[econ] some invention stats

apps/econ/migrations/0026_invention_num_downloads.sql

@@ -0,0 +1,20 @@
+-- An invention's `NumDownloads` is the number of players who have it: the rows in
+-- `inventory_invention` that name it. `grantInvention` now re-derives it on every grant
+-- (packages/domain/src/inventory-invention-db.ts); every purchase before that left it at
+-- the 0 a save mints, so this backfills the inventions already bought.
+--
+-- The `invention` table is the `api` worker's (same database). `ModifiedAt` is left alone:
+-- being bought is not an edit of the invention.
+
+-- Backs that per-invention count; the primary key leads with account_id.
+-- Generated from INVENTORY_INVENTION_SCHEMA_DDL — keep in sync.
+CREATE INDEX IF NOT EXISTS idx_inventory_invention_invention
+  ON inventory_invention (invention_id);
+
+UPDATE invention
+SET data = json_set(
+  data,
+  '$.NumDownloads',
+  (SELECT COUNT(*) FROM inventory_invention WHERE invention_id = invention.id)
+)
+WHERE id IN (SELECT invention_id FROM inventory_invention);

apps/econ/src/econ.app.ts

@@ -2675,9 +2675,8 @@ interface SettledInventionPurchase {
  *
  * Ownership is recorded in `inventory_invention`; the creator is not sold their own
  * invention (they own it already, via CreatorPlayerId) and a re-buy is a 409 rather
- * than a second row. The invention’s `NumDownloads` counter is deliberately NOT
- * bumped: that column lives on the `invention` table the `api` worker owns, and this
- * worker only reads it.
+ * than a second row. The grant also resyncs the invention’s `NumDownloads` — the count
+ * of players who have it — and the invention returned carries the new number.
  */
 async function settleInventionPurchase(
 	c: Context<App>,
@@ -2723,7 +2722,7 @@ async function settleInventionPurchase(
 	// around them, so order them by what a failure costs. A buyer who paid and got the
 	// invention but left the creator unpaid is recoverable; a buyer charged for nothing
 	// is not.
-	await grantInvention(c.env.DB, id, inventionId)
+	const downloads = await grantInvention(c.env.DB, id, inventionId)
 
 	if (price > 0) {
 		// Seed the creator's signup grant BEFORE crediting them: `creditCurrency` upserts
@@ -2760,7 +2759,7 @@ async function settleInventionPurchase(
 	if (price > 0) {
 		await pushBalancePurchase(c, id, CurrencyType.RecCenterTokens, -price, balance)
 	}
-	return { invention, balance }
+	return { invention: { ...invention, NumDownloads: downloads }, balance }
 }
 
 // strict: false so trailing-slash routes (e.g. `/gifts/consume/`, which the client

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

@@ -5054,7 +5054,7 @@ describe('econ endpoints', () => {
 			}
 			InventionResponse: {
 				Status: number
-				Invention: { InventionId: number; Name: string }
+				Invention: { InventionId: number; Name: string; NumDownloads: number }
 				InventionVersion: { InventionId: number; VersionNumber: number }
 			}
 		}
@@ -5070,9 +5070,22 @@ describe('econ endpoints', () => {
 
 		expect(await getOwnedInventionIds(env.DB, 50)).toEqual([8])
 
-		// Owning an invention is boolean: buying it again is a conflict, not a second row.
+		// `NumDownloads` is the number of players who have it, re-derived on the grant:
+		// the response carries it and so does the stored record.
+		const storedDownloads = async (): Promise<number> =>
+			(
+				await env.DB.prepare(
+					"SELECT json_extract(data, '$.NumDownloads') AS n FROM invention WHERE id = 8"
+				).first<{ n: number }>()
+			)?.n ?? -1
+		expect(body.InventionResponse.Invention.NumDownloads).toBe(1)
+		expect(await storedDownloads()).toBe(1)
+
+		// Owning an invention is boolean: buying it again is a conflict, not a second row —
+		// and not a second download.
 		expect((await buyInvention('50', 8)).status).toBe(409)
 		expect(await getOwnedInventionIds(env.DB, 50)).toEqual([8])
+		expect(await storedDownloads()).toBe(1)
 	})
 
 	test('GET /api/storefronts/v2/buyInvention pays the creator the buyer’s tokens', async () => {

packages/domain/src/inventory-invention-db.ts

@@ -9,6 +9,10 @@
  * creator is not listed here either — they own their invention through its
  * `CreatorPlayerId`, and the buy path refuses to sell an invention to its own creator.
  *
+ * The one thing a grant does write on the invention record is its `NumDownloads`: the
+ * number of rows here that name it, re-derived on every grant (see `grantInvention`), the
+ * way `CheerCount` is re-derived from `invention_interaction` on every cheer.
+ *
  * The `econ` worker owns the schema/migration (apps/econ/migrations/
  * 0008_inventory_invention.sql) and is the only writer; `api` only reads, to fold bought
  * inventions into `GET /api/inventions/v2/mine`. Both import these helpers so the table
@@ -23,24 +27,46 @@ export const INVENTORY_INVENTION_SCHEMA_DDL: string[] = [
 		acquired_at TEXT NOT NULL,
 		PRIMARY KEY (account_id, invention_id)
 	)`,
+	// Backs the per-invention count `grantInvention` re-derives (migrations/0026).
+	`CREATE INDEX IF NOT EXISTS idx_inventory_invention_invention
+		ON inventory_invention (invention_id)`,
 ]
 
 /**
  * Grant an invention to a player. INSERT OR IGNORE on the (account, invention) primary
  * key: owning an invention is boolean, so a second grant keeps the original
  * `acquired_at` rather than back-dating the purchase to now.
+ *
+ * Then resyncs the invention's denormalized `NumDownloads` — the number of players who
+ * have it — and returns it. The count is DERIVED from this table rather than incremented,
+ * so a repeated grant can't inflate it and a drifted number heals on the next one. It is
+ * a `json_set` on the one key, like the cheer count, so it doesn't touch `ModifiedAt` or
+ * race a full-record rewrite into losing anything but this number.
  */
 export async function grantInvention(
 	db: D1Database,
 	accountId: number,
 	inventionId: number
-): Promise<void> {
+): Promise<number> {
 	await db
 		.prepare(
 			'INSERT OR IGNORE INTO inventory_invention (account_id, invention_id, acquired_at) VALUES (?1, ?2, ?3)'
 		)
 		.bind(accountId, inventionId, new Date().toISOString())
 		.run()
+
+	const row = await db
+		.prepare('SELECT COUNT(*) AS n FROM inventory_invention WHERE invention_id = ?1')
+		.bind(inventionId)
+		.first<{ n: number }>()
+	const downloads = row?.n ?? 0
+	await db
+		.prepare(
+			"UPDATE invention SET data = json_set(data, '$.NumDownloads', CAST(?2 AS INTEGER)) WHERE id = ?1"
+		)
+		.bind(inventionId, downloads)
+		.run()
+	return downloads
 }
 
 /**