diff --git a/scripts/precommit-server-unit.cjs b/scripts/precommit-server-unit.cjs
index 86fdb23202..5424af05c1 100644
--- a/scripts/precommit-server-unit.cjs
+++ b/scripts/precommit-server-unit.cjs
@@ -104,7 +104,7 @@ function main() {
   }
 
   console.log(`Running ${plan.files.length} changed server unit test file(s).`);
-  return run('npm', ['exec', '--', 'vitest', 'run', ...plan.files]);
+  return run('npm', ['exec', '--', 'vitest', 'run', '--config', 'server/vitest.config.ts', ...plan.files]);
 }
 
 if (require.main === module) {
diff --git a/server/vitest.config.ts b/server/vitest.config.ts
index 43b10a4cb9..1403b12ae3 100644
--- a/server/vitest.config.ts
+++ b/server/vitest.config.ts
@@ -7,11 +7,9 @@ export default defineConfig({
     root: __dirname,
     setupFiles: ['./tests/setup/revenue-tracking-env.ts'],
     testTimeout: 30000,
-    // The module-level `pool` singleton in db/index.ts is shared across all
-    // tests in a worker. Running files in parallel lets one file's
-    // `afterAll(closeDatabase)` null the pool while a sibling file is
-    // mid-query, producing "Database not initialized" 500s that look like
-    // transient Anthropic flakes.
+    // Keep process isolation explicit so module-level singletons (database
+    // pool, WorkOS client, env-cached secrets) cannot bleed between files.
+    pool: 'forks',
     fileParallelism: false,
   },
 });