fix: resolve env files from project root in monorepo Vitest workspaces (#542)

* Initial plan

* fix: resolve env files from project root in monorepo vitest workspaces

When running Vitest from a monorepo root using the `projects` config,
varlock now correctly uses each child project's root directory (from
Vite's config.root) to find .env.schema and .env files, instead of
only looking in process.cwd() (the monorepo root).

Changes:
- execSyncVarlock: forward `cwd` option to execSync calls and fallback
  walk-up
- vite integration: reloadConfig accepts optional `cwd` parameter
- vite plugin config hook: detect project root from config.root and
  reload with correct cwd when it differs from process.cwd()

Agent-Logs-Url: https://github.com/dmno-dev/varlock/sessions/f2ed5ca5-a4f7-4db0-9f9e-10c8807a76cc

Co-authored-by: theoephraim <1158956+theoephraim@users.noreply.github.com>

* fix: address review feedback - remove unnecessary toString, use path.relative for comparison

Agent-Logs-Url: https://github.com/dmno-dev/varlock/sessions/f2ed5ca5-a4f7-4db0-9f9e-10c8807a76cc

Co-authored-by: theoephraim <1158956+theoephraim@users.noreply.github.com>

* fix: always reload with project root when it differs from cwd

When config.root differs from process.cwd(), always reload varlock
from the project root — even if the initial module-level load
succeeded. This handles monorepo setups where the root also has env
files, which would cause the initial load to succeed with the wrong
project's config.

Agent-Logs-Url: https://github.com/dmno-dev/varlock/sessions/eb9ac880-b592-41ee-9d3d-4b1859e8d3cf

Co-authored-by: theoephraim <1158956+theoephraim@users.noreply.github.com>

---------

Co-authored-by: copilot-swe-agent[bot] <198982749+Copilot@users.noreply.github.com>
Co-authored-by: theoephraim <1158956+theoephraim@users.noreply.github.com>

Author: Copilot

.changeset/fix-monorepo-vitest.md

@@ -0,0 +1,6 @@
+---
+"varlock": patch
+"@varlock/vite-integration": patch
+---
+
+Fix Vitest workspace projects in monorepos: when running Vitest from the monorepo root using the `projects` config, varlock now correctly resolves `.env.schema` and `.env` files from each child package's directory instead of only looking in the monorepo root.

packages/integrations/vite/src/index.ts

@@ -54,11 +54,12 @@ function resetStaticReplacements() {
 
 
 let loadCount = 0;
-function reloadConfig() {
-  debug('loading config - count =', ++loadCount);
+function reloadConfig(cwd?: string) {
+  debug('loading config - count =', ++loadCount, cwd ? `(cwd: ${cwd})` : '');
   try {
     const execResult = execSyncVarlock('load --format json-full --compact', {
       env: originalProcessEnv,
+      ...(cwd && { cwd }),
     });
     process.env.__VARLOCK_ENV = execResult;
     varlockLoadedEnv = JSON.parse(process.env.__VARLOCK_ENV) as SerializedEnvGraph;
@@ -140,11 +141,28 @@ See https://varlock.dev/integrations/vite/ for more details.
 
       isDevCommand = env.command === 'serve';
 
-      // this gets re-triggered after .env file updates
-      // TODO: be smarter about only reloading if the env files changed?
-      if (isFirstLoad) {
+      // Determine the project root for the current Vite/Vitest project.
+      // In monorepo setups with Vitest workspace projects, config.root
+      // points to the child package directory rather than the monorepo root
+      // where process.cwd() points. We need to reload varlock from the
+      // correct directory so it can find .env.schema and .env files.
+      const projectRoot = config.root ? path.resolve(config.root) : undefined;
+      const rootDiffersFromCwd = !!(projectRoot && path.relative(projectRoot, process.cwd()) !== '');
+
+      if (rootDiffersFromCwd) {
+        // Always reload with the correct project root when it differs from
+        // cwd. This handles monorepo Vitest workspace setups where each child
+        // project has its own env files — even if the monorepo root also has
+        // env files (which would cause the initial module-level load to
+        // succeed with the wrong project's config).
+        reloadConfig(projectRoot);
+      } else if (isFirstLoad) {
         isFirstLoad = false;
+        // Roots match — the module-level reloadConfig() already loaded from
+        // the correct directory, no need to reload.
       } else if (isDevCommand) {
+        // Dev mode re-trigger (e.g., after .env file updates)
+        // TODO: be smarter about only reloading if the env files changed?
         reloadConfig();
       }
 

packages/varlock/src/lib/exec-sync-varlock.ts

@@ -62,6 +62,7 @@ export function execSyncVarlock(
     try {
       const result = execSync(`varlock ${command}`, {
         ...opts?.env && { env: opts.env },
+        ...opts?.cwd && { cwd: opts.cwd },
         stdio: 'pipe',
       });
       return result.toString();
@@ -73,11 +74,13 @@ export function execSyncVarlock(
 
     // if varlock was not found, it either means it is not installed
     // or we must find the path to node_modules/.bin ourselves.
-    // Search from callerDir first (if provided), then from process.cwd().
+    // Search from cwd (if provided), callerDir, then process.cwd().
     // This handles monorepo setups where cwd may be an unrelated workspace
     // root while varlock is only installed in a sub-package - the callerDir
     // supplied by auto-load.ts points inside that sub-package's node_modules.
+    const cwdStr = opts?.cwd ? String(opts.cwd) : undefined;
     const searchDirs = [
+      ...(cwdStr ? [cwdStr] : []),
       ...(opts?.callerDir ? [opts.callerDir] : []),
       process.cwd(),
     ];