fix(@next/env): include dir in loadEnvConfig cache key

[Shailesh93602]

What?

Include dir as part of the loadEnvConfig cache key in @next/env.

Why?

loadEnvConfig caches its result in module-level state, but the cache check only tested whether any load had happened — it never compared the dir argument:

// Before (broken)
if (combinedEnv && !forceReload) {
  return { combinedEnv, parsedEnv, loadedEnvFiles: cachedLoadedEnvFiles }
}

In a monorepo where .env lives at the workspace root, Next.js internally calls loadEnvConfig with the app directory first (no .env there, so loadedEnvFiles: []). When user code then calls it with the monorepo root — a common pattern to load shared env vars — it silently hits the stale cache and returns empty results. DATABASE_URL (and all other vars) are undefined with no error and no warning.

The only workaround was the undocumented forceReload: true 4th argument, which also requires passing undefined twice to reach it.

Reproduction: https://github.com/aynaitlamine/loadenvconfig-nextjs-issue-reproduction

How?

Added a module-level cachedDir variable. The cache is now only returned when cachedDir === dir, and cachedDir is updated whenever a fresh load runs. The forceReload path is unchanged.

// After (fixed)
if (combinedEnv && !forceReload && cachedDir === dir) {
  return { combinedEnv, parsedEnv, loadedEnvFiles: cachedLoadedEnvFiles }
}

• Related issues linked using fixes #92040
• Tests added: test/unit/load-env-config-dir-cache.test.ts

fixes #92040

[nextjs-bot]

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