diff --git a/app/api/playground/copy-repo/route.ts b/app/api/playground/copy-repo/route.ts
index 5a55a0b17..6eadcfa9a 100644
--- a/app/api/playground/copy-repo/route.ts
+++ b/app/api/playground/copy-repo/route.ts
@@ -1,6 +1,9 @@
 import { NextRequest, NextResponse } from "next/server"
 
-import { copyRepoToExistingContainer } from "@/lib/utils/container"
+import {
+  copyRepoToExistingContainer,
+  startDevServerInContainer,
+} from "@/lib/utils/container"
 import { setupLocalRepository } from "@/lib/utils/utils-server"
 
 export async function POST(req: NextRequest) {
@@ -39,6 +42,17 @@ export async function POST(req: NextRequest) {
       )
     }
 
+    // Start a dev server in the background inside the container
+    try {
+      await startDevServerInContainer({ containerName, mountPath })
+    } catch (err) {
+      // Do not fail the whole request if dev server fails to start; surface as warning
+      return NextResponse.json(
+        { error: `Copied repo but failed to start dev server: ${err}` },
+        { status: 202 }
+      )
+    }
+
     return NextResponse.json({ success: true })
   } catch (err) {
     return NextResponse.json(
diff --git a/lib/utils/container.ts b/lib/utils/container.ts
index a6714cbad..9878619e7 100644
--- a/lib/utils/container.ts
+++ b/lib/utils/container.ts
@@ -366,3 +366,42 @@ export async function copyRepoToExistingContainer({
     throw new Error(`Failed to copy repository to container: ${e}`)
   }
 }
+
+/**
+ * Start a dev server inside an existing container for the app in `mountPath`.
+ * This determines the appropriate package manager based on lockfiles and then
+ * runs install and dev in the background using nohup so this call can return
+ * immediately. Logs are written to .dev.log and PID to .dev.pid under mountPath.
+ */
+export async function startDevServerInContainer({
+  containerName,
+  mountPath = "/workspace",
+}: {
+  containerName: string
+  mountPath?: string
+}): Promise<{ stdout: string; stderr: string; exitCode: number }> {
+  // Build a shell script that:
+  // - chooses package manager (pnpm > yarn > npm)
+  // - runs install (preferring frozen/ci if lockfile present)
+  // - starts dev server
+  // - backgrounds the process with nohup and stores logs/pid
+  const script = [
+    "set -e",
+    `cd ${mountPath}`,
+    // Pick package manager
+    "if [ -f pnpm-lock.yaml ]; then PM=pnpm; elif [ -f yarn.lock ]; then PM=yarn; else PM=npm; fi",
+    // Construct install command
+    'if [ "$PM" = "pnpm" ]; then INSTALL="pnpm install --frozen-lockfile || pnpm install"; ' +
+      'elif [ "$PM" = "yarn" ]; then INSTALL="yarn install --frozen-lockfile || yarn install"; ' +
+      'else INSTALL="if [ -f package-lock.json ]; then npm ci || npm i; else npm i; fi"; fi',
+    // Start dev in background after install completes
+    'nohup sh -c "$INSTALL && "$PM" run -s dev" > .dev.log 2>&1 & echo $! > .dev.pid',
+    'echo "Dev server starting with $PM. Logs: .dev.log, PID: $(cat .dev.pid)"',
+  ].join(" && ")
+
+  return await execInContainerWithDockerode({
+    name: containerName,
+    command: script,
+    cwd: mountPath,
+  })
+}
diff --git a/shared/src/lib/utils/container.ts b/shared/src/lib/utils/container.ts
index 9a072358a..e45998791 100644
--- a/shared/src/lib/utils/container.ts
+++ b/shared/src/lib/utils/container.ts
@@ -362,3 +362,42 @@ export async function copyRepoToExistingContainer({
     await chownExec.start({})
   }
 }
+
+/**
+ * Start a dev server inside an existing container for the app in `mountPath`.
+ * This determines the appropriate package manager based on lockfiles and then
+ * runs install and dev in the background using nohup so this call can return
+ * immediately. Logs are written to .dev.log and PID to .dev.pid under mountPath.
+ */
+export async function startDevServerInContainer({
+  containerName,
+  mountPath = "/workspace",
+}: {
+  containerName: string
+  mountPath?: string
+}): Promise<{ stdout: string; stderr: string; exitCode: number }> {
+  // Build a shell script that:
+  // - chooses package manager (pnpm > yarn > npm)
+  // - runs install (preferring frozen/ci if lockfile present)
+  // - starts dev server
+  // - backgrounds the process with nohup and stores logs/pid
+  const script = [
+    "set -e",
+    `cd ${mountPath}`,
+    // Pick package manager
+    "if [ -f pnpm-lock.yaml ]; then PM=pnpm; elif [ -f yarn.lock ]; then PM=yarn; else PM=npm; fi",
+    // Construct install command
+    'if [ "$PM" = "pnpm" ]; then INSTALL="pnpm install --frozen-lockfile || pnpm install"; ' +
+      'elif [ "$PM" = "yarn" ]; then INSTALL="yarn install --frozen-lockfile || yarn install"; ' +
+      'else INSTALL="if [ -f package-lock.json ]; then npm ci || npm i; else npm i; fi"; fi',
+    // Start dev in background after install completes
+    'nohup sh -c "$INSTALL && "$PM" run -s dev" > .dev.log 2>&1 & echo $! > .dev.pid',
+    'echo "Dev server starting with $PM. Logs: .dev.log, PID: $(cat .dev.pid)"',
+  ].join(" && ")
+
+  return await execInContainerWithDockerode({
+    name: containerName,
+    command: script,
+    cwd: mountPath,
+  })
+}