diff --git a/scripts/pb-init-v3.sh b/scripts/pb-init-v3.sh
index eb9f62f..ca932f4 100755
--- a/scripts/pb-init-v3.sh
+++ b/scripts/pb-init-v3.sh
@@ -62,6 +62,39 @@ create() {
   esac
 }
 
+# add_index COLLECTION INDEX_NAME SQL_EXPR
+# Fetches current schema, adds index if absent by name, PATCHes collection.
+add_index() {
+  COLL="$1"; INAME="$2"; ISQL="$3"
+  SCHEMA=$(curl -sf -H "Authorization: Bearer $TOK" "$PB/api/collections/$COLL" 2>/dev/null)
+  PARSED=$(echo "$SCHEMA" | python3 -c "
+import sys, json
+d = json.load(sys.stdin)
+indexes = d.get('indexes', [])
+exists = any('$INAME' in idx for idx in indexes)
+print('exists=' + str(exists))
+print('id=' + d.get('id', ''))
+if not exists:
+    indexes.append('$ISQL')
+    print('indexes=' + json.dumps(indexes))
+" 2>/dev/null)
+  if echo "$PARSED" | grep -q "^exists=True"; then
+    log "index exists (skip): $COLL.$INAME"; return
+  fi
+  COLL_ID=$(echo "$PARSED" | grep "^id=" | sed 's/^id=//')
+  [ -z "$COLL_ID" ] && { log "WARNING: cannot resolve id for $COLL"; return; }
+  NEW_INDEXES=$(echo "$PARSED" | grep "^indexes=" | sed 's/^indexes=//')
+  STATUS=$(curl -s -o /dev/null -w "%{http_code}" \
+    -X PATCH "$PB/api/collections/$COLL_ID" \
+    -H "Content-Type: application/json" \
+    -H "Authorization: Bearer $TOK" \
+    -d "{\"indexes\":${NEW_INDEXES}}")
+  case "$STATUS" in
+    200|201) log "added index: $COLL.$INAME" ;;
+    *)       log "WARNING: add_index $COLL.$INAME returned $STATUS" ;;
+  esac
+}
+
 # add_field COLLECTION FIELD_NAME FIELD_TYPE
 # Fetches current schema, appends field if absent, PATCHes collection.
 # Requires python3 for safe JSON manipulation.
@@ -294,4 +327,8 @@ add_field "app_users"      "polar_subscription_id"  "text"
 add_field "user_library"   "shelf"                  "text"
 add_field "user_sessions"  "device_fingerprint"     "text"
 
+# ── 6. Indexes ────────────────────────────────────────────────────────────────
+add_index "chapters_idx" "idx_chapters_idx_slug_number" \
+  "CREATE UNIQUE INDEX idx_chapters_idx_slug_number ON chapters_idx (slug, number)"
+
 log "done"
diff --git a/ui/src/lib/paraglide/messages.js b/ui/src/lib/paraglide/messages.js
index 608d20d..83a0d9d 100644
--- a/ui/src/lib/paraglide/messages.js
+++ b/ui/src/lib/paraglide/messages.js
@@ -1,4 +1,2 @@
 /* eslint-disable */
-export * from './messages/_index.js'
-// enabling auto-import by exposing all messages as m
-export * as m from './messages/_index.js'
\ No newline at end of file
+export * from './messages/_index.js'
\ No newline at end of file
diff --git a/ui/src/routes/+layout.server.ts b/ui/src/routes/+layout.server.ts
index d08b713..62fb80e 100644
--- a/ui/src/routes/+layout.server.ts
+++ b/ui/src/routes/+layout.server.ts
@@ -28,7 +28,7 @@ export const load: LayoutServerLoad = async ({ locals, url, cookies }) => {
 				theme: row.theme ?? 'amber',
 				locale: row.locale ?? 'en',
 				fontFamily: row.font_family ?? 'system',
-				fontSize: row.font_size ?? 1.0
+				fontSize: row.font_size || 1.0
 			};
 		}
 	} catch (e) {
diff --git a/ui/src/routes/+layout.svelte b/ui/src/routes/+layout.svelte
index 969bb12..73af50e 100644
--- a/ui/src/routes/+layout.svelte
+++ b/ui/src/routes/+layout.svelte
@@ -100,7 +100,7 @@
 			// Always sync theme + font (profile page calls invalidateAll after saving)
 			currentTheme = data.settings.theme ?? 'amber';
 			currentFontFamily = data.settings.fontFamily ?? 'system';
-			currentFontSize = data.settings.fontSize ?? 1.0;
+			currentFontSize = data.settings.fontSize || 1.0;
 			// Mark dirty only after the synchronous apply is done so the save
 			// effect doesn't fire for this initial load.
 			setTimeout(() => { settingsDirty = true; }, 0);
diff --git a/ui/src/routes/api/settings/+server.ts b/ui/src/routes/api/settings/+server.ts
index 552c15a..d449a16 100644
--- a/ui/src/routes/api/settings/+server.ts
+++ b/ui/src/routes/api/settings/+server.ts
@@ -18,7 +18,7 @@ export const GET: RequestHandler = async ({ locals }) => {
 			theme: settings?.theme ?? 'amber',
 			locale: settings?.locale ?? 'en',
 			fontFamily: settings?.font_family ?? 'system',
-			fontSize: settings?.font_size ?? 1.0
+			fontSize: settings?.font_size || 1.0
 		});
 	} catch (e) {
 		log.error('settings', 'GET failed', { err: String(e) });
@@ -61,9 +61,9 @@ export const PUT: RequestHandler = async ({ request, locals }) => {
 		error(400, `Invalid fontFamily — must be one of: ${validFontFamilies.join(', ')}`);
 	}
 
-	// fontSize is optional — if provided (and non-zero) it must be one of the valid steps
+	// fontSize is optional — if provided it must be one of the valid steps (0 is not valid)
 	const validFontSizes = [0.9, 1.0, 1.15, 1.3];
-	if (body.fontSize !== undefined && body.fontSize !== 0 && !validFontSizes.includes(body.fontSize)) {
+	if (body.fontSize !== undefined && !validFontSizes.includes(body.fontSize)) {
 		error(400, `Invalid fontSize — must be one of: ${validFontSizes.join(', ')}`);
 	}