Move to a single prisma client connection for the ui backend to prevent competing connections.

ui/src/server/prisma.ts

@@ -0,0 +1,16 @@
+import { PrismaClient } from '@prisma/client';
+
+// Single shared PrismaClient for the whole server. Route files must import
+// this instead of constructing their own client — each PrismaClient spawns
+// its own query engine + connection pool, and a pile of them contending for
+// the same sqlite file just adds lock pressure. The globalThis stash keeps
+// dev hot-reload from leaking a new client on every recompile.
+const globalForPrisma = globalThis as unknown as { prisma?: PrismaClient };
+
+const prisma = globalForPrisma.prisma ?? new PrismaClient();
+
+if (process.env.NODE_ENV !== 'production') {
+  globalForPrisma.prisma = prisma;
+}
+
+export default prisma;

ui/src/server/settings.ts

@@ -1,10 +1,9 @@
-import { PrismaClient } from '@prisma/client';
+import prisma from '@/server/prisma';
 import { defaultDatasetsFolder, defaultDataRoot } from '@/paths';
 import { defaultTrainFolder } from '@/paths';
 import NodeCache from 'node-cache';
 
 const myCache = new NodeCache();
-const prisma = new PrismaClient();
 
 export const flushCache = () => {
   myCache.flushAll();