Fix memory leak in dev server

dist/utils/import-fresh.js

@@ -1,10 +1,65 @@
+import { existsSync, statSync } from "fs";
+import path from "path";
 import isDevelopment from "./is-development";
 /**
- * Dev: bypass Bun's module registry so rebuilt files are picked up.
- * Prod: import by stable path so each module is loaded (and kept) once.
- * A unique `?t=` per call creates a new, never-evicted module record, so
- * using it in production leaks memory on every request.
+ * File path -> mtime of the version currently held in Bun's module
+ * registry (dev only).
  */
-export default function importFresh(file_path) {
-    return import(isDevelopment() ? `${file_path}?t=${Date.now()}` : file_path);
+const loaded_versions = new Map();
+/**
+ * Imports a module by its stable path.
+ *
+ * Dev: when the file changed since it was last imported, its registry
+ * entry is evicted first so the new version is evaluated and the old one
+ * can be garbage collected. A cache-busting `?t=` query would instead
+ * create a new, never-evicted module record on every call.
+ *
+ * Prod: plain import, so each module is loaded (and kept) once.
+ */
+export default async function importFresh(file_path) {
+    if (!isDevelopment()) {
+        return import(file_path);
+    }
+    let mtime;
+    try {
+        mtime = statSync(file_path).mtimeMs;
+    }
+    catch { }
+    if (loaded_versions.has(file_path) &&
+        loaded_versions.get(file_path) !== mtime) {
+        evictModule(file_path);
+    }
+    try {
+        const mod = await import(file_path);
+        loaded_versions.set(file_path, mtime);
+        return mod;
+    }
+    catch (error) {
+        // Don't keep a failed evaluation around: the next request retries.
+        evictModule(file_path);
+        throw error;
+    }
+}
+/**
+ * Drops a module from Bun's registry so its memory can be reclaimed and the
+ * next import re-evaluates it. Only the module itself is evicted, not the
+ * modules it imports.
+ */
+export function evictModule(file_path) {
+    delete require.cache[file_path];
+    loaded_versions.delete(file_path);
+}
+/**
+ * Evicts every registry entry under `dir` whose file no longer exists. Bundle
+ * outputs (entries and shared chunks) are content-hashed and esbuild deletes
+ * the superseded ones on rebuild, so a missing file means no current module
+ * imports it anymore.
+ */
+export function evictDeletedModules(dir) {
+    const prefix = dir.endsWith(path.sep) ? dir : dir + path.sep;
+    for (const key of Object.keys(require.cache)) {
+        if (key.startsWith(prefix) && !existsSync(key)) {
+            evictModule(key);
+        }
+    }
 }