diff --git a/packages/polydev/src/middleware/router/createRouterFromFiles.js b/packages/polydev/src/middleware/router/createRouterFromFiles.js
index 887c799..f7ae2bd 100644
--- a/packages/polydev/src/middleware/router/createRouterFromFiles.js
+++ b/packages/polydev/src/middleware/router/createRouterFromFiles.js
@@ -42,9 +42,9 @@ module.exports = function createRouterFromFiles(routesPath, files) {
       case "*":
         handle(router, file, [
           ["GET", route],
-          ["GET", `${route}/*`],
+          ["GET", path.join(route, "*")],
           ["POST", route],
-          ["POST", `${route}/*`]
+          ["POST", path.join(route, "*")]
         ])
         break
 
diff --git a/packages/polydev/src/middleware/router/launcher.js b/packages/polydev/src/middleware/router/launcher.js
index 74aec34..ad386c9 100644
--- a/packages/polydev/src/middleware/router/launcher.js
+++ b/packages/polydev/src/middleware/router/launcher.js
@@ -9,7 +9,9 @@ require("hot-module-replacement")({
   ignore: /node_modules/ // regexp to decide if module should be ignored; also can be a function accepting string and returning true/false
 })
 
+const { spawn } = require("child_process")
 const express = require("express")
+const path = require("path")
 
 const bridge = require("./bridge")
 
@@ -79,12 +81,21 @@ async function startHandler() {
     app.listen(PORT, async () => {
       console.log(`↩︎  ${handlerPath.replace(process.cwd(), ".")} from ${url}`)
     })
+  } else if (typeof handler === "string") {
+    // Expected to have path to `package.json`
+    const pkg = require(handler)
+    const cwd = path.dirname(handler)
+
+    spawn("yarn", [pkg.scripts.dev ? "dev" : "start"], {
+      cwd,
+      stdio: "inherit"
+    })
   } else {
     console.warn(
       `${handlerPath.replace(
         process.cwd(),
         "."
-      )} does not return a Function, Server, or path to package.json`
+      )} does not return a Function, Server, or path to a package.json`
     )
     // In development, at least listen on PORT so that we can 404
     express().listen(PORT)