diff --git a/src/app/api/cron/round-scheduler/route.ts b/src/app/api/cron/round-scheduler/route.ts
deleted file mode 100644
index 256f583..0000000
--- a/src/app/api/cron/round-scheduler/route.ts
+++ /dev/null
@@ -1,82 +0,0 @@
-import { NextResponse } from 'next/server'
-import type { NextRequest } from 'next/server'
-import { prisma } from '@/lib/prisma'
-import { activateRound, closeRound } from '@/server/services/round-engine'
-
-export async function GET(request: NextRequest): Promise<NextResponse> {
-  const cronSecret = request.headers.get('x-cron-secret')
-
-  if (!cronSecret || cronSecret !== process.env.CRON_SECRET) {
-    return NextResponse.json({ error: 'Unauthorized' }, { status: 401 })
-  }
-
-  try {
-    const now = new Date()
-    const results: Array<{ roundId: string; action: string; success: boolean; errors?: string[] }> = []
-
-    // Find a SUPER_ADMIN to use as the actor for audit logging
-    const systemActor = await prisma.user.findFirst({
-      where: { role: 'SUPER_ADMIN' },
-      select: { id: true },
-    })
-
-    if (!systemActor) {
-      return NextResponse.json({
-        ok: false,
-        error: 'No SUPER_ADMIN user found for system actions',
-      }, { status: 500 })
-    }
-
-    // 1. Activate DRAFT rounds whose windowOpenAt has arrived
-    const roundsToOpen = await prisma.round.findMany({
-      where: {
-        status: 'ROUND_DRAFT',
-        windowOpenAt: { lte: now },
-        competition: { status: { not: 'ARCHIVED' } },
-      },
-      select: { id: true, name: true },
-    })
-
-    for (const round of roundsToOpen) {
-      const result = await activateRound(round.id, systemActor.id, prisma)
-      results.push({
-        roundId: round.id,
-        action: `activate: ${round.name}`,
-        success: result.success,
-        errors: result.errors,
-      })
-    }
-
-    // 2. Close ACTIVE rounds whose windowCloseAt has passed
-    const roundsToClose = await prisma.round.findMany({
-      where: {
-        status: 'ROUND_ACTIVE',
-        windowCloseAt: { lte: now },
-      },
-      select: { id: true, name: true },
-    })
-
-    for (const round of roundsToClose) {
-      const result = await closeRound(round.id, systemActor.id, prisma)
-      results.push({
-        roundId: round.id,
-        action: `close: ${round.name}`,
-        success: result.success,
-        errors: result.errors,
-      })
-    }
-
-    return NextResponse.json({
-      ok: true,
-      processed: results.length,
-      results,
-      timestamp: now.toISOString(),
-    })
-  } catch (error) {
-    console.error('Cron round-scheduler failed:', error)
-    return NextResponse.json(
-      { error: 'Internal server error' },
-      { status: 500 }
-    )
-  }
-}
diff --git a/src/instrumentation.ts b/src/instrumentation.ts
index 50ee69d..5aa4bd1 100644
--- a/src/instrumentation.ts
+++ b/src/instrumentation.ts
@@ -25,5 +25,19 @@ export async function register() {
           })
       })
       .catch(() => {})
+
+    // Round scheduler: check every 60s for rounds that need to open/close
+    import('./server/services/round-scheduler')
+      .then(({ processScheduledRounds }) => {
+        console.log('[Startup] Round scheduler started (60s interval)')
+        // Run once immediately, then every 60 seconds
+        processScheduledRounds().catch(() => {})
+        setInterval(() => {
+          processScheduledRounds().catch((err) => {
+            console.error('[RoundScheduler] Error:', err)
+          })
+        }, 60_000)
+      })
+      .catch(() => {})
   }
 }
diff --git a/src/server/services/round-scheduler.ts b/src/server/services/round-scheduler.ts
new file mode 100644
index 0000000..de94754
--- /dev/null
+++ b/src/server/services/round-scheduler.ts
@@ -0,0 +1,67 @@
+import { prisma } from '@/lib/prisma'
+import { activateRound, closeRound } from './round-engine'
+
+/**
+ * Check for rounds that need to be automatically opened or closed
+ * based on their windowOpenAt / windowCloseAt timestamps.
+ * Called on a 60-second interval from instrumentation.ts.
+ */
+export async function processScheduledRounds(): Promise<{
+  activated: number
+  closed: number
+}> {
+  const now = new Date()
+  let activated = 0
+  let closed = 0
+
+  // Find a SUPER_ADMIN to use as the actor for audit logging
+  const systemActor = await prisma.user.findFirst({
+    where: { role: 'SUPER_ADMIN' },
+    select: { id: true },
+  })
+
+  if (!systemActor) {
+    return { activated, closed }
+  }
+
+  // 1. Activate DRAFT rounds whose windowOpenAt has arrived
+  const roundsToOpen = await prisma.round.findMany({
+    where: {
+      status: 'ROUND_DRAFT',
+      windowOpenAt: { lte: now },
+      competition: { status: { not: 'ARCHIVED' } },
+    },
+    select: { id: true, name: true },
+  })
+
+  for (const round of roundsToOpen) {
+    const result = await activateRound(round.id, systemActor.id, prisma)
+    if (result.success) {
+      activated++
+      console.log(`[RoundScheduler] Activated round: ${round.name}`)
+    } else {
+      console.warn(`[RoundScheduler] Failed to activate "${round.name}":`, result.errors)
+    }
+  }
+
+  // 2. Close ACTIVE rounds whose windowCloseAt has passed
+  const roundsToClose = await prisma.round.findMany({
+    where: {
+      status: 'ROUND_ACTIVE',
+      windowCloseAt: { lte: now },
+    },
+    select: { id: true, name: true },
+  })
+
+  for (const round of roundsToClose) {
+    const result = await closeRound(round.id, systemActor.id, prisma)
+    if (result.success) {
+      closed++
+      console.log(`[RoundScheduler] Closed round: ${round.name}`)
+    } else {
+      console.warn(`[RoundScheduler] Failed to close "${round.name}":`, result.errors)
+    }
+  }
+
+  return { activated, closed }
+}