need that cache for HMR

src/utils.tsx

@@ -1,4 +1,5 @@
 import { type Context } from 'hono'
+import { stat } from 'fs/promises'
 
 // template literal tag for inline CSS. returns a <style> tag
 export function css(strings: TemplateStringsArray, ...values: any[]) {
@@ -142,8 +143,10 @@ const transpileCache: Record<string, string> = {}
 
 // transpile frontend ts to js
 export async function transpile(path: string): Promise<string> {
-  // cache by path; --watch restarts server on file changes, clearing the cache
-  let cached = transpileCache[path]
+  const { mtime } = await stat(path)
+  const key = `${path}?${mtime}`
+
+  let cached = process.env.NODE_ENV === 'production' ? transpileCache[key] : undefined
 
   if (!cached) {
     const result = await Bun.build({
@@ -156,7 +159,7 @@ export async function transpile(path: string): Promise<string> {
     if (!result.outputs[0]) throw new Error(`Failed to build ${path}`)
 
     cached = await result.outputs[0].text()
-    transpileCache[path] = cached
+    transpileCache[key] = cached
   }
 
   return cached