3b8Bs53hbiNvcNeBilzE/+IhDTWKjSBB3v/ztr664nZk65j0xr+5IHMBNz3CFppmX7o/aBta2PxY+t+4KoPg=="],
@@ -57,6 +81,10 @@
 
     "@types/node": ["@types/node@25.0.9", "", { "dependencies": { "undici-types": "~7.16.0" } }, "sha512-/rpCXHlCWeqClNBwUhDcusJxXYDjZTyE8v5oTO7WbL8eij2nKhUeU89/6xgjU7N4/Vh3He0BtyhJdQbDyhiXAw=="],
 
+    "arkregex": ["arkregex@0.0.5", "", { "dependencies": { "@ark/util": "0.56.0" } }, "sha512-ncYjBdLlh5/QnVsAA8De16Tc9EqmYM7y/WU9j+236KcyYNUXogpz3sC4ATIZYzzLxwI+0sEOaQLEmLmRleaEXw=="],
+
+    "arktype": ["arktype@2.1.29", "", { "dependencies": { "@ark/schema": "0.56.0", "@ark/util": "0.56.0", "arkregex": "0.0.5" } }, "sha512-jyfKk4xIOzvYNayqnD8ZJQqOwcrTOUbIU4293yrzAjA3O1dWh61j71ArMQ6tS/u4pD7vabSPe7nG3RCyoXW6RQ=="],
+
     "bun-types": ["bun-types@1.3.6", "", { "dependencies": { "@types/node": "*" } }, "sha512-OlFwHcnNV99r//9v5IIOgQ9Uk37gZqrNMCcqEaExdkVq3Avwqok1bJFmvGMCkCE0FqzdY8VMOZpfpR3lwI+CsQ=="],
 
     "oxfmt": ["oxfmt@0.24.0", "", { "dependencies": { "tinypool": "2.0.0" }, "optionalDependencies": { "@oxfmt/darwin-arm64": "0.24.0", "@oxfmt/darwin-x64": "0.24.0", "@oxfmt/linux-arm64-gnu": "0.24.0", "@oxfmt/linux-arm64-musl": "0.24.0", "@oxfmt/linux-x64-gnu": "0.24.0", "@oxfmt/linux-x64-musl": "0.24.0", "@oxfmt/win32-arm64": "0.24.0", "@oxfmt/win32-x64": "0.24.0" }, "bin": { "oxfmt": "bin/oxfmt" } }, "sha512-UjeM3Peez8Tl7IJ9s5UwAoZSiDRMww7BEc21gDYxLq3S3/KqJnM3mjNxsoSHgmBvSeX6RBhoVc2MfC/+96RdSw=="],

packages/aris-core/README.md

@@ -0,0 +1,186 @@
+# @aris/core
+
+Core orchestration layer for ARIS feed reconciliation.
+
+## Overview
+
+```mermaid
+flowchart TB
+    subgraph Sources["Feed Sources (Graph)"]
+        LS[Location Source]
+        WS[Weather Source]
+        TS[TFL Source]
+        CS[Calendar Source]
+    end
+
+    LS --> WS
+    LS --> TS
+
+    subgraph Controller["FeedController"]
+        direction TB
+        C1[Holds context]
+        C2[Manages source graph]
+        C3[Reconciles on update]
+        C4[Notifies subscribers]
+    end
+
+    Sources --> Controller
+    Controller --> Sub[Subscribers]
+```
+
+## Concepts
+
+### FeedSource
+
+A unified interface for sources that provide context and/or feed items. Sources form a dependency graph.
+
+```ts
+interface FeedSource<TItem extends FeedItem = FeedItem> {
+	readonly id: string
+	readonly dependencies?: readonly string[]
+
+	// Context production (optional)
+	onContextUpdate?(
+		callback: (update: Partial<Context>) => void,
+		getContext: () => Context,
+	): () => void
+	fetchContext?(context: Context): Promise<Partial<Context>>
+
+	// Feed item production (optional)
+	onItemsUpdate?(callback: (items: TItem[]) => void, getContext: () => Context): () => void
+	fetchItems?(context: Context): Promise<TItem[]>
+}
+```
+
+A source may:
+
+- Provide context for other sources (implement `fetchContext`/`onContextUpdate`)
+- Produce feed items (implement `fetchItems`/`onItemsUpdate`)
+- Both
+
+### Context Keys
+
+Each package exports typed context keys for type-safe access:
+
+```ts
+import { contextKey, type ContextKey } from "@aris/core"
+
+interface Location {
+	lat: number
+	lng: number
+}
+
+export const LocationKey: ContextKey<Location> = contextKey("location")
+```
+
+## Usage
+
+### Define a Context-Only Source
+
+```ts
+import type { FeedSource } from "@aris/core"
+
+const locationSource: FeedSource = {
+	id: "location",
+
+	onContextUpdate(callback, _getContext) {
+		const watchId = navigator.geolocation.watchPosition((pos) => {
+			callback({
+				[LocationKey]: { lat: pos.coords.latitude, lng: pos.coords.longitude },
+			})
+		})
+		return () => navigator.geolocation.clearWatch(watchId)
+	},
+
+	async fetchContext() {
+		const pos = await getCurrentPosition()
+		return {
+			[LocationKey]: { lat: pos.coords.latitude, lng: pos.coords.longitude },
+		}
+	},
+}
+```
+
+### Define a Source with Dependencies
+
+```ts
+import type { FeedSource, FeedItem } from "@aris/core"
+import { contextValue } from "@aris/core"
+
+type WeatherItem = FeedItem<"weather", { temp: number; condition: string }>
+
+const weatherSource: FeedSource<WeatherItem> = {
+	id: "weather",
+	dependencies: ["location"],
+
+	async fetchContext(context) {
+		const location = contextValue(context, LocationKey)
+		if (!location) return {}
+
+		const weather = await fetchWeatherApi(location)
+		return { [WeatherKey]: weather }
+	},
+
+	async fetchItems(context) {
+		const weather = contextValue(context, WeatherKey)
+		if (!weather) return []
+
+		return [
+			{
+				id: `weather-${Date.now()}`,
+				type: "weather",
+				priority: 0.5,
+				timestamp: new Date(),
+				data: { temp: weather.temp, condition: weather.condition },
+			},
+		]
+	},
+}
+```
+
+### Graph Behavior
+
+The source graph:
+
+1. Validates all dependencies exist
+2. Detects circular dependencies
+3. Topologically sorts sources
+
+On refresh:
+
+1. `fetchContext` runs in dependency order
+2. `fetchItems` runs on all sources
+3. Combined items returned to subscribers
+
+On reactive update:
+
+1. Source pushes context update via `onContextUpdate` callback
+2. Dependent sources re-run `fetchContext`
+3. Affected sources re-run `fetchItems`
+4. Subscribers notified
+
+## API
+
+### Context
+
+| Export                       | Description                             |
+| ---------------------------- | --------------------------------------- |
+| `ContextKey<T>`              | Branded type for type-safe context keys |
+| `contextKey<T>(key)`         | Creates a typed context key             |
+| `contextValue(context, key)` | Type-safe context value accessor        |
+| `Context`                    | Time + arbitrary key-value bag          |
+
+### Feed
+
+| Export                   | Description              |
+| ------------------------ | ------------------------ |
+| `FeedSource<TItem>`      | Unified source interface |
+| `FeedItem<TType, TData>` | Single item in the feed  |
+
+### Legacy (deprecated)
+
+| Export                       | Description              |
+| ---------------------------- | ------------------------ |
+| `DataSource<TItem, TConfig>` | Use `FeedSource` instead |
+| `ContextProvider<T>`         | Use `FeedSource` instead |
+| `ContextBridge`              | Use source graph instead |

packages/aris-core/context.ts

@@ -1,10 +0,0 @@
-export interface Location {
-	lat: number
-	lng: number
-	accuracy: number
-}
-
-export interface Context {
-	time: Date
-	location?: Location
-}

packages/aris-core/data-source.ts

@@ -1,7 +0,0 @@
-import type { Context } from "./context"
-import type { FeedItem } from "./feed"
-
-export interface DataSource<TItem extends FeedItem = FeedItem, TConfig = unknown> {
-	readonly type: TItem["type"]
-	query(context: Context, config: TConfig): Promise<TItem[]>
-}

packages/aris-core/feed.ts

@@ -1,10 +0,0 @@
-export interface FeedItem<
-	TType extends string = string,
-	TData extends Record<string, unknown> = Record<string, unknown>,
-> {
-	id: string
-	type: TType
-	priority: number
-	timestamp: Date
-	data: TData
-}

packages/aris-core/index.ts

@@ -1,5 +0,0 @@
-export type { Context, Location } from "./context"
-export type { FeedItem } from "./feed"
-export type { DataSource } from "./data-source"
-export type { ReconcilerConfig, ReconcileResult, SourceError } from "./reconciler"
-export { Reconciler } from "./reconciler"

packages/aris-core/reconciler.test.ts

@@ -1,240 +0,0 @@
-import { describe, expect, test } from "bun:test"
-
-import type { Context } from "./context"
-import type { DataSource } from "./data-source"
-import type { FeedItem } from "./feed"
-
-import { Reconciler } from "./reconciler"
-
-type WeatherData = { temp: number }
-type WeatherItem = FeedItem<"weather", WeatherData>
-
-type CalendarData = { title: string }
-type CalendarItem = FeedItem<"calendar", CalendarData>
-
-const createMockContext = (): Context => ({
-	time: new Date("2026-01-15T12:00:00Z"),
-})
-
-const createWeatherSource = (items: WeatherItem[], delay = 0): DataSource<WeatherItem> => ({
-	type: "weather",
-	async query() {
-		if (delay > 0) {
-			await new Promise((resolve) => setTimeout(resolve, delay))
-		}
-		return items
-	},
-})
-
-const createCalendarSource = (items: CalendarItem[]): DataSource<CalendarItem> => ({
-	type: "calendar",
-	async query() {
-		return items
-	},
-})
-
-const createFailingSource = (type: string, error: Error): DataSource<FeedItem> => ({
-	type,
-	async query() {
-		throw error
-	},
-})
-
-describe("Reconciler", () => {
-	test("returns empty result when no sources registered", async () => {
-		const reconciler = new Reconciler()
-		const result = await reconciler.reconcile(createMockContext())
-
-		expect(result.items).toEqual([])
-		expect(result.errors).toEqual([])
-	})
-
-	test("collects items from single source", async () => {
-		const items: WeatherItem[] = [
-			{
-				id: "weather-1",
-				type: "weather",
-				priority: 0.5,
-				timestamp: new Date(),
-				data: { temp: 20 },
-			},
-		]
-
-		const reconciler = new Reconciler().register(createWeatherSource(items))
-		const result = await reconciler.reconcile(createMockContext())
-
-		expect(result.items).toEqual(items)
-		expect(result.errors).toEqual([])
-	})
-
-	test("collects items from multiple sources", async () => {
-		const weatherItems: WeatherItem[] = [
-			{
-				id: "weather-1",
-				type: "weather",
-				priority: 0.5,
-				timestamp: new Date(),
-				data: { temp: 20 },
-			},
-		]
-
-		const calendarItems: CalendarItem[] = [
-			{
-				id: "calendar-1",
-				type: "calendar",
-				priority: 0.8,
-				timestamp: new Date(),
-				data: { title: "Meeting" },
-			},
-		]
-
-		const reconciler = new Reconciler()
-			.register(createWeatherSource(weatherItems))
-			.register(createCalendarSource(calendarItems))
-
-		const result = await reconciler.reconcile(createMockContext())
-
-		expect(result.items).toHaveLength(2)
-		expect(result.errors).toEqual([])
-	})
-
-	test("sorts items by priority descending", async () => {
-		const weatherItems: WeatherItem[] = [
-			{
-				id: "weather-1",
-				type: "weather",
-				priority: 0.2,
-				timestamp: new Date(),
-				data: { temp: 20 },
-			},
-		]
-
-		const calendarItems: CalendarItem[] = [
-			{
-				id: "calendar-1",
-				type: "calendar",
-				priority: 0.9,
-				timestamp: new Date(),
-				data: { title: "Meeting" },
-			},
-		]
-
-		const reconciler = new Reconciler()
-			.register(createWeatherSource(weatherItems))
-			.register(createCalendarSource(calendarItems))
-
-		const result = await reconciler.reconcile(createMockContext())
-
-		expect(result.items[0]?.id).toBe("calendar-1")
-		expect(result.items[1]?.id).toBe("weather-1")
-	})
-
-	test("captures errors from failing sources", async () => {
-		const error = new Error("Source failed")
-
-		const reconciler = new Reconciler().register(createFailingSource("failing", error))
-
-		const result = await reconciler.reconcile(createMockContext())
-
-		expect(result.items).toEqual([])
-		expect(result.errors).toHaveLength(1)
-		expect(result.errors[0]?.sourceType).toBe("failing")
-		expect(result.errors[0]?.error.message).toBe("Source failed")
-	})
-
-	test("returns partial results when some sources fail", async () => {
-		const items: WeatherItem[] = [
-			{
-				id: "weather-1",
-				type: "weather",
-				priority: 0.5,
-				timestamp: new Date(),
-				data: { temp: 20 },
-			},
-		]
-
-		const reconciler = new Reconciler()
-			.register(createWeatherSource(items))
-			.register(createFailingSource("failing", new Error("Failed")))
-
-		const result = await reconciler.reconcile(createMockContext())
-
-		expect(result.items).toHaveLength(1)
-		expect(result.errors).toHaveLength(1)
-	})
-
-	test("times out slow sources", async () => {
-		const items: WeatherItem[] = [
-			{
-				id: "weather-1",
-				type: "weather",
-				priority: 0.5,
-				timestamp: new Date(),
-				data: { temp: 20 },
-			},
-		]
-
-		const reconciler = new Reconciler({ timeout: 50 }).register(createWeatherSource(items, 100))
-
-		const result = await reconciler.reconcile(createMockContext())
-
-		expect(result.items).toEqual([])
-		expect(result.errors).toHaveLength(1)
-		expect(result.errors[0]?.sourceType).toBe("weather")
-		expect(result.errors[0]?.error.message).toContain("timed out")
-	})
-
-	test("unregister removes source", async () => {
-		const items: WeatherItem[] = [
-			{
-				id: "weather-1",
-				type: "weather",
-				priority: 0.5,
-				timestamp: new Date(),
-				data: { temp: 20 },
-			},
-		]
-
-		const reconciler = new Reconciler().register(createWeatherSource(items)).unregister("weather")
-
-		const result = await reconciler.reconcile(createMockContext())
-		expect(result.items).toEqual([])
-	})
-
-	test("infers discriminated union type from chained registers", async () => {
-		const weatherItems: WeatherItem[] = [
-			{
-				id: "weather-1",
-				type: "weather",
-				priority: 0.5,
-				timestamp: new Date(),
-				data: { temp: 20 },
-			},
-		]
-
-		const calendarItems: CalendarItem[] = [
-			{
-				id: "calendar-1",
-				type: "calendar",
-				priority: 0.8,
-				timestamp: new Date(),
-				data: { title: "Meeting" },
-			},
-		]
-
-		const reconciler = new Reconciler()
-			.register(createWeatherSource(weatherItems))
-			.register(createCalendarSource(calendarItems))
-
-		const { items } = await reconciler.reconcile(createMockContext())
-
-		// Type narrowing should work
-		for (const item of items) {
-			if (item.type === "weather") {
-				expect(typeof item.data.temp).toBe("number")
-			} else if (item.type === "calendar") {
-				expect(typeof item.data.title).toBe("string")
-			}
-		}
-	})
-})

packages/aris-core/src/context-bridge.ts

@@ -0,0 +1,102 @@
+import type { Context } from "./context"
+import type { ContextProvider } from "./context-provider"
+
+interface ContextUpdatable {
+	pushContextUpdate(update: Partial<Context>): void
+}
+
+export interface ProviderError {
+	key: string
+	error: Error
+}
+
+export interface RefreshResult {
+	errors: ProviderError[]
+}
+
+/**
+ * Bridges context providers to a feed controller.
+ *
+ * Subscribes to provider updates and forwards them to the controller.
+ * Supports manual refresh to gather current values from all providers.
+ *
+ * @example
+ * ```ts
+ * const controller = new FeedController()
+ *   .addDataSource(new WeatherDataSource())
+ *   .addDataSource(new TflDataSource())
+ *
+ * const bridge = new ContextBridge(controller)
+ *   .addProvider(new LocationProvider())
+ *   .addProvider(new MusicProvider())
+ *
+ * // Manual refresh gathers from all providers
+ * await bridge.refresh()
+ *
+ * // Cleanup
+ * bridge.stop()
+ * controller.stop()
+ * ```
+ */
+export class ContextBridge {
+	private controller: ContextUpdatable
+	private providers = new Map<string, ContextProvider>()
+	private cleanups: Array<() => void> = []
+
+	constructor(controller: ContextUpdatable) {
+		this.controller = controller
+	}
+
+	/**
+	 * Registers a context provider. Immediately subscribes to updates.
+	 */
+	addProvider<T>(provider: ContextProvider<T>): this {
+		this.providers.set(provider.key, provider as ContextProvider)
+
+		const cleanup = provider.onUpdate((value) => {
+			this.controller.pushContextUpdate({ [provider.key]: value })
+		})
+		this.cleanups.push(cleanup)
+
+		return this
+	}
+
+	/**
+	 * Gathers current values from all providers and pushes to controller.
+	 * Use for manual refresh when user pulls to refresh.
+	 * Returns errors from providers that failed to fetch.
+	 */
+	async refresh(): Promise<RefreshResult> {
+		const updates: Partial<Context> = {}
+		const errors: ProviderError[] = []
+
+		const entries = Array.from(this.providers.entries())
+		const results = await Promise.allSettled(
+			entries.map(([_, provider]) => provider.fetchCurrentValue()),
+		)
+
+		entries.forEach(([key], i) => {
+			const result = results[i]
+			if (result?.status === "fulfilled") {
+				updates[key] = result.value
+			} else if (result?.status === "rejected") {
+				errors.push({
+					key,
+					error: result.reason instanceof Error ? result.reason : new Error(String(result.reason)),
+				})
+			}
+		})
+
+		this.controller.pushContextUpdate(updates)
+
+		return { errors }
+	}
+
+	/**
+	 * Unsubscribes from all providers.
+	 */
+	stop(): void {
+		this.cleanups.forEach((cleanup) => cleanup())
+		this.cleanups = []
+	}
+}

packages/aris-core/src/context-provider.ts

@@ -0,0 +1,35 @@
+/**
+ * Provides context values reactively and on-demand.
+ *
+ * Implementations push updates when values change (reactive) and
+ * return current values when requested (for manual refresh).
+ *
+ * @example
+ * ```ts
+ * class LocationProvider implements ContextProvider<Location> {
+ *   readonly key = LocationKey
+ *
+ *   onUpdate(callback: (value: Location) => void): () => void {
+ *     const watchId = navigator.geolocation.watchPosition(pos => {
+ *       callback({ lat: pos.coords.latitude, lng: pos.coords.longitude, accuracy: pos.coords.accuracy })
+ *     })
+ *     return () => navigator.geolocation.clearWatch(watchId)
+ *   }
+ *
+ *   async fetchCurrentValue(): Promise<Location> {
+ *     const pos = await getCurrentPosition()
+ *     return { lat: pos.coords.latitude, lng: pos.coords.longitude, accuracy: pos.coords.accuracy }
+ *   }
+ * }
+ * ```
+ */
+export interface ContextProvider<T = unknown> {
+	/** The context key this provider populates */
+	readonly key: string
+
+	/** Subscribe to value changes. Returns cleanup function. */
+	onUpdate(callback: (value: T) => void): () => void
+
+	/** Fetch current value on-demand (used for manual refresh). */
+	fetchCurrentValue(): Promise<T>
+}

packages/aris-core/src/context.ts

@@ -0,0 +1,46 @@
+/**
+ * Branded type for type-safe context keys.
+ *
+ * Each package defines its own keys with associated value types:
+ * ```ts
+ * const LocationKey: ContextKey<Location> = contextKey("location")
+ * ```
+ */
+export type ContextKey<T> = string & { __contextValue?: T }
+
+/**
+ * Creates a typed context key.
+ *
+ * @example
+ * ```ts
+ * interface Location { lat: number; lng: number; accuracy: number }
+ * const LocationKey: ContextKey<Location> = contextKey("location")
+ * ```
+ */
+export function contextKey<T>(key: string): ContextKey<T> {
+	return key as ContextKey<T>
+}
+
+/**
+ * Type-safe accessor for context values.
+ *
+ * @example
+ * ```ts
+ * const location = contextValue(context, LocationKey)
+ * if (location) {
+ *   console.log(location.lat, location.lng)
+ * }
+ * ```
+ */
+export function contextValue<T>(context: Context, key: ContextKey<T>): T | undefined {
+	return context[key] as T | undefined
+}
+
+/**
+ * Arbitrary key-value bag representing the current state.
+ * Always includes `time`. Other keys are added by context providers.
+ */
+export interface Context {
+	time: Date
+	[key: string]: unknown
+}

packages/aris-core/src/data-source.ts

@@ -0,0 +1,35 @@
+import type { Context } from "./context"
+import type { FeedItem } from "./feed"
+
+/**
+ * Produces feed items from an external source.
+ *
+ * @example
+ * ```ts
+ * type WeatherItem = FeedItem<"weather", { temp: number }>
+ *
+ * class WeatherDataSource implements DataSource<WeatherItem> {
+ *   readonly type = "weather"
+ *
+ *   async query(context: Context): Promise<WeatherItem[]> {
+ *     const location = contextValue(context, LocationKey)
+ *     if (!location) return []
+ *     const data = await fetchWeather(location)
+ *     return [{
+ *       id: `weather-${Date.now()}`,
+ *       type: this.type,
+ *       priority: 0.5,
+ *       timestamp: context.time,
+ *       data: { temp: data.temperature },
+ *     }]
+ *   }
+ * }
+ * ```
+ */
+export interface DataSource<TItem extends FeedItem = FeedItem, TConfig = unknown> {
+	/** Unique identifier for this source type */
+	readonly type: TItem["type"]
+
+	/** Queries the source and returns feed items */
+	query(context: Context, config: TConfig): Promise<TItem[]>
+}

packages/aris-core/src/feed-controller.ts

@@ -0,0 +1,161 @@
+import type { Context } from "./context"
+import type { DataSource } from "./data-source"
+import type { FeedItem } from "./feed"
+import type { ReconcileResult } from "./reconciler"
+
+import { Reconciler } from "./reconciler"
+
+export interface FeedControllerConfig {
+	/** Timeout for each data source query in milliseconds */
+	timeout?: number
+	/** Debounce window for batching context updates (default: 100ms) */
+	debounceMs?: number
+	/** Initial context state */
+	initialContext?: Context
+}
+
+export type FeedSubscriber<TItems extends FeedItem> = (result: ReconcileResult<TItems>) => void
+
+interface RegisteredSource {
+	source: DataSource<FeedItem, unknown>
+	config: unknown
+}
+
+const DEFAULT_DEBOUNCE_MS = 100
+
+/**
+ * Orchestrates feed reconciliation in response to context updates.
+ *
+ * Holds context state, debounces updates, queries data sources, and
+ * notifies subscribers. Each user should have their own instance.
+ *
+ * @example
+ * ```ts
+ * const controller = new FeedController({ debounceMs: 100 })
+ *   .addDataSource(new WeatherDataSource())
+ *   .addDataSource(new TflDataSource())
+ *
+ * controller.subscribe((result) => {
+ *   console.log(result.items)
+ * })
+ *
+ * // Context update triggers debounced reconcile
+ * controller.pushContextUpdate({ [LocationKey]: location })
+ *
+ * // Direct reconcile (no debounce)
+ * const result = await controller.reconcile()
+ *
+ * // Cleanup
+ * controller.stop()
+ * ```
+ */
+export class FeedController<TItems extends FeedItem = never> {
+	private sources = new Map<string, RegisteredSource>()
+	private subscribers = new Set<FeedSubscriber<TItems>>()
+	private context: Context
+	private debounceMs: number
+	private timeout: number | undefined
+	private pendingTimeout: ReturnType<typeof setTimeout> | null = null
+	private stopped = false
+
+	constructor(config?: FeedControllerConfig) {
+		this.context = config?.initialContext ?? { time: new Date() }
+		this.debounceMs = config?.debounceMs ?? DEFAULT_DEBOUNCE_MS
+		this.timeout = config?.timeout
+	}
+
+	/** Registers a data source. */
+	addDataSource<TItem extends FeedItem, TConfig>(
+		source: DataSource<TItem, TConfig>,
+		config?: TConfig,
+	): FeedController<TItems | TItem> {
+		this.sources.set(source.type, {
+			source: source as DataSource<FeedItem, unknown>,
+			config,
+		})
+		return this as FeedController<TItems | TItem>
+	}
+
+	/** Removes a data source by type. */
+	removeDataSource<T extends TItems["type"]>(
+		sourceType: T,
+	): FeedController<Exclude<TItems, { type: T }>> {
+		this.sources.delete(sourceType)
+		return this as unknown as FeedController<Exclude<TItems, { type: T }>>
+	}
+
+	/** Stops the controller and cancels pending reconciles. */
+	stop(): void {
+		this.stopped = true
+
+		if (this.pendingTimeout) {
+			clearTimeout(this.pendingTimeout)
+			this.pendingTimeout = null
+		}
+	}
+
+	/** Merges update into context and schedules a debounced reconcile. */
+	pushContextUpdate(update: Partial<Context>): void {
+		this.context = { ...this.context, ...update, time: new Date() }
+		this.scheduleReconcile()
+	}
+
+	/** Subscribes to feed updates. Returns unsubscribe function. */
+	subscribe(callback: FeedSubscriber<TItems>): () => void {
+		this.subscribers.add(callback)
+
+		return () => {
+			this.subscribers.delete(callback)
+		}
+	}
+
+	/** Immediately reconciles with current or provided context. */
+	async reconcile(context?: Context): Promise<ReconcileResult<TItems>> {
+		const ctx = context ?? this.context
+		const reconciler = this.createReconciler()
+		return reconciler.reconcile(ctx)
+	}
+
+	/** Returns current context. */
+	getContext(): Context {
+		return this.context
+	}
+
+	private scheduleReconcile(): void {
+		if (this.pendingTimeout) return
+
+		this.pendingTimeout = setTimeout(() => {
+			this.flushPending()
+		}, this.debounceMs)
+	}
+
+	private async flushPending(): Promise<void> {
+		this.pendingTimeout = null
+
+		if (this.stopped) return
+		if (this.sources.size === 0) return
+
+		const reconciler = this.createReconciler()
+		const result = await reconciler.reconcile(this.context)
+
+		this.notifySubscribers(result)
+	}
+
+	private createReconciler(): Reconciler<TItems> {
+		const reconciler = new Reconciler<TItems>({ timeout: this.timeout })
+		Array.from(this.sources.values()).forEach(({ source, config }) => {
+			reconciler.register(source, config)
+		})
+		return reconciler as Reconciler<TItems>
+	}
+
+	private notifySubscribers(result: ReconcileResult<TItems>): void {
+		this.subscribers.forEach((callback) => {
+			try {
+				callback(result)
+			} catch {
+				// Subscriber errors shouldn't break other subscribers
+			}
+		})
+	}
+}

packages/aris-core/src/feed-source.test.ts

@@ -0,0 +1,422 @@
+import { describe, expect, test } from "bun:test"
+
+import type { Context, ContextKey, FeedItem, FeedSource } from "./index"
+
+import { contextKey, contextValue } from "./index"
+
+// =============================================================================
+// CONTEXT KEYS
+// =============================================================================
+
+interface Location {
+	lat: number
+	lng: number
+}
+
+interface Weather {
+	temperature: number
+	condition: string
+}
+
+const LocationKey: ContextKey<Location> = contextKey("location")
+const WeatherKey: ContextKey<Weather> = contextKey("weather")
+
+// =============================================================================
+// FEED ITEMS
+// =============================================================================
+
+type WeatherFeedItem = FeedItem<"weather", { temperature: number; condition: string }>
+type AlertFeedItem = FeedItem<"alert", { message: string }>
+
+// =============================================================================
+// TEST HELPERS
+// =============================================================================
+
+interface SimulatedLocationSource extends FeedSource {
+	simulateUpdate(location: Location): void
+}
+
+function createLocationSource(): SimulatedLocationSource {
+	let callback: ((update: Partial<Context>) => void) | null = null
+	let currentLocation: Location = { lat: 0, lng: 0 }
+
+	return {
+		id: "location",
+
+		onContextUpdate(cb) {
+			callback = cb
+			return () => {
+				callback = null
+			}
+		},
+
+		async fetchContext() {
+			return { [LocationKey]: currentLocation }
+		},
+
+		simulateUpdate(location: Location) {
+			currentLocation = location
+			callback?.({ [LocationKey]: location })
+		},
+	}
+}
+
+function createWeatherSource(
+	fetchWeather: (location: Location) => Promise<Weather> = async () => ({
+		temperature: 20,
+		condition: "sunny",
+	}),
+): FeedSource<WeatherFeedItem> {
+	return {
+		id: "weather",
+		dependencies: ["location"],
+
+		async fetchContext(context) {
+			const location = contextValue(context, LocationKey)
+			if (!location) return {}
+
+			const weather = await fetchWeather(location)
+			return { [WeatherKey]: weather }
+		},
+
+		async fetchItems(context) {
+			const weather = contextValue(context, WeatherKey)
+			if (!weather) return []
+
+			return [
+				{
+					id: `weather-${Date.now()}`,
+					type: "weather",
+					priority: 0.5,
+					timestamp: new Date(),
+					data: {
+						temperature: weather.temperature,
+						condition: weather.condition,
+					},
+				},
+			]
+		},
+	}
+}
+
+function createAlertSource(): FeedSource<AlertFeedItem> {
+	return {
+		id: "alert",
+		dependencies: ["weather"],
+
+		async fetchItems(context) {
+			const weather = contextValue(context, WeatherKey)
+			if (!weather) return []
+
+			if (weather.condition === "storm") {
+				return [
+					{
+						id: "alert-storm",
+						type: "alert",
+						priority: 1.0,
+						timestamp: new Date(),
+						data: { message: "Storm warning!" },
+					},
+				]
+			}
+
+			return []
+		},
+	}
+}
+
+// =============================================================================
+// GRAPH SIMULATION (until FeedController is updated)
+// =============================================================================
+
+interface SourceGraph {
+	sources: Map<string, FeedSource>
+	sorted: FeedSource[]
+	dependents: Map<string, string[]>
+}
+
+function buildGraph(sources: FeedSource[]): SourceGraph {
+	const byId = new Map<string, FeedSource>()
+	for (const source of sources) {
+		byId.set(source.id, source)
+	}
+
+	// Validate dependencies exist
+	for (const source of sources) {
+		for (const dep of source.dependencies ?? []) {
+			if (!byId.has(dep)) {
+				throw new Error(`Source "${source.id}" depends on "${dep}" which is not registered`)
+			}
+		}
+	}
+
+	// Check for cycles and topologically sort
+	const visited = new Set<string>()
+	const visiting = new Set<string>()
+	const sorted: FeedSource[] = []
+
+	function visit(id: string, path: string[]): void {
+		if (visiting.has(id)) {
+			const cycle = [...path.slice(path.indexOf(id)), id].join(" → ")
+			throw new Error(`Circular dependency detected: ${cycle}`)
+		}
+		if (visited.has(id)) return
+
+		visiting.add(id)
+		const source = byId.get(id)!
+		for (const dep of source.dependencies ?? []) {
+			visit(dep, [...path, id])
+		}
+		visiting.delete(id)
+		visited.add(id)
+		sorted.push(source)
+	}
+
+	for (const source of sources) {
+		visit(source.id, [])
+	}
+
+	// Build reverse dependency map
+	const dependents = new Map<string, string[]>()
+	for (const source of sources) {
+		for (const dep of source.dependencies ?? []) {
+			const list = dependents.get(dep) ?? []
+			list.push(source.id)
+			dependents.set(dep, list)
+		}
+	}
+
+	return { sources: byId, sorted, dependents }
+}
+
+async function refreshGraph(graph: SourceGraph): Promise<{ context: Context; items: FeedItem[] }> {
+	let context: Context = { time: new Date() }
+
+	// Run fetchContext in topological order
+	for (const source of graph.sorted) {
+		if (source.fetchContext) {
+			const update = await source.fetchContext(context)
+			context = { ...context, ...update }
+		}
+	}
+
+	// Run fetchItems on all sources
+	const items: FeedItem[] = []
+	for (const source of graph.sorted) {
+		if (source.fetchItems) {
+			const sourceItems = await source.fetchItems(context)
+			items.push(...sourceItems)
+		}
+	}
+
+	// Sort by priority descending
+	items.sort((a, b) => b.priority - a.priority)
+
+	return { context, items }
+}
+
+// =============================================================================
+// TESTS
+// =============================================================================
+
+describe("FeedSource", () => {
+	describe("interface", () => {
+		test("source with only context production", () => {
+			const source = createLocationSource()
+
+			expect(source.id).toBe("location")
+			expect(source.dependencies).toBeUndefined()
+			expect(source.fetchContext).toBeDefined()
+			expect(source.onContextUpdate).toBeDefined()
+			expect(source.fetchItems).toBeUndefined()
+		})
+
+		test("source with dependencies and both context and items", () => {
+			const source = createWeatherSource()
+
+			expect(source.id).toBe("weather")
+			expect(source.dependencies).toEqual(["location"])
+			expect(source.fetchContext).toBeDefined()
+			expect(source.fetchItems).toBeDefined()
+		})
+
+		test("source with only item production", () => {
+			const source = createAlertSource()
+
+			expect(source.id).toBe("alert")
+			expect(source.dependencies).toEqual(["weather"])
+			expect(source.fetchContext).toBeUndefined()
+			expect(source.fetchItems).toBeDefined()
+		})
+	})
+
+	describe("graph validation", () => {
+		test("validates all dependencies exist", () => {
+			const orphan: FeedSource = {
+				id: "orphan",
+				dependencies: ["nonexistent"],
+			}
+
+			expect(() => buildGraph([orphan])).toThrow(
+				'Source "orphan" depends on "nonexistent" which is not registered',
+			)
+		})
+
+		test("detects circular dependencies", () => {
+			const a: FeedSource = { id: "a", dependencies: ["b"] }
+			const b: FeedSource = { id: "b", dependencies: ["a"] }
+
+			expect(() => buildGraph([a, b])).toThrow("Circular dependency detected: a → b → a")
+		})
+
+		test("detects longer cycles", () => {
+			const a: FeedSource = { id: "a", dependencies: ["c"] }
+			const b: FeedSource = { id: "b", dependencies: ["a"] }
+			const c: FeedSource = { id: "c", dependencies: ["b"] }
+
+			expect(() => buildGraph([a, b, c])).toThrow("Circular dependency detected")
+		})
+
+		test("topologically sorts sources", () => {
+			const location = createLocationSource()
+			const weather = createWeatherSource()
+			const alert = createAlertSource()
+
+			// Register in wrong order
+			const graph = buildGraph([alert, weather, location])
+
+			expect(graph.sorted.map((s) => s.id)).toEqual(["location", "weather", "alert"])
+		})
+
+		test("builds reverse dependency map", () => {
+			const location = createLocationSource()
+			const weather = createWeatherSource()
+			const alert = createAlertSource()
+
+			const graph = buildGraph([location, weather, alert])
+
+			expect(graph.dependents.get("location")).toEqual(["weather"])
+			expect(graph.dependents.get("weather")).toEqual(["alert"])
+			expect(graph.dependents.get("alert")).toBeUndefined()
+		})
+	})
+
+	describe("graph refresh", () => {
+		test("runs fetchContext in dependency order", async () => {
+			const order: string[] = []
+
+			const location: FeedSource = {
+				id: "location",
+				async fetchContext() {
+					order.push("location")
+					return { [LocationKey]: { lat: 51.5, lng: -0.1 } }
+				},
+			}
+
+			const weather: FeedSource = {
+				id: "weather",
+				dependencies: ["location"],
+				async fetchContext(ctx) {
+					order.push("weather")
+					const loc = contextValue(ctx, LocationKey)
+					expect(loc).toBeDefined()
+					return { [WeatherKey]: { temperature: 20, condition: "sunny" } }
+				},
+			}
+
+			const graph = buildGraph([weather, location])
+			await refreshGraph(graph)
+
+			expect(order).toEqual(["location", "weather"])
+		})
+
+		test("accumulates context across sources", async () => {
+			const location = createLocationSource()
+			location.simulateUpdate({ lat: 51.5, lng: -0.1 })
+
+			const weather = createWeatherSource()
+
+			const graph = buildGraph([location, weather])
+			const { context } = await refreshGraph(graph)
+
+			expect(contextValue(context, LocationKey)).toEqual({ lat: 51.5, lng: -0.1 })
+			expect(contextValue(context, WeatherKey)).toEqual({ temperature: 20, condition: "sunny" })
+		})
+
+		test("collects items from all sources", async () => {
+			const location = createLocationSource()
+			location.simulateUpdate({ lat: 51.5, lng: -0.1 })
+
+			const weather = createWeatherSource()
+
+			const graph = buildGraph([location, weather])
+			const { items } = await refreshGraph(graph)
+
+			expect(items).toHaveLength(1)
+			expect(items[0]!.type).toBe("weather")
+		})
+
+		test("downstream source receives upstream context", async () => {
+			const location = createLocationSource()
+			location.simulateUpdate({ lat: 51.5, lng: -0.1 })
+
+			const weather = createWeatherSource(async () => ({
+				temperature: 15,
+				condition: "storm",
+			}))
+
+			const alert = createAlertSource()
+
+			const graph = buildGraph([location, weather, alert])
+			const { items } = await refreshGraph(graph)
+
+			expect(items).toHaveLength(2)
+			expect(items[0]!.type).toBe("alert") // priority 1.0
+			expect(items[1]!.type).toBe("weather") // priority 0.5
+		})
+
+		test("source without location context returns empty items", async () => {
+			// Location source exists but hasn't been updated (returns default 0,0)
+			const location: FeedSource = {
+				id: "location",
+				async fetchContext() {
+					// Simulate no location available
+					return {}
+				},
+			}
+
+			const weather = createWeatherSource()
+
+			const graph = buildGraph([location, weather])
+			const { context, items } = await refreshGraph(graph)
+
+			expect(contextValue(context, WeatherKey)).toBeUndefined()
+			expect(items).toHaveLength(0)
+		})
+	})
+
+	describe("reactive updates", () => {
+		test("onContextUpdate receives callback and returns cleanup", () => {
+			const location = createLocationSource()
+			let updateCount = 0
+
+			const cleanup = location.onContextUpdate!(
+				() => {
+					updateCount++
+				},
+				() => ({ time: new Date() }),
+			)
+
+			location.simulateUpdate({ lat: 1, lng: 1 })
+			expect(updateCount).toBe(1)
+
+			location.simulateUpdate({ lat: 2, lng: 2 })
+			expect(updateCount).toBe(2)
+
+			cleanup()
+
+			location.simulateUpdate({ lat: 3, lng: 3 })
+			expect(updateCount).toBe(2) // no more updates after cleanup
+		})
+	})
+})

packages/aris-core/src/feed-source.ts

@@ -0,0 +1,76 @@
+import type { Context } from "./context"
+import type { FeedItem } from "./feed"
+
+/**
+ * Unified interface for sources that provide context and/or feed items.
+ *
+ * Sources form a dependency graph - a source declares which other sources
+ * it depends on, and the graph ensures dependencies are resolved before
+ * dependents run.
+ *
+ * A source may:
+ * - Provide context for other sources (implement fetchContext/onContextUpdate)
+ * - Produce feed items (implement fetchItems/onItemsUpdate)
+ * - Both
+ *
+ * @example
+ * ```ts
+ * // Location source - provides context only
+ * const locationSource: FeedSource = {
+ *   id: "location",
+ *   fetchContext: async () => {
+ *     const pos = await getCurrentPosition()
+ *     return { location: { lat: pos.coords.latitude, lng: pos.coords.longitude } }
+ *   },
+ * }
+ *
+ * // Weather source - depends on location, provides both context and items
+ * const weatherSource: FeedSource<WeatherFeedItem> = {
+ *   id: "weather",
+ *   dependencies: ["location"],
+ *   fetchContext: async (ctx) => {
+ *     const weather = await fetchWeather(ctx.location)
+ *     return { weather }
+ *   },
+ *   fetchItems: async (ctx) => {
+ *     return createWeatherFeedItems(ctx.weather)
+ *   },
+ * }
+ * ```
+ */
+export interface FeedSource<TItem extends FeedItem = FeedItem> {
+	/** Unique identifier for this source */
+	readonly id: string
+
+	/** IDs of sources this source depends on */
+	readonly dependencies?: readonly string[]
+
+	/**
+	 * Subscribe to reactive context updates.
+	 * Called when the source can push context changes proactively.
+	 * Returns cleanup function.
+	 */
+	onContextUpdate?(
+		callback: (update: Partial<Context>) => void,
+		getContext: () => Context,
+	): () => void
+
+	/**
+	 * Fetch context on-demand.
+	 * Called during manual refresh or initial load.
+	 */
+	fetchContext?(context: Context): Promise<Partial<Context>>
+
+	/**
+	 * Subscribe to reactive feed item updates.
+	 * Called when the source can push item changes proactively.
+	 * Returns cleanup function.
+	 */
+	onItemsUpdate?(callback: (items: TItem[]) => void, getContext: () => Context): () => void
+
+	/**
+	 * Fetch feed items on-demand.
+	 * Called during manual refresh or when dependencies update.
+	 */
+	fetchItems?(context: Context): Promise<TItem[]>
+}

packages/aris-core/src/feed.ts

@@ -0,0 +1,31 @@
+/**
+ * A single item in the feed.
+ *
+ * @example
+ * ```ts
+ * type WeatherItem = FeedItem<"weather", { temp: number; condition: string }>
+ *
+ * const item: WeatherItem = {
+ *   id: "weather-123",
+ *   type: "weather",
+ *   priority: 0.5,
+ *   timestamp: new Date(),
+ *   data: { temp: 18, condition: "cloudy" },
+ * }
+ * ```
+ */
+export interface FeedItem<
+	TType extends string = string,
+	TData extends Record<string, unknown> = Record<string, unknown>,
+> {
+	/** Unique identifier */
+	id: string
+	/** Item type, matches the data source type */
+	type: TType
+	/** Sort priority (higher = more important, shown first) */
+	priority: number
+	/** When this item was generated */
+	timestamp: Date
+	/** Type-specific payload */
+	data: TData
+}

packages/aris-core/src/index.ts

@@ -0,0 +1,27 @@
+// Context
+export type { Context, ContextKey } from "./context"
+export { contextKey, contextValue } from "./context"
+
+// Feed
+export type { FeedItem } from "./feed"
+
+// Feed Source
+export type { FeedSource } from "./feed-source"
+
+// Data Source (deprecated - use FeedSource)
+export type { DataSource } from "./data-source"
+
+// Context Provider
+export type { ContextProvider } from "./context-provider"
+
+// Context Bridge
+export type { ProviderError, RefreshResult } from "./context-bridge"
+export { ContextBridge } from "./context-bridge"
+
+// Reconciler
+export type { ReconcileResult, ReconcilerConfig, SourceError } from "./reconciler"
+export { Reconciler } from "./reconciler"
+
+// Feed Controller
+export type { FeedControllerConfig, FeedSubscriber } from "./feed-controller"
+export { FeedController } from "./feed-controller"

packages/aris-data-source-tfl/package.json

@@ -0,0 +1,15 @@
+{
+	"name": "@aris/data-source-tfl",
+	"version": "0.0.0",
+	"type": "module",
+	"main": "src/index.ts",
+	"types": "src/index.ts",
+	"scripts": {
+		"test": "bun test src/",
+		"fetch-fixtures": "bun run scripts/fetch-fixtures.ts"
+	},
+	"dependencies": {
+		"@aris/core": "workspace:*",
+		"arktype": "^2.1.0"
+	}
+}

packages/aris-data-source-tfl/scripts/fetch-fixtures.ts

@@ -0,0 +1,35 @@
+// Fetches real TfL API responses and saves them as test fixtures
+
+const TEST_LINES = ["northern", "central", "elizabeth"]
+const BASE_URL = "https://api.tfl.gov.uk"
+
+async function fetchFixtures() {
+	console.log("Fetching line statuses...")
+	const statusRes = await fetch(`${BASE_URL}/Line/${TEST_LINES.join(",")}/Status`)
+	const lineStatuses = await statusRes.json()
+
+	console.log("Fetching stop points...")
+	const stopPoints: Record<string, unknown> = {}
+	for (const lineId of TEST_LINES) {
+		console.log(`  Fetching ${lineId}...`)
+		const res = await fetch(`${BASE_URL}/Line/${lineId}/StopPoints`)
+		stopPoints[lineId] = await res.json()
+	}
+
+	const fixtures = {
+		fetchedAt: new Date().toISOString(),
+		lineStatuses,
+		stopPoints,
+	}
+
+	const path = new URL("../fixtures/tfl-responses.json", import.meta.url)
+	await Bun.write(path, JSON.stringify(fixtures))
+
+	console.log(`\nFixtures saved to fixtures/tfl-responses.json`)
+	console.log(`  Line statuses: ${(lineStatuses as unknown[]).length} lines`)
+	for (const [lineId, stops] of Object.entries(stopPoints)) {
+		console.log(`  ${lineId} stops: ${(stops as unknown[]).length}`)
+	}
+}
+
+fetchFixtures().catch(console.error)

packages/aris-data-source-tfl/src/data-source.ts

@@ -0,0 +1,115 @@
+import type { Context, DataSource } from "@aris/core"
+
+import type {
+	StationLocation,
+	TflAlertData,
+	TflAlertFeedItem,
+	TflAlertSeverity,
+	TflDataSourceConfig,
+	TflDataSourceOptions,
+	TflLineId,
+} from "./types.ts"
+
+import { TflApi, type ITflApi } from "./tfl-api.ts"
+
+const SEVERITY_PRIORITY: Record<TflAlertSeverity, number> = {
+	closure: 100,
+	"major-delays": 80,
+	"minor-delays": 60,
+}
+
+function haversineDistance(lat1: number, lng1: number, lat2: number, lng2: number): number {
+	const R = 6371 // Earth's radius in km
+	const dLat = ((lat2 - lat1) * Math.PI) / 180
+	const dLng = ((lng2 - lng1) * Math.PI) / 180
+	const a =
+		Math.sin(dLat / 2) * Math.sin(dLat / 2) +
+		Math.cos((lat1 * Math.PI) / 180) *
+			Math.cos((lat2 * Math.PI) / 180) *
+			Math.sin(dLng / 2) *
+			Math.sin(dLng / 2)
+	const c = 2 * Math.atan2(Math.sqrt(a), Math.sqrt(1 - a))
+	return R * c
+}
+
+function findClosestStationDistance(
+	lineId: TflLineId,
+	stations: StationLocation[],
+	userLat: number,
+	userLng: number,
+): number | null {
+	const lineStations = stations.filter((s) => s.lines.includes(lineId))
+	if (lineStations.length === 0) return null
+
+	let minDistance = Infinity
+	for (const station of lineStations) {
+		const distance = haversineDistance(userLat, userLng, station.lat, station.lng)
+		if (distance < minDistance) {
+			minDistance = distance
+		}
+	}
+
+	return minDistance
+}
+
+export class TflDataSource implements DataSource<TflAlertFeedItem, TflDataSourceConfig> {
+	readonly type = "tfl-alert"
+	private api: ITflApi
+
+	constructor(options: TflDataSourceOptions)
+	constructor(api: ITflApi)
+	constructor(optionsOrApi: TflDataSourceOptions | ITflApi) {
+		if ("fetchLineStatuses" in optionsOrApi) {
+			this.api = optionsOrApi
+		} else {
+			this.api = new TflApi(optionsOrApi.apiKey)
+		}
+	}
+
+	async query(context: Context, config: TflDataSourceConfig): Promise<TflAlertFeedItem[]> {
+		const [statuses, stations] = await Promise.all([
+			this.api.fetchLineStatuses(config.lines),
+			this.api.fetchStations(),
+		])
+
+		const items: TflAlertFeedItem[] = statuses.map((status) => {
+			const closestStationDistance = context.location
+				? findClosestStationDistance(
+						status.lineId,
+						stations,
+						context.location.lat,
+						context.location.lng,
+					)
+				: null
+
+			const data: TflAlertData = {
+				line: status.lineId,
+				lineName: status.lineName,
+				severity: status.severity,
+				description: status.description,
+				closestStationDistance,
+			}
+
+			return {
+				id: `tfl-alert-${status.lineId}-${status.severity}`,
+				type: this.type,
+				priority: SEVERITY_PRIORITY[status.severity],
+				timestamp: context.time,
+				data,
+			}
+		})
+
+		// Sort by severity (desc), then by proximity (asc) if location available
+		items.sort((a, b) => {
+			if (b.priority !== a.priority) {
+				return b.priority - a.priority
+			}
+			if (a.data.closestStationDistance !== null && b.data.closestStationDistance !== null) {
+				return a.data.closestStationDistance - b.data.closestStationDistance
+			}
+			return 0
+		})
+
+		return items
+	}
+}

packages/aris-data-source-tfl/src/index.ts

@@ -0,0 +1,11 @@
+export { TflDataSource } from "./data-source.ts"
+export { TflApi, type ITflApi, type TflLineStatus } from "./tfl-api.ts"
+export type {
+	TflAlertData,
+	TflAlertFeedItem,
+	TflAlertSeverity,
+	TflDataSourceConfig,
+	TflDataSourceOptions,
+	TflLineId,
+	StationLocation,
+} from "./types.ts"

packages/aris-data-source-tfl/src/integration.test.ts

@@ -0,0 +1,208 @@
+import type { Context } from "@aris/core"
+
+import { describe, expect, test } from "bun:test"
+
+import type { ITflApi, TflLineStatus } from "./tfl-api.ts"
+import type { StationLocation, TflLineId } from "./types.ts"
+
+import fixtures from "../fixtures/tfl-responses.json"
+import { TflDataSource } from "./data-source.ts"
+
+// Mock API that returns fixture data
+class FixtureTflApi implements ITflApi {
+	async fetchLineStatuses(_lines?: TflLineId[]): Promise<TflLineStatus[]> {
+		const statuses: TflLineStatus[] = []
+
+		for (const line of fixtures.lineStatuses as Record<string, unknown>[]) {
+			for (const status of line.lineStatuses as Record<string, unknown>[]) {
+				const severityCode = status.statusSeverity as number
+				const severity = this.mapSeverity(severityCode)
+				if (severity) {
+					statuses.push({
+						lineId: line.id as TflLineId,
+						lineName: line.name as string,
+						severity,
+						description: (status.reason as string) ?? (status.statusSeverityDescription as string),
+					})
+				}
+			}
+		}
+
+		return statuses
+	}
+
+	async fetchStations(): Promise<StationLocation[]> {
+		const stationMap = new Map<string, StationLocation>()
+
+		for (const [lineId, stops] of Object.entries(fixtures.stopPoints)) {
+			for (const stop of stops as Record<string, unknown>[]) {
+				const id = stop.naptanId as string
+				const existing = stationMap.get(id)
+				if (existing) {
+					if (!existing.lines.includes(lineId as TflLineId)) {
+						existing.lines.push(lineId as TflLineId)
+					}
+				} else {
+					stationMap.set(id, {
+						id,
+						name: stop.commonName as string,
+						lat: stop.lat as number,
+						lng: stop.lon as number,
+						lines: [lineId as TflLineId],
+					})
+				}
+			}
+		}
+
+		return Array.from(stationMap.values())
+	}
+
+	private mapSeverity(code: number): "minor-delays" | "major-delays" | "closure" | null {
+		const map: Record<number, "minor-delays" | "major-delays" | "closure" | null> = {
+			1: "closure",
+			2: "closure",
+			3: "closure",
+			4: "closure",
+			5: "closure",
+			6: "major-delays",
+			7: "major-delays",
+			8: "major-delays",
+			9: "minor-delays",
+			10: null,
+		}
+		return map[code] ?? null
+	}
+}
+
+const createContext = (location?: { lat: number; lng: number }): Context => ({
+	time: new Date("2026-01-15T12:00:00Z"),
+	location: location ? { ...location, accuracy: 10 } : undefined,
+})
+
+describe("TfL Feed Items (using fixture data)", () => {
+	const api = new FixtureTflApi()
+
+	test("query returns feed items array", async () => {
+		const dataSource = new TflDataSource(api)
+		const items = await dataSource.query(createContext(), {})
+		expect(Array.isArray(items)).toBe(true)
+	})
+
+	test("feed items have correct base structure", async () => {
+		const dataSource = new TflDataSource(api)
+		const items = await dataSource.query(createContext({ lat: 51.5074, lng: -0.1278 }), {})
+
+		for (const item of items) {
+			expect(typeof item.id).toBe("string")
+			expect(item.id).toMatch(/^tfl-alert-/)
+			expect(item.type).toBe("tfl-alert")
+			expect(typeof item.priority).toBe("number")
+			expect(item.timestamp).toBeInstanceOf(Date)
+		}
+	})
+
+	test("feed items have correct data structure", async () => {
+		const dataSource = new TflDataSource(api)
+		const items = await dataSource.query(createContext({ lat: 51.5074, lng: -0.1278 }), {})
+
+		for (const item of items) {
+			expect(typeof item.data.line).toBe("string")
+			expect(typeof item.data.lineName).toBe("string")
+			expect(["minor-delays", "major-delays", "closure"]).toContain(item.data.severity)
+			expect(typeof item.data.description).toBe("string")
+			expect(
+				item.data.closestStationDistance === null ||
+					typeof item.data.closestStationDistance === "number",
+			).toBe(true)
+		}
+	})
+
+	test("feed item ids are unique", async () => {
+		const dataSource = new TflDataSource(api)
+		const items = await dataSource.query(createContext(), {})
+
+		const ids = items.map((item) => item.id)
+		const uniqueIds = new Set(ids)
+		expect(uniqueIds.size).toBe(ids.length)
+	})
+
+	test("feed items are sorted by priority descending", async () => {
+		const dataSource = new TflDataSource(api)
+		const items = await dataSource.query(createContext(), {})
+
+		for (let i = 1; i < items.length; i++) {
+			const prev = items[i - 1]!
+			const curr = items[i]!
+			expect(prev.priority).toBeGreaterThanOrEqual(curr.priority)
+		}
+	})
+
+	test("priority values match severity levels", async () => {
+		const dataSource = new TflDataSource(api)
+		const items = await dataSource.query(createContext(), {})
+
+		const severityPriority: Record<string, number> = {
+			closure: 100,
+			"major-delays": 80,
+			"minor-delays": 60,
+		}
+
+		for (const item of items) {
+			expect(item.priority).toBe(severityPriority[item.data.severity]!)
+		}
+	})
+
+	test("closestStationDistance is number when location provided", async () => {
+		const dataSource = new TflDataSource(api)
+		const items = await dataSource.query(createContext({ lat: 51.5074, lng: -0.1278 }), {})
+
+		for (const item of items) {
+			expect(typeof item.data.closestStationDistance).toBe("number")
+			expect(item.data.closestStationDistance!).toBeGreaterThan(0)
+		}
+	})
+
+	test("closestStationDistance is null when no location provided", async () => {
+		const dataSource = new TflDataSource(api)
+		const items = await dataSource.query(createContext(), {})
+
+		for (const item of items) {
+			expect(item.data.closestStationDistance).toBeNull()
+		}
+	})
+})
+
+describe("TfL Fixture Data Shape", () => {
+	test("fixtures have expected structure", () => {
+		expect(typeof fixtures.fetchedAt).toBe("string")
+		expect(Array.isArray(fixtures.lineStatuses)).toBe(true)
+		expect(typeof fixtures.stopPoints).toBe("object")
+	})
+
+	test("line statuses have required fields", () => {
+		for (const line of fixtures.lineStatuses as Record<string, unknown>[]) {
+			expect(typeof line.id).toBe("string")
+			expect(typeof line.name).toBe("string")
+			expect(Array.isArray(line.lineStatuses)).toBe(true)
+
+			for (const status of line.lineStatuses as Record<string, unknown>[]) {
+				expect(typeof status.statusSeverity).toBe("number")
+				expect(typeof status.statusSeverityDescription).toBe("string")
+			}
+		}
+	})
+
+	test("stop points have required fields", () => {
+		for (const [lineId, stops] of Object.entries(fixtures.stopPoints)) {
+			expect(typeof lineId).toBe("string")
+			expect(Array.isArray(stops)).toBe(true)
+
+			for (const stop of stops as Record<string, unknown>[]) {
+				expect(typeof stop.naptanId).toBe("string")
+				expect(typeof stop.commonName).toBe("string")
+				expect(typeof stop.lat).toBe("number")
+				expect(typeof stop.lon).toBe("number")
+			}
+		}
+	})
+})

packages/aris-data-source-tfl/src/tfl-api.ts

@@ -0,0 +1,184 @@
+import { type } from "arktype"
+
+import type { StationLocation, TflAlertSeverity } from "./types.ts"
+
+const TFL_API_BASE = "https://api.tfl.gov.uk"
+
+const ALL_LINE_IDS: TflLineId[] = [
+	"bakerloo",
+	"central",
+	"circle",
+	"district",
+	"hammersmith-city",
+	"jubilee",
+	"metropolitan",
+	"northern",
+	"piccadilly",
+	"victoria",
+	"waterloo-city",
+	"lioness",
+	"mildmay",
+	"windrush",
+	"weaver",
+	"suffragette",
+	"liberty",
+	"elizabeth",
+]
+
+// TfL severity codes: https://api.tfl.gov.uk/Line/Meta/Severity
+// 0 = Special Service, 1 = Closed, 6 = Severe Delays, 9 = Minor Delays, 10 = Good Service
+const SEVERITY_MAP: Record<number, TflAlertSeverity | null> = {
+	1: "closure",
+	2: "closure", // Suspended
+	3: "closure", // Part Suspended
+	4: "closure", // Planned Closure
+	5: "closure", // Part Closure
+	6: "major-delays", // Severe Delays
+	7: "major-delays", // Reduced Service
+	8: "major-delays", // Bus Service
+	9: "minor-delays", // Minor Delays
+	10: null, // Good Service
+	11: null, // Part Closed
+	12: null, // Exit Only
+	13: null, // No Step Free Access
+	14: null, // Change of frequency
+	15: null, // Diverted
+	16: null, // Not Running
+	17: null, // Issues Reported
+	18: null, // No Issues
+	19: null, // Information
+	20: null, // Service Closed
+}
+
+export interface TflLineStatus {
+	lineId: TflLineId
+	lineName: string
+	severity: TflAlertSeverity
+	description: string
+}
+
+export interface ITflApi {
+	fetchLineStatuses(lines?: TflLineId[]): Promise<TflLineStatus[]>
+	fetchStations(): Promise<StationLocation[]>
+}
+
+export class TflApi implements ITflApi {
+	private apiKey: string
+	private stationsCache: StationLocation[] | null = null
+
+	constructor(apiKey: string) {
+		this.apiKey = apiKey
+	}
+
+	private async fetch<T>(path: string): Promise<T> {
+		const url = new URL(path, TFL_API_BASE)
+		url.searchParams.set("app_key", this.apiKey)
+		const response = await fetch(url.toString())
+		if (!response.ok) {
+			throw new Error(`TfL API error: ${response.status} ${response.statusText}`)
+		}
+		return response.json() as Promise<T>
+	}
+
+	async fetchLineStatuses(lines?: TflLineId[]): Promise<TflLineStatus[]> {
+		const lineIds = lines ?? ALL_LINE_IDS
+		const data = await this.fetch<unknown>(`/Line/${lineIds.join(",")}/Status`)
+
+		const parsed = lineResponseArray(data)
+		if (parsed instanceof type.errors) {
+			throw new Error(`Invalid TfL API response: ${parsed.summary}`)
+		}
+
+		const statuses: TflLineStatus[] = []
+
+		for (const line of parsed) {
+			for (const status of line.lineStatuses) {
+				const severity = SEVERITY_MAP[status.statusSeverity]
+				if (severity) {
+					statuses.push({
+						lineId: line.id,
+						lineName: line.name,
+						severity,
+						description: status.reason ?? status.statusSeverityDescription,
+					})
+				}
+			}
+		}
+
+		return statuses
+	}
+
+	async fetchStations(): Promise<StationLocation[]> {
+		if (this.stationsCache) {
+			return this.stationsCache
+		}
+
+		// Fetch stations for all lines in parallel
+		const responses = await Promise.all(
+			ALL_LINE_IDS.map(async (id) => {
+				const data = await this.fetch<unknown>(`/Line/${id}/StopPoints`)
+				const parsed = lineStopPointsArray(data)
+				if (parsed instanceof type.errors) {
+					throw new Error(`Invalid TfL API response for line ${id}: ${parsed.summary}`)
+				}
+				return { lineId: id, stops: parsed }
+			}),
+		)
+
+		// Merge stations, combining lines for shared stations
+		const stationMap = new Map<string, StationLocation>()
+
+		for (const { lineId: currentLineId, stops } of responses) {
+			for (const stop of stops) {
+				const existing = stationMap.get(stop.naptanId)
+				if (existing) {
+					if (!existing.lines.includes(currentLineId)) {
+						existing.lines.push(currentLineId)
+					}
+				} else {
+					stationMap.set(stop.naptanId, {
+						id: stop.naptanId,
+						name: stop.commonName,
+						lat: stop.lat,
+						lng: stop.lon,
+						lines: [currentLineId],
+					})
+				}
+			}
+		}
+
+		this.stationsCache = Array.from(stationMap.values())
+		return this.stationsCache
+	}
+}
+
+// Schemas
+
+const lineId = type(
+	"'bakerloo' | 'central' | 'circle' | 'district' | 'hammersmith-city' | 'jubilee' | 'metropolitan' | 'northern' | 'piccadilly' | 'victoria' | 'waterloo-city' | 'lioness' | 'mildmay' | 'windrush' | 'weaver' | 'suffragette' | 'liberty' | 'elizabeth'",
+)
+
+export type TflLineId = typeof lineId.infer
+
+const lineStatus = type({
+	statusSeverity: "number",
+	statusSeverityDescription: "string",
+	"reason?": "string",
+})
+
+const lineResponse = type({
+	id: lineId,
+	name: "string",
+	lineStatuses: lineStatus.array(),
+})
+
+const lineResponseArray = lineResponse.array()
+
+const lineStopPoint = type({
+	naptanId: "string",
+	commonName: "string",
+	lat: "number",
+	lon: "number",
+})
+
+const lineStopPointsArray = lineStopPoint.array()

packages/aris-data-source-tfl/src/types.ts

@@ -0,0 +1,33 @@
+import type { FeedItem } from "@aris/core"
+
+import type { TflLineId } from "./tfl-api.ts"
+
+export type { TflLineId } from "./tfl-api.ts"
+
+export type TflAlertSeverity = "minor-delays" | "major-delays" | "closure"
+
+export interface TflAlertData extends Record<string, unknown> {
+	line: TflLineId
+	lineName: string
+	severity: TflAlertSeverity
+	description: string
+	closestStationDistance: number | null
+}
+
+export type TflAlertFeedItem = FeedItem<"tfl-alert", TflAlertData>
+
+export interface TflDataSourceConfig {
+	lines?: TflLineId[]
+}
+
+export interface TflDataSourceOptions {
+	apiKey: string
+}
+
+export interface StationLocation {
+	id: string
+	name: string
+	lat: number
+	lng: number
+	lines: TflLineId[]
+}

packages/aris-data-source-weatherkit/.env.example

@@ -0,0 +1,4 @@
+WEATHERKIT_PRIVATE_KEY="-----BEGIN PRIVATE KEY-----\n...\n-----END PRIVATE KEY-----"
+WEATHERKIT_KEY_ID=ABC123DEFG
+WEATHERKIT_TEAM_ID=TEAM123456
+WEATHERKIT_SERVICE_ID=com.example.weatherkit.test

packages/aris-data-source-weatherkit/README.md

@@ -0,0 +1,58 @@
+# @aris/data-source-weatherkit
+
+Weather data source using Apple WeatherKit REST API.
+
+## Usage
+
+```typescript
+import { WeatherKitDataSource, Units } from "@aris/data-source-weatherkit"
+
+const dataSource = new WeatherKitDataSource({
+	credentials: {
+		privateKey: "-----BEGIN PRIVATE KEY-----\n...",
+		keyId: "ABC123",
+		teamId: "DEF456",
+		serviceId: "com.example.weatherkit",
+	},
+	hourlyLimit: 12, // optional, default: 12
+	dailyLimit: 7, // optional, default: 7
+})
+
+const items = await dataSource.query(context, {
+	units: Units.metric, // or Units.imperial
+})
+```
+
+## Feed Items
+
+The data source returns four types of feed items:
+
+| Type              | Description                |
+| ----------------- | -------------------------- |
+| `weather-current` | Current weather conditions |
+| `weather-hourly`  | Hourly forecast            |
+| `weather-daily`   | Daily forecast             |
+| `weather-alert`   | Weather alerts             |
+
+## Priority
+
+Base priorities are adjusted based on weather conditions:
+
+- Severe conditions (tornado, hurricane, blizzard, etc.): +0.3
+- Moderate conditions (thunderstorm, heavy rain, etc.): +0.15
+- Alert severity: extreme=1.0, severe=0.9, moderate=0.75, minor=0.7
+
+## Authentication
+
+WeatherKit requires Apple Developer credentials. Generate a private key in the Apple Developer portal under Certificates, Identifiers & Profiles > Keys.
+
+## Validation
+
+API responses are validated using [arktype](https://arktype.io) schemas.
+
+## Generating Test Fixtures
+
+To regenerate fixture data from the real API:
+
+1. Create a `.env` file with your credentials (see `.env.example`)
+2. Run `bun run scripts/generate-fixtures.ts`

packages/aris-data-source-weatherkit/package.json

@@ -0,0 +1,14 @@
+{
+	"name": "@aris/data-source-weatherkit",
+	"version": "0.0.0",
+	"type": "module",
+	"main": "src/index.ts",
+	"types": "src/index.ts",
+	"scripts": {
+		"test": "bun test ."
+	},
+	"dependencies": {
+		"@aris/core": "workspace:*",
+		"arktype": "^2.1.0"
+	}
+}

packages/aris-data-source-weatherkit/scripts/generate-fixtures.ts

@@ -0,0 +1,60 @@
+import { DefaultWeatherKitClient } from "../src/weatherkit"
+
+function loadEnv(): Record<string, string> {
+	const content = require("fs").readFileSync(".env", "utf-8")
+	const env: Record<string, string> = {}
+
+	for (const line of content.split("\n")) {
+		const trimmed = line.trim()
+		if (!trimmed || trimmed.startsWith("#")) continue
+
+		const eqIndex = trimmed.indexOf("=")
+		if (eqIndex === -1) continue
+
+		const key = trimmed.slice(0, eqIndex)
+		let value = trimmed.slice(eqIndex + 1)
+
+		if (value.startsWith('"') && value.endsWith('"')) {
+			value = value.slice(1, -1)
+		}
+
+		env[key] = value.replace(/\\n/g, "\n")
+	}
+
+	return env
+}
+
+const env = loadEnv()
+
+const client = new DefaultWeatherKitClient({
+	privateKey: env.WEATHERKIT_PRIVATE_KEY!,
+	keyId: env.WEATHERKIT_KEY_ID!,
+	teamId: env.WEATHERKIT_TEAM_ID!,
+	serviceId: env.WEATHERKIT_SERVICE_ID!,
+})
+
+const locations = {
+	sanFrancisco: { lat: 37.7749, lng: -122.4194 },
+}
+
+async function main() {
+	console.log("Fetching weather data for San Francisco...")
+
+	const response = await client.fetch({
+		lat: locations.sanFrancisco.lat,
+		lng: locations.sanFrancisco.lng,
+	})
+
+	const fixture = {
+		generatedAt: new Date().toISOString(),
+		location: locations.sanFrancisco,
+		response,
+	}
+
+	const output = JSON.stringify(fixture)
+	await Bun.write("fixtures/san-francisco.json", output)
+
+	console.log("Fixture written to fixtures/san-francisco.json")
+}
+
+main().catch(console.error)

packages/aris-data-source-weatherkit/src/data-source.test.ts

@@ -0,0 +1,210 @@
+import type { Context } from "@aris/core"
+
+import { describe, expect, test } from "bun:test"
+
+import type { WeatherKitClient, WeatherKitResponse } from "./weatherkit"
+
+import fixture from "../fixtures/san-francisco.json"
+import { WeatherKitDataSource, Units } from "./data-source"
+import { WeatherFeedItemType } from "./feed-items"
+
+const mockCredentials = {
+	privateKey: "mock",
+	keyId: "mock",
+	teamId: "mock",
+	serviceId: "mock",
+}
+
+const createMockClient = (response: WeatherKitResponse): WeatherKitClient => ({
+	fetch: async () => response,
+})
+
+const createMockContext = (location?: { lat: number; lng: number }): Context => ({
+	time: new Date("2026-01-17T00:00:00Z"),
+	location: location ? { ...location, accuracy: 10 } : undefined,
+})
+
+describe("WeatherKitDataSource", () => {
+	test("returns empty array when location is missing", async () => {
+		const dataSource = new WeatherKitDataSource({ credentials: mockCredentials })
+		const items = await dataSource.query(createMockContext())
+
+		expect(items).toEqual([])
+	})
+
+	test("type is weather-current", () => {
+		const dataSource = new WeatherKitDataSource({ credentials: mockCredentials })
+
+		expect(dataSource.type).toBe(WeatherFeedItemType.current)
+	})
+
+	test("throws error if neither client nor credentials provided", () => {
+		expect(() => new WeatherKitDataSource({})).toThrow(
+			"Either client or credentials must be provided",
+		)
+	})
+})
+
+describe("WeatherKitDataSource with fixture", () => {
+	const response = fixture.response
+
+	test("parses current weather from fixture", () => {
+		const current = response.currentWeather
+
+		expect(typeof current.conditionCode).toBe("string")
+		expect(typeof current.temperature).toBe("number")
+		expect(typeof current.humidity).toBe("number")
+		expect(current.pressureTrend).toMatch(/^(rising|falling|steady)$/)
+	})
+
+	test("parses hourly forecast from fixture", () => {
+		const hours = response.forecastHourly.hours
+
+		expect(hours.length).toBeGreaterThan(0)
+
+		const firstHour = hours[0]!
+		expect(firstHour.forecastStart).toBeDefined()
+		expect(typeof firstHour.temperature).toBe("number")
+		expect(typeof firstHour.precipitationChance).toBe("number")
+	})
+
+	test("parses daily forecast from fixture", () => {
+		const days = response.forecastDaily.days
+
+		expect(days.length).toBeGreaterThan(0)
+
+		const firstDay = days[0]!
+		expect(firstDay.forecastStart).toBeDefined()
+		expect(typeof firstDay.temperatureMax).toBe("number")
+		expect(typeof firstDay.temperatureMin).toBe("number")
+		expect(firstDay.sunrise).toBeDefined()
+		expect(firstDay.sunset).toBeDefined()
+	})
+
+	test("hourly limit is respected", () => {
+		const dataSource = new WeatherKitDataSource({
+			credentials: mockCredentials,
+			hourlyLimit: 6,
+		})
+
+		expect(dataSource["hourlyLimit"]).toBe(6)
+	})
+
+	test("daily limit is respected", () => {
+		const dataSource = new WeatherKitDataSource({
+			credentials: mockCredentials,
+			dailyLimit: 3,
+		})
+
+		expect(dataSource["dailyLimit"]).toBe(3)
+	})
+
+	test("default limits are applied", () => {
+		const dataSource = new WeatherKitDataSource({ credentials: mockCredentials })
+
+		expect(dataSource["hourlyLimit"]).toBe(12)
+		expect(dataSource["dailyLimit"]).toBe(7)
+	})
+})
+
+describe("unit conversion", () => {
+	test("Units enum has metric and imperial", () => {
+		expect(Units.metric).toBe("metric")
+		expect(Units.imperial).toBe("imperial")
+	})
+})
+
+describe("query() with mocked client", () => {
+	const mockClient = createMockClient(fixture.response as WeatherKitResponse)
+
+	test("transforms API response into feed items", async () => {
+		const dataSource = new WeatherKitDataSource({ client: mockClient })
+		const context = createMockContext({ lat: 37.7749, lng: -122.4194 })
+
+		const items = await dataSource.query(context)
+
+		expect(items.length).toBeGreaterThan(0)
+		expect(items.some((i) => i.type === WeatherFeedItemType.current)).toBe(true)
+		expect(items.some((i) => i.type === WeatherFeedItemType.hourly)).toBe(true)
+		expect(items.some((i) => i.type === WeatherFeedItemType.daily)).toBe(true)
+	})
+
+	test("applies hourly and daily limits", async () => {
+		const dataSource = new WeatherKitDataSource({
+			client: mockClient,
+			hourlyLimit: 3,
+			dailyLimit: 2,
+		})
+		const context = createMockContext({ lat: 37.7749, lng: -122.4194 })
+
+		const items = await dataSource.query(context)
+
+		const hourlyItems = items.filter((i) => i.type === WeatherFeedItemType.hourly)
+		const dailyItems = items.filter((i) => i.type === WeatherFeedItemType.daily)
+
+		expect(hourlyItems.length).toBe(3)
+		expect(dailyItems.length).toBe(2)
+	})
+
+	test("sets timestamp from context.time", async () => {
+		const dataSource = new WeatherKitDataSource({ client: mockClient })
+		const queryTime = new Date("2026-01-17T12:00:00Z")
+		const context = createMockContext({ lat: 37.7749, lng: -122.4194 })
+		context.time = queryTime
+
+		const items = await dataSource.query(context)
+
+		for (const item of items) {
+			expect(item.timestamp).toEqual(queryTime)
+		}
+	})
+
+	test("converts temperatures to imperial", async () => {
+		const dataSource = new WeatherKitDataSource({ client: mockClient })
+		const context = createMockContext({ lat: 37.7749, lng: -122.4194 })
+
+		const metricItems = await dataSource.query(context, { units: Units.metric })
+		const imperialItems = await dataSource.query(context, { units: Units.imperial })
+
+		const metricCurrent = metricItems.find((i) => i.type === WeatherFeedItemType.current)
+		const imperialCurrent = imperialItems.find((i) => i.type === WeatherFeedItemType.current)
+
+		expect(metricCurrent).toBeDefined()
+		expect(imperialCurrent).toBeDefined()
+
+		const metricTemp = (metricCurrent!.data as { temperature: number }).temperature
+		const imperialTemp = (imperialCurrent!.data as { temperature: number }).temperature
+
+		// Verify conversion: F = C * 9/5 + 32
+		const expectedImperial = (metricTemp * 9) / 5 + 32
+		expect(imperialTemp).toBeCloseTo(expectedImperial, 2)
+	})
+
+	test("assigns priority based on weather conditions", async () => {
+		const dataSource = new WeatherKitDataSource({ client: mockClient })
+		const context = createMockContext({ lat: 37.7749, lng: -122.4194 })
+
+		const items = await dataSource.query(context)
+
+		for (const item of items) {
+			expect(item.priority).toBeGreaterThanOrEqual(0)
+			expect(item.priority).toBeLessThanOrEqual(1)
+		}
+
+		const currentItem = items.find((i) => i.type === WeatherFeedItemType.current)
+		expect(currentItem).toBeDefined()
+		// Base priority for current is 0.5, may be adjusted for conditions
+		expect(currentItem!.priority).toBeGreaterThanOrEqual(0.5)
+	})
+
+	test("generates unique IDs for each item", async () => {
+		const dataSource = new WeatherKitDataSource({ client: mockClient })
+		const context = createMockContext({ lat: 37.7749, lng: -122.4194 })
+
+		const items = await dataSource.query(context)
+		const ids = items.map((i) => i.id)
+		const uniqueIds = new Set(ids)
+
+		expect(uniqueIds.size).toBe(ids.length)
+	})
+})

packages/aris-data-source-weatherkit/src/data-source.ts

@@ -0,0 +1,306 @@
+import type { Context, DataSource } from "@aris/core"
+
+import {
+	WeatherFeedItemType,
+	type CurrentWeatherFeedItem,
+	type DailyWeatherFeedItem,
+	type HourlyWeatherFeedItem,
+	type WeatherAlertFeedItem,
+	type WeatherFeedItem,
+} from "./feed-items"
+import {
+	ConditionCode,
+	DefaultWeatherKitClient,
+	Severity,
+	type CurrentWeather,
+	type DailyForecast,
+	type HourlyForecast,
+	type WeatherAlert,
+	type WeatherKitClient,
+	type WeatherKitCredentials,
+} from "./weatherkit"
+
+export const Units = {
+	metric: "metric",
+	imperial: "imperial",
+} as const
+
+export type Units = (typeof Units)[keyof typeof Units]
+
+export interface WeatherKitDataSourceOptions {
+	credentials?: WeatherKitCredentials
+	client?: WeatherKitClient
+	hourlyLimit?: number
+	dailyLimit?: number
+}
+
+export interface WeatherKitQueryConfig {
+	units?: Units
+}
+
+export class WeatherKitDataSource implements DataSource<WeatherFeedItem, WeatherKitQueryConfig> {
+	private readonly DEFAULT_HOURLY_LIMIT = 12
+	private readonly DEFAULT_DAILY_LIMIT = 7
+
+	readonly type = WeatherFeedItemType.current
+	private readonly client: WeatherKitClient
+	private readonly hourlyLimit: number
+	private readonly dailyLimit: number
+
+	constructor(options: WeatherKitDataSourceOptions) {
+		if (!options.client && !options.credentials) {
+			throw new Error("Either client or credentials must be provided")
+		}
+		this.client = options.client ?? new DefaultWeatherKitClient(options.credentials!)
+		this.hourlyLimit = options.hourlyLimit ?? this.DEFAULT_HOURLY_LIMIT
+		this.dailyLimit = options.dailyLimit ?? this.DEFAULT_DAILY_LIMIT
+	}
+
+	async query(context: Context, config: WeatherKitQueryConfig = {}): Promise<WeatherFeedItem[]> {
+		if (!context.location) {
+			return []
+		}
+
+		const units = config.units ?? Units.metric
+		const timestamp = context.time
+
+		const response = await this.client.fetch({
+			lat: context.location.lat,
+			lng: context.location.lng,
+		})
+
+		const items: WeatherFeedItem[] = []
+
+		if (response.currentWeather) {
+			items.push(createCurrentWeatherFeedItem(response.currentWeather, timestamp, units))
+		}
+
+		if (response.forecastHourly?.hours) {
+			const hours = response.forecastHourly.hours.slice(0, this.hourlyLimit)
+			for (let i = 0; i < hours.length; i++) {
+				const hour = hours[i]
+				if (hour) {
+					items.push(createHourlyWeatherFeedItem(hour, i, timestamp, units))
+				}
+			}
+		}
+
+		if (response.forecastDaily?.days) {
+			const days = response.forecastDaily.days.slice(0, this.dailyLimit)
+			for (let i = 0; i < days.length; i++) {
+				const day = days[i]
+				if (day) {
+					items.push(createDailyWeatherFeedItem(day, i, timestamp, units))
+				}
+			}
+		}
+
+		if (response.weatherAlerts?.alerts) {
+			for (const alert of response.weatherAlerts.alerts) {
+				items.push(createWeatherAlertFeedItem(alert, timestamp))
+			}
+		}
+
+		return items
+	}
+}
+
+const BASE_PRIORITY = {
+	current: 0.5,
+	hourly: 0.3,
+	daily: 0.2,
+	alert: 0.7,
+} as const
+
+const SEVERE_CONDITIONS = new Set<ConditionCode>([
+	ConditionCode.SevereThunderstorm,
+	ConditionCode.Hurricane,
+	ConditionCode.Tornado,
+	ConditionCode.TropicalStorm,
+	ConditionCode.Blizzard,
+	ConditionCode.FreezingRain,
+	ConditionCode.Hail,
+	ConditionCode.Frigid,
+	ConditionCode.Hot,
+])
+
+const MODERATE_CONDITIONS = new Set<ConditionCode>([
+	ConditionCode.Thunderstorm,
+	ConditionCode.IsolatedThunderstorms,
+	ConditionCode.ScatteredThunderstorms,
+	ConditionCode.HeavyRain,
+	ConditionCode.HeavySnow,
+	ConditionCode.FreezingDrizzle,
+	ConditionCode.BlowingSnow,
+])
+
+function adjustPriorityForCondition(basePriority: number, conditionCode: ConditionCode): number {
+	if (SEVERE_CONDITIONS.has(conditionCode)) {
+		return Math.min(1, basePriority + 0.3)
+	}
+	if (MODERATE_CONDITIONS.has(conditionCode)) {
+		return Math.min(1, basePriority + 0.15)
+	}
+	return basePriority
+}
+
+function adjustPriorityForAlertSeverity(severity: Severity): number {
+	switch (severity) {
+		case Severity.Extreme:
+			return 1
+		case Severity.Severe:
+			return 0.9
+		case Severity.Moderate:
+			return 0.75
+		case Severity.Minor:
+			return BASE_PRIORITY.alert
+	}
+}
+
+function convertTemperature(celsius: number, units: Units): number {
+	if (units === Units.imperial) {
+		return (celsius * 9) / 5 + 32
+	}
+	return celsius
+}
+
+function convertSpeed(kmh: number, units: Units): number {
+	if (units === Units.imperial) {
+		return kmh * 0.621371
+	}
+	return kmh
+}
+
+function convertDistance(km: number, units: Units): number {
+	if (units === Units.imperial) {
+		return km * 0.621371
+	}
+	return km
+}
+
+function convertPrecipitation(mm: number, units: Units): number {
+	if (units === Units.imperial) {
+		return mm * 0.0393701
+	}
+	return mm
+}
+
+function convertPressure(mb: number, units: Units): number {
+	if (units === Units.imperial) {
+		return mb * 0.02953
+	}
+	return mb
+}
+
+function createCurrentWeatherFeedItem(
+	current: CurrentWeather,
+	timestamp: Date,
+	units: Units,
+): CurrentWeatherFeedItem {
+	const priority = adjustPriorityForCondition(BASE_PRIORITY.current, current.conditionCode)
+
+	return {
+		id: `weather-current-${timestamp.getTime()}`,
+		type: WeatherFeedItemType.current,
+		priority,
+		timestamp,
+		data: {
+			conditionCode: current.conditionCode,
+			daylight: current.daylight,
+			humidity: current.humidity,
+			precipitationIntensity: convertPrecipitation(current.precipitationIntensity, units),
+			pressure: convertPressure(current.pressure, units),
+			pressureTrend: current.pressureTrend,
+			temperature: convertTemperature(current.temperature, units),
+			temperatureApparent: convertTemperature(current.temperatureApparent, units),
+			uvIndex: current.uvIndex,
+			visibility: convertDistance(current.visibility, units),
+			windDirection: current.windDirection,
+			windGust: convertSpeed(current.windGust, units),
+			windSpeed: convertSpeed(current.windSpeed, units),
+		},
+	}
+}
+
+function createHourlyWeatherFeedItem(
+	hourly: HourlyForecast,
+	index: number,
+	timestamp: Date,
+	units: Units,
+): HourlyWeatherFeedItem {
+	const priority = adjustPriorityForCondition(BASE_PRIORITY.hourly, hourly.conditionCode)
+
+	return {
+		id: `weather-hourly-${timestamp.getTime()}-${index}`,
+		type: WeatherFeedItemType.hourly,
+		priority,
+		timestamp,
+		data: {
+			forecastTime: new Date(hourly.forecastStart),
+			conditionCode: hourly.conditionCode,
+			daylight: hourly.daylight,
+			humidity: hourly.humidity,
+			precipitationAmount: convertPrecipitation(hourly.precipitationAmount, units),
+			precipitationChance: hourly.precipitationChance,
+			precipitationType: hourly.precipitationType,
+			temperature: convertTemperature(hourly.temperature, units),
+			temperatureApparent: convertTemperature(hourly.temperatureApparent, units),
+			uvIndex: hourly.uvIndex,
+			windDirection: hourly.windDirection,
+			windGust: convertSpeed(hourly.windGust, units),
+			windSpeed: convertSpeed(hourly.windSpeed, units),
+		},
+	}
+}
+
+function createDailyWeatherFeedItem(
+	daily: DailyForecast,
+	index: number,
+	timestamp: Date,
+	units: Units,
+): DailyWeatherFeedItem {
+	const priority = adjustPriorityForCondition(BASE_PRIORITY.daily, daily.conditionCode)
+
+	return {
+		id: `weather-daily-${timestamp.getTime()}-${index}`,
+		type: WeatherFeedItemType.daily,
+		priority,
+		timestamp,
+		data: {
+			forecastDate: new Date(daily.forecastStart),
+			conditionCode: daily.conditionCode,
+			maxUvIndex: daily.maxUvIndex,
+			precipitationAmount: convertPrecipitation(daily.precipitationAmount, units),
+			precipitationChance: daily.precipitationChance,
+			precipitationType: daily.precipitationType,
+			snowfallAmount: convertPrecipitation(daily.snowfallAmount, units),
+			sunrise: new Date(daily.sunrise),
+			sunset: new Date(daily.sunset),
+			temperatureMax: convertTemperature(daily.temperatureMax, units),
+			temperatureMin: convertTemperature(daily.temperatureMin, units),
+		},
+	}
+}
+
+function createWeatherAlertFeedItem(alert: WeatherAlert, timestamp: Date): WeatherAlertFeedItem {
+	const priority = adjustPriorityForAlertSeverity(alert.severity)
+
+	return {
+		id: `weather-alert-${alert.id}`,
+		type: WeatherFeedItemType.alert,
+		priority,
+		timestamp,
+		data: {
+			alertId: alert.id,
+			areaName: alert.areaName,
+			certainty: alert.certainty,
+			description: alert.description,
+			detailsUrl: alert.detailsUrl,
+			effectiveTime: new Date(alert.effectiveTime),
+			expireTime: new Date(alert.expireTime),
+			severity: alert.severity,
+			source: alert.source,
+			urgency: alert.urgency,
+		},
+	}
+}

packages/aris-data-source-weatherkit/src/feed-items.ts

@@ -0,0 +1,97 @@
+import type { FeedItem } from "@aris/core"
+
+import type { Certainty, ConditionCode, PrecipitationType, Severity, Urgency } from "./weatherkit"
+
+export const WeatherFeedItemType = {
+	current: "weather-current",
+	hourly: "weather-hourly",
+	daily: "weather-daily",
+	alert: "weather-alert",
+} as const
+
+export type WeatherFeedItemType = (typeof WeatherFeedItemType)[keyof typeof WeatherFeedItemType]
+
+export type CurrentWeatherData = {
+	conditionCode: ConditionCode
+	daylight: boolean
+	humidity: number
+	precipitationIntensity: number
+	pressure: number
+	pressureTrend: "rising" | "falling" | "steady"
+	temperature: number
+	temperatureApparent: number
+	uvIndex: number
+	visibility: number
+	windDirection: number
+	windGust: number
+	windSpeed: number
+}
+
+export interface CurrentWeatherFeedItem extends FeedItem<
+	typeof WeatherFeedItemType.current,
+	CurrentWeatherData
+> {}
+
+export type HourlyWeatherData = {
+	forecastTime: Date
+	conditionCode: ConditionCode
+	daylight: boolean
+	humidity: number
+	precipitationAmount: number
+	precipitationChance: number
+	precipitationType: PrecipitationType
+	temperature: number
+	temperatureApparent: number
+	uvIndex: number
+	windDirection: number
+	windGust: number
+	windSpeed: number
+}
+
+export interface HourlyWeatherFeedItem extends FeedItem<
+	typeof WeatherFeedItemType.hourly,
+	HourlyWeatherData
+> {}
+
+export type DailyWeatherData = {
+	forecastDate: Date
+	conditionCode: ConditionCode
+	maxUvIndex: number
+	precipitationAmount: number
+	precipitationChance: number
+	precipitationType: PrecipitationType
+	snowfallAmount: number
+	sunrise: Date
+	sunset: Date
+	temperatureMax: number
+	temperatureMin: number
+}
+
+export interface DailyWeatherFeedItem extends FeedItem<
+	typeof WeatherFeedItemType.daily,
+	DailyWeatherData
+> {}
+
+export type WeatherAlertData = {
+	alertId: string
+	areaName: string
+	certainty: Certainty
+	description: string
+	detailsUrl: string
+	effectiveTime: Date
+	expireTime: Date
+	severity: Severity
+	source: string
+	urgency: Urgency
+}
+
+export interface WeatherAlertFeedItem extends FeedItem<
+	typeof WeatherFeedItemType.alert,
+	WeatherAlertData
+> {}
+
+export type WeatherFeedItem =
+	| CurrentWeatherFeedItem
+	| HourlyWeatherFeedItem
+	| DailyWeatherFeedItem
+	| WeatherAlertFeedItem

packages/aris-data-source-weatherkit/src/index.ts

@@ -0,0 +1,38 @@
+export {
+	WeatherKitDataSource,
+	Units,
+	type Units as UnitsType,
+	type WeatherKitDataSourceOptions,
+	type WeatherKitQueryConfig,
+} from "./data-source"
+
+export {
+	WeatherFeedItemType,
+	type WeatherFeedItemType as WeatherFeedItemTypeType,
+	type CurrentWeatherData,
+	type CurrentWeatherFeedItem,
+	type DailyWeatherData,
+	type DailyWeatherFeedItem,
+	type HourlyWeatherData,
+	type HourlyWeatherFeedItem,
+	type WeatherAlertData,
+	type WeatherAlertFeedItem,
+	type WeatherFeedItem,
+} from "./feed-items"
+
+export {
+	Severity,
+	Urgency,
+	Certainty,
+	PrecipitationType,
+	ConditionCode,
+	DefaultWeatherKitClient,
+	type Severity as SeverityType,
+	type Urgency as UrgencyType,
+	type Certainty as CertaintyType,
+	type PrecipitationType as PrecipitationTypeType,
+	type ConditionCode as ConditionCodeType,
+	type WeatherKitCredentials,
+	type WeatherKitClient,
+	type WeatherKitQueryOptions,
+} from "./weatherkit"

packages/aris-data-source-weatherkit/src/weatherkit.ts

@@ -0,0 +1,367 @@
+// WeatherKit REST API client and response types
+// https://developer.apple.com/documentation/weatherkitrestapi
+
+import { type } from "arktype"
+
+export interface WeatherKitCredentials {
+	privateKey: string
+	keyId: string
+	teamId: string
+	serviceId: string
+}
+
+export interface WeatherKitQueryOptions {
+	lat: number
+	lng: number
+	language?: string
+	timezone?: string
+}
+
+export interface WeatherKitClient {
+	fetch(query: WeatherKitQueryOptions): Promise<WeatherKitResponse>
+}
+
+export class DefaultWeatherKitClient implements WeatherKitClient {
+	private readonly credentials: WeatherKitCredentials
+
+	constructor(credentials: WeatherKitCredentials) {
+		this.credentials = credentials
+	}
+
+	async fetch(query: WeatherKitQueryOptions): Promise<WeatherKitResponse> {
+		const token = await generateJwt(this.credentials)
+
+		const dataSets = ["currentWeather", "forecastHourly", "forecastDaily", "weatherAlerts"].join(
+			",",
+		)
+
+		const url = new URL(
+			`${WEATHERKIT_API_BASE}/weather/${query.language ?? "en"}/${query.lat}/${query.lng}`,
+		)
+		url.searchParams.set("dataSets", dataSets)
+		if (query.timezone) {
+			url.searchParams.set("timezone", query.timezone)
+		}
+
+		const response = await fetch(url.toString(), {
+			headers: {
+				Authorization: `Bearer ${token}`,
+			},
+		})
+
+		if (!response.ok) {
+			const body = await response.text()
+			throw new Error(`WeatherKit API error: ${response.status} ${response.statusText}: ${body}`)
+		}
+
+		const json = await response.json()
+		const result = weatherKitResponseSchema(json)
+
+		if (result instanceof type.errors) {
+			throw new Error(`WeatherKit API response validation failed: ${result.summary}`)
+		}
+
+		return result
+	}
+}
+
+export const Severity = {
+	Minor: "minor",
+	Moderate: "moderate",
+	Severe: "severe",
+	Extreme: "extreme",
+} as const
+
+export type Severity = (typeof Severity)[keyof typeof Severity]
+
+export const Urgency = {
+	Immediate: "immediate",
+	Expected: "expected",
+	Future: "future",
+	Past: "past",
+	Unknown: "unknown",
+} as const
+
+export type Urgency = (typeof Urgency)[keyof typeof Urgency]
+
+export const Certainty = {
+	Observed: "observed",
+	Likely: "likely",
+	Possible: "possible",
+	Unlikely: "unlikely",
+	Unknown: "unknown",
+} as const
+
+export type Certainty = (typeof Certainty)[keyof typeof Certainty]
+
+export const PrecipitationType = {
+	Clear: "clear",
+	Precipitation: "precipitation",
+	Rain: "rain",
+	Snow: "snow",
+	Sleet: "sleet",
+	Hail: "hail",
+	Mixed: "mixed",
+} as const
+
+export type PrecipitationType = (typeof PrecipitationType)[keyof typeof PrecipitationType]
+
+export const ConditionCode = {
+	Clear: "Clear",
+	Cloudy: "Cloudy",
+	Dust: "Dust",
+	Fog: "Fog",
+	Haze: "Haze",
+	MostlyClear: "MostlyClear",
+	MostlyCloudy: "MostlyCloudy",
+	PartlyCloudy: "PartlyCloudy",
+	ScatteredThunderstorms: "ScatteredThunderstorms",
+	Smoke: "Smoke",
+	Breezy: "Breezy",
+	Windy: "Windy",
+	Drizzle: "Drizzle",
+	HeavyRain: "HeavyRain",
+	Rain: "Rain",
+	Showers: "Showers",
+	Flurries: "Flurries",
+	HeavySnow: "HeavySnow",
+	MixedRainAndSleet: "MixedRainAndSleet",
+	MixedRainAndSnow: "MixedRainAndSnow",
+	MixedRainfall: "MixedRainfall",
+	MixedSnowAndSleet: "MixedSnowAndSleet",
+	ScatteredShowers: "ScatteredShowers",
+	ScatteredSnowShowers: "ScatteredSnowShowers",
+	Sleet: "Sleet",
+	Snow: "Snow",
+	SnowShowers: "SnowShowers",
+	Blizzard: "Blizzard",
+	BlowingSnow: "BlowingSnow",
+	FreezingDrizzle: "FreezingDrizzle",
+	FreezingRain: "FreezingRain",
+	Frigid: "Frigid",
+	Hail: "Hail",
+	Hot: "Hot",
+	Hurricane: "Hurricane",
+	IsolatedThunderstorms: "IsolatedThunderstorms",
+	SevereThunderstorm: "SevereThunderstorm",
+	Thunderstorm: "Thunderstorm",
+	Tornado: "Tornado",
+	TropicalStorm: "TropicalStorm",
+} as const
+
+export type ConditionCode = (typeof ConditionCode)[keyof typeof ConditionCode]
+
+const WEATHERKIT_API_BASE = "https://weatherkit.apple.com/api/v1"
+
+const severitySchema = type.enumerated(
+	Severity.Minor,
+	Severity.Moderate,
+	Severity.Severe,
+	Severity.Extreme,
+)
+
+const urgencySchema = type.enumerated(
+	Urgency.Immediate,
+	Urgency.Expected,
+	Urgency.Future,
+	Urgency.Past,
+	Urgency.Unknown,
+)
+
+const certaintySchema = type.enumerated(
+	Certainty.Observed,
+	Certainty.Likely,
+	Certainty.Possible,
+	Certainty.Unlikely,
+	Certainty.Unknown,
+)
+
+const precipitationTypeSchema = type.enumerated(
+	PrecipitationType.Clear,
+	PrecipitationType.Precipitation,
+	PrecipitationType.Rain,
+	PrecipitationType.Snow,
+	PrecipitationType.Sleet,
+	PrecipitationType.Hail,
+	PrecipitationType.Mixed,
+)
+
+const conditionCodeSchema = type.enumerated(...Object.values(ConditionCode))
+
+const pressureTrendSchema = type.enumerated("rising", "falling", "steady")
+
+const currentWeatherSchema = type({
+	asOf: "string",
+	conditionCode: conditionCodeSchema,
+	daylight: "boolean",
+	humidity: "number",
+	precipitationIntensity: "number",
+	pressure: "number",
+	pressureTrend: pressureTrendSchema,
+	temperature: "number",
+	temperatureApparent: "number",
+	temperatureDewPoint: "number",
+	uvIndex: "number",
+	visibility: "number",
+	windDirection: "number",
+	windGust: "number",
+	windSpeed: "number",
+})
+
+export type CurrentWeather = typeof currentWeatherSchema.infer
+
+const hourlyForecastSchema = type({
+	forecastStart: "string",
+	conditionCode: conditionCodeSchema,
+	daylight: "boolean",
+	humidity: "number",
+	precipitationAmount: "number",
+	precipitationChance: "number",
+	precipitationType: precipitationTypeSchema,
+	pressure: "number",
+	snowfallIntensity: "number",
+	temperature: "number",
+	temperatureApparent: "number",
+	temperatureDewPoint: "number",
+	uvIndex: "number",
+	visibility: "number",
+	windDirection: "number",
+	windGust: "number",
+	windSpeed: "number",
+})
+
+export type HourlyForecast = typeof hourlyForecastSchema.infer
+
+const dayWeatherConditionsSchema = type({
+	conditionCode: conditionCodeSchema,
+	humidity: "number",
+	precipitationAmount: "number",
+	precipitationChance: "number",
+	precipitationType: precipitationTypeSchema,
+	snowfallAmount: "number",
+	temperatureMax: "number",
+	temperatureMin: "number",
+	windDirection: "number",
+	"windGust?": "number",
+	windSpeed: "number",
+})
+
+export type DayWeatherConditions = typeof dayWeatherConditionsSchema.infer
+
+const dailyForecastSchema = type({
+	forecastStart: "string",
+	forecastEnd: "string",
+	conditionCode: conditionCodeSchema,
+	maxUvIndex: "number",
+	moonPhase: "string",
+	"moonrise?": "string",
+	"moonset?": "string",
+	precipitationAmount: "number",
+	precipitationChance: "number",
+	precipitationType: precipitationTypeSchema,
+	snowfallAmount: "number",
+	sunrise: "string",
+	sunriseCivil: "string",
+	sunriseNautical: "string",
+	sunriseAstronomical: "string",
+	sunset: "string",
+	sunsetCivil: "string",
+	sunsetNautical: "string",
+	sunsetAstronomical: "string",
+	temperatureMax: "number",
+	temperatureMin: "number",
+	"daytimeForecast?": dayWeatherConditionsSchema,
+	"overnightForecast?": dayWeatherConditionsSchema,
+})
+
+export type DailyForecast = typeof dailyForecastSchema.infer
+
+const weatherAlertSchema = type({
+	id: "string",
+	areaId: "string",
+	areaName: "string",
+	certainty: certaintySchema,
+	countryCode: "string",
+	description: "string",
+	detailsUrl: "string",
+	effectiveTime: "string",
+	expireTime: "string",
+	issuedTime: "string",
+	responses: "string[]",
+	severity: severitySchema,
+	source: "string",
+	urgency: urgencySchema,
+})
+
+export type WeatherAlert = typeof weatherAlertSchema.infer
+
+const weatherKitResponseSchema = type({
+	"currentWeather?": currentWeatherSchema,
+	"forecastHourly?": type({
+		hours: hourlyForecastSchema.array(),
+	}),
+	"forecastDaily?": type({
+		days: dailyForecastSchema.array(),
+	}),
+	"weatherAlerts?": type({
+		alerts: weatherAlertSchema.array(),
+	}),
+})
+
+export type WeatherKitResponse = typeof weatherKitResponseSchema.infer
+
+async function generateJwt(credentials: WeatherKitCredentials): Promise<string> {
+	const header = {
+		alg: "ES256",
+		kid: credentials.keyId,
+		id: `${credentials.teamId}.${credentials.serviceId}`,
+	}
+
+	const now = Math.floor(Date.now() / 1000)
+	const payload = {
+		iss: credentials.teamId,
+		iat: now,
+		exp: now + 3600,
+		sub: credentials.serviceId,
+	}
+
+	const encoder = new TextEncoder()
+	const headerB64 = btoa(JSON.stringify(header))
+		.replace(/\+/g, "-")
+		.replace(/\//g, "_")
+		.replace(/=+$/, "")
+	const payloadB64 = btoa(JSON.stringify(payload))
+		.replace(/\+/g, "-")
+		.replace(/\//g, "_")
+		.replace(/=+$/, "")
+
+	const signingInput = `${headerB64}.${payloadB64}`
+
+	const pemContents = credentials.privateKey
+		.replace(/-----BEGIN PRIVATE KEY-----/, "")
+		.replace(/-----END PRIVATE KEY-----/, "")
+		.replace(/\s/g, "")
+
+	const binaryKey = Uint8Array.from(atob(pemContents), (c) => c.charCodeAt(0))
+
+	const cryptoKey = await crypto.subtle.importKey(
+		"pkcs8",
+		binaryKey,
+		{ name: "ECDSA", namedCurve: "P-256" },
+		false,
+		["sign"],
+	)
+
+	const signature = await crypto.subtle.sign(
+		{ name: "ECDSA", hash: "SHA-256" },
+		cryptoKey,
+		encoder.encode(signingInput),
+	)
+
+	const signatureB64 = btoa(String.fromCharCode(...new Uint8Array(signature)))
+		.replace(/\+/g, "-")
+		.replace(/\//g, "_")
+		.replace(/=+$/, "")
+
+	return `${signingInput}.${signatureB64}`
+}