[2026] fix a few wire shapes

apps/datacollection/src/datacollection.app.ts

@@ -48,12 +48,13 @@ const app = new Hono<App>()
 		return c.json([])
 	})
 
-	// Sampling configuration, asked for once per session (`?sessionId=<guid>`). An empty
-	// object carries no per-event overrides, which the client reads as "sample everything
-	// at the built-in default rates". Since the events are discarded anyway, the rate it
-	// picks makes no difference here.
+	// Sampling configuration, asked for once per session (`?sessionId=<guid>`). A BARE ARRAY
+	// of `{ EventType, ShouldBeSampled }` entries (the client decodes a `List<EventDTO>`),
+	// e.g. `[{ "EventType": "player_join", "ShouldBeSampled": true }]` — not an object: the
+	// `{}` this once served made the client's decoder throw. Empty says "sample nothing",
+	// which is the right answer since the events are discarded anyway.
 	.get('/sampling', async (c) => {
-		return c.json({})
+		return c.json([])
 	})
 
 export default app

apps/datacollection/src/test/integration/api.test.ts

@@ -49,7 +49,7 @@ it('acknowledges an unreadable body on both event paths', async () => {
 it('serves an empty sampling configuration', async () => {
 	const res = await SELF.fetch(`${ORIGIN}/sampling?sessionId=e9a899ce-ce46-447d-bb22-11e82ed68f8d`)
 	expect(res.status).toBe(200)
-	expect(await res.json()).toEqual({})
+	expect(await res.json()).toEqual([])
 })
 
 // The client always sends `sessionId`, but nothing here reads it, so a missing one must
@@ -57,5 +57,5 @@ it('serves an empty sampling configuration', async () => {
 it('serves the sampling configuration without a sessionId', async () => {
 	const res = await SELF.fetch(`${ORIGIN}/sampling`)
 	expect(res.status).toBe(200)
-	expect(await res.json()).toEqual({})
+	expect(await res.json()).toEqual([])
 })