feat: replace FeedItem.priority with signals

Remove priority field from FeedItem and engine-level sorting.
Add FeedItemSignals with urgency and timeRelevance fields.
Update all source packages to emit signals instead of priority.

Ranking is now the post-processing layer's responsibility.
Urgency values are unchanged from the old priority values.

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

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

@@ -18,9 +18,9 @@ import type { FeedItem } from "./feed"
  *     return [{
  *       id: `weather-${Date.now()}`,
  *       type: this.type,
- *       priority: 0.5,
  *       timestamp: context.time,
  *       data: { temp: data.temperature },
+ *       signals: { urgency: 0.5, timeRelevance: "ambient" },
  *     }]
  *   }
  * }

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

@@ -3,7 +3,7 @@ import { describe, expect, test } from "bun:test"
 import type { ActionDefinition, Context, ContextKey, FeedItem, FeedSource } from "./index"
 
 import { FeedEngine } from "./feed-engine"
-import { UnknownActionError, contextKey, contextValue } from "./index"
+import { TimeRelevance, UnknownActionError, contextKey, contextValue } from "./index"
 
 // No-op action methods for test sources
 const noActions = {
@@ -100,12 +100,12 @@ function createWeatherSource(
 				{
 					id: `weather-${Date.now()}`,
 					type: "weather",
-					priority: 0.5,
 					timestamp: new Date(),
 					data: {
 						temperature: weather.temperature,
 						condition: weather.condition,
 					},
+					signals: { urgency: 0.5, timeRelevance: TimeRelevance.Ambient },
 				},
 			]
 		},
@@ -131,9 +131,9 @@ function createAlertSource(): FeedSource<AlertFeedItem> {
 					{
 						id: "alert-storm",
 						type: "alert",
-						priority: 1.0,
 						timestamp: new Date(),
 						data: { message: "Storm warning!" },
+						signals: { urgency: 1.0, timeRelevance: TimeRelevance.Imminent },
 					},
 				]
 			}
@@ -322,7 +322,7 @@ describe("FeedEngine", () => {
 			expect(items[0]!.type).toBe("weather")
 		})
 
-		test("sorts items by priority descending", async () => {
+		test("returns items in source graph order (no engine-level sorting)", async () => {
 			const location = createLocationSource()
 			location.simulateUpdate({ lat: 51.5, lng: -0.1 })
 
@@ -338,8 +338,12 @@ describe("FeedEngine", () => {
 			const { items } = await engine.refresh()
 
 			expect(items).toHaveLength(2)
-			expect(items[0]!.type).toBe("alert") // priority 1.0
-			expect(items[1]!.type).toBe("weather") // priority 0.5
+			// Items returned in topological order (weather before alert)
+			expect(items[0]!.type).toBe("weather")
+			expect(items[1]!.type).toBe("alert")
+			// Signals are preserved for post-processors to consume
+			expect(items[0]!.signals?.urgency).toBe(0.5)
+			expect(items[1]!.signals?.urgency).toBe(1.0)
 		})
 
 		test("handles missing upstream context gracefully", async () => {

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

@@ -150,9 +150,6 @@ export class FeedEngine<TItems extends FeedItem = FeedItem> {
 			}
 		}
 
-		// Sort by priority descending
-		items.sort((a, b) => b.priority - a.priority)
-
 		this.context = context
 
 		const result: FeedResult<TItems> = { context, items: items as TItems[], errors }
@@ -314,8 +311,6 @@ export class FeedEngine<TItems extends FeedItem = FeedItem> {
 			}
 		}
 
-		items.sort((a, b) => b.priority - a.priority)
-
 		const result: FeedResult<TItems> = {
 			context: this.context,
 			items: items as TItems[],

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

@@ -2,7 +2,7 @@ import { describe, expect, test } from "bun:test"
 
 import type { ActionDefinition, Context, ContextKey, FeedItem, FeedSource } from "./index"
 
-import { UnknownActionError, contextKey, contextValue } from "./index"
+import { TimeRelevance, UnknownActionError, contextKey, contextValue } from "./index"
 
 // No-op action methods for test sources
 const noActions = {
@@ -99,12 +99,12 @@ function createWeatherSource(
 				{
 					id: `weather-${Date.now()}`,
 					type: "weather",
-					priority: 0.5,
 					timestamp: new Date(),
 					data: {
 						temperature: weather.temperature,
 						condition: weather.condition,
 					},
+					signals: { urgency: 0.5, timeRelevance: TimeRelevance.Ambient },
 				},
 			]
 		},
@@ -130,9 +130,9 @@ function createAlertSource(): FeedSource<AlertFeedItem> {
 					{
 						id: "alert-storm",
 						type: "alert",
-						priority: 1.0,
 						timestamp: new Date(),
 						data: { message: "Storm warning!" },
+						signals: { urgency: 1.0, timeRelevance: TimeRelevance.Imminent },
 					},
 				]
 			}
@@ -226,9 +226,6 @@ async function refreshGraph(graph: SourceGraph): Promise<{ context: Context; ite
 		}
 	}
 
-	// Sort by priority descending
-	items.sort((a, b) => b.priority - a.priority)
-
 	return { context, items }
 }
 
@@ -441,8 +438,12 @@ describe("FeedSource", () => {
 			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
+			// Items returned in topological order (weather before alert)
+			expect(items[0]!.type).toBe("weather")
+			expect(items[1]!.type).toBe("alert")
+			// Signals preserved for post-processors
+			expect(items[0]!.signals?.urgency).toBe(0.5)
+			expect(items[1]!.signals?.urgency).toBe(1.0)
 		})
 
 		test("source without location context returns empty items", async () => {

packages/aris-core/src/feed.ts

@@ -1,3 +1,28 @@
+/**
+ * Source-provided hints for post-processors.
+ *
+ * Sources express domain-specific relevance without determining final ranking.
+ * Post-processors consume these signals alongside other inputs (user affinity,
+ * time of day, interaction history) to produce the final feed order.
+ */
+export const TimeRelevance = {
+	/** Needs attention now (e.g., event starting in minutes, severe alert) */
+	Imminent: "imminent",
+	/** Relevant soon (e.g., event in the next hour, approaching deadline) */
+	Upcoming: "upcoming",
+	/** Background information (e.g., daily forecast, low-priority status) */
+	Ambient: "ambient",
+} as const
+
+export type TimeRelevance = (typeof TimeRelevance)[keyof typeof TimeRelevance]
+
+export interface FeedItemSignals {
+	/** Source-assessed urgency (0-1). Post-processors use this as one ranking input. */
+	urgency?: number
+	/** How time-sensitive this item is relative to now. */
+	timeRelevance?: TimeRelevance
+}
+
 /**
  * A single item in the feed.
  *
@@ -8,9 +33,9 @@
  * const item: WeatherItem = {
  *   id: "weather-123",
  *   type: "weather",
- *   priority: 0.5,
  *   timestamp: new Date(),
  *   data: { temp: 18, condition: "cloudy" },
+ *   signals: { urgency: 0.5, timeRelevance: "ambient" },
  * }
  * ```
  */
@@ -22,10 +47,10 @@ export interface FeedItem<
 	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
+	/** Source-provided hints for post-processors. Optional — omit if no signals apply. */
+	signals?: FeedItemSignals
 }

packages/aris-core/src/index.ts

@@ -7,7 +7,8 @@ export type { ActionDefinition } from "./action"
 export { UnknownActionError } from "./action"
 
 // Feed
-export type { FeedItem } from "./feed"
+export type { FeedItem, FeedItemSignals } from "./feed"
+export { TimeRelevance } from "./feed"
 
 // Feed Source
 export type { FeedSource } from "./feed-source"

packages/aris-core/src/reconciler.ts

@@ -72,8 +72,6 @@ export class Reconciler<TItems extends FeedItem = never> {
 			}
 		})
 
-		items.sort((a, b) => b.priority - a.priority)
-
 		return { items, errors } as ReconcileResult<TItems>
 	}
 }