diff --git a/test/e2e/mechanical.test.ts b/test/e2e/mechanical.test.ts
index 3b21e1e92..edd3477d7 100644
--- a/test/e2e/mechanical.test.ts
+++ b/test/e2e/mechanical.test.ts
@@ -24,6 +24,29 @@ import { importFromContent } from '../../src/core/import-file.ts';
 const skip = !hasDatabase();
 const describeE2E = skip ? describe.skip : describe;
 
+// HOME isolation. Several tests in this file shell out to `gbrain init` and
+// `gbrain import` via Bun.spawnSync. `gbrain init` calls saveConfig() which
+// writes to $HOME/.gbrain/config.json, and `gbrain import` writes a sync
+// bookmark to the same directory. Without isolating $HOME, these tests
+// clobber the user's real production gbrain config every time `bun run
+// test:e2e` is executed. Sibling test/e2e/migration-flow.test.ts solved
+// this with a module-level temp HOME; mirror that pattern here so the
+// E2E suite stops mutating user state.
+let _origHome: string | undefined;
+let _tmpHome: string | undefined;
+if (!skip) {
+  _origHome = process.env.HOME;
+  _tmpHome = mkdtempSync(join(tmpdir(), 'gbrain-e2e-mechanical-home-'));
+  process.env.HOME = _tmpHome;
+}
+
+afterAll(() => {
+  if (skip) return;
+  if (_origHome === undefined) delete process.env.HOME;
+  else process.env.HOME = _origHome;
+  try { if (_tmpHome) rmSync(_tmpHome, { recursive: true, force: true }); } catch { /* best-effort */ }
+});
+
 function makeCtx(opts: { remote?: boolean } = {}): OperationContext {
   return {
     engine: getEngine(),