diff --git a/apps/api/migrations/0035_custom_avatar_item_badge_room.sql b/apps/api/migrations/0035_custom_avatar_item_badge_room.sql
new file mode 100644
index 0000000..375cdd7
--- /dev/null
+++ b/apps/api/migrations/0035_custom_avatar_item_badge_room.sql
@@ -0,0 +1,18 @@
+-- Index the room-badge lookup that hydrates every room list (`attachBadges` in
+-- packages/domain/src/rooms-db.ts). Every room page — feeds, search, the owned list, a single
+-- room read — asks this table for the published badges of the rooms on the page, and without an
+-- index that was a full scan of every custom avatar item (thousands of first-party rows) per
+-- page. At the time of writing it was half of the database's row reads.
+--
+-- PARTIAL, over only the badge rows (`OutfitType` 1000), keyed by the badge's room. SQLite uses
+-- a partial index only when the query's WHERE contains its term as written, and an expression
+-- index only when the query names the same expression, so the query must keep BOTH
+-- `outfit_type = 1000` and `json_extract(data, '$.CustomBadgeMetadata.RoomId')` exactly —
+-- change either and the index silently stops being used. The key is an expression rather than
+-- a new generated column so the query reads the same whether or not this migration has run yet
+-- (the `rooms` worker can deploy ahead of `api`'s migrations).
+-- Generated from src/custom-avatar-items-db.ts (SCHEMA_DDL) — keep in sync.
+
+CREATE INDEX IF NOT EXISTS idx_custom_avatar_item_badge_room
+  ON custom_avatar_item (json_extract(data, '$.CustomBadgeMetadata.RoomId'))
+  WHERE outfit_type = 1000;
diff --git a/apps/api/src/custom-avatar-items-db.ts b/apps/api/src/custom-avatar-items-db.ts
index f30e0df..cc84160 100644
--- a/apps/api/src/custom-avatar-items-db.ts
+++ b/apps/api/src/custom-avatar-items-db.ts
@@ -29,7 +29,7 @@
 
 import { COACH_ACCOUNT_ID } from './custom-avatar-items-load'
 
-/** Schema DDL (mirror of migrations/0022_custom_avatar_item_json.sql). */
+/** Schema DDL (mirror of migrations/0022_custom_avatar_item_json.sql and 0035_custom_avatar_item_badge_room.sql). */
 export const SCHEMA_DDL: string[] = [
 	`CREATE TABLE IF NOT EXISTS custom_avatar_item (
 		data TEXT NOT NULL,
@@ -45,6 +45,9 @@ export const SCHEMA_DDL: string[] = [
 	)`,
 	`CREATE UNIQUE INDEX IF NOT EXISTS idx_custom_avatar_item_id ON custom_avatar_item (custom_avatar_item_id)`,
 	`CREATE INDEX IF NOT EXISTS idx_custom_avatar_item_creator ON custom_avatar_item (creator_account_id)`,
+	// The room-badge lookup (`attachBadges`, packages/domain/src/rooms-db.ts) runs on every room
+	// page; partial over the badge rows, keyed by the badge's room (migrations/0035).
+	`CREATE INDEX IF NOT EXISTS idx_custom_avatar_item_badge_room ON custom_avatar_item (json_extract(data, '$.CustomBadgeMetadata.RoomId')) WHERE outfit_type = 1000`,
 ]
 
 /**
diff --git a/apps/rooms/src/test/integration/api.test.ts b/apps/rooms/src/test/integration/api.test.ts
index 5a6d473..54164ca 100644
--- a/apps/rooms/src/test/integration/api.test.ts
+++ b/apps/rooms/src/test/integration/api.test.ts
@@ -34,6 +34,7 @@ import {
 	UNITY_ASSET_SCHEMA_DDL,
 } from '@repo/domain'
 
+import { SCHEMA_DDL as CUSTOM_AVATAR_ITEM_SCHEMA_DDL } from '../../../../api/src/custom-avatar-items-db'
 import { SCHEMA_DDL as INVENTION_SCHEMA_DDL } from '../../../../api/src/inventions-db'
 import { SCHEMA_DDL as ROOM_VOTE_SCHEMA_DDL } from '../../../../api/src/votes-db'
 import { NotificationType } from '../../../../notify/src/notification-types'
@@ -134,6 +135,7 @@ beforeAll(async () => {
 	for (const stmt of ROOM_VOTE_SCHEMA_DDL) await env.DB.prepare(stmt).run()
 	// Inventions (owned by the api worker) — a room save writes each one's room count.
 	for (const stmt of INVENTION_SCHEMA_DDL) await env.DB.prepare(stmt).run()
+	for (const stmt of CUSTOM_AVATAR_ITEM_SCHEMA_DDL) await env.DB.prepare(stmt).run()
 	for (const stmt of ROOM_INVITE_SCHEMA_DDL) await env.DB.prepare(stmt).run()
 	// Baked unity asset bundles — what `POST /unity_assets/baked/bulk` serves.
 	for (const stmt of UNITY_ASSET_SCHEMA_DDL) await env.DB.prepare(stmt).run()
@@ -7209,3 +7211,39 @@ it('omits hydrated Badges when persisting a room settings edit', async () => {
 	}>()
 	expect(JSON.parse(stored!.data)).not.toHaveProperty('Badges')
 })
+
+// The badge lookup runs on every room page, served by a partial index over the badge rows
+// (api migrations/0035, mirrored in SCHEMA_DDL above). Only a PUBLISHED badge with a built save
+// hydrates; a draft stays on its creator's Studio shelf.
+it('GET /rooms/:id hydrates the room\'s published badges', async () => {
+	await seedRoomWithSubRooms(env.DB, {
+		RoomId: 987671,
+		Name: 'BadgeHydration',
+		CreatorAccountId: 987671,
+		SubRooms: [],
+	})
+	const badge = (id: string, roomId: number, accessibility: number, saves: unknown[]) =>
+		JSON.stringify({
+			CustomAvatarItemId: id,
+			CreatorAccountId: 987671,
+			Name: id,
+			OutfitType: 1000,
+			Accessibility: accessibility,
+			CurrentSaves: saves,
+			CustomBadgeMetadata: { RoomId: roomId },
+		})
+	const insert = env.DB.prepare('INSERT INTO custom_avatar_item (data) VALUES (?)')
+	await env.DB.batch([
+		insert.bind(badge('badge-published', 987671, 1, [{ BodyType: 0 }])),
+		insert.bind(badge('badge-draft', 987671, 0, [{ BodyType: 0 }])),
+		insert.bind(badge('badge-unbuilt', 987671, 1, [])),
+		insert.bind(badge('badge-other-room', 987670, 1, [{ BodyType: 0 }])),
+	])
+	// Twice: the second read takes the path that remembers the table exists.
+	for (let i = 0; i < 2; i++) {
+		const res = await SELF.fetch(`${ORIGIN}/rooms/987671`)
+		expect(res.status).toBe(200)
+		const room = (await res.json()) as { Badges: Array<{ CustomAvatarItemId: string }> }
+		expect(room.Badges.map((b) => b.CustomAvatarItemId)).toEqual(['badge-published'])
+	}
+})
diff --git a/packages/domain/src/rooms-db.ts b/packages/domain/src/rooms-db.ts
index 6cc985e..32466d9 100644
--- a/packages/domain/src/rooms-db.ts
+++ b/packages/domain/src/rooms-db.ts
@@ -2846,17 +2846,31 @@ async function hydrateRooms(db: D1Database, rooms: Room[]): Promise<Room[]> {
 	return rooms
 }
 
+/**
+ * Whether `custom_avatar_item` has been seen on this database. API owns that table's migration
+ * and room deployments can precede it, so {@link attachBadges} probes for it — but a table
+ * never goes away once created, so a hit is remembered and the probe (a scan of
+ * `sqlite_master`, on every room page) runs only until the first hit.
+ */
+let badgeTableSeen = false
+
 /** Published room-linked image badges; drafts remain on the creator's Studio shelf. */
 async function attachBadges(db: D1Database, rooms: Room[]): Promise<void> {
 	if (!rooms.length) return
-	// API owns this table's migration; room deployments can precede that migration.
-	const exists = await db
-		.prepare("SELECT 1 FROM sqlite_master WHERE type='table' AND name='custom_avatar_item'")
-		.first()
-	if (!exists) {
-		for (const room of rooms) room.Badges = []
-		return
+	if (!badgeTableSeen) {
+		const exists = await db
+			.prepare("SELECT 1 FROM sqlite_master WHERE type='table' AND name='custom_avatar_item'")
+			.first()
+		if (!exists) {
+			for (const room of rooms) room.Badges = []
+			return
+		}
+		badgeTableSeen = true
 	}
+	// Served by `idx_custom_avatar_item_badge_room` (api migrations/0035), a PARTIAL index over
+	// `outfit_type = 1000` keyed by the `json_extract(data,'$.CustomBadgeMetadata.RoomId')`
+	// expression. SQLite matches both only as written: drop or rephrase either term and this
+	// goes back to scanning every custom avatar item on every room page.
 	const rows = await db
 		.prepare(
 			"SELECT data,json_extract(data,'$.CustomBadgeMetadata.RoomId') AS room_id FROM custom_avatar_item WHERE outfit_type=1000 AND accessibility<>0 AND json_array_length(json_extract(data,'$.CurrentSaves'))>0 AND json_extract(data,'$.CustomBadgeMetadata.RoomId') IN (SELECT value FROM json_each(?))"